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BACKGROUND: We prospectively assessed the reproducibility of a novel low-dose single-volume dynamic computed tomography (CT) myocardial blood flow measurement technique. METHODS: Thirty-four pairs of measurements were made under rest and stress conditions in 13 swine (54.3 ± 12.3 kg). One or two acquisition pairs were acquired in each animal with a 10-min delay between each pair. Contrast (370 mgI/mL; 0.5 mL/kg) and a diluted contrast/saline chaser (0.5 mL/kg; 30:70 contrast/saline) were injected peripherally at 5 mL/s, followed by bolus tracking and acquisition of a single volume scan (100 kVp; 200 mA) with a 320-slice CT scanner. Bolus tracking and single volume scan data were used to derive perfusion in mL/min/g using a first-pass analysis model; the coronary perfusion territories of the left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA) were automatically assigned using a previously validated minimum-cost path technique. The reproducibility of CT myocardial perfusion measurement within the LAD, LCx, RCA, and the whole myocardium was assessed via regression analysis. The average CT dose index (CTDI) of perfusion measurement was recorded. RESULTS: The repeated first (Pmyo1) and second (Pmyo2) single-volume CT perfusion measurements were related by Pmyo2 = 1.01Pmyo1 - 0.03(ρ = 0.96; RMSE = 0.08 mL/min/g; RMSE = 0.07 mL/min/g) for the whole myocardium, and by Preg2 = 0.86Preg1 + 0.13(ρ = 0.87; RMSE = 0.31 mL/min/g; RMSE = 0.29 mL/min/g) for the LAD, LCx, and RCA perfusion territories. The average CTDI of the single-volume CT perfusion measurement was 10.5 mGy. CONCLUSION: The single-volume CT blood flow measurement technique provides reproducible low-dose myocardial perfusion measurement using only bolus tracking data and a single whole-heart volume scan. RELEVANCE STATEMENT: The single-volume CT blood flow measurement technique is a noninvasive tool that reproducibly measures myocardial perfusion and provides coronary CT angiograms, allowing for simultaneous anatomic-physiologic assessment of myocardial ischemia. KEY POINTS: A low-dose single-volume dynamic CT myocardial blood flow measurement technique is reproducible. Motion misregistration artifacts are eliminated using a single-volume CT perfusion technique. This technique enables combined anatomic-physiologic assessment of coronary artery disease.

PURPOSE: Long axial field-of-view (LAFOV) positron emission tomography (PET) systems allow to image all major organs with one bed position, which is particularly useful for acquiring whole-body dynamic data using short-lived radioisotopes like 82Rb. METHODS: We determined the absorbed dose in target organs of three subjects (29, 40, and 57 years old) using two different methods, i.e., MIRD and voxel dosimetry. The subjects were injected with 407.0 to 419.61 MBq of [82Rb]Cl and were scanned dynamically for 7 min with a LAFOV PET/CT scanner. RESULTS: Using the MIRD formalism and voxel dosimetry, the absorbed dose ranged from 1.84 to 2.78 μGy/MBq (1.57 to 3.92 μGy/MBq for voxel dosimetry) for the heart wall, 2.76 to 5.73 μGy/MBq (3.22 to 5.37 μGy/MBq for voxel dosimetry) for the kidneys, and 0.94 to 1.88 μGy/MBq (0.98 to 1.92 μGy/MBq for voxel dosimetry) for the lungs. The total body effective dose lied between 0.50 and 0.76 μSv/MBq. CONCLUSION: Our study suggests that the radiation dose associated with [82Rb]Cl PET/CT can be assessed by means of dynamic LAFOV PET and that it is lower compared to literature values.

Background: Myocardial perfusion SPECT (MPS) and exercise electrocardiography (Ex‐ECG) results are of prognostic importance for short‐term follow up duration. However, the value of MPS or Ex‐ECG findings for long‐term risk assessment is less evident as underlying risk factors for ischemic heart disease (IHD) gain in importance. Objectives: To assess the short‐ and long‐term prognostic value of MPS and Ex‐ECG in relation to known risk factors. Methods and Materials: An observational study of 908 patients (age 63 years, 49% male, 45% prior IHD) referred for MPS and Ex‐ECG. Follow‐up was divided into two periods (short‐term: <5 years and long‐term: >5 years). Cardiac events were defined as a composite of acute myocardial infarction, unstable angina, unplanned revascularization and cardiovascular death. Results: The composite endpoint occurred in 95 patients (short‐term follow up) and in 94 patients (long‐term follow up). In multivariable models stress testing had a strong predictive value for short‐term follow up (HR for MPS = 2.9, CI = 1.9–4.5, p < 0.001 and HR for Ex‐ECG = 2.1, CI 1.3–3.3, p = 0.002), but no predictive value for long‐term follow up (HR for MPS = 0.9, CI = 0.5–1.5, p = 0.70 and HR for Ex‐ECG = 1.0, CI = 0.6–1.6, p = 0.92). Male sex and prior IHD were significant predictors regardless of follow up duration. Age, diabetes and decreased exercise capacity were risk factors for long‐term follow up. Conclusions: The prognostic value of MPS and Ex‐ECG results are strong for short‐term follow up but diminish over time and do not contribute significantly in multivariable models after 5 years. Long‐term prognosis is primarily governed by underlying risk factors and exercise capacity. [ABSTRACT FROM AUTHOR]

Background Purpose Materials and methods Results Conclusion Coronary artery disease (CAD) has one of the highest mortality rates in humans worldwide. Single‐photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) provides clinicians with myocardial metabolic information non‐invasively. However, there are some limitations to interpreting SPECT images performed by physicians or automatic quantitative approaches. Radiomics analyzes images objectively by extracting quantitative features and can potentially reveal biological characteristics that the human eye cannot detect. However, the reproducibility and repeatability of some radiomic features can be highly susceptible to segmentation and imaging conditions.We aimed to assess the reproducibility of radiomic features extracted from uncorrected MPI‐SPECT images reconstructed with 15 different settings before and after ComBat harmonization, along with evaluating the effectiveness of ComBat in realigning feature distributions.A total of 200 patients (50% normal and 50% abnormal) including rest and stress (without attenuation and scatter corrections) MPI‐SPECT images were included. Images were reconstructed using 15 combinations of filter cut‐off frequencies, filter orders, filter types, reconstruction algorithms, number of iterations and subsets resulting in 6000 images. Image segmentation was performed on the left ventricle in the first reconstruction for each patient and applied to 14 others. A total of 93 radiomic features were extracted from the segmented area, and ComBat was used to harmonize them. The intraclass correlation coefficient (ICC) and overall concordance correlation coefficient (OCCC) tests were performed before and after ComBat to examine the impact of each parameter on feature robustness and to assess harmonization efficiency. The ANOVA and the Kruskal–Wallis tests were performed to evaluate the effectiveness of ComBat in correcting feature distributions. In addition, the Student's t‐test, Wilcoxon rank‐sum, and signed‐rank tests were implemented to assess the significance level of the impacts made by each parameter of different batches and patient groups (normal vs. abnormal) on radiomic features.Before applying ComBat, the majority of features (ICC: 82, OCCC: 61) achieved high reproducibility (ICC/OCCC ≥ 0.900) under every batch except Reconstruction. The largest and smallest number of poor features (ICC/OCCC < 0.500) were obtained by IterationSubset and Order batches, respectively. The most reliable features were from the first‐order (FO) and gray‐level co‐occurrence matrix (GLCM) families. Following harmonization, the minimum number of robust features increased (ICC: 84, OCCC: 78). Applying ComBat showed that Order and Reconstruction were the least and the most responsive batches, respectively. The most robust families, in a descending order, were found to be FO, neighborhood gray‐tone difference matrix (NGTDM), GLCM, gray‐level run length matrix (GLRLM), gray‐level size zone matrix (GLSZM), and gray‐level dependence matrix (GLDM) under Cut‐off, Filter, and Order batches. The Wilcoxon rank‐sum test showed that the number of robust features significantly differed under most batches in the Normal and Abnormal groups.The majority of radiomic features show high levels of robustness across different OSEM reconstruction parameters in uncorrected MPI‐SPECT. ComBat is effective in realigning feature distributions and enhancing radiomic features reproducibility. [ABSTRACT FROM AUTHOR]

Background: Coronary artery disease (CAD) is associated with a large clinical and economic burden. However, consensus on the optimal approach to CAD diagnosis is lacking. This study sought to compare downstream healthcare resource utilisation following different cardiac imaging modalities, to inform test selection for CAD diagnosis. Methods: Claims and electronic health records data from the Decision Resources Group Real-World Evidence US Data Repository were analysed for 2.5 million US patients who underwent single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI), positron emission tomography myocardial perfusion imaging (PET MPI), coronary computed tomography angiography (cCTA), or stress echocardiography between January 2016 and March 2018. Patients were stratified into nine cohorts based on suspected or existing CAD diagnosis, pre-test risk, and prior events or interventions. Downstream healthcare utilisation, including additional diagnostic imaging, coronary angiography, and cardiac-related health system encounters, was compared by cohort and index imaging modality. Results: Among patients with suspected CAD diagnosed within 3 months of the index test, PET MPI was associated with lower downstream utilisation; 25–37% of patients who underwent PET MPI required additional downstream healthcare resources compared with 40–49% of patients who received SPECT MPI, 35–41% of patients who underwent cCTA, and 44–47% of patients who received stress echocardiography. Patients who underwent PET MPI experienced fewer acute cardiac events (5.3–9.4%) and generally had lower rates of healthcare encounters (0.8–4.1%) and invasive coronary angiography (ICA, 15.4–24.2%) than those who underwent other modalities. SPECT MPI was associated with more downstream ICA (31.3–38.2%) and a higher rate of cardiac events (9.5–13.2%) compared with PET MPI (5.3–9.4%) and cCTA (6.9–9.9%). Across all cohorts, additional diagnostic imaging was 1.6 to 4.7 times more frequent with cCTA compared with PET MPI. Conclusion: Choice of imaging modality for CAD diagnosis impacts downstream healthcare utilisation. PET MPI was associated with lower utilisation across multiple metrics compared with other imaging modalities studied. [ABSTRACT FROM AUTHOR]

