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ApoE -/- mice are a widely used preclinical model of atherosclerosis, potentially accelerated by a Western diet (WD) or uremia. We aimed to compare hybrid 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography-magnetic resonance (PET-MR) and immunostaining in ApoE -/- models of accelerated atherosclerosis. Five groups were studied: standard diet-fed ApoE -/- (n = 7), standard diet-fed and uremic ApoE -/- (n = 7), WD ApoE -/- (n = 7), WD and uremic ApoE -/- (n = 6), and control C57BL/6J mice (n = 6). Uremia was induced by electrocoagulation of the right kidney at 8 weeks old, followed 2 weeks later by a contralateral nephrectomy. 18 F-FDG PET-MR imaging and histological staining (anti-CD4, -CD8, -CD11c, -CD20, -CD31, -CD68, -CD163, -interferon-γ, interleukin-1α, -1β, -6, -17 A antibodies) were performed in 18-week-old mice, i.e., 8 weeks after 5/6 nephrectomy and/or WD.  18 F-FDG uptake was similar in all groups. In contrast, histological staining highlighted higher percentages of CD8-, CD68-, or CD11c-positive cells in ApoE -/- aortic samples than in wild-type aortic samples. In addition, immunostaining revealed some differences between ApoE -/- mouse groups. Only the WD seemed to contribute to these differences. Using immunostaining, WD appeared to be a stronger accelerator of atherosclerosis than uremia. However, 18 F-FDG PET-MR imaging failed to demonstrate in vivo increased aortic glucose uptake in these models., Competing Interests: Declarations Ethical approval All animal procedures were approved by the regional animal ethics committee (Comité d’Éthique NOrmand en Matière d’EXpérimentation Animale, CENOMEXA 054, n°29982) and were performed in accordance with the European directive 2010/63/EU on the protection of animals used for scientific purposes and specific French laws (decree n°2013–118). Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Thoracic aortic graft infections are infrequent yet grave complications of cardiovascular surgery. Risk factors include prolonged operative time, postoperative wound infections, and patient-specific risk factors like diabetes or malnutrition (Van Hemelrijck et al., Vessel Plus 6:47, 2022). In postoperative vascular scenarios, it is critical to utilize cross-sectional imaging to detect the presence of a complication, followed by describing the morphology, extent, and ancillary features. FDG-PET/CT can help differentiate between expected postoperative changes and worrisome infection by metabolic activity (FDG uptake). We present an extensive case of ascending aortic graft infection in the setting of ongoing sternal osteomyelitis. CT and PET/CT reveal chronic sternal osteomyelitic changes spreading into the retrosternal soft tissues, and a large intraluminal thrombus in the ascending aortic graft. Small mobile strands propagate toward the right brachiocephalic origin, posing a significant stroke risk. PET/CT confirmed postoperative infection by demonstrating increased FDG uptake., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Purpose: Study aims to investigate the consistency of delayed enhancement cardiac magnetic resonance imaging (DE-CMR) and 18 F-FDG PET myocardial imaging in evaluating myocardial viability before CABG., Methods: The study analyzed data from 100 patients who were examined with DE-CMR, PET imaging, and echocardiography before and after CABG. All subjects were followed up for 6-12 month post- CABG., Results: DE-CMR and PET imaging have high consistency (90.1%; Kappa value = 0.71, p < 0.01) in determining myocardial viability. The degree of delayed enhancement was negatively correlated with the improvement in myocardial contractile function in this segment after revascularization (P < 0.001). The ratio of scarred myocardial segments and total DE score was significantly lower in the improvement group than non-improvement group. Multivariate regression identified that hibernating myocardium (OR = 1.229, 95%CI: 1.053-1.433, p = 0.009) was influencing factor of LVEF improvement after CABG., Conclusion: Both imaging techniques are consistent in evaluating myocardial viability. Detecting the number of hibernating myocardium by PET is also important to predict the left heart function improvement after CABG., (© 2024. The Author(s).)

Purpose: To examine the prognostic significance of pretreatment 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]-FDG) positron emission tomography (PET)-based radiomic features using a machine learning approach in patients with endometrial cancers., Procedures: Included in this retrospective study were 53 patients with endometrial cancers who underwent [ 18 F]-FDG PET/X-ray computed tomography (CT) before treatment. Since two different PET scanners were used, post-reconstruction harmonization was performed for all PET parameters using the ComBat harmonization method. Four clinical (age, histological type, stage, and treatment method) and 40 [ 18 F]-FDG PET-based radiomic features were ranked, and a subset of useful features was selected based on the decrease in the Gini impurity in terms of associations with disease progression. The machine learning algorithms (random forest, neural network, k-nearest neighbors (kNN), naive Bayes, logistic regression, and support vector machine) were compared using the areas under the receiver operating characteristic curve (AUC) and validated by the random sampling method. Progression-free survival (PFS) and overall survival (OS) were assessed by the Cox regression analysis., Results: The five best predictors of disease progression were coarseness, gray-level run length nonuniformity, stage, treatment method, and gray-level zone length nonuniformity. The kNN model obtained the best performance classifier for predicting the disease progression (AUC =0.890, accuracy =0.849, F1 score =0.848, precision =0.857, and recall =0.849). Coarseness which was the first ranked radiomic feature was selected for survival analyses, and only coarseness remained as a significant and independent factor for both PFS (hazard ratios (HR), 0.65; 95 % confidence interval [CI], 0.49-0.86; p=0.003) and OS (HR, 0.52; 95 % CI, 0.36-0.76; p<0.001) at multivariate Cox regression analysis., Conclusions: [ 18 F]-FDG PET-based radiomic analysis using a machine learning approach may be useful for predicting tumor progression and prognosis in patients with endometrial cancers., (© 2021. World Molecular Imaging Society.)

Purpose: To investigate the possibility of reducing the injected activity for whole-body [18F]FDG-PET/CT studies of paediatric oncology patients and to assess the usefulness of time-of-flight (TOF) acquisition on PET image quality at reduced count levels., Procedures: Twenty-nine paediatric oncology patients (12F/17M, 3-18 years old (median age 13y), weight 45±20 kg, BMI 19±4 kg/m 2 ), who underwent routine whole-body PET/CT examinations on a Siemens Biograph mCT TrueV system with TOF capability (555ps) were included in this study. The mean injected activity was 156 ± 45 MBq (3.8 ± 0.8 kg/MBq) and scaled to patient weight. The raw data was collected in listmode (LM) format and pre-processed to simulate reduced levels of [18F]FDG activity (75, 50, 35, 20 and 10% of the original counts) by randomly removing events from the original LM data. All data were reconstructed using the vendor-specific e7-tools with standard OSEM only, with OSEM plus resolution recovery (PSF). The reconstructions were repeated with added TOF (TOF) and PSF+TOF. The benefit of TOF together with the reduced count levels was evaluated by calculating the gains in signal-to-noise ratio (SNR) in the liver and contrast-to-noise ratio (CNR) in all PET-positive lesions before and after TOF employed at every simulated reduced count level. Finally, the PSF+TOF images at 50, 75 and 100% of counts were evaluated clinically on a 5-point scale by three nuclear medicine physicians., Results: The visual inspection of the reconstructed images did not reveal significant differences in image quality between 75 and 100% count levels for PSF+TOF. The improvements in SNR and CNR were the greatest for TOF reconstruction and PSF combined. Both SNR and CNR gains did increase linearly with the patients BMI for both OSEM only and PSF reconstruction. These benefits were observed until reducing the counts to 50 and 35% for SNR and CNR, respectively., Conclusions: The benefit of using TOF was noticeable when using 50% or greater of the counts when evaluating the CNR and SNR. For [18F]FDG-PET/CT, whole-body paediatric imaging the injected activity can be reduced to 75% of the original dose without compromising PET image quality., (© 2021. The Author(s).)

