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Purpose Several effective radiation dose reduction methods have been developed for coronary computed tomography angiography (CTA); however, their use in daily clinical practice remains unknown. We aimed to investigate radiation exposure and the utilization of dose-saving strategies for coronary CTA in hospitals in Mie Prefecture, Japan. Materials and methods Image acquisition details and dose reports of 30 consecutive cardiac CT examinations performed in 2021 were obtained from 18 hospitals. The inclusion criteria were patients aged 20–80 years who weighed 50–70 kg and underwent coronary CTA using ≥ 64-row multidetector CT. The doses for the overall cardiac CT examination and coronary CTA were analyzed using the dose-length product (DLP) and CT dose index (CTDIvol), respectively. Multivariate analysis was performed to determine independent predictors that affect the radiation dose in coronary CTA. Results The median DLP of cardiac CT was 774 (interquartile range [IQR]: 538–1119) mGy*cm, and the median CTDIvol of coronary CTA was 33 (IQR: 25–48) mGy. The 75th percentile values of DLP for cardiac CT and that of CTDIvol for coronary CTA were slightly lower than the values recorded in the Japan Diagnostic Reference Level (DRLs) 2020 report (1285 mGy*cm and 66.4 mGy, respectively) but were substantially higher than those reported in a previous large international dose survey (402 mGy*cm and 24 mGy, respectively). Iterative reconstruction was performed during all examinations. Only six hospitals (33%) used a low tube potential (≤ 100 kVp), and nine hospitals (50%) used electrocardiogram-triggered prospective scanning. Multivariate analysis revealed low heart rate, low tube potential, and use of electrocardiogram-triggered prospective scanning as independent predictors of CTDIvol ≤ 24 mGy (p Conclusion As of 2021, low tube potential and prospective scanning are underutilized, whereas iterative reconstruction is used in every coronary CTA in Mie Prefecture. Further efforts to optimize the radiation exposure from cardiac CT scans are necessary.

Coronary computed tomographic angiography (CCTA) is becoming the first-line investigation for establishing the presence of coronary artery disease and, with fractional flow reserve (FFRCT), its haemodynamic significance. In patients without significant epicardial obstruction, its role is either to rule out atherosclerosis or to detect subclinical plaque that should be monitored for plaque progression/regression following prevention therapy and provide risk classification. Ischaemic non-obstructive coronary arteries are also expected to be assessed by non-invasive imaging, including CCTA. In patients with significant epicardial obstruction, CCTA can assist in planning revascularisation by determining the disease complexity, vessel size, lesion length and tissue composition of the atherosclerotic plaque, as well as the best fluoroscopic viewing angle; it may also help in selecting adjunctive percutaneous devices (e.g., rotational atherectomy) and in determining the best landing zone for stents or bypass grafts.

Several effective radiation dose reduction methods have been developed for coronary computed tomography angiography (CTA); however, their use in daily clinical practice remains unknown. We aimed to investigate radiation exposure and the utilization of dose-saving strategies for coronary CTA in hospitals in Mie Prefecture, Japan.Image acquisition details and dose reports of 30 consecutive cardiac CT examinations performed in 2021 were obtained from 18 hospitals. The inclusion criteria were patients aged 20-80 years who weighed 50-70 kg and underwent coronary CTA using ≥ 64-row multidetector CT. The doses for the overall cardiac CT examination and coronary CTA were analyzed using the dose-length product (DLP) and CT dose index (CTDIvol), respectively. Multivariate analysis was performed to determine independent predictors that affect the radiation dose in coronary CTA.The median DLP of cardiac CT was 774 (interquartile range [IQR]: 538-1119) mGy*cm, and the median CTDIvol of coronary CTA was 33 (IQR: 25-48) mGy. The 75th percentile values of DLP for cardiac CT and that of CTDIvol for coronary CTA were slightly lower than the values recorded in the Japan Diagnostic Reference Level (DRLs) 2020 report (1285 mGy*cm and 66.4 mGy, respectively) but were substantially higher than those reported in a previous large international dose survey (402 mGy*cm and 24 mGy, respectively). Iterative reconstruction was performed during all examinations. Only six hospitals (33%) used a low tube potential (≤ 100 kVp), and nine hospitals (50%) used electrocardiogram-triggered prospective scanning. Multivariate analysis revealed low heart rate, low tube potential, and use of electrocardiogram-triggered prospective scanning as independent predictors of CTDIvol ≤ 24 mGy (p 0.001, respectively).As of 2021, low tube potential and prospective scanning are underutilized, whereas iterative reconstruction is used in every coronary CTA in Mie Prefecture. Further efforts to optimize the radiation exposure from cardiac CT scans are necessary.

Myocardial extracellular volume (ECV) by cardiac magnetic resonance (CMR) in the acute phase of acute myocardial infarction (MI) more precisely predicts the functional recovery of infarct-related wall motion abnormalities and left ventricular (LV) remodeling than late gadolinium enhancement (LGE). The purpose of this study was to evaluate the prognostic importance of acute phase ECV in patients with AMI. We evaluated 61 consecutive AMI patients using 3.0 T CMR. CMR examination was performed median 10 days (7-15 days) after PCI. Primary endpoint was defined as major adverse cardiac event (MACE). The median follow-up duration was 3.1 years, and MACE occurred in 11 (18%) patients. Although LVEF and % infarct LGE volume were not associated with MACE in this study population, higher infarct ECV predicted the MACE with a hazard ratio (HR) of 4.04 (P = 0.02). High global ECV, which was a combined assessment of infarct ECV and remote ECV, also predicted MACE with a HR of 5.24 (P = 0.035). The addition of infarct ECV to remote ECV (global chi-squared score: 1.4) resulted in a significantly increased global chi-squared score (6.7; P = 0.017). Furthermore, after adjusting for the calculated propensity score for high global ECV, it remained an independent predictor of MACE with HR of 5.10 (P = 0.04). The quantification of ECV in the acute phase among AMI patients may provide an incremental prognostic value for predicting MACE beyond that of clinical, angiographic, and functional variables.