Purpose: The problem of image denoising in single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a fundamental challenge. Although various image processing techniques have been presented, they may degrade the contrast of denoised images. The proposed idea in this study is to use a deep neural network as the denoising procedure during the iterative reconstruction process rather than the post-reconstruction phase. This method could decrease the background coefficient of variation (COV_bkg) of the final reconstructed image, which represents the amount of random noise, while improving the contrast-to-noise ratio (CNR). Methods: In this study, a generative adversarial network is used, where its generator is trained by a two-phase approach. In the first phase, the network is trained by a confined image region around the heart in transverse view. The second phase improves the network's generalization by tuning the network weights with the full image size as the input. The network was trained and tested by a dataset of 247 patients who underwent two immediate serially high- and low-noise SPECT-MPI. Results: Quantitative results show that compared to post-reconstruction low pass filtering and post-reconstruction deep denoising methods, our proposed method can decline the COV_bkg of the images by up to 10.28% and 12.52% and enhance the CNR by up to 54.54% and 45.82%, respectively. Conclusion: The iterative deep denoising method outperforms 2D low-pass Gaussian filtering with an 8.4-mm FWHM and post-reconstruction deep denoising approaches. [ABSTRACT FROM AUTHOR]

Background: Graft occlusions are commonly present in symptomatic patients after coronary artery bypass surgery (CABG). The aim of this study was to evaluate the diagnostic accuracy of coronary computed tomography angiography (CCTA) and stress single photon emission computed tomographic (SPECT) myocardial perfusion imaging (MPI) for detecting graft disease in symptomatic post-CABG patients. Methods: This was a prospective, single centre study of 100 symptomatic post-CABG patients with native coronary artery/graft occlusions on invasive angiography (CAG). Grafts were evaluated for degree of stenosis qualitatively on CCTA. Reversible perfusion defects were graded using summed difference score (SDS) on MPI. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of CCTA and MPI were evaluated against CAG. Results: CCTA identified 17/31 (55%), 30/43 (70%) and 18/19 (95%) patients with ≥50% stenosis of arterial, venous and both grafts respectively with specificity and PPV of 100%. Reversible perfusion defects were present in 81% of the patients with a mean SDS score of 5.4 ± 3.39 and sensitivity of 84%. Accuracy of CCTA and MPI for detection of graft occlusions were 99% and 84% respectively. 63/65 (97%) patients with ≥50% stenosis of grafts had ≥ 5 SDS score (moderate to severe grade ischemia) and 64% patients were revascularized. Conclusion: CCTA has a comparable diagnostic accuracy to CAG and can be used as an initial investigation in symptomatic post-CABG patients. Reversible perfusion defects on stress MPI help to risk stratify symptomatic post-CABG patients and guide further treatment. Hemodynamically significant occlusions may benefit from revascularization. [ABSTRACT FROM AUTHOR]

Background: Systematic revascularization of asymptomatic coronary artery stenosis before transcatheter aortic valve replacement (TAVR) is controversial. Purpose: The purpose of this study was to evaluate the feasibility and safety of functional evaluation of coronary artery disease (CAD) followed by selective ischemia-guided percutaneous coronary revascularization following TAVR. Methods: This prospective, bi-centric, single-arm, open-label trial included all patients with severe aortic stenosis (AS) eligible for TAVR and with significant CAD defined as ≥1 coronary stenosis ≥ 70%. Patients with left main stenosis ≥ 50%, proximal left anterior descending artery (LAD) stenosis ≥ 90% or > class 2 Canadian Classification Society (CCS) angina were excluded. Myocardial ischemia was evaluated by stress cardiac imaging one month after TAVR. The primary endpoint was a composite of all-cause death, stroke, major bleeding (Bleeding Academic Research Consotium ≥ 3), major vascular complication (Valve Academic Research Consortium 3 criteria), acute coronary syndrome (ACS) and hospitalization for cardiac causes within 6 months of receiving TAVR. Results: Between June 2020 and June 2022, 64 patients were included in this study. The mean age was 84 ± 5.2 years. CAD mostly involved LAD (n = 27, 42%) with frequent multivessel disease (n = 30, 47%) and calcified lesions (n = 39, 61%). Stress cardiac imaging could be achieved in 70% (n = 46) of the patients, while 30% (n = 18) did not attend the stress test. Significant myocardial ischemia was observed in only three patients (4.5%). At 6-month follow-up, fifteen patients (23%) reached the primary endpoint, including death in six patients (9%), stroke in three patients (5%) and major bleeding in three patients (5%). ACS was observed in only two patients (3%) but both had severe coronary stenosis (≥90%) and did not refer for stress imaging for personal reasons. Hospital readmission (n = 27, 41%) was mostly related to non-cardiac causes (n = 17, 27%). Conclusions: In patients with asymptomatic CAD scheduled to undergo TAVR, a selective ischemia-guided coronary revascularization after TAVR seems to be safe, with a very low rate of ACS and few cases of myocardial ischemia requiring revascularization, despite low adherence to medical follow-up in this elderly population. This strategy could be evaluated in a randomized study. [ABSTRACT FROM AUTHOR]

Stable chest pain is a common symptom with multiple potential causes. Non-invasive imaging has an important role in diagnosis and guiding management through the assessment of coronary stenoses, atherosclerotic plaque, myocardial ischaemia or infarction, and cardiac function. Computed tomography (CT) provides the anatomical evaluation of coronary artery disease (CAD) with the assessment of stenosis, plaque type and plaque burden, with additional functional information available from CT fractional flow reserve (FFR) or CT myocardial perfusion imaging. Stress magnetic resonance imaging, nuclear stress myocardial perfusion imaging, and stress echocardiography can assess myocardial ischaemia and other cardiac functional parameters. Coronary CT angiography can be used as a first-line test for many patients with stable chest pain, particularly those with low to intermediate pre-test probability. Functional testing may be considered for patients with known CAD, where the clinical significance is uncertain based on anatomical testing, or in patients with high pre-test probability. This practice recommendations document can be used to guide the selection of non-invasive imaging for patients with stable chest pain and provides brief recommendations on how to perform and report these diagnostic tests. Key Points: The selection of non-invasive imaging tests for patients with stable chest pain should be based on symptoms, pre-test probability, and previous history. Coronary CT angiography can be used as a first-line test for many patients with stable chest pain, particularly those with low to intermediate pre-test probability. Functional testing can be considered for patients with known CAD, where the clinical significance of CAD is uncertain based on anatomical testing, or in patients with high pre-test probability. Key recommendations: Non-invasive imaging is an important part of the assessment of patients with stable chest pain. The selection of non-invasive imaging test should be based on symptoms, pre-test probability, and previous history. (Level of evidence: High). Coronary CT angiography can be used as a first line test for many patients with stable chest pain, particularly those with low to intermediate pre-test probability. CT provides information on stenoses, plaque type, plaque volume, and if required functional information with CT fractional flow reserve or CT perfusion. (Level of evidence: High). Functional testing can be considered for patients with known CAD, where the clinical significance of CAD is uncertain based on anatomical testing, or in patients with high pre-test probability. Stress MRI, SPECT, PET, and echocardiography can provide information on myocardial ischemia, along with cardiac functional and other information. (Level of evidence: Medium). [ABSTRACT FROM AUTHOR]

Cardiovascular imaging has rapidly advanced over the past decades. Traditional imaging techniques such as echocardiography, computed tomography, and cardiovascular magnetic resonance are essential for assessing the structural and functional aspects of the cardiovascular system but often fall short in providing direct insights into disease activity. This gap is increasingly being bridged by molecular nuclear imaging techniques, including positron emission tomography and singlephoton emission computed tomography, which enable the visualization of disease processes at the molecular and cellular levels. This review highlights the role of cardiovascular molecular imaging, emphasizing its current and potential applications in diagnosing and managing cardiovascular disease. With advancements in positron emission tomography scanners, novel radiotracers, and sophisticated imaging software, molecular imaging is set to play an essential role in precision medicine by enhancing our understanding of disease mechanisms, accelerating the development of targeted therapies, and facilitating personalized patient care. [ABSTRACT FROM AUTHOR]

Background: Magnetocardiography (MCG) is a novel non-invasive technique that detects subtle magnetic fields generated by cardiomyocyte electrical activity, offering sensitive detection of myocardial ischemia. This study aimed to assess the ability of MCG to predict impaired myocardial perfusion using single-photon emission computed tomography (SPECT). Methods: A total of 112 patients with chest pain underwent SPECT and MCG scans, from which 65 MCG output parameters were analyzed. Using least absolute shrinkage and selection operator (LASSO) regression to screen for significant MCG variables, three machine learning models were established to detect impaired myocardial perfusion: random forest (RF), decision tree (DT), and support vector machine (SVM). The diagnostic performance was evaluated based on the sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUC). Results: Five variables, the ratio of magnetic field amplitude at R-peak and positive T-peak (RoART+), R and T-peak magnetic field angle (RTA), maximum magnetic field angle (MAmax), maximum change in current angle (CCAmax), and change positive pole point area between the T-wave beginning and peak (CPPPATbp), were selected from 65 automatic output parameters. RTA emerged as the most critical variable in the RF, DT, and SVM models. All three models exhibited excellent diagnostic performance, with AUCs of 0.796, 0.780, and 0.804, respectively. While all models showed high sensitivity (RF = 0.870, DT = 0.826, SVM = 0.913), their specificity was comparatively lower (RF = 0.500, DT = 0.300, SVM = 0.100). Conclusions: Machine learning models utilizing five key MCG variables successfully predicted impaired myocardial perfusion, as confirmed by SPECT. These findings underscore the potential of MCG as a promising future screening tool for detecting impaired myocardial perfusion. [ABSTRACT FROM AUTHOR]