Background: To determine the normal perivalvular 18 F-Fluorodeoxyglucose ( 18 F-FDG) uptake on positron emission tomography (PET) with computed tomography (CT) within one year after aortic prosthetic heart valve (PHV) implantation., Methods: Patients with uncomplicated aortic PHV implantation were prospectively included and underwent 18 F-FDG PET/CT at either 5 (± 1) weeks (group 1), 12 (± 2) weeks (group 2) or 52 (± 8) weeks (group 3) after implantation. 18 F-FDG uptake around the PHV was scored qualitatively (none/low/intermediate/high) and quantitatively by measuring the maximum Standardized Uptake Value (SUV max ) and target to background ratio (SUV ratio )., Results: In total, 37 patients (group 1: n = 12, group 2: n = 12, group 3: n = 13) (mean age 66 ± 8 years) were prospectively included. Perivalvular 18 F-FDG uptake was low (8/12 (67%)) and intermediate (4/12 (33%)) in group 1, low (7/12 (58%)) and intermediate (5/12 (42%)) in group 2, and low (8/13 (62%)) and intermediate (5/13 (38%)) in group 3 (P = 0.91). SUV max was 4.1 ± 0.7, 4.6 ± 0.9 and 3.8 ± 0.7 (mean ± SD, P = 0.08), and SUV ratio was 2.0 [1.9 to 2.2], 2.0 [1.8 to 2.6], and 1.9 [1.7 to 2.0] (median [IQR], P = 0.81) for groups 1, 2, and 3, respectively., Conclusion: Non-infected aortic PHV have similar low to intermediate perivalvular 18 F-FDG uptake with similar SUV max and SUV ratio at 5, 12, and 52 weeks after implantation., (© 2020. The Author(s).)

Over the past several decades, molecular imaging techniques to assess cellular processes in vivo have been integral in advancing our understanding of disease pathogenesis. 18 F-fluorodeoxyglucose (18-FDG) positron emission tomography (PET) imaging in particular has shaped the field of atherosclerosis research by highlighting the importance of underlying inflammatory processes that are responsible for driving disease progression. The ability to assess physiology using molecular imaging, combining it with anatomic delineation using cardiac coronary angiography (CCTA) and magnetic resonance imaging (MRI) and lab-based techniques, provides a powerful combination to advance both research and ultimately clinical care. In this review, we demonstrate how molecular imaging studies, specifically using 18-FDG PET, have revealed that early vascular disease is a systemic process with multiple, concurrent biological mechanisms using inflammatory diseases as a basis to understand early atherosclerotic mechanisms in humans., (© 2020. This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection.)

Background: 18 F-fluoromisonidazole (FMISO) is a hypoxia positron emission tomography (PET) tracer. Here, we evaluated cardiac and extra-cardiac sarcoidosis using both FMISO and 18 F-fluorodeoxyglucose (FDG) PET/CT in a prospective cohort of patients with sarcoidosis., Methods: Ten consecutive sarcoidosis patients with suspected cardiac involvement were prospectively enrolled. Each patient fasted overnight (for ≥ 18 hours) preceded by a low-carbohydrate diet before FDG PET/CT but not given special dietary instructions before the FMISO PET/CT scan. We visually and semiquantitatively assessed the uptakes of FMISO and FDG using the maximal standardized uptake value (SUV max ). The metabolic volume (MV) of FDG was calculated as the volume within the boundary determined by the threshold (mean SUV of blood pool × 1.5)., Results: Nine patients showed focal FDG uptake in the myocardium and were diagnosed with cardiac sarcoidosis. Among the patients with extra-cardiac lesions, FDG uptake was seen in 8 lymph nodes and 3 lung lesions. FMISO uptake was seen in the 7 cardiac (77.8%) and 6 extra-cardiac (54.5%) lesions. None of the patients showed physiological FMISO uptake in the myocardium. The SUV max values of the lesions with FMISO uptake were higher than those of the lesions without FMISO uptake in both the cardiac (SUV max : 9.9, IQR: 8.4-10.0 vs 7.3, IQR: 6.3-8.2) and non-cardiac lesions (SUV max : 17.6, IQR: 14.5-19.3 vs 6.1, IQR: 5.9-6.2; P = 0.006). The MV values of the lesions with FMISO uptake were significantly higher than those of the lesions without FMISO uptake (111.3, IQR: 78.3-135.7 vs 6.4, IQR: 1.9-23.3; P = 0.0009)., Conclusions: FMISO showed no physiological myocardial uptake and did not require special preparation. FMISO PET has the potential to detect hypoxic lesions in patients with sarcoidosis., (© 2019. American Society of Nuclear Cardiology.)

Purpose: The aim of this study was the evaluation of quantitative and qualitative parameters for the diagnosis of aortic graft infection (AGI) using [ 18 F]-FDG PET/CT., Methods: PET/CT was performed in 50 patients with clinically suspected AGI. 12 oncological patients with aortic repair but without suspicion of AGI were included in the analysis to serve as control cohort. The [ 18 F]-FDG uptake pattern around the graft was assessed using (a) a five-point visual grading scale (VGS), (b) SUV max and (c) different graft-to-background ratios (GBRs). The diagnostic performance of VGS, SUV max and GBRs was assessed and compared by ROC analysis., Results: 28 infected and 34 uninfected grafts were identified by standard of reference. SUV max and VGS were the most powerful predictors for the diagnosis of AGI according to the area under the curve (AUC 0.988 and 0.983, respectively) without a significant difference compared to GBRs. SUV max and VGS showed congruent and accurate findings in 54 patients (i.e. either both positive or negative), yielding sensitivity and specificity (100%) in this subgroup of patients., Conclusion: Quantitative analysis by SUV max and qualitative analysis by VGS are highly effective in the diagnosis of AGI and should be tested as an outcome measure in prospective trials., (© 2020. American Society of Nuclear Cardiology.)

Background: Hybrid PET/MR imaging has significant potential in cardiology due to its combination of molecular PET imaging and cardiac MR. Multi-tissue-class MR-based attenuation correction (MRAC) is necessary for accurate PET quantification. Moreover, for thoracic PET imaging, respiration is known to lead to misalignments of MRAC and PET data that result in PET artifacts. These factors can be addressed by using multi-echo MR for tissue segmentation and motion-robust or motion-gated acquisitions. However, the combination of these strategies is not routinely available and can be prone to errors. In this study, we examine the qualitative and quantitative impacts of multi-class MRAC compared to a more widely available simple two-class MRAC for cardiac PET/MR., Methods and Results: In a cohort of patients with cardiac sarcoidosis, we acquired MRAC data using multi-echo radial gradient-echo MR imaging. Water-fat separation was used to produce attenuation maps with up to 4 tissue classes including water-based soft tissue, fat, lung, and background air. Simultaneously acquired 18F-fluorodeoxyglucose PET data were subsequently reconstructed using each attenuation map separately. PET uptake values were measured in the myocardium and compared between different PET images. The inclusion of lung and subcutaneous fat in the MRAC maps significantly affected the quantification of 18F-fluorodeoxyglucose activity in the myocardium but only moderately altered the appearance of the PET image without introduction of image artifacts., Conclusion: Optimal MRAC for cardiac PET/MR applications should include segmentation of all tissues in combination with compensation for the respiratory-related motion of the heart. Simple two-class MRAC is adequate for qualitative clinical assessment., (© 2020. American Society of Nuclear Cardiology.)