Transcatheter aortic valve implantation (TAVI) improved outcome of patients with severe aortic valve stenosis (AS). Myocardial fibrosis is associated with AS-related pathological left ventricular (LV) remodeling and predicts cardiovascular mortality after TAVI. The present study aimed to investigate the impact of preoperative extracellular volume (ECV) assessed by computed tomography (CT) on left ventricular mass (LVM) regression and clinical outcomes in severe AS patients after TAVI.We examined 71 consecutive severe AS patients who underwent CT with ECV determination before TAVI. ECV was calculated as the ratio of the change in Hounsfield units in the myocardium and LV blood before and after contrast administration, multiplied by (1-hematocrit). Delayed scan was performed at 5 min after contrast injection. Echocardiography was performed before and 6 months after TAVI. The primary endpoint was heart failure (HF) hospitalization after TAVI. Patients were divided into two subgroups according to the median value of global ECV with 32 % (Low-ECV group: n = 35, and High-ECV group: n = 36).No significant differences were observed in background characteristics between the 2 groups. However, the preoperative LV ejection fraction and LVM index were similar between the 2 groups, the Low-ECV group had greater LVM index reduction than the High-CV group after 6 months (p 0.001). Kaplan-Meier curves demonstrated that the High-ECV group had significantly higher rate of HF hospitalization than the Low-ECV group (p = 0.016). In addition, multivariate analyses identified high global ECV as an independent predictor of HF hospitalization (HR 10.8, 95 % confidence interval 1.36 to 84.8, p = 0.024).The low preoperative ECV assessed by CT is associated with the greater LVM regression, and predict better outcome in AS patients after TAVI.

Late adverse cardiac events after radiation therapy (RT) for thoracic malignancies are known, but the underlying mechanisms are poorly understood. This study aimed to determine the radiation dose that can cause MBF alterations in the subacute phase after RT for thoracic esophageal cancer using stress dynamic myocardial computed tomography perfusion imaging (CTP).Twenty-five patients with esophageal cancer scheduled for RT were prospectively enrolled. The quantitative analysis of MBF by CTP was performed before and 3 months after RT. The mean radiation dose and hyperemic MBF in 15 segments of the left ventricular (LV) myocardium were determined. ΔMBF was calculated in each segment as MBFafter RT - MBFbeforeRT. The myocardial segments were classified into the following 5 groups according to the mean radiation dose: group A,10 Gy; B1, 10-15 Gy; B2, 15-20 Gy; C, 20-30 Gy; and D,30 Gy.The final cohort included 22 patients who completed pre- and post-RT CTP. A one-way analysis of variance revealed a significant difference (p=0.005) in ΔMBF among the five groups of LV segments classified by the mean radiation dose. ΔMBF was significantly lower in group C (-7.7 ± 28.9 mL/min/100 g, p=0.020) and group D (-8.4 ± 34.8 mL/min/100 g, p=0.004) in comparison to ΔMBF in group A (4.9 ± 26.1 mL/min/100 g).This study using CTP early after RT demonstrated a significant reduction of the MBF in the LV segments with ≥20 Gy of radiation. The results might provide important insights into preventing radiotherapy-induced cardiac events.

Objectives This study sought to evaluate the potential of cardiac magnetic resonance T1 mapping to detect load-independent left ventricular (LV) chamber stiffness by histological confirmat...

This study sought to evaluate the prognostic value of stress dynamic computed tomography (CT) perfusion (CTP) with CT delayed enhancement (CTDE) in patients with suspected or known coronary artery disease (CAD) and in subgroups of patients with stent, heavy calcification, or stenosis.The prognostic value of stress dynamic CTP with CTDE is unknown.Participants were 540 patients with suspected or known CAD. Major adverse cardiac event(s) (MACE) consisted of cardiac death, nonfatal myocardial infarction, unstable angina, or hospitalization for congestive heart failure. Ischemic score was calculated by scoring the reduction of normalized myocardial blood flow in 16 segments excluding areas of myocardial scarring. Ischemic perfusion defect (IPD) was defined as Ischemic score ≥4. Scar score was also calculated by scoring the transmural extent of scarring in each segment on CTDE.During a median follow-up of 2.9 years, 43 MACEs occurred. By adding IPD to obstructive CAD (≥50% stenosis) on coronary CT angiography, the concordance index for predicting MACEs increased from 0.73 to 0.82 in patients with suspected CAD (p = 0.028) and from 0.61 to 0.73 in patients with known CAD (p = 0.004). IPD and scar score of ≥4 were independent predictors when adjusted for each other in patients with suspected (adjusted hazard ratios: 7.5 [p 0.001] and 3.0 [p = 0.034], respectively) or known CAD (adjusted hazard ratios: 4.4 [p = 0.001] and 3.2 [p = 0.024], respectively). Patients with IPD had a higher annualized event rate than those without IPD in subgroups of those with stent (11.5% vs. 2.6%; p 0.001), heavy calcification (13.3% vs. 3.1%; p 0.001), 50% to 69% stenosis (8.8% vs. 1.0%; p 0.001), or ≥70% stenosis (12.4% vs. 3.6%; p 0.001).Stress dynamic CTP with CTDE had incremental prognostic value over CT angiography in each group with suspected or known CAD and was prognostically useful in subgroups of patients with stent, heavy calcification, or obstructive CAD. IPD and myocardial scarring may play complementary roles in prognostic stratification.