Aims This study aimed to assess the impact of adenosine on quantitative myocardial blood flow (MBF) in a rapid stress–rest protocol compared with a rest–stress protocol using 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI) and to gain insights into the time dependency of such effects. Methods and results Quantitative MBF at rest (rMBF) and during adenosine-induced stress (sMBF) and myocardial flow reserve (MFR) were obtained from 331 retrospectively identified patients who underwent 13N-ammonia PET MPI for suspected chronic coronary syndrome and who all exhibited no perfusion defects. Of these, 146 (44.1%) underwent a rapid stress–rest protocol with a time interval (Δ t stress–rest) of 20 ± 4 min between adenosine infusion offset and rest imaging, as per clinical routine. The remaining 185 (55.9%) patients underwent a rest–stress protocol and served as the reference. Groups did not differ regarding demographics, risk factors, medication, left ventricular function, and calcium scores. rMBF was significantly higher in the stress–rest vs. the rest–stress group [0.80 (interquartile range 0.66–1.00) vs. 0.70 (0.58–0.83) mL·min−1·g−1, P < 0.001], and, as sMBF was identical between groups [2.52 (2.20–2.96) vs. 2.50 (1.96–3.11), P = 0.347], MFR was significantly lower in the stress–rest group [3.07 (2.43–3.88) vs. 3.50 (2.63–4.10), P = 0.007]. There was a weak correlation between Δ t stress–rest and rMBF (r = −0.259, P = 0.002) and between Δ t stress–rest and MFR (r = 0.163, P = 0.049), and the proportion of patients with abnormally high rMBF was significantly decreasing with increasing Δ t stress–rest. Conclusion Intravenously applied adenosine induces a long-lasting hyperaemic effect on the myocardium. Consequently, rapid stress–rest protocols could lead to an overestimation of rMBF and an underestimation of MFR. [ABSTRACT FROM AUTHOR]

Objective: This study seeks to evaluate how recent COVID-19 infection affects myocardial perfusion and functional parameters derived from gated myocardial perfusion imaging in patients undergoing evaluation for coronary artery disease. The goal is to enhance our understanding of COVID-19's influence on the cardiovascular system. Method: Conducted at Farshchian Heart Hospital from 2022 to 2023, this case–control study enrolled patients suspected of coronary artery disease, stratified into two groups: those with confirmed COVID-19 infection within the past 6 months (study group) and those without prior COVID-19 infection (control group). Employing a 2-day protocol, stress testing and gated SPECT MPI were performed. Statistical analysis included descriptive statistics, Chi-square test, Student's t test, and Mann–Whitney U test. Result: Among the 86 patients included, 43 were in each group. Significantly higher summed stress core and summed difference score values were observed in the study group compared to the control group (p < 0.05). In addition, the study group exhibited significantly altered global left ventricular ejection fraction, end-diastolic volume, and end-systolic volume (p < 0.05). Non-perfusion findings, including transient ischemic dilation and transient right ventricular visualization, were more prevalent in the study group. Conclusion: Recent COVID-19 infection is associated with impaired myocardial perfusion and altered functional parameters as detected by MPI. These findings underscore the intricate interplay between COVID-19 and cardiovascular health, emphasizing the importance of comprehensive evaluation and management strategies to address cardiac complications in affected individuals. Further research is warranted to elucidate the underlying mechanisms and optimize patient care in the context of COVID-19-associated cardiovascular manifestations. [ABSTRACT FROM AUTHOR]

Aortic valve replacement (AVR) leads to reverse cardiac remodeling in patients with aortic stenosis (AS). The aim of this secondary pooled analysis was to assess the degree and determinants of changes in myocardial perfusion post AVR, and its link with exercise capacity, in patients with severe AS. A total of 68 patients underwent same-day echocardiography and cardiac magnetic resonance imaging with adenosine stress pre and 6–12 months post-AVR. Of these, 50 had matched perfusion data available (age 67 ± 8 years, 86% male, aortic valve peak velocity 4.38 ± 0.63 m/s, aortic valve area index 0.45 ± 0.13cm2/m2). A subgroup of 34 patients underwent a symptom-limited cardiopulmonary exercise test (CPET) to assess maximal exercise capacity (peak VO2). Baseline and post-AVR parameters were compared and linear regression was used to determine associations between baseline variables and change in myocardial perfusion and exercise capacity. Following AVR, stress myocardial blood flow (MBF) increased from 1.56 ± 0.52 mL/min/g to 1.80 ± 0.62 mL/min/g (p < 0.001), with a corresponding 15% increase in myocardial perfusion reserve (MPR) (2.04 ± 0.57 to 2.34 ± 0.68; p = 0.004). Increasing severity of AS, presence of late gadolinium enhancement, lower baseline stress MBF and MPR were associated with a greater improvement in MPR post-AVR. On multivariable analysis low baseline MPR was independently associated with increased MPR post-AVR. There was no significant change in peak VO2 post-AVR, but a significant increase in exercise duration. Change in MPR was associated with change in peak VO2 post AVR (r = 0.346, p = 0.045). Those with the most impaired stress MBF and MPR at baseline demonstrate the greatest improvements in these parameters following AVR and the magnitude of change in MPR correlated with improvement in peak VO2, the gold standard measure of aerobic exercise capacity. [ABSTRACT FROM AUTHOR]

Background and Purpose Methods Results Conclusions Ischemic strokes due to isolated posterior cerebral artery (PCA) occlusions represent 5% of all strokes but have significant impacts on patients’ quality of life, primarily due to visual deficits and thalamic involvement. Current guidelines for acute PCA occlusion management are sparse, and the prognostic value of perfusion imaging parameters remains underexplored.We conducted a retrospective analysis of 32 patients with isolated PCA occlusions treated at Johns Hopkins Medical Institutions between January 2017 and March 2023. Patients underwent pretreatment perfusion imaging, with perfusion parameters analyzed using RAPID software. The primary outcome was short‐term clinical outcome as measured by the National Institutes of Health Stroke Scale (NIHSS) at discharge.The median age of the cohort was 70 years, with 34% female and 66% male. Significant correlations were found between NIHSS at discharge and various perfusion parameters, including time‐to‐maximum (Tmax) >6 seconds (ρ = .55, p = .004), Tmax >8 seconds (ρ = .59, p = .002), Tmax >10 seconds (ρ = .6, p = .001), mismatch volume (ρ = .51, p = .008), and cerebral blood volume (CBV) < 34% (ρ = .59, p = .002).Tmax and CBV volumes significantly correlated with discharge NIHSS with marginal superiority of Tmax >10 seconds and CBV <42% volumes. These findings suggest that CT and MR perfusion imaging can play a crucial role in the acute management of PCA strokes, though larger, standardized studies are needed to validate these results and refine imaging thresholds specific to posterior circulation infarcts. [ABSTRACT FROM AUTHOR]

Aim: To present an interesting case of detection of AL myocardial amyloidosis by cardiac scintigraphy with 99mTc-DPD in a 73-year-old patient investigated for exertional dyspnea and heart failure. Method: Cardiac ultrasound revealed left ventricular hypertrophy with decreased left ventricular systolic function. The patient subsequently underwent coronary angiography with normal coronary findings. Myocardial amyloidosis was suspected and myocardial scintigraphy with 99mTc-butedronate was indicated. The administered activity of 99mTc-DPD was 700 MBq intravenously. Planar scintigraphy and chest SPECT were performed 3 hours after intravenous administration of the radiopharmaceutical. Results: Diffusely increased uptake of 99mTc- DPD in the myocardium of the left and right ventricles was observed. The intensity of tracer uptake corresponded to Perugini scale grade 3. The examination was suggestive of cardiac amyloidosis. To differentiate transthyretin and AL amyloidosis, we performed immunoelectrophoresis of serum and urinary proteins together with assessment of free immunoglobulin light chains. The analysis revealed marked elevation of free lambda chains and detected paraprotein IgG lambda 6,5 g/L, which confirmed an increased level of free immunoglobulin light chains. An endomyocardial biopsy confirmed the lambda light chaintype of myocardial amyloidosis. A biological therapy, with daratumumab in a combination with bortezomib, cyclophosphamide and dexamethasone, was initiated. Conclusion: Myocardial scintigraphy with 99mTc-DPD is a highly sensitive method for the diagnosis of transthyretin amyloid cardiomyopathy. However, it can be false positive in AL amyloidosis and monoclonal gammopathy must be evaluated in all subjects with cardiac amyloidosis by means of immunoelectrophoresis of serum and urine together with assessment of free immunoglobulin light chains. An abnormal result of these assays requires a bioptic verification of amyloid. [ABSTRACT FROM AUTHOR]

This document discusses the use of computed tomography coronary angiography (CTCA) as an imaging technique for evaluating coronary artery abnormalities (CAAs) in children with Kawasaki disease (KD). It compares CTCA to other imaging modalities such as 2D-echocardiography (2DE) and magnetic resonance coronary angiography (MRCA), highlighting the advantages of CTCA in terms of radiation exposure, detection of distal CAAs, and evaluation of temporal changes in CAAs. The document also mentions the use of calcium scoring in identifying undiagnosed CAAs. It concludes that with advancements in technology, CTCA is likely to become the preferred imaging modality for evaluating coronary arteries in children with KD. [Extracted from the article]

Cardiovascular diseases (CVDs) continue to be a major global health concern, representing a leading cause of morbidity and mortality. This review provides a comprehensive examination of CVDs, encompassing their pathophysiology, diagnostic biomarkers, advanced imaging techniques, pharmacological treatments, surgical interventions, and the emerging role of herbal remedies. The review covers various cardiovascular conditions such as coronary artery disease, atherosclerosis, peripheral artery disease, deep vein thrombosis, pulmonary embolism, cardiomyopathy, rheumatic heart disease, hypertension, ischemic heart disease, heart failure, cerebrovascular diseases, and congenital heart defects. The review presents a wide range of cardiac biomarkers such as troponins, C-reactive protein, CKMB, BNP, NT-proBNP, galectin, adiponectin, IL-6, TNF-α, miRNAs, and oxylipins. Advanced molecular imaging techniques, including chest X-ray, ECG, ultrasound, CT, SPECT, PET, and MRI, have significantly enhanced our ability to visualize myocardial perfusion, plaque characterization, and cardiac function. Various synthetic drugs including statins, ACE inhibitors, ARBs, β-blockers, calcium channel blockers, antihypertensives, anticoagulants, and antiarrhythmics are fundamental in managing CVDs. Nonetheless, their side effects such as hepatic dysfunction, renal impairment, and bleeding risks necessitate careful monitoring and personalized treatment strategies. In addition to conventional therapies, herbal remedies have garnered attention for their potential cardiovascular benefits. Plant extracts and their bioactive compounds, such as flavonoids, phenolic acids, saponins, and alkaloids, offer promising cardioprotective effects and enhanced cardiovascular health. This review underscores the value of combining traditional and modern therapeutic approaches to improve cardiovascular outcomes. This review serves as a vital resource for researchers by integrating a broad spectrum of information on CVDs, diagnostic tools, imaging techniques, pharmacological treatments and their side effects, and the potential of herbal remedies. [ABSTRACT FROM AUTHOR]