Background: 18 F-Fluoride uptake denotes calcification activity in aortic stenosis and atherosclerosis. While PET/MR has several advantages over PET/CT, attenuation correction of PET/MR data is challenging, limiting cardiovascular application. We compared PET/MR and PET/CT assessments of 18 F-fluoride uptake in the aortic valve and coronary arteries., Methods and Results: 18 patients with aortic stenosis or recent myocardial infarction underwent 18 F-fluoride PET/CT followed immediately by PET/MR. Valve and coronary 18 F-fluoride uptake were evaluated independently. Both standard (Dixon) and novel radial GRE) MR attenuation correction (AC) maps were validated against PET/CT with results expressed as tissue-to-background ratios (TBRs). Visually, aortic valve 18 F-fluoride uptake was similar on PET/CT and PET/MR. TBR MAX values were comparable with radial GRE AC (PET/CT 1.55±0.33 vs. PET/MR 1.58 ± 0.34, P = 0.66; 95% limits of agreement - 27% to + 25%) but performed less well with Dixon AC (1.38 ± 0.44, P = 0.06; bias (-)14%; 95% limits of agreement - 25% to + 53%). In native coronaries, 18 F-fluoride uptake was similar on PET/MR to PET/CT regardless of AC approach. PET/MR identified 28/29 plaques identified on PET/CT; however, stents caused artifact on PET/MR making assessment of 18 F-fluoride uptake challenging., Conclusion: Cardiovascular PET/MR demonstrates good visual and quantitative agreement with PET/CT. However, PET/MR is hampered by stent-related artifacts currently limiting clinical application., (© 2019. The Author(s).)

Background: Despite the association of physical activity with improved cardiovascular outcomes and the association of high coronary artery calcification (CAC) scores with poor prognosis, elite endurance athletes have increased CAC. Yet, they nevertheless have better cardiovascular survival. We hypothesized that exercise may transform vascular calcium deposits to a more stable morphology., Methods: To test this, hyperlipidemic mice (Apoe -/- ) with baseline aortic calcification were separated into 2 groups (n = 9/group) with control mice allowed to move ad-lib while the exercise group underwent a progressive treadmill regimen for 9 weeks. All mice underwent blood collections and in vivo 18 F-NaF μPET/μCT imaging both at the start and end of the exercise regimen. At euthanasia, aortic root specimens were obtained for histomorphometry., Results: Results showed that, while aortic calcification progressed similarly in both groups based on µCT, the fold change in 18 F-NaF density was significantly less in the exercise group. Histomorphometric analysis of the aortic root calcium deposits showed that the exercised mice had a lower mineral surface area index than the control group. The exercise regimen also raised serum PTH levels twofold., Conclusion: These findings suggest that weeks-long progressive exercise alters the microarchitecture of atherosclerotic calcium deposits by reducing mineral surface growth, potentially favoring plaque stability., (© 2020. American Society of Nuclear Cardiology.)

Background: To evaluate the diagnostic value of 18 F-FDG PET/CT in distinguishing benign versus malignant cardiac tumors as well as to assess its prognostic value., Methods: We analyzed 38 patients with cardiac tumors who underwent 18 F-FDG PET/CT and followed for median 8.5 ± 12.5 months. SUV max and TBR max (maximum tumor-to-background ratio) by receiver-operating characteristic (ROC) curve analysis were used to obtain threshold for the diagnosis of malignancy as defined by histology (n = 38). Survival was assessed and correlated with the dignity of the lesions and PET parameters., Results: Optimal cut-off values indicating malignancy were as follows: SUV max  = 3.44, with 100% sensitivity and 92.9% specificity, and TBR max  = 1.55, with 95.8% sensitivity and 92.9% specificity. A significant difference of 18 F-FDG uptake was observed between primary benign (n = 14, SUV max  = 2.35 ± 1.31, TBR max  = 1.05 ± 0.50) compared to primary malignant cardiac tumors (n = 11, SUV max  = 8.90 ± 4.23, TBR max  = 3.82 ± 1.44) as well as cardiac metastases and lymphoma (n = 13, SUV max  = 14.37 ± 8.05, TBR max  = 6.19 ±  3.38) (all P < .001). Survival rate was significantly lower in patients with malignant as compared to benign cardiac tumors (P < .05). Regression analysis revealed that the lesion dignity determined by the cut-off value of SUV max was an independent predictor for death in patients with cardiac tumors (P < .05)., Conclusion: 18 F-FDG uptake in cardiac tumors can differentiate between benign and malignant cardiac tumors and predicts survival., (© 2020. American Society of Nuclear Cardiology.)

Background: 18 F-florbetapir PET is emerging as an excellent quantitative tool to quantify cardiac light chain (AL) amyloidosis burden. The primary aim of this study was to determine interobserver reproducibility and intraobserver repeatability, defined per the recommendations of the Quantitative Imaging Biomarker Alliance technical performance group, of PET 18 F-florbetapir retention index (RI) in patients with cardiac AL amyloidosis., Methods: The study cohort comprised 37 subjects with systemic AL amyloidosis enrolled in the prospective study: Molecular Imaging of Primary Amyloid Cardiomyopathy (clinical trials.gov NCT: 02641145). Using 10 mCi of 18 F-florbetapir, a 60-minute dynamic cardiac scan was acquired. Global and segmental left ventricular estimates of retention index (RI) of 18 F-florbetapir were calculated (Carimas 2.9 software, Turku, Finland). RI was analyzed twice, at least 24 hours apart, by two independent observers. Intraobserver repeatability and interobserver reproducibility were evaluated using Bland-Altman plots and scatter plots with fitted linear regression curves., Results: All reproducibility (interobserver, r = 0.98) and repeatability (intraobserver, R=0.99 for each observer) measures of 18 F-florbetapir RI are excellent. On the Bland-Altman plots, the agreement limits for global 18 F-florbetapir RI were high and ranged for reproducibility (interobserver) from - 9.3 to + 9.4% (Fig. 1), and for repeatability (observer 1 from - 10.8 to + 10.7% and from - 9.2 to + 11.4%, for observer 2)., Conclusions: The present study showed excellent interobserver reproducibility and intraobserver repeatability of 18 F-florbetapir PET retention index in patients with cardiac AL amyloidosis., (© 2019. American Society of Nuclear Cardiology.)

Abdominal aortic aneurysm (AAA) disease is characterized by an asymptomatic, permanent, focal dilatation of the abdominal aorta progressing towards rupture, which confers significant mortality. Patient management and surgical decisions rely on aortic diameter measurements via abdominal ultrasound surveillance. However, AAA rupture can occur at small diameters or may never occur at large diameters, implying that anatomical size is not necessarily a sufficient indicator. Molecular imaging may help identify high-risk patients through AAA evaluation independent of aneurysm size, and there is the question of the potential role of positron emission tomography (PET) and emerging role of novel radiotracers for AAA. Therefore, this review summarizes PET studies conducted in the last 10 years and discusses the usefulness of PET radiotracers for AAA risk stratification. The most frequently reported radiotracer was [ 18 F]fluorodeoxyglucose, indicating inflammatory activity and reflecting the biomechanical properties of AAA. Emerging radiotracers include [ 18 F]-labeled sodium fluoride, a calcification marker, [ 64 Cu]DOTA-ECL1i, an indicator of chemokine receptor type 2 expression, and [ 18 F]fluorothymidine, a marker of cell proliferation. For novel radiotracers, preliminary trials in patients are warranted before their widespread clinical implementation. AAA rupture risk is challenging to evaluate; therefore, clinicians may benefit from PET-based risk assessment to guide patient management and surgical decisions., (© 2021. The Author(s).)

Purpose: To evaluate the effectiveness of propranolol at mitigating FDG uptake in brown adipose tissue (BAT) of pediatric patients with known or suspected malignancies., Methods: PET/CT scans of 3 cohorts of patients treated from 2005 to 2017 were scored for the presence of FDG uptake by BAT at 7 sites: right or left neck/supraclavicular area, right or left axilla, mediastinum, posterior thorax, and abdomen/pelvis. Uptake was scored as follows: 0, none; 1, mild uptake < liver; 2, moderate uptake = liver; and 3, intense uptake > liver. Group 1 consisted of 323 patients (630 scans) who had no specific preparation to mitigate FDG uptake by BAT. Group 2 consisted of 345 patients (705 scans) who underwent only warming in an uptake room with a fixed temperature at 24 °C. Group 3 consisted of 622 patients (1457 scans) who underwent warming. In group 3, patients 8 years and older, 471 patients (1114 scans), were also pre-medicated with oral propranolol 60 min before injection of FDG. Generalized estimation equation, using the logit link method, was used to model the relationship between the incidence of BAT score > 0, in any site, as a function of age, sex, seasonal effect, and body surface area (BSA)., Results: In patients aged 8 years or older, the incidence of BAT uptake was 35-44 % and declined to 15 % with propranolol. BAT was most frequent in the neck (26 %), axilla (18 %), posterior thorax (18 %), mediastinum (14 %), and abdomen/pelvis (8 %); BAT was less common in warm months (p = 0.001). No substantial benefit was shown with pre-injection warming alone. No significant effect was found for age, sex, or BSA separately. When BAT uptake was present, it was usually intense., Conclusion: Propranolol preparation minimizes FDG uptake by BAT and should be considered routine for pediatric FDG PET/CT cancer-related protocols in children, adolescents, and young adults.