Combined computed tomography-derived myocardial blood flow (CTP-MBF) and computed tomography angiography (CTA) has shown good diagnostic performance for detection of coronary artery disease (CAD). However, fractal analysis might provide additional insight into ischemia pathophysiology by characterizing multiscale perfusion patterns and, therefore, may be useful in diagnosing hemodynamically significant CAD.The purpose of this study was to investigate, in a multicenter setting, whether fractal analysis of perfusion improves detection of hemodynamically relevant CAD over myocardial blood flow quantification (CTP-MBF) using dynamic, 4-dimensional, dynamic stress myocardial computed tomography perfusion (CTP) imaging.In total, 7 centers participating in the prospective AMPLIFiED (Assessment of Myocardial Perfusion Linked to Infarction and Fibrosis Explored with Dual-source CT) study acquired CTP and CTA data in patients with suspected or known CAD. Hemodynamically relevant CAD was defined as ≥90% stenosis on invasive coronary angiography or fractional flow reserve 0.80. Both fractal analysis and CTP-MBF quantification were performed on CTP images and were combined with CTA results.This study population included 127 participants, among them 61 patients, or 79 vessels, with CAD as per invasive reference standard. Compared with the combination of CTP-MBF and CTA, combined fractal analysis and CTA improved sensitivity on the per-patient level from 84% (95% CI: 72%-92%) to 95% (95% CI: 86%-99%; P = 0.01) and specificity from 70% (95% CI: 57%-82%) to 89% (95% CI: 78%-96%; P = 0.02). The area under the receiver-operating characteristic curve improved from 0.83 (95% CI: 0.75-0.90) to 0.92 (95% CI: 0.86-0.98; P = 0.01).Fractal analysis constitutes a quantitative and pathophysiologically meaningful approach to myocardial perfusion analysis using dynamic stress CTP, which improved diagnostic performance over CTP-MBF when combined with anatomical information from CTA.

Fractal analysis of dynamic, four-dimensional computed tomography myocardial perfusion (4D-CTP) imaging might have potential for noninvasive differentiation of microvascular ischemia and macrovascular coronary artery disease (CAD) using fractal dimension (FD) as quantitative parameter for perfusion complexity. This multi-center proof-of-concept study included 30 rigorously characterized patients from the AMPLIFiED trial with nonoverlapping and confirmed microvascular ischemia (nmicro = 10), macrovascular CAD (nmacro = 10), or normal myocardial perfusion (nnormal = 10) with invasive coronary angiography and fractional flow reserve (FFR) measurements as reference standard. Perfusion complexity was comparatively high in normal perfusion (FDnormal = 4.49, interquartile range [IQR]:4.46–4.53), moderately reduced in microvascular ischemia (FDmicro = 4.37, IQR:4.36–4.37), and strongly reduced in macrovascular CAD (FDmacro = 4.26, IQR:4.24–4.27), which allowed to differentiate both ischemia types, p

True myocardial blood flow can be accurately estimated from dynamic dual-source CT perfusion data using a correction method that is based on contrast kinetics in the myocardium.

Objectives The aim of this study was to assess the use of low tube potentials for coronary computed tomography angiography (CCTA) in worldwide clinical practice and its influence on radiation exposure, contrast agent volume, and image quality. Background CCTA is frequently used in clinical practice. Lowering of tube potential is a potent method to reduce radiation exposure and to economize contrast agent volume. Methods CCTAs of 4,006 patients from 61 international study sites were analyzed regarding very-low (≤80 kVp), low (90 to 100 kVp), conventional (110 to 120 kVp), and high (≥130 kVp) tube potentials. The impact on dose-length product (DLP) and contrast agent volume was analyzed. Image quality was determined by evaluation of the diagnostic applicability and assessment of the objective image parameters signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR). Results When compared with conventional tube potentials, low tube potentials were used in 56% of CCTAs (≤80 kVp: 9%; 90 to 100 kVp: 47%), which varied among sites from 0% to 100%. Tube potential reduction was associated with low–cardiovascular risk profile, low body mass index (BMI), and new-generation scanners. Median radiation exposure was lowered by 68% or 50% and median contrast agent volume by 25% or 13% for tube potential protocols of ≤80 kVp or 90 to 100 kVp when compared with conventional tube potentials, respectively (all p Conclusions This large international registry confirms the feasibility of tube potential reduction in clinical practice leading to lower radiation exposure and lower contrast volumes. The current registry also demonstrates that this strategy is still underused in daily practice. (PROspective multicenter registry on radiaTion dose Estimates of cardiac CT angIOgraphy iN daily practice in 2017 [PROTECTION-VI]; NCT02996903)