Objectives: To compare the diagnostic performance of machine learning (ML)–based computed tomography–derived fractional flow reserve (CT-FFR) and cardiac magnetic resonance (MR) perfusion mapping for functional assessment of coronary stenosis. Methods: Between October 2020 and March 2022, consecutive participants with stable coronary artery disease (CAD) were prospectively enrolled and underwent coronary CTA, cardiac MR, and invasive fractional flow reserve (FFR) within 2 weeks. Cardiac MR perfusion analysis was quantified by stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). Hemodynamically significant stenosis was defined as FFR ≤ 0.8 or > 90% stenosis on invasive coronary angiography (ICA). The diagnostic performance of CT-FFR, MBF, and MPR was compared, using invasive FFR as a reference. Results: The study protocol was completed in 110 participants (mean age, 62 years ± 8; 73 men), and hemodynamically significant stenosis was detected in 36 (33%). Among the quantitative perfusion indices, MPR had the largest area under receiver operating characteristic curve (AUC) (0.90) for identifying hemodynamically significant stenosis, which is in comparison with ML-based CT-FFR on the vessel level (AUC 0.89, p = 0.71), with comparable sensitivity (89% vs 79%, p = 0.20), specificity (87% vs 84%, p = 0.48), and accuracy (88% vs 83%, p = 0.24). However, MPR outperformed ML-based CT-FFR on the patient level (AUC 0.96 vs 0.86, p = 0.03), with improved specificity (95% vs 82%, p = 0.01) and accuracy (95% vs 81%, p < 0.01). Conclusion: ML-based CT-FFR and quantitative cardiac MR showed comparable diagnostic performance in detecting vessel-specific hemodynamically significant stenosis, whereas quantitative perfusion mapping had a favorable performance in per-patient analysis. Clinical relevance statement: ML-based CT-FFR and MPR derived from cardiac MR performed well in diagnosing vessel-specific hemodynamically significant stenosis, both of which showed no statistical discrepancy with each other. Key Points: • Both machine learning (ML)–based computed tomography–derived fractional flow reserve (CT-FFR) and quantitative perfusion cardiac MR performed well in the detection of hemodynamically significant stenosis. • Compared with stress myocardial blood flow (MBF) from quantitative perfusion cardiac MR, myocardial perfusion reserve (MPR) provided higher diagnostic performance for detecting hemodynamically significant coronary artery stenosis. • ML-based CT-FFR and MPR from quantitative cardiac MR perfusion yielded similar diagnostic performance in assessing vessel-specific hemodynamically significant stenosis, whereas MPR had a favorable performance in per-patient analysis. [ABSTRACT FROM AUTHOR]

BACKGROUND: The value of physiological ischemia versus anatomic severity of disease for prognosis and management of patients with stable coronary artery disease (CAD) is widely debated. METHODS: A total of 1764 patients who had rest-stress cadmium-zinc-telluride single-photon emission computed tomography myocardial perfusion imaging and angiography (invasive or computed tomography) were prospectively enrolled and followed for cardiac death/nonfatal myocardial infarction. The CAD prognostic index (CADPI) was used to quantify the extent and severity of angiographic disease. Prognostic value was assessed using Cox models, adjusted for pretest risk, known CAD, stressor, left ventricular ejection fraction, %ischemia and infarct, CADPI, and early (90-day) revascularization. Incremental prognostic value was evaluated using net reclassification index. RESULTS: The mean age was 69.7±9.5 years, 24.4% were women, and 29.3% had known CAD. Significant ischemia (>10%) was present in 28.4%. Nonobstructive, single, and multivessel disease was present in 256 (14.5%), 772 (43.8%), and 736 (41.7%), respectively. Early revascularization occurred in 579 (32.8%). Cardiac death/myocardial infarction occurred in 148 (8.4%) over a 4.6-year median follow-up. Both %ischemia and CADPI provided independent and incremental prognostic value over pretest clinical risk (P<0.001). In a model containing both ischemia and anatomy, ischemia was prognostic (hazard ratio per 5% ↑, 1.35 [95% CI, 1.11--1.63]; P=0.002) but CADPI was not (hazard ratio per 10-unit ↑, 1.09 [95% CI, 0.99--1.20]; P=0.07). Early revascularization modified the risk associated with %ischemia (interaction P=0.003) but not with CADPI (interaction P=0.6). %Ischemia and single-photon emission computed tomography variables added incremental prognostic value over clinical risk and CADPI (net reclassification index, 20.3% [95% CI, 9%--32%]; P<0.05); however, CADPI was not incrementally prognostic beyond pretest risk, %ischemia, and single-photon emission computed tomography variables (net reclassification index, 3.1% [95% CI, -5% to 15%]; P=0.21). CONCLUSIONS: Ischemic burden provides independent and incremental prognostic value beyond CAD anatomy and identifies patients who benefit from early revascularization. The anatomic extent of disease has independent prognostic value over clinical risk factors but offers limited incremental benefit for prognosis and guiding revascularization beyond physiological severity (ischemia). [ABSTRACT FROM AUTHOR]

This study aimed to assess the diagnostic efficacy of left ventricular synchrony (LVS) for detecting coronary artery disease (CAD). We explored whether the LVS index derived from phase analysis of D-SPECT provides superior diagnostic value compared to conventional perfusion analysis in identifying obstructive CAD. Patients with suspected or confirmed CAD underwent drug-stress/rest gated D-SPECT myocardial perfusion imaging (MPI) and coronary angiography (CAG). A 50% stenosis was set as the threshold for obstructive CAD. 110 participants were enrolled in this analysis. There were significant differences in phase standard deviation (PSD), phase histogram bandwidth (PHB) and entropy among the four groups. Patients without cardiac disease and those with mild-moderate stenosis exhibited no noticeable contraction asynchrony. However, LVS indices demonstrated a gradual increase with the progression of coronary stenosis when compared to NC (P < 0.001). Obstructive CAD was identified in 43 out of 110 participants (39%). Optimal cutoff values for diagnosing obstructive CAD during stress were determined as 7.6° for PSD, 24° for PHB, and 37% for entropy, respectively. Notably, PSD, PHB, and entropy indices exhibited higher sensitivity compared to MPI. The integration of the stress-induced LVS indices into routine MPI analysis resulted in a significantly greater area under the curve (AUC), leading to improved diagnostic performance and enhanced differential capacity. Stress-induced LVS indices increase with the severity of coronary artery stenosis by D-SPECT phase analysis. Further, the indices-derived phase analysis exhibits superior sensitivity and discriminatory ability compared to MPI in detecting obstructive CAD. [ABSTRACT FROM AUTHOR]

Purpose: To develop and evaluate a deep learning (DL) ‐based rapid image reconstruction and motion correction technique for high‐resolution Cartesian first‐pass myocardial perfusion imaging at 3T with whole‐heart coverage for both single‐slice (SS) and simultaneous multi‐slice (SMS) acquisitions. Methods: 3D physics‐driven unrolled network architectures were utilized for the reconstruction of high‐resolution Cartesian perfusion imaging. The SS and SMS multiband (MB) = 2 networks were trained from 135 slices from 20 subjects. Structural similarity index (SSIM), peak SNR (PSNR), and normalized RMS error (NRMSE) were assessed, and prospective images were blindly graded by two experienced cardiologists (5, excellent; 1, poor). For respiratory motion correction, a 2D U‐Net based motion corrected network was proposed, and the temporal fidelity and second‐order derivative were calculated to assess the performance of the motion correction. Results: Excellent performance was demonstrated in the proposed technique with high SSIM and PSNR, and low NRMSE. Image quality scores were (4.3 [4.3, 4.4], 4.5 [4.4, 4.6], 4.3 [4.3, 4.4], and 4.5 [4.3, 4.5]) for SS DL and SS L1‐SENSE, MB = 2 DL and MB = 2 SMS‐L1‐SENSE, respectively, showing no statistically significant difference (p > 0.05 for SS and SMS) between (SMS)‐L1‐SENSE and the proposed DL technique. The network inference time was around 4 s per dynamic perfusion series with 40 frames while the time of (SMS)‐L1‐SENSE with GPU acceleration was approximately 30 min. Conclusion: The proposed DL‐based image reconstruction and motion correction technique enabled rapid and high‐quality reconstruction for SS and SMS MB = 2 high‐resolution Cartesian first‐pass perfusion imaging at 3T. [ABSTRACT FROM AUTHOR]

Various techniques have been used in attempts to reduce interfering gastrointestinal activity in myocardial perfusion imaging (MPI); however, these approaches have yielded inconsistent results. The goal of this study was to investigate the efficacy of monitored walking, a previously unexplored technique, in reducing subdiaphragmatic activity–related artifacts during pharmacologic stress 99mTc-tetrofosmin MPI with SPECT to improve the overall image quality. Methods: The study included patients who underwent MPI with pharmacologic stress. They were given a step counter immediately after the radiotracer injection and were randomized into a group A, with a request to walk at least 1,000 steps before imaging, and a group B, with no specific instructions about walking. The reconstructed SPECT images were assessed visually. Moderate and severe levels of subdiaphragmatic tracer activity were considered relevant for the interpretation of the scans. Additionally, myocardial and abdominal activity was semiquantitatively assessed on raw planar images, and the mean myocardium-to-abdomen count ratios were calculated. Results: We enrolled 199 patients (95 patients in group A and 104 patients in group B). Clinical characteristics did not differ significantly between the 2 groups. Patients in group A walked more steps than patients in group B (P < 0.001), but there were no differences in the proportion of accepted scans between the 2 groups (P = 0.41). Additionally, there were no differences in the proportion of relevant subdiaphragmatic activity between the groups (P = 0.91). The number of steps did not impact the acceptance rate (P = 0.29). Conclusion: A higher number of steps walked during the waiting period between pharmacologic stress and acquisition does not affect subdiaphragmatic activity–related artifacts or the proportion of accepted scans after pharmacologic stress. However, pedometer use and clear instructions motivate patients to walk while awaiting imaging. Larger studies are required to compare a higher-step-count group with a sedentary control group to assess the influence of walking on gastrointestinal artifacts in MPI. [ABSTRACT FROM AUTHOR]