We compared the effects of ezetimibe/rosuvastatin 10/5 mg versus rosuvastatin 20 mg on carotid atherosclerotic plaque inflammation measured by 18 FDG PET/CT. Fifty patients with acute coronary syndrome (ACS) were randomly assigned to the ezetimibe/rosuvastatin 10/5 mg and rosuvastatin 20 mg groups. The primary outcome was the percent change in the target-to-background ratio (TBR) of the index vessel in the most diseased segment (MDS), as assessed by 18 FDG PET/CT at baseline and at 6 months. Forty-eight patients completed follow-up PET/CT. MDS TBR was - 6.2 ± 13.9% for patients in the ezetimibe/rosuvastatin group and - 10.8 ± 17.7% for those in the rosuvastatin group (difference, 4.6 percentage points; upper limitation of one-sided confidence interval = 13.8; p = 0.60 for noninferiority). In conclusion, combination therapy with ezetimibe 10 mg and rosuvastatin 5 mg compared with rosuvastatin 20 mg did not meet the criterion for non-inferiority for primary outcome, and the present study was not conclusive on whether the former was non-inferior to the latter. Graphical Abstract.

To compare the left ventricular (LV) phase dyssynchrony parameters obtained from Tc-99m Sestamibi SPECT (GSPECT) and F-18 FDG PET(GPET), as well as the prognostic values in patients with ischemic cardiomyopathy (ICM). Consecutive ICM patients referred for myocardial viability assessment were retrospectively evaluated and were followed-up for 21 ± 5 months. Phase parameter from both GSPECT and GPET were analyzed by QGS software, including histogram bandwidth (BW), standard deviation (SD) and entropy. Independent predictor for cardiac death was analyzed by Cox regression analysis. The estimated cardiac survival curve was analyzed by and was compared with the log-rank test. Eight-eight (mean age 56 ± 10, male 94%, LVEF SPECT 23 ± 10%) ICM patients were included for analysis. Moderate correlations were observed for BW (r = 0.65; p < 0.001), SD (r = 0.63; p < 0.001) and entropy (r = 0.73; p < 0.001) between GSPECT and GPET. Among all covariates, the extent of myocardial scar was significantly associated with the differences of SD (r = 0.22; p < 0.05) and entropy (r = - 0.7; p < 0.05), whereas the extent of myocardial viability was not (all p > 0.05). Entropy measured by GSPECT was the predictor for cardiac death (p = 0.037) while QRS duration was not. The cardiac survival of patients with a high entropy (≥ 59%) was significantly lower than that of patients with low entropy (< 59%) (p < 0.05). GSPECT and GPET-derived phase parameters were not interchangeable in ICM patients. Patients with LV dyssynchrony measured by gated SPECT were associated with a worse outcome.

Purpose: Integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) offers promising tools for evaluating brain disorders, including the minimization of exposure to ionizing radiation. Considering the length of scanning time with PET/MRI systems and their high sensitivity, we assumed that the activity could be reduced by one half compared with recommended activity for brain 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) PET exams without degrading image quality., Procedures: We retrospectively simulated the reduction of injected activity (1 vs. 2 MBq/kg, [ 18 F]FDG) in 100 patients assessed for cognitive impairment with simultaneous PET/MRI imaging. A list-mode acquisition was used to generate a 20-min image set as a reference (PET STD ) and to simulate a low-dose injection with a 10-min image (PET LD ). We tested the reproducibility between PET LD and PET STD with a blinded visual interpretation by two nuclear physicians asked to classify metabolic patterns, and a quantitative analysis conducted with regions-of-interest. Voxelwise comparisons between patients suggestive of Alzheimer's disease (AD) and frontotemporal dementia (FTD) were also conducted., Results: The intra-operator agreement was high between the PET STD and PET LD visual assessments for both readers (kappa 0.92 and 0.99). SUV ratios were strongly reproducible (intraclass correlation coefficient 0.95). The voxelwise and regional comparisons between AD vs. FTD metabolic profiles yielded very similar results with PET STD and PET LD ., Conclusions: A reduction of the [ 18 F]FDG dose down to 1 MBq/kg is possible when performing 20-min brain PET/MRI without modifying diagnostic performance and quantitative assessments. The advantage is a significant reduction in the patient effective dose, which is non-negligible in longitudinal follow-up studies and in research protocols involving healthy volunteers.

The aim of the study was to evaluate the ability to detect extra-cardiac foci by means of whole-body 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients with definite endocarditis (IE) according to the modified Duke criteria and investigate the clinical impact of the findings. From January 2011 to December 2015 we included 178 patients (mean age 66 ± 14 years, 25% female) with IE in this multicentre study. FDG-PET/CT was part of the work-up for extra-cardiac foci in the including hospitals and was performed at a median of 9 days (IQR 10) after IE was diagnosed. In 114 patients FDG-PET/CT identified 166 lesions: 52 (31%) infectious lesions, 21 (13%) cases of cancer, 7 (4%) cases of embolism, 60 (36%) reactive findings, and 26 (16%) other types of lesions. A total of 74 new extra-cardiac findings, not previously discovered by other modalities, were identified in 62 patients and resulted in additional investigations in 29 patients and a change in treatment in 18 patients (10%). The most frequent diagnoses discovered by FDG-PET/CT were colon polyps, cancer, and spondylodiscitis. There was a higher rate of findings leading to a change in treatment in patients above 67 years of age infected with other bacterial aetiologies than streptococci. FDG-PET/CT was useful to detect extra-cardiac foci. FDG-PET/CT findings may lead to unnecessary investigations. One out of 10 the patients with definite endocarditis had underwent a change in treatment regimen based on the FDG-PET/CT findings.

Vascular wall 18 F-FDG uptake is often used as a surrogate marker of atherosclerotic plaque inflammation. A potential caveat is that vascular wall 18 F-FDG uptake is higher simply because more atherosclerosis is present. To determine if the degree of inflammation is high or low relative to the extent of atherosclerosis, vascular wall 18 F-FDG uptake may require statistical adjustment for a non-inflammatory marker reflecting the extent of atherosclerosis, e.g. calcification. Adjustments is probably needed if (1) vascular wall 18 F-FDG uptake correlates sufficiently strongly with arterial calcification and (2) adjustment for extent of calcification affects determinants of vascular 18 F-FDG uptake. This study addresses these questions. 18 F-FDG PET/low-dose-CT scans of 99 patients were used. Cardiovascular risk factors were assessed and PET/CT scans were analysed for standardized 18 F-FDG uptake values and calcification. ANOVA was used to establish the association between vascular 18 F-FDG uptake and calcification. Multiple linear regression (with and without calcification as independent variable) was used to show whether determinants of vascular 18 F-FDG uptake were affected by the degree of calcification. 18 F-FDG uptake was related to increased calcification in the aortic arch, descending and abdominal aorta. However, 18 F-FDG uptake showed considerable overlap between categories of calcification. Age and body mass index were main determinants of vascular 18 F-FDG uptake. In multiple regression analyses, most standardized beta coefficients of these determinants were not affected by adjustment for the degree of calcification. Although vascular 18 F-FDG uptake is related to total atherosclerotic burden, as reflected by vascular calcification, the association is weak and unlikely to affect the identification of determinants of atherosclerotic inflammation implicating no need for adjustment in future studies.