Objectives This study aimed to evaluate whether myocardial blood flow (MBF) quantified with dynamic computed tomography perfusion imaging (CTP) has an incremental prognostic value over coronary CT angiography (CTA) for major adverse cardiac events (MACEs) in patients with suspected coronary artery disease (CAD). Background The incremental prognostic value of CTP over CTA is unclear. The quantification of MBF with dynamic CTP may potentially enhance risk stratification. Methods A total of 332 patients (67% men; age: 67 ± 10 years) with suspected CAD who underwent CTA and dynamic CTP was analyzed. A MACE was defined as cardiac death, nonfatal myocardial infarction (MI), unstable angina, or hospitalization for congestive heart failure. A summed stress score (SSS) was calculated by adding scores of all myocardial segments according to normalized MBF values. Abnormal perfusion was defined as SSS ≥4. Obstructive CAD was defined as ≥50% stenosis in ≥1 vessel on CTA. Results During a median follow-up of 2.5 years, 19 patients had a MACE. Multivariate analysis showed that, when adjusted for obstructive CAD on CTA, abnormal perfusion was significantly associated with hazards for MACEs (hazard ratio [HR]: 5.7; 95% confidence interval [CI]: 1.9 to 16.9; p = 0.002), with a significant improvement in the prognostic value. Abnormal perfusion was an independent predictor even when adjusted for ≥70% stenosis in ≥1 vessel (HR: 5.4; 95% CI: 1.7 to 16.7; p = 0.003) or adjusted for ≥50% stenosis in ≥2 vessels (HR: 6.5; 95% CI: 2.2 to 18.9; p = 0.001). In the setting of obstructive CAD, annualized event rates showed a significant difference between the patients with and without abnormal perfusion for all events (12.2% vs. 1.5%; p = 0.002) and for cardiac death and nonfatal MI (4.2% vs. 0%; p = 0.015). Conclusions MBF quantified with dynamic CTP has an incremental prognostic value over CTA. The addition of dynamic CTP to CTA allows improved risk stratification of patients with CTA-detected stenosis.

Background Patient preference is pivotal for widespread adoption of tests in clinical practice. Patient preferences for invasive versus other noninvasive tests for coronary artery disease are not known. Purpose To compare patient acceptance and preferences for noninvasive and invasive cardiac imaging in North and South America, Asia, and Europe. Materials and Methods This was a prospective 16-center trial in 381 study participants undergoing coronary CT angiography with stress perfusion, SPECT, and invasive coronary angiography (ICA). Patient preferences were collected by using a previously validated questionnaire translated into eight languages. Responses were converted to ordinal scales and were modeled with generalized linear mixed models. Results In patients in whom at least one test was associated with pain, CT and SPECT showed reduced median pain levels, reported on 0-100 visual analog scales, from 20 for ICA (interquartile range [IQR], 4-50) to 6 for CT (IQR, 0-27.5) and 5 for SPECT (IQR, 0-25) (P < .001). Patients from Asia reported significantly more pain than patients from other continents for ICA (median, 25; IQR, 10-50; P = .01), CT (median, 10; IQR, 0-30; P = .02), and SPECT (median, 7; IQR, 0-28; P = .03). Satisfaction with preparation differed by continent and test (P = .01), with patients from Asia reporting generally lower ratings. Patients from North America had greater percentages of "very high" or "high" satisfaction than patients from other continents for ICA (96% vs 82%, respectively; P < .001) and SPECT (95% vs 79%, respectively; P = .04) but not for CT (89% vs 86%, respectively; P = .70). Among all patients, CT was preferred by 54% of patients, compared with 18% for SPECT and 28% for ICA (P < .001). Conclusion For cardiac imaging, patients generally favored CT angiography with stress perfusion, while study participants from Asia generally reported lowest satisfaction. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Woodard and Nguyen in this issue.

This study aimed to evaluate the effect of implementing the consensus statement from the Asian Society of Cardiovascular Imaging-Practical Tutorial 2020 (ASCI-PT 2020) on the reliability of cardiac MR with late gadolinium enhancement (CMR-LGE) myocardial viability scoring between observers in the context of ischemic cardiomyopathy.A total of 17 cardiovascular imaging experts from five different countries evaluated CMR obtained in 26 patients (male:female, 23:3; median age [interquartile range], 55.5 years [50-61.8]) with ischemic cardiomyopathy. For LGE scoring, based on the 17 segments, the extent of LGE in each segment was graded using a five-point scoring system ranging from 0 to 4 before and after exposure according to the consensus statement. All scoring was performed via web-based review. Scores for slices, vascular territories, and total scores were obtained as the sum of the relevant segmental scores. Interobserver reliability for segment scores was assessed using Fleiss' kappa, while the intraclass correlation coefficient (ICC) was used for slice score, vascular territory score, and total score. Inter-observer agreement was assessed using the limits of agreement from the mean (LoA).Interobserver reliability (Fleiss' kappa) in each segment ranged 0.242-0.662 before the consensus and increased to 0.301-0.774 after the consensus. The interobserver reliability (ICC) for each slice, each vascular territory, and total score increased after the consensus (slice, 0.728-0.805 and 0.849-0.884; vascular territory, 0.756-0.902 and 0.852-0.941; total score, 0.847 and 0.913, before and after implementing the consensus statement, respectively. Interobserver agreement in scoring also improved with the implementation of the consensus for all slices, vascular territories, and total score. The LoA for the total score narrowed from ± 10.36 points to ± 7.12 points.The interobserver reliability and agreement for CMR-LGE scoring for ischemic cardiomyopathy improved when following guidance from the ASCI-PT 2020 consensus statement.

