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Detecting cardiac sarcoidosis; a potentially life-threatening condition is challenging and requires a multimodality imaging approach using echocardiography, PET/CT and CMR. Although 18F-FDG is the recommended PET tracer for evaluating cardiac sarcoidosis, it is limited by physiological cardiac FDG uptake and requires stringent patient preparation/ dietary modifications before imaging. We hereby present a case of cardiac sarcoidosis demonstrating myocardial FAPI uptake on cardiac PET, highlighting the potential role of 68Ga-FAPI PET in the evaluation of cardiac sarcoidosis., (Copyright © 2024 American Society of Nuclear Cardiology. Published by Elsevier Inc. All rights reserved.)

Background: Soft-tissue attenuation remains a major limitation of SPECT-MPI which interferes with the diagnosis of CAD. The current study aims to evaluate the pattern of attenuation artifacts in supine and semi-reclining positions on CZT cardiac camera and their interaction with gender, BMI and stress protocols., Methods: We prospectively analysed 150 patients acquired in supine and semi-reclining positions on CZT camera. The images were evaluated for severity and extent of defect using 17-segment model. An additional CT scan was acquired to generate AC image in the first 50 patients studied to assist investigator learning for comparison of artifact vs true defects in the two SPECT systems. The defects present in one position or showing change in severity within two positions were considered as positional artifacts and further validated using CTAC supine image., Results: In overall analysis, higher extent and severity of positional artifacts were observed more in semi-reclining position affecting the apex, apico-inferior, inferolateral and inferoseptal segments. Females showed more positional artifacts than males with inferior wall attenuation in the semireclining position and anterior wall attenuation in the supine position. A positive correlation of the extent and severity of positional artifacts was noted with an increasing BMI. In patients with BMI > 30, mid inferior and inferolateral segments were most affected followed by anterior wall segments. Highest correction of artifactual perfusion defects by CTAC was noted in inferior wall followed by inferolateral segments., Conclusion: The incidence of positional artifacts was greater in semi-reclining position in females, higher BMI groups and adenosine stress subsets. Knowledge of the pattern of positional artifacts appears to be a reliable alternative of CTAC for correct interpretation of myocardial perfusion images., (© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.)

Background: 18 F-NaF PET/CT identifies high-risk plaques due to active calcification in coronary arteries with potential to characterize plaques in ST-elevation myocardial infarction (MI) and chronic stable angina (CSA) patients., Methods: Twenty-four MI and 17 CSA patients were evaluated with 18 F-NaF PET/CTCA for SUV max and TBR values of culprit and non-culprit plaques in both groups (inter-group and intra-group comparison), and pre- and post-interventional MI plaques sub-analysis., Results: Culprit plaques in MI patients had significantly higher SUV max (1.6; IQR 0.6 vs 1.3; IQR 0.3, P = 0.03) and TBR (1.4; IQR 0.6 vs 1.1; IQR 0.4, P = 0.006) than culprit plaques of CSA. Pre-interventional culprit plaques of MI group (n = 11) revealed higher SUV max (P = 0.007) and TBR (P = 0.008) values than culprit CSA plaques. Culprit plaques showed significantly higher SUV max (P = 0.006) and TBR (P = 0.0003) than non-culprit plaques in MI group, but without significant difference between culprit and non-culprit plaques in CSA group. With median TBR cutoff value of 1.4 in MI culprit plaques, 6/7 plaques (85.7%) among the event prone non-culprit lesions had TBR values > 1.4 in CSA group., Conclusion: The study shows higher SUV max and TBR values in MI culprit plaques and comparable TBR values for event prone plaques of CSA group in identifying high-risk plaques., (© 2020. American Society of Nuclear Cardiology.)