No data exist whether statins have robust anti-inflammatory effects of atherosclerotic plaques primarily during the early treatment period or continuously throughout use. This prospective three time point 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) study of the carotid artery assessed anti-inflammatory effects of statin during the early treatment period (initiation to 3 months) and late treatment period (3 months to 1 year) and their correlation with lipid and inflammatory profile changes during a year of therapy. Nine statin-naïve stable angina patients with inflammatory carotid plaques received 20 mg/day atorvastatin after undergoing initial 18 F-FDG PET/CT scanning of carotid arteries and ascending thoracic aorta, and then completed serial 18 F-FDG PET/CT imaging at 3 and 12 months whose data were analyzed. The primary outcome was the inter-scan percent change in target-to-background ratio (ΔTBR) within the index vessel. At 3 months of atorvastatin treatment, mean serum low-density lipoprotein cholesterol (LDL-C) level decreased by 36.4% to < 70 mg/dL (p = 0.001) and mean serum high-density lipoprotein cholesterol level increased to > 40 mg/dL (p = 0.041), with both maintained with no further reduction up to 1 year (p = 0.516 and 0.715, respectively) while mean serum high sensitivity C-reactive protein level only numerically decreased (p = 0.093). The index vessel ΔTBR showed continuous plaque inflammation reduction over 1 year, by 4.4% (p = 0.015) from the initiation to 3rd months and 6.2% (p = 0.009) from 3rd months to 1 year, respectively, without correlation with lipid profile changes. The ΔTBR of the bilateral carotid arteries and ascending aorta also continuously decreased from 3 months to 1 year. Three time point 18 F-FDG PET/CT imaging demonstrates that statin's anti-inflammatory effect continues throughout its use up to 1 year, even though yielding stable below-target plasma LDL-C levels at 3 months.

To determine the value of 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in differentiating malignancy of pulmonary artery (PA) from pulmonary thromboembolism (PTE) based on a larger number of cases by pooling our cases and those from the literature. Consecutive patients with a PA lesion who had undergone 18 F-FDG PET/CT in our hospital were retrospectively reviewed. Moreover, PubMed, Embase, and Medline were searched for literature reporting individual maximum standardised uptake value (SUV max ) of the malignant PA lesion and/or PTE. 18 F-FDG activity was compared between PA malignancy and PTE by pooling the data from literature and our patients. Receiver operating characteristic curve analysis was performed to determine the ability of SUV max to differentiate PA malignancy from PTE. From our database, we identified 11 patients with pulmonary artery sarcoma (PAS), and nine cases of PTE. Fifty patients with a malignant PA lesion (40 cases of PAS and 10 cases of tumor embolism) and 22 subjects with PTE were extracted from the literature. In our cases, the SUV max of PAS (11.1 ± 4.9, range: 5.5-19.9) was significantly higher than that of PTE (1.9 ± 0.6, range: 1.1-3.2; P < 0.001). There was no significant difference in the SUV max between the literature data and our cases in malignant lesions or in PTE. Based on the pooled analysis of the literature data and our cases (61 cases of malignant lesions and 31 cases of PTE), the area under the curve for SUV max to differentiate PA malignancy from PTE was 0.996 (95% CI: 0.989-1.000). At a cutoff value of 3.3, the sensitivity, specificity, and accuracy were 98.4%, 96.8%, and 97.8%, respectively. The 18 F-FDG uptake value is an accurate index for determining PA malignancy.

Glucose metabolism in atherosclerotic arteries has been shown to be an indicator of inflammation, which might be a precursor of plaque rupture. In this prospective study, we assessed the correlation between artery calcification and glucose metabolism by means of 18F-FDG PET/CT imaging in elderly subjects. Nineteen elderly subjects, with age ranging from 65 to 85 years, underwent CT and dynamic 18F-FDG-PET imaging. The artery calcification was determined with a threshold of 130 Hounsfield units. Intensity of calcification and ratio of calcification area to total artery area were classified in four sequential classes from CT images. The CT artery images were also classified as having single or multi-spot calcifications. Their respective glucose metabolism was assessed with fractional uptake rate (FUR). Factor analysis was used in this study to separate blood images from tissue to extract the blood time activity curves for FUR calculations. The artery images in PET data were corrected for partial volume effect. The total arterial segments analyzed were 1332, with 1085 without calcification (81%), 247 (19%) with calcification, and 94 segments were having multi-spot of calcifications. There was a statistically significant difference in FUR values between non-calcified to calcified segments and between subjects under medication to non-medication when comparing the subjects based on calcification area. No statistically significant differences of FUR were found between single spot as a function of intensity, while in the multi-spots, there was a statistically significant difference for all artery segments. Metabolism activity varies for non-calcified to calcified segments. Based on the metabolic activity represented by FUR, calcifications in multi-spots have different effects than in single spots.

To develop and test a model predicting 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) standardized uptake value (SUV) changes over time in the aorta and the superior vena cava (SVC). Maximum aortic SUV and mean SVC SUV were determined at two time points (T1 and T2) in the ascending (ASC), descending (DSC), abdominal (ABD) aorta, aortic arch (ARC) and SVC of patients who have undergone [ 18 F]FDG PET/CT for clinical purposes. For SUV prediction at T2, linear and non-linear models of SUV difference for a given time change were developed in a derivation group. The results were tested in an independent validation group, whilst model reproducibility was tested in patients of the validation group who have undergone a second clinically indicated scan. Applying the linear model in the derivation group, there were no statistically significant differences in measurements obtained in the examined segments: mean differences ranged from 0 ± 0.10 in SVC to 0.01 ± 0.13 in ARC between measured and predicted SUV. In contrast, in the non-linear model, there were statistically significant differences in measurements, except in ARC, with mean differences ranging from 0.04 ± 0.14 in ARC to 0.28 ± 0.13 in ABD. In the validation group using the linear model, there were no statistically significant differences, with mean differences ranging from - 0.01 ± 0.08 in ASC to - 0.03 ± 0.11 in ABD. Regarding reproducibility, mean differences were no statistically significant, ranging from 0.004 ± 0.06 in ASC to - 0.02 ± 0.16 in ABD. We have developed a linear model allowing accurate and reproducible prediction of SUV changes over time in the aorta and SVC.

Purpose: Myocardial uptake can hamper visualization of lung tumors, atherosclerotic plaques, and inflammatory diseases in 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) studies because it leads to spillover in adjacent structures. Several preparatory pre-imaging protocols (including dietary restrictions and drugs) have been proposed to decrease physiological [ 18 F]FDG uptake by the heart, although their effect on tumor glucose metabolism remains largely unknown. The objective of this study was to assess the effects of a ketogenic diet (as an alternative protocol to fasting) on tumor glucose metabolism assessed by [ 18 F]FDG positron emission tomography (PET) in a mouse model of lung cancer., Procedures: PET scans were performed 60 min after injection of 18.5 MBq of [ 18 F]FDG. PET data were collected for 45 min, and an x-ray computed tomograph (CT) image was acquired after the PET scan. A PET/CT study was obtained for each mouse after fasting and after the ketogenic diet. Quantitative data were obtained from regions of interest in the left ventricular myocardium and lung tumor., Results: Three days on a ketogenic diet decreased mean standard uptake value (SUVmean) in the myocardium (SUVmean 0.95 ± 0.36) more than one night of fasting (SUVmean 1.64 ± 0.93). Tumor uptake did not change under either dietary condition., Conclusions: These results show that 3 days on high-fat diets prior to [ 18 F]FDG-PET imaging does not change tumor glucose metabolism compared with one night of fasting, although high-fat diets suppress myocardial [ 18 F]FDG uptake better than fasting.