OBJECTIVES: In this international, multicenter study, using third-generation dual-source computed tomography (CT), we investigated the diagnostic performance of dynamic stress CT myocardial perfusion imaging (CT-MPI) in addition to coronary CT angiography (CTA) compared to invasive coronary angiography (ICA) and invasive fractional flow reserve (FFR).BACKGROUND: CT-MPI combined with coronary CTA integrates coronary artery anatomy with inducible myocardial ischemia, showing promising results for the diagnosis of hemodynamically significant coronary artery disease in single-center studies.METHODS: At 9 centers in Europe, Japan, and the United States, 132 patients scheduled for ICA were enrolled; 114 patients successfully completed coronary CTA, adenosine-stress dynamic CT-MPI, and ICA. Invasive FFR was performed in vessels with 25% to 90% stenosis. Data were analyzed by independent core laboratories. For the primary analysis, for each coronary artery the presence of hemodynamically significant obstruction was interpreted by coronary CTA with CT-MPI compared to coronary CTA alone, using an FFR of ≤0.80 and angiographic severity as reference. Territorial absolute myocardial blood flow (MBF) and relative MBF were compared using C-statistics.RESULTS: ICA and FFR identified hemodynamically significant stenoses in 74 of 289 coronary vessels (26%). Coronary CTA with ≥50% stenosis demonstrated a per-vessel sensitivity, specificity, and accuracy for the detection of hemodynamically significant stenosis of 96% (95% CI: 91-100), 72% (95% CI: 66-78), and 78% (95% CI: 73-83), respectively. Coronary CTA with CT-MPI showed a lower sensitivity (84%; 95% CI: 75-92) but higher specificity (89%; 95% CI: 85-93) and accuracy (88%; 95% CI: 84-92). The areas under the receiver-operating characteristic curve of absolute MBF and relative MBF were 0.79 (95% CI: 0.71-0.86) and 0.82 (95% CI: 0.74-0.88), respectively. The median dose-length product of CT-MPI and coronary CTA were 313 mGy·cm and 138 mGy·cm, respectively.CONCLUSIONS: Dynamic CT-MPI offers incremental diagnostic value over coronary CTA alone for the identification of hemodynamically significant coronary artery disease. Generalized results from this multicenter study encourage broader consideration of dynamic CT-MPI in clinical practice. (Dynamic Stress Perfusion CT for Detection of Inducible Myocardial Ischemia [SPECIFIC]; NCT02810795).

Single-center studies indicated a high diagnostic accuracy of dynamic computed tomography perfusion (CTP) imaging in the diagnosis of coronary artery disease (CAD).This prospective multicenter study determined the diagnostic performance of combined coronary computed tomography angiography (CTA) and CTP for detecting hemodynamically significant CAD defined by invasive coronary angiography (ICA) with fractional flow reserve (FFR).Seven centers enrolled 174 patients with suspected or known CAD who were clinically referred for ICA. CTA and dynamic CTP were performed using dual-source CT before ICA. FFR was done as part of ICA in the case of 26% to 90% coronary diameter stenosis. Hemodynamically significant stenosis was defined as FFR of 0.8 or90% stenosis on ICA.The study protocol was completed in 157 participants, and hemodynamically significant stenosis was detected in 76 of 157 patients (48%) and 112 of 442 vessels (25%). According to receiver-operating characteristic curve analysis, adding dynamic CTP to CTA significantly increased the area under the curve from 0.65 (95% CI: 0.57-0.72) to 0.74 (95% CI: 0.66-0.81; P = 0.011) on the patient level, with decreased sensitivity (93% vs 72%; P 0.001), improved specificity (36% vs 75%; P 0.001), and improved overall accuracy (64% vs 74%; P 0.001).In this prospective multicenter study on dynamic CTP, the combination of anatomic assessment with coronary CTA and functional evaluation with dynamic CTP allowed more accurate identification of hemodynamically significant CAD compared with CTA alone. However, the clinical significance of this approach needs to be further investigated, including its usefulness in improving prognosis. (Assessment of Myocardial Perfusion Linked to Infarction and Fibrosis Explored With Dual-Source CT [AMPLIFiED]; UMIN000016353).

To evaluate the usefulness of the deep learning image reconstruction (DLIR) to enhance the image quality of abdominal CT, compared to iterative reconstruction technique. Pre and post-contrast abdominal CT images in 50 patients were reconstructed with 2 different algorithms: hybrid iterative reconstruction (hybrid IR: ASiR-V 50%) and DLIR (TrueFidelity). Standard deviation of attenuation in normal liver parenchyma was measured as the image noise on pre and post-contrast CT. The contrast-to-noise ratio (CNR) for the aorta, and the signal-to-noise ratio (SNR) of the liver were calculated on post-contrast CT. The overall image quality was graded on a 5-point scale ranging from 1 (poor) to 5 (excellent). The image noise was significantly decreased by DLIR compared to hybrid-IR [hybrid IR, median 8.3 Hounsfield unit (HU) (interquartile range (IQR) 7.6–9.2 HU); DLIR, median 5.2 HU (IQR 4.6–5.8), P