Background: First‐pass perfusion cardiac MR imaging could reflect pulmonary hemodynamics. However, the clinical value of pulmonary transit time (PTT) derived from first‐pass perfusion MRI in light‐chain (AL) amyloidosis requires further evaluation. Purpose: To assess the clinical and prognostic value of PTT in patients with AL amyloidosis. Study Type: Prospective observational study. Population: 226 biopsy‐proven systemic AL amyloidosis patients (age 58.62 ± 10.10 years, 135 males) and 43 healthy controls (age 42 ± 16.2 years, 20 males). Field Strength/Sequence: SSFP cine and phase sensitive inversion recovery late gadolinium enhancement (LGE) sequences, and multislice first‐pass myocardial perfusion imaging with a saturation recovery turbo fast low‐angle shot (SR‐TurboFLASH) pulse sequence at 3.0T. Assessment: PTT was measured as the time interval between the peaks of right and left ventricular cavity arterial input function curves on first‐pass perfusion MR images. Statistical Tests: Independent‐sample t test, Mann–Whitney U test, Chi‐square test, Fisher's exact test, analysis of variance, or Kruskal–Wallis test, as appropriate; univariable and multivariable Cox proportional hazards models and Kaplan–Meier curves, area under receiver operating characteristic curve were used to determine statistical significance. Results: PTT could differentiate AL amyloidosis patients with (N = 188) and without (N = 38) cardiac involvement (area under the curve [AUC] = 0.839). During a median follow‐up of 35 months, 160 patients (70.8%) demonstrated all‐cause mortality. After adjustments for clinical (Hazard ratio [HR] 1.061, confidence interval [CI]: 1.021–1.102), biochemical (HR 1.055, CI: 1.014–1.097), cardiac MRI‐derived (HR 1.077, CI: 1.034–1.123), and therapeutic (HR 1.063, CI: 1.024–1.103) factors, PTT predicted mortality independently in patients with AL amyloidosis. Finally, PTT could identify worse outcomes in patients demonstrating New York Heart Association class III, Mayo 2004 stage III, and transmural LGE pattern. Data Conclusion: PTT may serve as a new imaging predictor of cardiac involvement and prognosis in AL amyloidosis. Level of Evidence: 2 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Myocardial perfusion imaging (MPI) with single photon emission computed tomography is an established non-invasive technique for assessing myocardial ischemia. This method involves the intravenous administration of a radiopharmaceutical that accumulates in the heart muscle proportional to regional blood flow. However, image quality and diagnostic accuracy can be compromised by various technical and patient-related factors, including high non-specific radiopharmaceutical uptake in abdominal organs such as the stomach, intestines, liver, and gall-bladder, leading to subdiaphragmatic artifacts. These artifacts are particularly problematic for evaluating inferior wall perfusion and often necessitate repeated imaging, which decreases gamma camera availability and prolongs imaging times. Despite numerous investigated techniques to reduce interfering gastrointestinal activity, results have been inconsistent, and current MPI guidelines provide scant information on effective procedures to mitigate this issue. Based on our experience, some possible approaches to reducing artifacts include choosing stress testing with an exercise stress test, when possible, late imaging, fluid intake, and consuming carbonated water immediately before imaging. [ABSTRACT FROM AUTHOR]

Abstract Background Coronary artery disease (CAD) is associated with a large clinical and economic burden. However, consensus on the optimal approach to CAD diagnosis is lacking. This study sought to compare downstream healthcare resource utilisation following different cardiac imaging modalities, to inform test selection for CAD diagnosis. Methods Claims and electronic health records data from the Decision Resources Group Real-World Evidence US Data Repository were analysed for 2.5 million US patients who underwent single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI), positron emission tomography myocardial perfusion imaging (PET MPI), coronary computed tomography angiography (cCTA), or stress echocardiography between January 2016 and March 2018. Patients were stratified into nine cohorts based on suspected or existing CAD diagnosis, pre-test risk, and prior events or interventions. Downstream healthcare utilisation, including additional diagnostic imaging, coronary angiography, and cardiac-related health system encounters, was compared by cohort and index imaging modality. Results Among patients with suspected CAD diagnosed within 3 months of the index test, PET MPI was associated with lower downstream utilisation; 25–37% of patients who underwent PET MPI required additional downstream healthcare resources compared with 40–49% of patients who received SPECT MPI, 35–41% of patients who underwent cCTA, and 44–47% of patients who received stress echocardiography. Patients who underwent PET MPI experienced fewer acute cardiac events (5.3–9.4%) and generally had lower rates of healthcare encounters (0.8–4.1%) and invasive coronary angiography (ICA, 15.4–24.2%) than those who underwent other modalities. SPECT MPI was associated with more downstream ICA (31.3–38.2%) and a higher rate of cardiac events (9.5–13.2%) compared with PET MPI (5.3–9.4%) and cCTA (6.9–9.9%). Across all cohorts, additional diagnostic imaging was 1.6 to 4.7 times more frequent with cCTA compared with PET MPI. Conclusion Choice of imaging modality for CAD diagnosis impacts downstream healthcare utilisation. PET MPI was associated with lower utilisation across multiple metrics compared with other imaging modalities studied.

Tissue perfusion can be affected by physiology or disease. With the advent of total-body PET, quantitative measurement of perfusion across the entire body is possible. [11C]-butanol is a perfusion tracer with a superior extraction fraction compared with [15O]-water and [13N]-ammonia. To develop the methodology for total-body perfusion imaging, a pilot study using [11C]-butanol on the uEXPLORER total-body PET/CT scanner was conducted. Methods: Eight participants (6 healthy volunteers and 2 patients with peripheral vascular disease [PVD]) were injected with a bolus of [11C]-butanol and underwent 30-min dynamic acquisitions. Three healthy volunteers underwent repeat studies at rest (baseline) to assess test-retest reproducibility; 1 volunteer underwent paired rest and cold pressor test (CPT) studies. Changes in perfusion were measured in the paired rest-CPT study. For PVD patients, local changes in perfusion were investigated and correlated with patient medical history. Regional and parametric kinetic analysis methods were developed using a 1-tissue compartment model and leading-edge delay correction. Results: Estimated baseline perfusion values ranged from 0.02 to 1.95 mL·min-1·cm-3 across organs. Test-retest analysis showed that repeat baseline perfusion measurements were highly correlated (slope, 0.99; Pearson r = 0.96, P < 0.001). For the CPT subject, the largest regional increases were in skeletal muscle (psoas, 142%) and the myocardium (64%). One of the PVD patients showed increased collateral vessel growth in the calf because of a peripheral stenosis. Comorbidities including myocardial infarction, hypothyroidism, and renal failure were correlated with variations in organ-specific perfusion. Conclusion: This pilot study demonstrates the ability to obtain reproducible measurements of total-body perfusion using [11C]-butanol. The methods are sensitive to local perturbations in flow because of physiologic stressors and disease.

Background: Stress myocardial perfusion single-photon emission computed tomography (SPECT) imaging (MPI) has been used to diagnose and predict the prognoses of patients with coronary artery disease (CAD). An ongoing multicenter collaboration established a Japanese database (J-ACCESS) in 2001 that includes a risk model and expert interpretations. The present study aimed to develop a novel algorithm using machine learning (ML) and resources from the J-ACCESS database to aid SPECT image interpretation. Methods: We analyzed data from 1288 patients in J-ACCESS 3 and 4 databases. Three-dimensional (3D) stereoscopic images of left ventricular myocardial perfusion were reconstructed with linear transformation from the original short-axis data. Segments were extracted from U-Net, then features were extracted from each segment during the ML process. We estimated segmental scores based on weighted features obtained from fully connected layers. Correlations between segment scores interpreted by nuclear cardiology experts and estimated by ML were evaluated using a 17-segment model, summed stress (SSS), summed rest (SRS), and summed difference (SDS) scores, and ratios (%) of summed different scores (%SDS). Results: The complete concordance rate of scores assessed by the experts and estimated by ML was 79.6%. The underestimated and overestimated rates were 10.3% and 10.0%, respectively. Associations between defect scores assessed by experts and ML were close, with correlation coefficients (r) of 0.923, 0.917, 0.842 and 0.853 for SSS, SRS, SDS, %SDS, respectively (p < 0.0001 for all). Conclusions: We created a new algorithm to estimate MPI scores using ML and the J-ACCESS database. This algorithm should provide accurate MPI interpretation even in facilities without specialist nuclear cardiologists, and might facilitate therapeutic decision-making and predict prognoses. [ABSTRACT FROM AUTHOR]