Levo-transposition of great arteries (L-TGA) is a rare acyanotic congenital heart anomaly characterized by transposition of morphological left and right ventricles along with their corresponding atrio-ventricular valves in addition to transposition of primary arteries. Many cases of L-TGA are asymptomatic and are diagnosed accidently in adulthood during workup of other conditions. We hereby report a patient with incidentally diagnosed L-TGA who was subjected to Equilibrium Radionuclide Ventriculography (ERNV) for assessment of ventricular function. Planar ERNV images in best septal view showed prominent tracer activity in the anteriorly transposed aorta which can be a helpful clue to raise the suspicion of L-TGA in an asymptomatic adult undergoing ERNV., (© 2020. American Society of Nuclear Cardiology.)

Background: Infra-cardiac tracer activity due to persistent hepatic activity interferes in inferior and infero-septal wall assessment during 99m Tc-MIBI SPECT/CT myocardial perfusion scintigraphy (MPS) in evaluation of patients with coronary artery disease. It affects image interpretation with increased study duration. Ursodeoxycholic acid (UDCA) is known to enhance hepatic excretion of bilirubin and bile salts, though its role in enhancing the hepatic tracer clearance in facilitating cardiac imaging is not known., Methods: This prospective, randomized double-blind, placebo controlled clinical trial of 120 patients, referred for adenosine stress or viability MPS studies were randomized 1:1 to receive either UDCA or placebo. Outcome was quantitative & qualitative improvement in imaging for better interpretation and to reduce the waiting time for scan., Results: 118 participants (59 ± 11.9 years; 84 men) underwent adenosine stress MPS or viability MPS. Sixty participants had UDCA while 58 had placebo intervention. The study showed significant decrease in liver counts with improved myocardial to liver ratio at 30 and 60 minutes in adenosine stress MPS group, and marginally significant alteration in liver counts at 60 minutes in viability MPS group receiving UDCA, resulting in better images., Conclusion: UDCA intervention in MPS provides early and better image due to faster hepatic tracer clearance.

Background: Stomach wall uptake (SWU) of tracer in 99m Tc-MIBI myocardial perfusion imaging (MPI) occasionally leads to imaging artifacts, thereby lowering the diagnostic accuracy. It is less-studied phenomenon for possible link with proton pump inhibitors (PPIs) intake. This prospective work looked for association of SWU with PPI intake and compared its incidence with H 2 antagonists (H 2 A) users and patients not on either gastroprotective medication., Methods: One hundred fifty-six patients undergoing one day stress/rest 99m Tc-MIBI SPECT-MPI were distributed into four groups: control group (n = 48, not on any gastroprotective medication), PPI group (n = 47, on PPI treatment), H 2 A group (n = 19, on H 2 A therapy), and intervention group (N = 42, PPI discontinued for 3 days before MPI). Poststress planar images were analyzed for clinically relevant SWU., Results: Clinically relevant SWU was seen in 36% of PPI group patients compared to 8% in the control group, 10.5% in the H 2 A group, and 9.5% in the intervention group, respectively, with statistically significant difference. Only 1/40 patients undergoing exercise stress showed clinically relevant SWU compared to 26/116 patients undergoing adenosine stress (P = .020)., Conclusion: Patients on PPIs scheduled for vasodilator stress MPI may discontinue PPIs for 3 days, or replace with H 2 A to reduce the incidence of clinically relevant SWU associated with PPI therapy.