Introduction: Single-center studies indicated a high diagnostic accuracy of dynamic computed tomography perfusion (CTP) imaging in the diagnosis of hemodynamically significant coronary artery disease (CAD). However, no prospective multicenter study has assessed the performance of combined coronary computed tomography angiography (CTA) and dynamic CTP. Hypothesis: In this prospective multicenter study, we assessed the hypothesis that dynamic CTP can provide an incremental diagnostic value over CTA detecting hemodynamically significant CAD defined by invasive coronary angiography (ICA) with fractional flow reserve (FFR). Methods: Seven centers enrolled 165 patients with suspected or known CAD, who were clinically referred for ICA. CTA and dynamic CTP were performed using dual-source CT prior to ICA. FFR was done as part of ICA in case of 26-90% coronary diameter stenosis. Hemodynamically significant stenosis was defined as of FFR Results: The study protocol was completed in 157 participants and hemodynamically significant stenosis was detected in 112 of 442 vessels (25%) and 123 of 157 patients (78%). According to receiver operating characteristic curve analysis, CTA showed an area under the curve (AUC) of 0.81 (95% confidence interval [CI], 0.73-0.86) on the patient level and 0.80 (95% CI, 0.76-0.84) on the vessel level. Adding dynamic CTP to CTA significantly increased the AUC to 0.85 (95% CI, 0.78-0.90; p=0.027) on the patient level and to 0.84 (95% CI, 0.80-0.87; p=0.002) on the vessel level. In the subgroups of patients with 1-, 2- and 3-vessel disease by CTA, the addition of dynamic CTP to CTA significantly increased AUC from 0.80 to 0.84 (p=0.041) in 2-vessel disease and from 0.65 to 0.73 (p=0.022) in 3-vessel disease, but not in 1-vessel disease (from 0.84 to 0.87, p=0.265). Conclusion: In this first prospective multicenter study on dynamic CTP, the combination of anatomical assessment with coronary CTA and functional evaluation with dynamic CTP allowed more accurate detection of hemodynamically significant coronary artery stenosis. Improved diagnostic performance with dynamic CTP was mainly obtained when multivessel disease was suspected by CTA.

Background Noninvasive evaluation of patients with stable angina is preferable over invasive testing if it leads to similar patient outcome. The combination of coronary angiography and vasodilator challenge myocardial perfusion imaging by computed tomography allows fast, comprehensive assessment of patients with suspected coronary heart disease. Purpose To compare the long-term prognostic value of combined computed tomography angiography (CTA) and myocardial CT perfusion imaging (CTP) with invasive coronary angiography (ICA) and single photon emission tomography (SPECT) in patients with suspected hemodynamically significant coronary heart disease. Methods At 16 centres, 381 patients were followed for major adverse cardiac events (MACE) for the CORE320 study. All patients underwent coronary CTA, CTP, and SPECT before ICA. Prognostic performance according binary results (normal/abnormal) was assessed by 5-year major cardiovascular events (MACE) free survival and area under the receiver-operating-characteristic curve (AUC). Results Follow up beyond 2-years was available in 323 patients. MACE-free survival rate was greater among patients with normal combined CTA/CTP findings compared to ICA/SPECT: 85 vs. 80% (95% confidence interval [CI] for difference 0.1, 11.3) though event-free survival time was similar (4.54 vs. 4.37 years, 95% CI for difference: 0.03, 0.36). Abnormal results by combined CTA/CTP was associated with 3.83 years event-free survival vs. 3.66 years after abnormal combined ICA/SPECT (95% CI for difference: 0.05, 0.39, CI −1.0, 11.1) (Figure). Predicting MACE by AUC also was similar: 65 vs. 65 (difference 0.1; 95% CI: −4.6, 4.9). When MACE was restricted to death, myocardial infarction, or stroke, AUC for CTA/CTP was 66 vs. 61 by ICA/SPECT (difference 5.1; 95% CI: −7.1, 12.9). Conclusions Combined CTA/CTP yield similar 5-year prognostic performance as joined ICA/SPECT assessment in patients presenting with suspected coronary heart disease and thus may represent a fast, non-invasive alternative to the traditional diagnostic approach. Figure 1. 5-year event-free survival Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): National Institutes of Health

Extent of myocardial fibrosis in hemodialysis patients has been associated with poor prognosis. Myocardial extracellular volume (ECV) quantification using contrast enhanced cardiac computed tomography (CT) is a novel method to determine extent of myocardial fibrosis. Cardiac CT-based myocardial ECV in hemodialysis patients with those of propensity-matched non-hemodialysis control subjects were compared. Twenty hemodialysis patients (mean age, 67.4 ± 9.6 years; 80% male) and 20 propensity-matched non-hemodialysis controls (mean age, 66.3 ± 9.1 years; 85% male) who underwent comprehensive cardiac CT consisted of calcium scoring, coronary CT angiography, stress perfusion CT and delayed enhancement CT were evaluated. Myocardial ECV was significantly greater in the hemodialysis group than in the control group (33.8 ± 4.7% versus 26.6 ± 2.9%; P r = 0.54; P = 0.01), while there was no correlation between myocardial ECV and other cardiac parameters including left ventricular mass index and severity of myocardial ischemia. Cardiac CT-based myocardial ECV may offer a potential imaging biomarker for myocardial fibrosis in HD patients.