Abstract Background We prospectively assessed the reproducibility of a novel low-dose single-volume dynamic computed tomography (CT) myocardial blood flow measurement technique. Methods Thirty-four pairs of measurements were made under rest and stress conditions in 13 swine (54.3 ± 12.3 kg). One or two acquisition pairs were acquired in each animal with a 10-min delay between each pair. Contrast (370 mgI/mL; 0.5 mL/kg) and a diluted contrast/saline chaser (0.5 mL/kg; 30:70 contrast/saline) were injected peripherally at 5 mL/s, followed by bolus tracking and acquisition of a single volume scan (100 kVp; 200 mA) with a 320-slice CT scanner. Bolus tracking and single volume scan data were used to derive perfusion in mL/min/g using a first-pass analysis model; the coronary perfusion territories of the left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA) were automatically assigned using a previously validated minimum-cost path technique. The reproducibility of CT myocardial perfusion measurement within the LAD, LCx, RCA, and the whole myocardium was assessed via regression analysis. The average CT dose index (CTDI) of perfusion measurement was recorded. Results The repeated first (Pmyo1) and second (Pmyo2) single-volume CT perfusion measurements were related by P myo2 = 1.01P myo1 − 0.03(ρ = 0.96; RMSE = 0.08 mL/min/g; RMSE = 0.07 mL/min/g) for the whole myocardium, and by P reg2 = 0.86P reg1 + 0.13(ρ = 0.87; RMSE = 0.31 mL/min/g; RMSE = 0.29 mL/min/g) for the LAD, LCx, and RCA perfusion territories. The average CTDI of the single-volume CT perfusion measurement was 10.5 mGy. Conclusion The single-volume CT blood flow measurement technique provides reproducible low-dose myocardial perfusion measurement using only bolus tracking data and a single whole-heart volume scan. Relevance statement The single-volume CT blood flow measurement technique is a noninvasive tool that reproducibly measures myocardial perfusion and provides coronary CT angiograms, allowing for simultaneous anatomic-physiologic assessment of myocardial ischemia. Key Points A low-dose single-volume dynamic CT myocardial blood flow measurement technique is reproducible. Motion misregistration artifacts are eliminated using a single-volume CT perfusion technique. This technique enables combined anatomic-physiologic assessment of coronary artery disease. Graphical Abstract

Abstract Background Several factors may decrease the accuracy of quantitative PET myocardial perfusion imaging (MPI). It is therefore essential to ensure that myocardial blood flow (MBF) values are reproducible and accurate, and to design systematic protocols to achieve this. Until now, no systematic phantom protocols have been available to assess the technical factors affecting measurement accuracy and reproducibility in MPI. Materials and methods We implemented a standard measurement protocol, which applies a flow phantom in order to compare image-derived flow values with respect to a ground truth flow value with [15O]H2O MPI performed on both a Discovery MI (DMI-20, GE Healthcare) and a Biograph Vision 600 (Vision-600, Siemens Healthineers) system. Both systems have automatic [15O]H2O radio water generators (Hidex Oy) individually installed, allowing us to also study the differences occurring due to two different bolus delivery systems. To investigate the technical factors contributing to the modelled flow values, we extracted the [15O]H2O bolus profiles, the flow values from the kinetic modeling (Qin and Qout), and finally calculated their differences between test-retest measurements on both systems. Results The measurements performed on the DMI-20 system produced Qin and Qout values corresponging to each other as well as to the reference flow value across all test-retest measurements. The repeatability differences on DMI-20 were 2.1% ± 2.6% and 3.3% ± 4.1% for Qin and Qout, respectively. On Vision-600 they were 10% ± 8.4% and 11% ± 10% for Qin and Qout, respectively. The measurements performed on the Vision-600 system showed more variation between Qin and Qout values across test-retest measurements and exceeded 15% difference in 7/24 of the measurements. Conclusions A preliminary protocol for measuring the accuracy and reproducibility of flow values in [15O]H2O MPI between digital PET/CT systems was assessed. The test-retest reproducibility falls below 15% in majority of the measurements conducted between two individual injector systems and two digital PET/CT systems. This study highlights the importance of implementing a standardized bolus injection and delivery protocol and importance of assessing technical factors affecting flow value reproducibility, which should be carefully investigated in a multi-center setting.

Abstract As patient exposure to ionizing radiation from medical imaging and its risks are continuing issues, this study aimed to evaluate DNA damage and repair markers after myocardial perfusion single-photon emission computed tomography (MPS). Thirty-two patients undergoing Tc-99m sestamibi MPS were studied. Peripheral blood was collected before radiotracer injection at rest and 60–90 min after injection. The comet assay (single-cell gel electrophoresis) was performed with peripheral blood cells to detect DNA strand breaks. Three descriptors were evaluated: the percentage of DNA in the comet tail, tail length, and tail moment (the product of DNA tail percentage and tail length). Quantitative PCR (qPCR) was performed to evaluate the expression of five genes related to signaling pathways in response to DNA damage and repair (ATM, ATR, BRCA1, CDKN1A, and XPC). Mann–Whitney’s test was employed for statistical analysis; p

To develop a deep learning-based model capable of segmenting the left ventricular (LV) myocardium on native T1 maps from cardiac MRI in both long-axis and short-axis orientations. Models were trained on native myocardial T1 maps from 50 healthy volunteers and 75 patients using manual segmentation as the reference standard. Based on a U-Net architecture, we systematically optimized the model design using two different training metrics (Sørensen-Dice coefficient = DSC and Intersection-over-Union = IOU), two different activation functions (ReLU and LeakyReLU) and various numbers of training epochs. Training with DSC metric and a ReLU activation function over 35 epochs achieved the highest overall performance (mean error in T1 10.6 ± 17.9 ms, mean DSC 0.88 ± 0.07). Limits of agreement between model results and ground truth were from -35.5 to + 36.1 ms. This was superior to the agreement between two human raters (-34.7 to + 59.1 ms). Segmentation was as accurate for long-axis views (mean error T1: 6.77 ± 8.3 ms, mean DSC: 0.89 ± 0.03) as for short-axis images (mean error ΔT1: 11.6 ± 19.7 ms, mean DSC: 0.88 ± 0.08). Fully automated segmentation and quantitative analysis of native myocardial T1 maps is possible in both long-axis and short-axis orientations with very high accuracy. [ABSTRACT FROM AUTHOR]

Objectives: To examine Relationship of Electrocardiographic Dynamicity to Ischemic Burden Using Myocardial Perfusion Imaging in Patients without Previous Myocardial Infarction. Background: Myocardial perfusion Imaging (MPI) provides powerful diagnostic and prognostic information in the management of patients with known or suspected coronary artery disease (CAD). The purpose of this study was to study the relationship of electrocardiographic dynamicity to ischemic burden using MPI in patients without previous myocardial infarction. Method: our study was a prospective observational which was carried out on 175 patients referred for diagnosis or risk stratification for coronary artery disease, patients were subjected to a history checkup and full clinical examination, a standard 12-lead electrocardiograms at rest & subjects underwent technetium(Tc)-99m sestamibi rest-stress gated SPECT MPI. Results: There was a fair agreement between exercise treadmill induced electrocardiogram (ECG) ischemic changes in anterior leads and myocardial perfusion defects in MPI at stress of the studied patients, and there was a moderate agreement between, exercise treadmill induced ECG ischemic changes in inferior leads and negative stress ECG, and myocardial perfusion defects in MPI at stress of the studied patients. In Age <50y with one or no risk factors, there was a fair agreement between MPI and stress ECG. In Age >50y with one or more risk factors, there was a moderate agreement between MPI and stress ECG. Stress ECG can diagnose CAD and ischemic heart disease as MPI at stress with82.9% sensitivity, 69.0% specificity. Conclusions: Exercise treadmill induced ECG ischemic changes can diagnose the ischemic burden with less accuracy than the MPI at stress regarding the evidence of ischemia while it was irrelevant with myocardial perfusion defects in MPI at stress regarding the distribution of ischemic changes. [ABSTRACT FROM AUTHOR]

This article examines the impact of risk stratification on cardiovascular outcomes in patients with stable chest pain. The study, conducted at the National Heart Centre Singapore, included 1658 patients who were classified based on their pre-test probability (PTP) of obstructive coronary artery disease (CAD) using risk scores. The findings indicate that patients with a low PTP had a favorable prognosis and low adverse clinical outcomes, suggesting that additional cardiac testing may be safely deferred in this group. The study also addresses the development of a risk prediction tool specifically for Southeast Asians, as the risk scores used in the study were originally developed for Western cohorts. The article emphasizes the importance of considering the outcomes of patients with stable chest pain and the potential benefits of reducing unnecessary testing, including the financial burden, anxiety, and false positive results associated with such testing. [Extracted from the article]

Objectives: To validate a novel stepwise strategy in which computed tomography–derived fractional flow reserve (FFRCT) is restricted to intermediate stenosis on coronary computed tomography angiography (CCTA) and computed tomography myocardial perfusion imaging (CT-MPI) was reserved for vessels with gray zone FFRCT values. Materials and methods: This retrospective study included 87 consecutive patients (age, 58 ± 10 years; 70% male) who underwent CCTA, dynamic CT-MPI, interventional coronary angiography (ICA), and fractional flow reserve (FFR) for suspected or known coronary artery disease. FFRCT was computed using a deep learning–based platform. Three stepwise strategies (CCTA + FFRCT + CT-MPI, CCTA + FFRCT, CCTA + CT-MPI) were constructed and their diagnostic performance was evaluated using ICA/FFR as the reference standard. The proportions of vessels requiring further ICA/FFR measurement based on different strategies were noted. Furthermore, the net reclassification index (NRI) was calculated to ascertain the superior model. Results: The CCTA + FFRCT + CT-MPI strategy yielded the lowest proportion of vessels requiring additional ICA/FFR measurement when compared to the CCTA + FFRCT and CCTA + CT-MPI strategies (12%, 22%, and 24%). The CCTA + FFRCT + CT-MPI strategy exhibited the highest accuracy for ruling-out (91%, 84%, and 85%) and ruling-in (90%, 85%, and 85%) functionally significant lesions. All strategies exhibited comparable sensitivity for ruling-out functionally significant lesions and specificity for ruling-in functionally significant lesions (p > 0.05). The NRI indicated that the CCTA + FFRCT + CT-MPI strategy outperformed the CCTA + FFRCT strategy (NRI = 0.238, p < 0.001) and the CCTA + CT-MPI strategy (NRI = 0.233%, p < 0.001). Conclusions: The CCTA + FFRCT + CT-MPI stepwise strategy was superior to the CCTA + FFRCT strategy and CCTA+ CT-MPI strategy by minimizing unnecessary invasive diagnostic catheterization without compromising the agreement rate with ICA/FFR. Clinical relevance statement: Our novel stepwise strategy facilitates greater confidence and accuracy when clinicians need to decide on interventional coronary angiography referral or deferral, reducing the burden of invasive investigations on patients. Key Points: • A stepwise CCTA + FFRCT + CT-MPI strategy holds promise as a viable method to reduce the need for invasive diagnostic catheterization, while maintaining a high level of agreement with ICA/FFR. • The CCTA + FFRCT + CT-MPI strategy performed better than the CCTA + FFRCT and CCTA + CT-MPI strategies. • A stepwise CCTA + FFRCT + CT-MPI strategy allows to minimize unnecessary invasive diagnostic catheterization and helps clinicians to referral or deferral for ICA/FFR with more confidence. [ABSTRACT FROM AUTHOR]