Objective: To test whether phase analysis indices from SPECT-MPI for left ventricular mechanical dyssynchrony (LVMD) are predictors of major adverse cardiac events (MACEs) in long-standing diabetes mellitus (DM)., Methods: A total of 136 DM patients with normal perfusion and left ventricular systolic functions were followed up for about two years and divided into two groups according to the presence and the absence of MACEs., Result: Thirteen (9.5%) patients experienced MACEs during follow-up. Patients experiencing MACEs showed significantly higher phase standard deviation (PSD) and wider phase bandwidth (PBW) than those who did not. Moreover, both PSD and PBW showed significant correlations (r = 0.25 and 0.27; P < 0.05) with duration of DM. Logistic regression analysis revealed significant associations of DM duration, microvascular complications, and LVMD indices for predicting MACEs. Kaplan-Meier event-free survival analysis revealed significantly higher rate of MACEs (Logrank = 10.02; P = 0.001) in patients with high PSD and wide PBW. An overall fit model consisting of high-PSD and wide-PBW group was improved with the addition of microvascular complications (χ 2  = 15.9; P = 0.03) and further by addition of DM duration of ≥ 15 years (χ 2  = 24.3; P = 0.007) as variables., Conclusion: LVMD indices are novel prognostic markers in diabetic patients with normal perfusion and left ventricular systolic functions and their increases in magnitudes with DM-duration and in the presence of microvascular complications.

Background: Direct ischemia imaging with F18-FDG can potentially overcome many limitations of SPECT-MPS inherent to "cold imaging". We compared SPECT-MPS with exercise F18-FDG PET in detection of ischemia in patients with suspected CAD., Methods: 45 patients with clinical suspicion of CAD without the history of myocardial infarction were prospectively included. All patients underwent Tc-99m tetrofosmin SPECT-MPS and exercise F18-FDG PET imaging within 7 days of SPECT-MPS, and both modalities were compared with coronary angiography for detecting ischemia., Results: 27 patients had an abnormal coronary angiography (at least one coronary artery with stenosis >50%). Exercise F18-FDG performed better than SPECT-MPS in LAD and LCX territory with comparably good performance in RCA territory. Exercise F18-FDG performed better in single-vessel disease and equally good in multi-vessel disease compared to SPECT-MPS. Performance of exercise 18F-FDG study was significantly better than SPECT-MPS (P = .0014) in the analysis of the 81 vascular territories in the 27 patients with abnormal coronary angiography. Performance of exercise F18-FDG was significantly better than SPECT-MPS in detecting ischemia in suspected CAD patients., Conclusion: Exercise F18-FDG imaging is a potentially useful ischemia imaging modality which offers the advantages of direct ischemia imaging in CAD patients.

Objective: To evaluate the performance parameters of FDG PET/CT in patients with Takayasu arteritis at diagnosis and during immunosuppression., Methods: Retrospective analysis of 60 FDG PET/CT studies in 51 patients was performed (17 scans at diagnosis out of which 4 had follow-up scans also and 43 scans on immunosuppression). The degree of FDG uptake in the vessels was assessed visually using a 4-point scale and maximum standardized uptake value (SUVmax), SUVratio, extent of vasculitis and association with ESR were calculated., Results: PET/CT was positive for active vasculitis in all 17 patients at diagnosis. The mean SUVmax and mean SUV ratio of the active areas were 5.1 ± 3.0 and 3.2 ± 1.9, respectively. On immunosuppression, PET scan was positive for active vasculitis in 14/43 (32.5%) scans. The mean SUVmax and mean SUVratio of the active areas were 1.7 ± 2.1 and 0.95 ± 1.2, respectively. There was significant difference between the mean SUVmax and mean SUVratio at diagnosis and on immunosuppression, respectively (P < .01). The median number of vascular segments in each uptake grade group was also statistically different (P < .01) between scans at diagnosis and on immunosuppression. The median ESR level in PET positive scans was 29 mm/hour (2-53), whereas in PET negative scans was 35.5 mm/hour (6-50) and the difference was not statistically significant., Conclusion: FDG PET/CT showed good sensitivity to detect active vasculitis at diagnosis and during immunosuppression. The change in SUVmax between the successive FDG PET/CT scans may give an objective assessment of response to immunosuppression.