Delayed enhancement cardiac CT is a potential tool for myocardial viability assessment and is essential for extracellular volume fraction (ECV) estimation with CT. The objective of this study is to determine the optimal delay time for acquisition of delayed CT scans. Thirty-five patients with enhancement pattern typical of previous myocardial infarction on delayed CT and 17 control subjects comprised the study population. Delayed scans were acquired at 3, 5 and 7 min after contrast material injection. Image quality and estimated ECV were compared among the three time points. Delayed CT at 5 min showed the highest signal-to-noise ratio of 15.2 ± 1.0 [p

The purpose of this study was to examine the histological correlation of native myocardial T1 and extracellular volume fraction (ECV) measurement at 3-T for the assessment of diffuse pathological changes in the myocardial tissue, including myocardial fibrosis and extracellular space in dilated cardiomyopathy (DCM).Cardiac magnetic resonance T1 techniques allow the quantification of diffuse myocardial fibrosis. However, there are no definitive head-to-head studies of native T1 versus ECV for the detection, quantification, and characterization of pathological changes in the myocardial tissue in DCM by using histological samples for confirmation.A total of 36 subjects with DCM (31 men, mean age 56 ± 16 years) underwent pre- and post-contrast T1 mapping as well as late gadolinium enhancement (LGE) cardiac magnetic resonance at 3-T. Biopsy samples were used for the quantification of collagen volume fraction using picrosirius red staining and an extracellular space component from hematoxylin and eosin-stained myocardium.Nonischemic LGE was observed in 14 of 36 patients. Although patients with LGE had significantly greater biopsy-proven collagen volume fraction than those without LGE (21 ± 12% vs. 11 ± 8%; p 0.01), there was substantial overlap of collagen volume fraction values between patients with and without LGE. Both native T1 value and ECV were similarly and significantly associated with biopsy-proven collagen volume fraction (r = 0.77 and r = 0.66, respectively; p 0.05). Furthermore, ECV had a strong correlation with the biopsy-proven extracellular space component (r = 0.86), whereas native T1 had only a moderate correlation (r = 0.55). Interobserver and intraobserver reproducibility for native T1 and ECV were 0.89, 0.95, 0.96, and 0.98, respectively.Native T1 exhibited comparable ability as ECV measurement in the detection and quantification of histological collagen volume fraction, with high reproducibility, and therefore diffuse myocardial fibrosis in DCM may be reliably assessed by native T1 mapping without the administration of gadolinium contrast agent. In addition, cardiac magnetic resonance-derived ECV showed excellent agreement with histological extracellular space.

Aims Unrecognized myocardial scar by late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) is strongly associated with cardiac event in patients with stable coronary artery disease. The purpose of this study was to evaluate the prognostic impact of unrecognized non-infarct-related LGE (non-IR-LGE) in patients with acute myocardial infarction (AMI). Methods and results We studied 269 patients with a first clinical episode of AMI underwent cardiac MRI within 6 weeks after onset (209 men; age, 66 ± 12 years). LGE, cine MRI and T2-weighted imaging were obtained to evaluate the presence and extent of LGE and to evaluate cardiac function. Major adverse cardiac events (MACE) were defined as cardiovascular death, non-fatal AMI, unstable angina requiring revascularization, fatal arrhythmia, and heart failure. Unrecognized non-IR LGE was observed in 13.0% of patients. During follow-up periods (median, 22 months; range, 3-95 months), 8.9% of patients experienced MACE in this study. In addition, 22.9% of patients with unrecognized non-IR LGE and 6.8% of patients without unrecognized non-IR-LGE experienced MACE (P

Combined CT angiography and CT myocardial perfusion enables similar prediction of 2-year major adverse cardiovascular event–free survival, including the need for myocardial revascularization procedures, similar to that achieved with standard invasive coronary angiography and single photon emission CT perfusion imaging.

The aim of this study was to compare myocardial strain by cardiovascular magnetic resonance feature tracking (CMR-FT) to those derived from displacement encoding with stimulated echoes (DENSE) in patients with acute myocardial infarction (AMI). Twenty patients (65 pa13 years) with AMI underwent cine, DENSE, black-blood T2-weighted and late gadolinium enhancement CMR at 1.5 T. Global and segmental strain was determined by CMR-FT analysis and DENSE on matched 3 short-axis planes. Global circumferential strain by CMR-FT showed a good agreement with that by DENSE (r = 0.85, p0.001; bias 0.02, limits of agreement -0.03 to 0.06). For segmental circumferential strain, r coefficient between CMR-FT and DENSE was 0.61 (p0.001) with bias of 0.02, limits of agreement of -0.07 to 0.11. Regional circumferential strain determined by CMR-FT in infarct segments (-0.08 ± 0.05) was significantly altered compared with that in remote normal segments (-0.15 ± 0.05, p0.001). CMR-FT measurement of regional and global circumferential strain showed good agreement with DENSE in patients with AMI.

Based on the “as low as reasonably practicable” principle, the amount of radiation exposure of CT should be decreased without impairing image quality. However, the excessive reduction of radiation exposure in CT results in the degraded images with noise and artifacts. The purpose of this study was to construct virtual normal dose CT images from ultra-low dose CT images by using dilated residual networks (DRN) that can expand the receptive field. Our database consisted of 1,860 pairs of normal dose and ultra-dose chest CT images obtained from 12 patients. In our proposed method, the DRN which consisted of seven dilated convolutional layers were trained the relationship of signal patterns between ultra-low dose CT patches (small region) and the corresponding normal dose CT patches. The trained DRN was employed to construct the virtual normal dose CT images from the ultra-low dose CT images. The root mean squared error, peak signal to noise ratio, and structural similarity index for the ultra-low dose CT images to the normal dose CT images were 59.3, 32.6dB, and 0.897, whereas those for the constructed images from ultra-low dose CT with a model-based iterative reconstruction (MBIR) were 49.1, 34.1dB, and 0.956. Those indices for virtual normal dose CT images were 44.4, 35.0dB, and 0.964, showing a significant improvement when compared with the ultra-low dose CT images and the constructed images with MBIR. The virtual normal dose CT images achieved higher image quality as compared with the ultra-low dose CT images and the constructed images with MBIR.