(1) To evaluate the prognostic value of LV remodeling parameters in patients with LV aneurysm by gated SPECT (GSPECT), gated PET (GPET) and CMR; (2) to evaluate the impact of myocardial viability and LV remodeling on the long-term cardiac survival in patients with LV aneurysm. One hundred and twenty-six consecutive patients underwent GPET, GSPECT and CMR within two weeks, with a mean follow-up of 3.9 ± 1.5 years. End-diastolic volume (EDV, mL) and end-systolic volume (ESV, mL) measured by GPET, GSPECT and CMR and corrected for BSA; EDVI and ESVI were calculated. Patients were divided into three groups by aneurysmal viability [mismatch score (MMS) of aneurysm ≥2.0] and LV remodeling (ESVI by GPET > 60 mL/m 2 ). Group 1 (Viability -, LV remodeling -); Group 2 (Viability -, LV remodeling +) and Group 3 (Viability +, LV remodeling -/+). ESVI by GPET, MMS of aneurysm and summed rest score of aneurysm by multivariate regression analysis; as well as ESVI by GPET (HR 1.024, 95% CI 1.011-1.037, p = .0004), MMS of aneurysm (HR 1.284, 95% CI 1.051-1.577, p = .015) by interaction analysis were approved being independent predictors for cardiac death (p < .05). The long-term cardiac survival was significantly improved by revascularization in comparison with medical therapy in Group3 (p < .01), but did not significantly differ between Groups 1 and 2. ESVI by GPET showed a significant positive predictive value for cardiac death. Patients with viable myocardial aneurysm were most likely at increased risk for cardiac death and coronary revascularization was significantly associated with improved long-term cardiac survival. In contrast, the long-term cardiac survival of patients without LV remodeling and without aneurysmal viability was promising and, thus, could be treated by medical therapy.

Human herpesvirus (HHV)-6 reactivation is associated with severe forms of encephalitis among patients undergoing hematopoietic stem cell transplantation. Cases in non-neutropenic patients are uncommon. The efficacy of ganciclovir and other compounds that are used for the treatment of HHV-6 encephalitis remains suboptimal and linked to toxicity. Valganciclovir, the oral prodrug of ganciclovir, could be practical to treat outpatients, but it is not commonly used for severe cases. We report a case of HHV-6 encephalitis in a non-neutropenic patient successfully treated with valganciclovir and undergoing therapeutic drug monitoring in plasma and in the cerebrospinal fluid. Resolution of infectious foci was documented by cerebral MRI and F18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). A review of the literature on HHV-6 encephalitis is also reported.

Large-vessel vasculitis (LVV) is a group of diseases mainly comprised of giant-cell arteritis (GCA), Takayasu arteritis, and a series of rare diseases like Behçet's disease, IgG4-related disease, infectious aortitis, and other unfrequent entities. Besides clinical and laboratory features, Doppler sonography (DS) can assist in establishing the diagnosis. Its diagnostic sensitivity has been evaluated in various studies, most of them, however, in temporal arteritis (TA) respectively in LVV with involvement of the temporal artery. Little is known in extracranial LVV. We retrospectively evaluated the diagnostic accuracy of DS in 30 patients with extracranial, non-temporal LVV using the highly sensitive PET/CT as method of reference in comparison to 20 controls who were found to have no LVV. We investigated ten arterial sites and documented the presence of the sonographic halo sign. Sensitivities of DS for LVV were highest in the subclavian and axillary arteries (71.4%/72.2%) and low in the abdominal aorta (26.1%) and the common femoral artery (16.7%). DS detected 24 out of 30 cases of LVV (overall sensitivity 80.0%). The LVV cases where DS was completely negative did not significantly differ in leukocyte count, C-reactive protein, or erythrocyte sedimentation rate from LVV cases with positive DS. DS is a potent method in diagnosing extracranial LVV especially in the axillary and the subclavian arteries. Aortic, intraabdominal, and lower extremity artery manifestations, however, are often missed by DS. A second imaging modality (e.g., PET/CT) is therefore required.

Increasing evidence supports a role of inflammation in the development of atrial fibrillation (AF). However, direct evidence of persistent inflammatory activity in the atria of AF patients is scarce. In this study, we used 18-Fluor-Deoxyglucose positron emission tomography computed tomography ( 18 F-FDG PET/CT) to determine atrial inflammation in patients with and without AF. Retrospectively, 18 F-FDG PET/CT scans were analyzed. 37 patients with a history of AF were compared to an age and sex matched control group with no history of AF. Standardized uptake values were obtained in the atrial walls, in the left ventricular wall, and in the right ventricular blood pool, respectively. Target to background ratios (TBR) were determined in the atrial and left ventricular walls and compared between the two groups. TBR values of the left atrial wall were slightly but not significantly higher in patients with AF (1.21 ± 0.27) compared to those without AF (1.14 ± 0.29; p = 0.85). Likewise, a weak but not significant difference was observed in signal intensities in the right atrial wall between patients in the AF (1.14 ± 0.45) and the control group (0.96 ± 0.2; p = 0.41). TBR values of the left ventricular myocardium did not differ between the groups; no significant correlation was found between the TBR in the left and right atrial wall and blood glucose levels. 18 F-FDG PET/CT performed under routine conditions did not detect a significant difference in inflammatory activity in the left or right atrium between patients with and without AF. Contrary to previous reports, these results therefore do not clearly support a role for ongoing atrial inflammation in patients with AF. Prospective clinical studies using myocardial glucose uptake suppression strategies may be helpful to clarify these issues.

The extra-cardiac work-up in infective endocarditis (IE) comprises a search for primary and secondary infective foci. Whether 18 FDG-PET/CT or WBC-SPECT/CT is superior in detection of clinically relevant extra-cardiac manifestations in IE is unexplored. The objectives of this study were to identify the numbers of positive findings detected by each imaging modality, to evaluate the clinical relevance of these findings and to define the reproducibility for extra-cardiac foci in patients with definite IE. Each modality was evaluated for numbers and location of positive extra-cardiac foci in patients with definite IE. A team of 2 × 2 cardiologists evaluated each finding to determine clinical relevance. Clinical utility was determined by 4 criteria converted into an ordinal scale. Using the manifestation with highest clinical utility rating in each patient, the clinical impact of the two imaging modalities was expressed in a clinical utility score. To evaluate reproducibility for each modality, an imaging core laboratory reviewed all findings. In 55 IE patients, 91 pathological foci were found by FDG-PET/CT and 37 foci were identified by WBC-SPECT/CT (p < 0.001). The clinical utility of FDG-PET/CT was significantly higher than that of WBC-SPECT/CT when comparing clinical utility score (2.06 vs. 1.17; p = 0.01). In assessment of extra-cardiac diagnostics in IE, inter-observer reproducibility was substantial for WBC-SPECT/CT (k 0.69, 95% CI 0.49-0.89) and substantial to excellent for FDG-PET/CT (k 0.79, 95% CI 0.61-0.98). FDG-PET/CT has a significantly higher clinical utility score than WBC SPECT/CT and is potentially superior to WBC-SPECT/CT in detection of extra-cardiac pathology in patients with IE.

Purpose: The purpose of the study was to evaluate the physiological accumulation of 18 F-FDG in the muscles in relation to the side of intravenous administration., Materials and Methods: We retrospectively investigated 3,118 18 F-FDG-PET/CT examinations. We evaluated the physiological accumulation of FDG in the muscles of the shoulder and arm relative to its dependence on the side of intravenous administration., Results: Six hundred six of the 3,118 examinations (19.4%) showed physiological accumulation of FDG in the teres minor muscle. Accumulation was seen on the side of administration in 486 examinations (80.2%), contralateral to the side of administration in 56 examinations (9.2%), and bilaterally in 64 examinations (10.6%). Five hundred seventy-seven of the 3,118 examinations (18.5%) showed accumulation of FDG in the muscles between the radioulna near the elbow. Accumulation was observed on the side of administration in 432 examinations (74.9%), contralateral to the side of the administration in 71 examinations (12.3%), and bilaterally in 74 examinations (12.8%)., Conclusion: The present study finds that not only accumulation in the teres minor muscles but also accumulation in the muscles between the radioulna near the elbow occurs significantly more frequently on the side of intravenous administration compared to the contralateral side.