Background: The effect of imaging selection modality on endovascular thrombectomy (EVT) clinical outcomes in patients with acute ischemic stroke due to large vessel occlusion (AIS‐LVO) remains unclear. This study aims to compare post‐EVT outcomes in patients with AIS‐LVO who underwent basic imaging (computed tomography with or without computed tomography angiography) and advanced imaging (computed tomography perfusion or magnetic resonance imaging) in early and late time windows. Method: A systematic literature search was conducted on PubMed, Cochrane Library, and Embase databases from inception until June 10, 2023. Studies investigating the relationship between the imaging selection modality and post‐EVT outcomes in patients with AIS‐LVO were retrieved. A random‐effects model was used to pool the effect estimates of successful reperfusion, symptomatic intracranial hemorrhage (sICH), functional independence, and mortality. The meta‐analysis was performed using Review Manager software v.4.3, and the outcomes were assessed using odds ratios (ORs) and 95% confidence intervals (CIs). Result: A total of 13 non‐randomized observational studies, comprising 19,694 patients, were included in this meta‐analysis. In the early time windows, AIS‐LVO patients receiving advanced imaging demonstrated a higher likelihood of functional independence (OR, 1.25, 95% CI, 1.08–1.46) and a lower risk of mortality (OR,.73 95% CI,.61–.86) compared to those receiving basic imaging. In the extended time windows, AIS‐LVO patients undergoing advanced imaging had a lower mortality rate (OR,.79, 95% CI,.68–.92). Regardless of the time of onset, there were no significant differences between the two groups in terms of sICH or successful reperfusion. Conclusion: Advanced imaging combined with EVT may achieve better clinical outcomes in patients with AIS‐LVO. Further high‐quality studies are needed to validate these findings. [ABSTRACT FROM AUTHOR]

Introduction: Myocardial perfusion imaging (MPI) is one of the most commonly ordered cardiac imaging tests. Accurate motion correction, image registration, and reconstruction are critical for high-quality imaging, but this can be technically challenging and has traditionally relied on expert manual processing. With accurate processing, there is a rich variety of clinical, stress, functional, and anatomic data that can be integrated to guide patient management. Areas covered: PubMed and Google Scholar were reviewed for articles related to artificial intelligence in nuclear cardiology published between 2020 and 2024. We will outline the prominent roles for artificial intelligence (AI) solutions to provide motion correction, image registration, and reconstruction. We will review the role for AI in extracting anatomic data for hybrid MPI which is otherwise neglected. Lastly, we will discuss AI methods to integrate the wealth of data to improve disease diagnosis or risk stratification. Expert opinion: There is growing evidence that AI will transform the performance of MPI by automating and improving on aspects of image acquisition and reconstruction. Physicians and researchers will need to understand the potential strengths of AI in order to benefit from the full clinical utility of MPI. [ABSTRACT FROM AUTHOR]

Early invasive revascularization guided by moderate to severe ischemia did not improve outcomes over medical therapy alone, underlying the need to identify high-risk patients for a more effective invasive referral. CMR could determine the myocardial extent and matching locations of ischemia and infarction. This study sought to investigate if CMR peri-infarct ischemia is associated with adverse events incremental to known risk markers. Consecutive patients were included in an expanded cohort of the multicenter SPINS (Stress CMR Perfusion Imaging in the United States) study. Peri-infarct ischemia was defined by the presence of any ischemic segment neighboring an infarcted segment by late gadolinium enhancement imaging. Primary outcome events included acute myocardial infarction and cardiovascular death, whereas secondary events included any primary events, hospitalization for unstable angina, heart failure hospitalization, and late coronary artery bypass surgery. Among 3,915 patients (age: 61.0 ± 12.9 years; 54.7% male), ischemia, infarct, and peri-infarct ischemia were present in 752 (19.2%), 1,123 (28.8%), and 382 (9.8%) patients, respectively. At 5.3 years (Q1-Q3: 3.9-7.2 years) of median follow-up, primary and secondary events occurred in 406 (10.4%) and 745 (19.0%) patients, respectively. Peri-infarct ischemia was the strongest multivariable predictor for primary and secondary events (HR adjusted : 1.72 [95% CI: 1.23-2.41] and 1.71 [95% CI: 1.32-2.20], respectively; both P < 0.001), adjusted for clinical risk factors, left ventricular function, ischemia extent, and infarct size. The presence of peri-infarct ischemia portended to a >6-fold increased annualized primary event rate compared to those with no infarct and ischemia (6.5% vs 0.9%). Peri-infarct ischemia is a novel and robust prognostic marker of adverse cardiovascular events. [ABSTRACT FROM AUTHOR]

Background and Purpose Methods Results Conclusion Early and reliable prediction of hemorrhagic transformation (HT) in patients with acute ischemic stroke (AIS) is crucial for treatment decisions and early intervention. The purpose of this study was to conduct a systematic review and meta‐analysis on the performance of artificial intelligence (AI) and machine learning (ML) models that utilize neuroimaging to predict HT.A systematic search of PubMed, EMBASE, and Web of Science was conducted until February 19, 2024. Inclusion criteria were as follows: patients with AIS who received reperfusion therapy; AI/ML algorithm using imaging to predict HT; or presence of sufficient data on the predictive performance. Exclusion criteria were as follows: articles with less than 20 patients; articles lacking algorithms that operate solely on images; or articles not detailing the algorithm used. The quality of eligible studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies‐2 and Checklist for Artificial Intelligence in Medical Imaging. Pooled sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated using a random‐effects model, and a summary receiver operating characteristic curve was constructed using the Reitsma method.We identified six eligible studies, which included 1640 patients. Aside from an unclear risk of bias regarding flow and timing identified in two of the studies, all studies showed low risk of bias and applicability concerns in all categories. Pooled sensitivity, specificity, and DOR were .849, .878, and 45.598, respectively.AI/ML models can reliably predict the occurrence of HT in AIS patients. More prospective studies are needed for subgroup analyses and higher clinical certainty and usefulness. [ABSTRACT FROM AUTHOR]

Dynamic assessment of myocardial blood flow (MBF) and myocardial flow reserve (MFR) provides additional information that can improve diagnostic accuracy of radionuclide myocardial perfusion imaging in some clinical situations. This study assessed processing repeatability of these parameters calculated using two models—net retention (RET) and one compartment (1CM) in dynamic SPECT studies, using the latest version of Corridor 4DM software (v2024). Data of 107 patients were analyzed retrospectively (57 of whom were assessed in our previous study using 4DM v2015). Dynamic SPECT studies were carried out using a routine two-day rest-dipyridamole protocol. Data was processed in 4DM v2024 twice by one operator and once by another operator. Automatic heart image positioning during post-processing in 4DM v2024 was significantly improved compared to v2015, reducing the number of studies requiring extensive manual corrections from 41 to 12%. This significantly improved interobserver processing repeatability of MFR values in RCA territory compared to our previous study using v2015—from r = 0.67 to 0.85 (p = 0.0034). Interobserver processing repeatability of MBF and MFR in all 107 patients was significantly better in RET model compared to 1CM model. In conclusion, RET model is more reliable for calculating MBF and MFR values based on dynamic SPECT studies. [ABSTRACT FROM AUTHOR]

[123I]β-methyl-p-iodophenyl-pentadecanoic acid ([123I]BMIPP), which is used for nuclear medicine imaging of myocardial fatty acid metabolism, accumulates in cancer cells. However, the mechanism of accumulation remains unknown. Therefore, this study aimed to elucidate the accumulation and accumulation mechanism of [123I]BMIPP in cancer cells. We compared the accumulation of [123I]BMIPP in cancer cells with that of [18F]FDG and found that [123I]BMIPP was a much higher accumulation than [18F]FDG. The accumulation of [123I]BMIPP was evaluated in the presence of sulfosuccinimidyl oleate (SSO), a CD36 inhibitor, and lipofermata, a fatty acid transport protein (FATP) inhibitor, under low-temperature conditions and in the presence of etomoxir, a carnitine palmitoyl transferase I (CPT1) inhibitor. The results showed that [123I]BMIPP accumulation was decreased in the presence of SSO and lipofermata in H441, LS180, and DLD-1 cells, suggesting that FATPs and CD36 are involved in [123I]BMIPP uptake in cancer cells. [123I]BMIPP accumulation in all cancer cell lines was significantly decreased at 4 °C compared to that at 37 °C and increased in the presence of etomoxir in all cancer cell lines, suggesting that the accumulation of [123I]BMIPP in cancer cells is metabolically dependent. In a biological distribution study conducted using tumor-bearing mice transplanted with LS180 cells, [123I]BMIPP highly accumulated in not only LS180 cells but also normal tissues and organs (including blood and muscle). The tumor-to-intestine or large intestine ratios of [123I]BMIPP were similar to those of [18F]FDG, and the tumor-to-large-intestine ratios exceeded 1.0 during 30 min after [123I]BMIPP administration in the in vivo study. [123I]BMIPP is taken up by cancer cells via CD36 and FATP and incorporated into mitochondria via CPT1. Therefore, [123I]BMIPP may be useful for imaging cancers with activated fatty acid metabolism, such as colon cancer. However, the development of novel imaging radiotracers based on the chemical structure analog of [123I]BMIPP is needed. [ABSTRACT FROM AUTHOR]