Background: Of various nuclear medicine techniques, F-18/flourodeoxyglucose (FDG) positron emission tomography (PET) is considered as the best modality for the assessment of viable myocardium (VM). In this study, we compared the diagnostic accuracy of nitrate augmented Tc-99m tetrofosmin gated G-single-photon emission computed tomography (SPECT) with FDG PET., Methods: 54 consecutive cases of angiographically proven CAD with severe LV dysfunction were enrolled in the study. The patients underwent Tc-99m tetrofosmin G-SPECT and FDG PET as per the standard protocols and were compared., Results: SPECT data analysis indicated functional abnormalities in 661/918 myocardial segments. F-18 FDG PET revealed VM in 496/661 segments. The diagnostic accuracy of baseline NAC, postnitrate NAC, baseline AC, and postnitrate AC Tc-99m tetrofosmin SPECT was 84%, 87%, 90%, and 94%, respectively. κ values for NAC baseline, NAC postnitrate, AC baseline, and AC postnitrate Tc-99m tetrofosmin G-SPECT were 0.65, 0.70, 0.77, and 0.85, respectively. Attenuation correction revealed viability additionally in 46 segments which were non-viable on NAC postnitrate study (P < .001). Nitrate augmentation showed viability additionally in 25 segments which were non-viable on AC baseline scan (P = .004). On patient-based analysis FDG PET changes the management only in 13% (7/54) of patients., Conclusions: Nitrate augmented AC Tc-99m tetrofosmin G-SPECT shows excellent (κ = .85) agreement with FDG PET. FDG PET changes management only in 13% of the patients. Tc-99m tetrofosmin G-SPECT being more widely available and cheaper imaging modality can be reliably used to detect VM where FDG PET is not available.

Introduction: Fluoro-deoxy-glucose (FDG) can be used to visualize inflammation in atherosclerotic plaques in coronary arteries, if myocardial FDG uptake is adequately suppressed. Prolonged fasting for suppressing myocardial FDG uptake is inconsistent. We evaluated the feasibility to consistently suppress myocardial FDG uptake with a low carbohydrate high fat protein permitted (LCHFPP) diet., Materials and Methods: This was a prospective study. 50 patients were included in fasting group (>12 hours fasting) and 60 patients were included into LCHFPP diet. Fasting group had no special dietary preparation. Patients in LCHFPP diet group were asked to consume LCHFPP diet the night before and 4 hours prior to the study. Visual analysis of myocardial FDG uptake was done on maximum intensity projection image. Using CT images for localization, the ability to delineate possible FDG uptake in the left coronary artery was assessed in the corresponding PET image and the studies were classified as "interpretable" or "Not interpretable"., Results: 60 patients (mean age 47 years) from LCHFPP diet group and 50 patients (mean age 49.9 years) from fasting group were included. None of the patients were known diabetics. The mean blood glucose level was 96 mg/dL. Forty-eight patients had consumed LCHFPP diet as per protocol. Twelve had consumed LCHFPP diet only on the night before the study (non-compliant). The average duration of fasting in compliant patients was 5.9 ± 0.9 hours in the diet group and 14.6 hours in fasting group. In LCHFPP diet group, the myocardial FDG uptake was classified as complete suppression in 31; minimal uptake in 15; moderate inhomogenous uptake in 8 and homogenous intense uptake in 6 patients. Fifty-four of the 60 patients had interpretable study. When non-compliant patients were excluded, 84% of the patients had significant FDG uptake suppression and 94% of the studies were classified as interpretable. In the fasting group, complete myocardial suppression of FDG uptake was noticed in 16; minimal in 8; moderate inhomogenous in 15; and homogenous intense in 11 patients. 27 patients (54%) had interpretable study., Conclusion: Consistent and significant myocardial FDG uptake suppression is possible in most patients using LCHFPP diet. The LCHFPP diet, if taken as per protocol, leads to consistent myocardial FDG uptake suppression to allow for adequate evaluation of the left coronary artery inflammation in nearly all the patients. LCHFPP diet is also significantly more efficacious than prolonged (>12 hours) fasting protocol in suppressing myocardial FDG uptake.