Purpose: Delineation of gross tumour volume in 3D is a critical step in the radiotherapy (RT) treatment planning for oropharyngeal cancer (OPC). Static [ 18 F]-FDG PET/CT imaging has been suggested as a method to improve the reproducibility of tumour delineation, but it suffers from low specificity. We undertook this pilot study in which dynamic features in time-activity curves (TACs) of [ 18 F]-FDG PET/CT images were applied to help the discrimination of tumour from inflammation and adjacent normal tissue., Methods: Five patients with OPC underwent dynamic [ 18 F]-FDG PET/CT imaging in treatment position. Voxel-by-voxel analysis was performed to evaluate seven dynamic features developed with the knowledge of differences in glucose metabolism in different tissue types and visual inspection of TACs. The Gaussian mixture model and K-means algorithms were used to evaluate the performance of the dynamic features in discriminating tumour voxels compared to the performance of standardized uptake values obtained from static imaging., Results: Some dynamic features showed a trend towards discrimination of different metabolic areas but lack of consistency means that clinical application is not recommended based on these results alone., Conclusions: Impact of inflammatory tissue remains a problem for volume delineation in RT of OPC, but a simple dynamic imaging protocol proved practicable and enabled simple data analysis techniques that show promise for complementing the information in static uptake values.

Purpose: In Japan, commercially delivered FDG is manufactured in three batches per day at fixed constant activity and distributed in vials. Consequently, the amount of activity administered to the patient varies depending on the timing of injection. We evaluated a method for adjusting the scan time according to the body mass index (BMI) to obtain equivalent image quality for every patient., Methods: We examined a total of 301 routine clinical oncology PET scans using commercially delivered FDG. The relation between the injected activity and the noise equivalent count per scan length (NECpatient) was evaluated as a marker of image quality; its association with BMI was also examined., Results: The injected activity and NECpatient exhibited large variations (230.4 ± 55.8 MBq and 19.9 ± 2.9 Mcounts/m). There was a weak correlation between the injected activity and NECpatient (r ~ 0.3) for thin patients (BMI < 21 kg/m(2)), but no correlation for patients with higher BMIs. However, a significant correlation was found between BMI and NECpatient (p < 0.0001)., Conclusion: In a community hospital using commercially delivered FDG, it is possible to reduce the variability of the NECpatient and obtain uniform image quality by changing the scan time as a function of patient BMI, even with uncontrollable injected activity.

This study sought to discover which atherosclerotic plaque components co-localize with enhanced [(18)F]-fluorodeoxyglucose (FDG) uptake in carotid positron emission tomography (PET) images. Although in vivo PET currently lacks the resolution, high-resolution ex vivo FDG-microPET with histology validation of excised carotid plaque might accomplish this goal. Thirteen patients were injected with FDG before carotid endarterectomy. After excision, the plaque specimens were scanned by microPET and magnetic resonance imaging, and then serially sectioned for histological analysis. Two analyses were performed using generalized linear mixed models: (1) a PET-driven analysis which sampled high and low FDG uptake areas from PET images to identify their components in matched histology specimens; and (2) a histology-driven analysis where specific plaque components were selected and matched to corresponding PET images. In the PET-driven analysis, regions of high FDG uptake were more likely to contain inflammatory cells (p < 0.001) and neovasculature (p = 0.008) than regions of low FDG uptake. In the histology-driven analysis, regions with inflammatory cells (p = 0.001) and regions with loose extracellular matrix (p = 0.001) were associated with enhanced FDG uptake. Furthermore, areas of complex inflammatory cell infiltrate (co-localized macrophages, lymphocytes and foam cells) had the highest FDG uptake among inflammatory subgroups (p < 0.001). In conclusion, in carotid plaque, regions of inflammatory cell infiltrate, particularly complex one, co-localized with enhanced FDG uptake in high-resolution FDG-microPET images. Loose extracellular matrix and areas containing neovasculature also produced FDG signal. This study points to the potential ability of FDG-PET to detect the cellular components of the vulnerable plaque.

The aim of this study was to assess the impact of cardiovascular risk factors and plaque inflammation on the progression of atherosclerosis as assessed by positron emission tomography/computed tomography (PET/CT) imaging with (18)F-radiolabled fluorodeoxyglucose ((18)F-FDG). This study was designed as a retrospective cohort study. Patients who received a (18)F-FDG PET/CT scan and follow-up scan 9-24 months later without systemic inflammation or steroid medication were eligible for the study. (18)F-FDG PET/CT included a full diagnostic contrast enhanced CT scan. Cardiovascular risk factors and medication were documented. Calcified plaque volume, lumen area and (18)F-FDG uptake, quantified by the target-to-background ratio (TBR), were measured in the carotid arteries, aorta and iliac arteries. Influence of cardiovascular risk factors and vessel wall inflammation on atherosclerotic disease progression was analyzed. Ninety-four patients underwent baseline and follow-up whole body (18)F-FDG PET/CT (mean follow-up time 14.5 ± 3.5 months). Annualized calcified plaque volume increased by 15.4 % (p < 0.0001), carotid and aortic lumen area decreased by 10.5 % (p < 0.0001) and 1.7 % (p = 0.045). There was no significant difference in (18)F-FDG uptake at baseline and follow-up (mean TBR 1.44 ± 0.18 vs. 1.42 ± 0.19, p = 0.18). Multiple linear regression analysis identified hypertension as an independent predictor for total, aortic and iliac calcified plaque volume progression (all p < 0.04). Carotid lumen reduction was predicted by hypercholesterolemia (p = 0.008) while aortic lumen reduction was associated with BMI and mean (18)F-FDG uptake (p ≤ 0.005). Furthermore we observed a dose response relationship between the number of cardiovascular risk factors and calcified plaque volume progression in the aorta (p = 0.03). Findings from this study provide data on the natural history of atherosclerotic disease burden in multiple vascular beds and emphasize the value of morphological and physiologic information provided by (18)F-FDG PET/CT imaging.

Inflammation is associated with the development of atrial fibrillation (AF). Activity in hematopoietic tissues, which produce inflammatory leukocytes, is closely related to systemic inflammation, arterial inflammation and cardiovascular events, but its relationship to AF is unknown. Using 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging, we examined the relationships between AF, splenic metabolic activity and vascular inflammation. We conducted a cross sectional study of 70 participants: 35 with AF, who were matched (by age, sex and history of active cancer) to 35 controls without AF. Splenic metabolic activity and vascular aortic inflammation were measured by the mean FDG maximum standard uptake values (SUV Max) by PET. We examined (1) the association between AF and splenic activity, and (2) AF and aortic inflammation. The mean age of the population was 68.13 (standard deviation (SD) 8.98) years and 46 (65 %) participants were male. Splenic activity was higher in AF participants [2.31 (SD 0.45) vs. 2.07 (SD 0.37), p = 0.024], and remained significant after adjusting for demographic and clinical covariates. Aortic inflammation was also higher in AF participants [2.22 (SD 0.44) vs. 1.91 (SD 0.44), p = 0.004], and remained significant on multivariable analysis. Aortic inflammation and splenic activity were highly correlated (Pearson R = 0.61, p < 0.001). Atrial fibrillation is associated with higher hematopoietic tissue activation and arterial inflammation. Further studies are needed to clarify the mechanisms by which this cardio-splenic axis is implicated in AF.