This study sought to evaluate the potential of cardiac magnetic resonance TAccurate noninvasive diagnosis of LV diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF) remains challenging.Nineteen HFpEF patients (14 female, 65 ± 16 years of age) without primary cardiomyopathy were prospectively enrolled. Cine, late gadolinium enhancement cardiac magnetic resonance, and triple-slice TSix patients showed focal scar on late gadolinium enhancement. There was no significant difference in histological CVF between patients with and without focal myocardial scarring (p = 0.2). Septal ECV rather than native TMyocardial native T

To develop a dictionary learning (DL)-based processing technique for improving the image quality of sub-millisievert chest computed tomography (CT). Standard-dose and sub-millisievert chest CT were acquired in 12 patients. Dictionaries including standard- and low-dose image patches were generated from the CT datasets. For each patient, DL-based processing was performed for low-dose CT using the dictionaries generated from the remaining 11 patients. This procedure was repeated for all 12 patients. Image quality of normal thoracic structures on the processed sub-millisievert CT images was assessed with a 5-point scale (5 = excellent, 1 = very poor). Lung lesion conspicuity was also assessed on a 5-point scale. Image noise on sub-millisievert CT was significantly decreased with DL-based image processing (48.5 ± 13.7 HU vs 20.4 ± 7.9 HU, p = 0.0005). Image quality of lung structures was significantly improved with DL-based method (middle level of lung, 2.25 ± 0.75 vs 2.92 ± 0.79, p = 0.0078). Lung lesion conspicuity was also significantly improved with DL-based technique (solid nodules, 3.4 ± 0.6 vs 2.7 ± 0.6, p = 0.0273). Image quality and lesion conspicuity on sub-millisievert chest CT images may be improved by DL-based post-processing.

Whole-heart coronary magnetic resonance angiography (WHCMRA) permits the noninvasive assessment of coronary artery disease without radiation exposure. However, the image resolution of WHCMRA is limited. Recently, convolutional neural networks (CNNs) have obtained increased interest as a method for improving the resolution of medical images. The purpose of this study is to improve the resolution of WHCMRA images using a CNN. Free-breathing WHCMRA images with 512 × 512 pixels (pixel size = 0.65 mm) were acquired in 80 patients with known or suspected coronary artery disease using a 1.5 T magnetic resonance (MR) system with 32 channel coils. A CNN model was optimized by evaluating CNNs with different structures. The proposed CNN model was trained based on the relationship of signal patterns between low-resolution patches (small regions) and the corresponding high-resolution patches using a training dataset collected from 40 patients. Images with 512 × 512 pixels were restored from 256 × 256 down-sampled WHCMRA images (pixel size = 1.3 mm) with three different approaches: the proposed CNN, bicubic interpolation (BCI), and the previously reported super-resolution CNN (SRCNN). High-resolution WHCMRA images obtained using the proposed CNN model were significantly better than those of BCI and SRCNN in terms of root mean squared error, peak signal to noise ratio, and structure similarity index measure with respect to the original WHCMRA images. The proposed CNN approach can provide high-resolution WHCMRA images with better accuracy than BCI and SRCNN. The high-resolution WHCMRA obtained using the proposed CNN model will be useful for identifying coronary artery disease.

Background Left ventricular (LV) diastolic dysfunction is the main cause of heart failure with preserved ejection fraction (HFpEF), and is characterized by LV stiffness and relaxation. Abnormal LV global longitudinal strain (GLS) is frequently observed l in HFpEF, and was shown to be useful in identifying HFpEF patients at high risk for a cardiovascular event. Cardiovascular magnetic resonance (CMR) feature tracking (CMR-FT) enables the reproducible and non-invasive assessment of global strain from cine CMR images. However, the association between GLS and invasively measured parameters of diastolic function has not been investigated. We sought to determine the prevalence and severity of GLS impairment in patients with HFpEF by using CMR-FT, and to evaluate the correlation between GLS measured by CMR-FT and that measured by invasive diastolic functional indices. Methods Eighteen patients with HFpEF and 18 age- and sex-matched healthy control subjects were studied. All subjects underwent cine, pre- and post-contrast T1 mapping and late gadolinium-enhancement CMR. In the HFpEF patients, invasive pressure–volume loops were obtained to evaluate LV diastolic properties. GLS was quantified from cine CMR, and extracellular volume fraction (ECV) was quantified from pre- and post-contrast T1 mapping as a known imaging biomarker for predicting LV stiffness. Results GLS was significantly impaired in patients with HFpEF (− 14.8 ± 3.3 vs.–19.5 ± 2.8%, p p = 0.044). In HFpEF patients, the time constant of active LV relaxation (Tau) was strongly correlated with GLS (r = 0.817, p p = 0.021) and global radial strain (GRS) (r = − 0.552, p = 0.017). Multiple linear regression analysis revealed GLS as the only independent predictor of altered Tau (beta = 0.817, p Conclusions CMR-FT is a noninvasive approach that enables identification of the subgroup of HFpEF patients with impaired GLS. CMR LV GLS independently predicts abnormal invasive LV relaxation index Tau measurements in HFpEF patients. These findings suggest that feature-tracking CMR analysis in conjunction with ECV, may enable evaluation of diastolic dysfunction in patients with HFpEF.