Background: Positron emission tomography (PET) is now an established diagnostic method for myocardial perfusion imaging (MPI) in coronary artery disease, which is the main cause of death globally. The available tracers show several limitations, therefore, the 18F-labelled tracer is in high demand nowadays. The preclinical studies on normal Wistar rats aimed to characterise two potential, novel radiotracers, [18F]SYN1 and [18F]SYN2, to evaluate which is a better candidate for PET MPI cardiotracer. Results: The dynamic microPET images showed rapid myocardial uptake for both tracers. However, the uptake was higher and also stable for [18F]SYN2, with an average standardized uptake value of 3.8. The biodistribution studies confirmed that [18F]SYN2 uptake in the cardiac muscle was high and stable (3.02%ID/g at 15 min and 2.79%ID/g at 6 h) compared to [18F]SYN1 (1.84%ID/g at 15 min and 0.32%ID/g at 6 h). The critical organs determined in dosimetry studies were the small intestine and the kidneys. The estimated effective dose for humans was 0.00714 mSv/MBq for [18F]SYN1 and 0.0109 mSv/MBq for [18F]SYN2. The tested dose level of 2 mg/kg was considered to be the No Observed Adverse Effect Level (NOAEL) for both candidates. The better results were achieved for [18F]SYN2, therefore, further preclinical studies were conducted only for this tracer. Radioligand binding assays showed significant responses in 3 from 68 assays: muscarinic acetylcholine M1 and M2 receptors and potassium channel hERG. The compound was mostly metabolised via an oxidative N-dealkylation, while the fluor substituent was not separated from the molecule. Conclusion: [18F]SYN2 showed a favourable pharmacodynamic and pharmacokinetic profile, which enabled a clear visualization of the heart in microPET. The compound was well-tolerated in studies in normal rats with moderate radiation exposure. The results encourage further exploration of [18F]SYN2 in clinical studies. [ABSTRACT FROM AUTHOR]

This article, published in the journal Circulation, discusses the past, present, and future of coronary computed tomography angiography (CCTA) as a diagnostic tool for cardiovascular disease. The essay traces the historical milestones and technological advancements that have shaped cardiac CT, highlighting its ability to provide noninvasive assessment of coronary artery disease and other cardiovascular conditions. The article also discusses the role of CCTA in the evaluation of acute and stable chest pain, as well as its potential for risk stratification and guiding preventive treatments. The authors conclude that ongoing advancements in technology and clinical research will continue to enhance the role of cardiac CT in modern cardiology. [Extracted from the article]

Polymeric vascular bioresorbable stents (BRSs) have been widely used for the treatment of coronary artery diseases. While additive manufacturing (AM) is changing the landscape of the healthcare sector by enabling the realization of patient‐specific stents with highly complex structures. There are, however, challenges associated with the use of polymeric BRS, particularly in‐stent restenosis (ISR), related to its poor mechanical properties. Therefore, the aim of this review is to provide an overview of recent advancements in the development of polymeric BRSs designed to meet both mechanical and biological requirements. First, biopolymers as well as shape memory polymers (SMPs) that are suitable for BRSs are highlighted and briefly described. Second, different types of designing structures of vascular stents in addition to introducing effective mechanical metamaterials, e.g., negative Poisson ratio (NPR) structures are addressed. Subsequently, AM methods currently being used to fabricate polymeric BRSs, are discussed and compared with conventional fabrication methods. Lastly, future directions for research are proposed in relation to existing challenges to the realization of a new generation of AM BRSs. Overall, this paper serves as a benchmark for future cardiovascular applications, especially in order to obtain clinically viable polymeric vascular stents by selecting suitable polymers, designs, and AM technologies. [ABSTRACT FROM AUTHOR]

AbstractIn recent years, lattice cylindrical shells (LCSs) based on the triply periodic minimal surfaces (TPMS) have been researched in the energy absorption (EA) field due to their distinctive mechanical properties. However, LCS structures will generate severe lateral expansion and localized fragmentation during compressive deformation, resulting in a significant decrease on compression performance. To further improve EA properties, Gyroid LCS filled thin-walled tubes (LCS-T) are proposed and produced by selective laser melting (SLM). In this work, the influence of the interaction (hollow thin-walled tubes + LCSs core) of the Gyroid LCS-T with different filling radii on the compressive properties and EA were investigated by the quasi-static compression experiments and finite element simulation systematically. The results showed that the Gyroid LCS-T based on AlMgScZr alloy fabricated by SLM had high connection strength and no obvious defects. The specific EA (SEA) of Gyroid LCS-T with radius of 3, 6, and 9 increased by 42.1%, 49.3%, and 53.3%, respectively, compared to thin-walled tubes. Compared to the sum of all components individually, the Gyroid LCS-T achieved superior performance in both compressive properties and EA by transferring stresses from the LCS interior to the thin-walled tube. Furthermore, the gradient design realized adjustment of the structural deformation and improved EA with about 1.24 times compared to uniform structure. This research offered visionary insights into designing energy-absorbing structures and optimizing parameters for LCS-T. [ABSTRACT FROM AUTHOR]

Background: Several factors may decrease the accuracy of quantitative PET myocardial perfusion imaging (MPI). It is therefore essential to ensure that myocardial blood flow (MBF) values are reproducible and accurate, and to design systematic protocols to achieve this. Until now, no systematic phantom protocols have been available to assess the technical factors affecting measurement accuracy and reproducibility in MPI. Materials and methods: We implemented a standard measurement protocol, which applies a flow phantom in order to compare image-derived flow values with respect to a ground truth flow value with [15O]H2O MPI performed on both a Discovery MI (DMI-20, GE Healthcare) and a Biograph Vision 600 (Vision-600, Siemens Healthineers) system. Both systems have automatic [15O]H2O radio water generators (Hidex Oy) individually installed, allowing us to also study the differences occurring due to two different bolus delivery systems. To investigate the technical factors contributing to the modelled flow values, we extracted the [15O]H2O bolus profiles, the flow values from the kinetic modeling (Qin and Qout), and finally calculated their differences between test-retest measurements on both systems. Results: The measurements performed on the DMI-20 system produced Qin and Qout values corresponging to each other as well as to the reference flow value across all test-retest measurements. The repeatability differences on DMI-20 were 2.1% ± 2.6% and 3.3% ± 4.1% for Qin and Qout, respectively. On Vision-600 they were 10% ± 8.4% and 11% ± 10% for Qin and Qout, respectively. The measurements performed on the Vision-600 system showed more variation between Qin and Qout values across test-retest measurements and exceeded 15% difference in 7/24 of the measurements. Conclusions: A preliminary protocol for measuring the accuracy and reproducibility of flow values in [15O]H2O MPI between digital PET/CT systems was assessed. The test-retest reproducibility falls below 15% in majority of the measurements conducted between two individual injector systems and two digital PET/CT systems. This study highlights the importance of implementing a standardized bolus injection and delivery protocol and importance of assessing technical factors affecting flow value reproducibility, which should be carefully investigated in a multi-center setting. [ABSTRACT FROM AUTHOR]

While exercise-mediated vasoregulation in the myocardium is understood to be governed by autonomic, myogenic, and metabolic-mediated mechanisms, we do not yet understand the spatial heterogeneity of vasodilation or its effects on microvascular flow patterns and oxygen delivery. This study uses a simulation and modeling approach to explore the mechanisms underlying the recruitment of myocardial perfusion and oxygen delivery in exercise. The simulation approach integrates model components representing: whole-body cardiovascular hemodynamics, cardiac mechanics and myocardial work; myocardial perfusion; and myocardial oxygen transport. Integrating these systems together, model simulations reveal: (1.) To match expected flow and transmural flow ratios at increasing levels of exercise, a greater degree of vasodilation must occur in the subendocardium compared to the subepicardium. (2.) Oxygen extraction and venous oxygenation are predicted to substantially decrease with increasing exercise level preferentially in the subendocardium, suggesting that an oxygen-dependent error signal driving metabolic mediated recruitment of flow would be operative only in the subendocardium. (3.) Under baseline physiological conditions approximately 4% of the oxygen delivered to the subendocardium may be supplied via retrograde flow from coronary veins. [Display omitted] • The myocardium extracts >70% of the oxygen from inflowing arterial blood. • Myocardial contraction causes complex pulsatile transmural flow patterns. • We simulated transmural vasoregulation and oxygen delivery in the myocardium. • Simulations reveal insights into mechanisms governing metabolic mediated vasodilation [ABSTRACT FROM AUTHOR]

Background: Dementia with Lewy bodies (DLB) presents with various symptoms, posing challenges for early diagnosis challenging. Dopamine transporter (123I-FP-CIT) single-photon emission tomography (SPECT) and 123I-meta-iodobenzylguanidine (123I-MIBG) imaging are crucial diagnostic biomarkers. Hypothesis about body- and brain-first subtypes of DLB indicate that some DLB may show normal 123I-FP-CIT or 123I-MIBG results; but the characteristic expression of these two subtypes remains unclear. Objective: This study aimed to evaluate the diagnostic sensitivity of 123I-FP-CIT and 123I-MIBG imaging alone, combined in patients with DLB and explore symptoms associated with the abnormal imaging results. Methods: Demographic data, clinical status, and imaging results were retrospectively collected from patients diagnosed with possible DLB. Both images were quantified using semi-automated software, and the sensitivity of each imaging modality and their combination was calculated. Demographic data, cognition, and motor and non-motor symptoms were compared among the subgroups based on the imaging results. Symptoms related to each imaging abnormality were examined using binomial logistic regression analyses. Results: Among 114 patients with DLB, 80 underwent 123I-FP-CIT SPECT (sensitivity: 80.3%), 83 underwent 123I-MIBG imaging (68.2%), and 66 both (sensitivity of either abnormal result: 93.9%). Visual hallucinations differed among the four subgroups based on imaging results. Additionally, nocturia and orthostatic hypotension differed between abnormal and normal 123I-MIBG images. Conclusions: Overall, 123I-FP-CIT SPECT was slightly higher sensitivity than 123I-MIBG imaging, with combined imaging increasing diagnostic sensitivity. Normal results of a single imaging test may not refute DLB. Autonomic symptoms may lead to abnormal 123I-MIBG scintigraphy findings indicating body-first subtype of patients with DLB. [ABSTRACT FROM AUTHOR]