Aim of this study was to investigate the relationship between (18)F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) findings and serological biomarkers of inflammation and the related discriminant value of unfavourable outcome during follow-up in patients with acute aortic syndromes (AAS). Sixty patients with AAS underwent PET-CT imaging during the hospitalization along with measurement of C-reactive protein (CRP) and D-dimer (D-d) serum levels. An aortic wall pathology was considered PET-positive by a maximum standardized uptake value (SUVmax) >2.5. A combined endpoint of major adverse events (MAE) including aorta-related mortality, disease progression and re-intervention was used to compare patient subgroups at 3-year follow-up. PET-CT detected an elevated FDG uptake within the aortic wall in 25 (41.7%) patients. PET-positive patients showed significantly increased CRP levels (10.0 ± 6.6 mg/dL) and tended to higher D-d levels (5.1 ± 3.9 mg/L), compared to PET-negative patients (5.8 ± 6.1 mg/dL and 3.1 ± 4.7 mg/L respectively; P = 0.048, P = 0.19). At 3-year follow-up, all-cause mortality and MAE were higher in the PET-positive (21.7 and 47.8% respectively) than PET-negative group (0.0 and 13.3% respectively; P = 0.012, P = 0.006). On Kaplan-Meier analysis, PET-positive patients were at higher risk of MAE (P = 0.031). This tendency was more evident by combining PET results with D-d levels at a cutoff value of 4.8 mg/L (P < 0.001). In patients with AAS, a pathological glucose uptake in aortic wall lesions by PET-CT was associated with high CRP levels and increased mortality and MAE at 3-year follow-up. The combination of PET results with D-d levels had the best discriminant value of MAE.

Purpose: We evaluated the glucose metabolism after microinjections of a GABAA antagonist, bicuculline, and a GABAA agonist, muscimol, in the rat prelimbic cortex (PL) by small animal positron emission tomography (μPET)., Procedures: Following a microinjection of either 0.5 μl bicuculline (0.1 mg/ml), muscimol (1 mg/ml), or saline in the left PL of 11 healthy male Sprague Dawley rats (250-275 g), 2-deoxy-2-[(18)F]fluoro-β-D-glucose ([(18)F]FDG) PET images were acquired. Volume-of-interest (VOI)-based analysis and voxel-based statistical parametric mapping were performed (n = 9)., Results: VOI-based analysis revealed significantly different [(18)F]FDG uptake following bicuculline versus muscimol in PL (p < 0.001), infralimbic cortex (p < 0.01), and cingulate cortex (p < 0.01). Voxel-based analysis showed bicuculline induced widespread significant hypermetabolism throughout the brain while muscimol induced significant localized hypometabolism., Conclusions: Here, we visualize functional GABAA-mediated correlations of the PL following pharmacological stimulation. This could serve as a reference and shed light on the working and focality of other stimulation paradigms targeting this region.

Background: This study aimed to determine if delayed (18)F-fluorodeoxyglucose ((18)FDG) PET/CT imaging improves quantitation of atherosclerotic plaque inflammation. Blood-pool activity can disturb the arterial (18)FDG signal. With time, blood-pool activity declines. Therefore, delayed imaging can potentially improve quantitation of vascular inflammation., Methods and Results: 40 subjects were prospectively assessed by dual-time-point PET/CT imaging at approximately 90 and 180 minutes after (18)FDG administration. For both time-points, global uptake of (18)FDG was determined in the carotid arteries and thoracic aorta by calculating the blood-pool corrected maximum standardized uptake value (cSUVMAX). A target-to-background ratio (TBR) was calculated to determine the contrast resolution at 90 and 180 minutes. Furthermore, we assessed whether the acquisition time-point affected the relation between cSUVMAX and the estimated 10-year risk for fatal cardiovascular disease (SCORE %). A significant increase in carotid cSUVMAX (23%, P < .0001), carotid TBR (20%, P < .0001), aortic cSUVMAX (14%, P < .0001), and aortic TBR (20%, P < .0001) was observed with time. At 90 minutes, cSUVMAX did not relate to SCORE %, whereas at 180 minutes significant positive relations were observed between SCORE % and carotid (τ = 0.25, P = .045) and aortic (τ = 0.33, P = .008) cSUVMAX., Conclusions: Delayed (18)FDG PET/CT imaging at 180 minutes improves quantitation of atherosclerotic plaque inflammation over imaging at 90 minutes. Therefore, the optimal acquisition time-point to assess atherosclerotic plaque inflammation lies beyond the advocated time-point of 90 minutes after (18)FDG administration.

The separation of multiple PET tracers within an overlapped scan based on intrinsic difference of pharmacokinetics is challenging due to the limited SNR of PET measurements and high complexity of fitting models. This study developed a novel direct parametric reconstruction method by integrating a multi-tracer model with reduced number of fitting parameters into image reconstruction. To incorporate the multitracer model, we adopted EM surrogate functions for the optimization of the penalized log-likelihood. The algorithm was validated on realistic simulation phantoms and real rapid [18F]FDG and [18F]FLT PET imaging of mice with lymphoma mouse tumor. Both results have been compared with conventional methods and demonstrated evident improvements for the separation of multiple tracers.

Purpose: The aim of the study was to improve abdominal tumor detection by use of a dual radiologic contrast protocol., Procedures: eXia160® (Benitio international) was mixed with 2-deoxy-2-[¹⁸F]fluoro-D: -glucose or 3'-[¹⁸F]fluoro-3'-deoxythymidine for intravenous (IV) injections. Omnipaque® 300 (GE healthcare) was used for intraperitoneal (IP) injections. Positron emission tomography/computed tomography (PET/CT) scans were acquired on a Siemens Biograph® equipped with point spread function reconstruction. The optimal concentration and injection schedule of IP contrast agent was studied in 12 mice. The impact of IP contrast media on PET quantitative accuracy was investigated by phantom studies and by imaging six mice before and after IP injection of Omnipaque®. The impact of a dual contrast media protocol on tumor delineation and quantitation was evaluated in 15 tumor-bearing mice using ex vivo counting as the reference., Results: The optimal sequence was a mixture of tracer plus IV contrast agent followed by 1 mL of IP contrast agent (20 mg iodine/mL) administered 10 min before PET/CT acquisition. Phantom studies showed that the use of a 20-mg iodine/mL concentration of Omnipaque® led to a 4.8% overestimation of radioactivity concentration, as compared to saline. This was confirmed by animal studies that demonstrated a 4.3% overestimation. Tumor detection was excellent and correlation between PET/CT quantitative data and ex vivo counting was good (r² = 0.91, slope = 0.7)., Conclusions: A dual radiologic contrast protocol is useful in PET/CT scanning of mice bearing abdominal tumors. Contrast agents used in this manner lead to a small but acceptable overestimation of quantitative PET data.

Purpose: We developed a new type of scintillation detector ring for positron emission tomography (PET). In this device the scintillation detectors were connected with 2.6 m length optic fibers to transport scintillation light to a photomultiplier (PMT) located apart from the detector rings. The present study aimed to test the possibility of simultaneous imaging with PET and magnetic resonance imaging (MRI) by means of the present PET device in ex vivo rat brain., Materials and Methods: The scintillation detector ring of 4 cm diameter was located in a magnetic field of 0.15 T open MRI. Simultaneous measurements of PET and MRI were performed in ex vivo rat brain after injection of (18)F-fluorodeoxyglucose ((18)F-FDG) 37 MBq and (18)F-NaF 37 MBq. Simultaneous data acquisition was performed for 10 min for PET and 5 min for T1-weighted MRI., Results: Simultaneous imaging of PET and MRI was possible without noticeable image distortion in the PET and MRI scans. In the fusion images, high uptake of (18)F-FDG was identified in the Harderian glands and striatum. High uptake of (18)F-NaF was found in the skull base and vault., Conclusions: The present study indicated the possibility of simultaneous imaging of PET and MRI by means of optic fiber-based scintillation detectors.

The purpose of these guidelines is to assist nuclear medicine practitioners in recommending, performing, interpreting, and reporting the results of brain perfusion SPECT studies using Tc-99m radiopharmaceuticals and brain metabolism PET studies using F-18 fluorodeoxyglucose (FDG). These guidelines have been adapted and extended from those produced by the Society of Nuclear Medicine (Juni et al., 1998) and the European Association of Nuclear Medicine by a Belgian group of experts in the field trained in neurology and/or nuclear medicine. Some indications are not universally approved (e.g. brain death), but largely supported by the literature. They have been included in these guidelines in order to provide recommendations and a standardised protocol.