ABSTRACT
Objective To study the ambient radiation of patients undergoing 18F-FDG PET/CT myocardial metabolism imaging, and to provide data for protection of surrounding people against radiation. Methods A total of 33 patients were selected for 18F-FDG PET/CT myocardial metabolism imaging. Dose equivalent rate was measured at the height of patient chest, in different directions, at different time points and at different distances, to investigate the distribution of ambient radiation of the patient. Results At the same time point and distance, the dose equivalent rates at the left and right sides of the patient were lower than the front and back sides. The dose equivalent rate at 1 m in front of the patient was 13-21 μSv/h after 18F-FDG injection, and decreased to 5-14 μSv/h after PET/CT imaging, with a mean decrease of 46%. The ambient dose equivalent rate decreased exponentially with distance (10~300 cm), and the mean power was −1.2. Conclusion The ambient radiation of patients undergoing 18F-FDG PET/CT myocardial metabolism imaging was high after 18F-FDG injection, and the ambient dose equivalent rate decreased rapidly with time and distance. Our results suggest that patients undergoing myocardial metabolism imaging should avoid prolonged and close contact with other people on the day of examination.
ABSTRACT
Objective: To assess the effect of coronary collateral circulation (CCC) on myocardial viabilityin patients with chronic total occlusion of left anterior descending (LAD) artery. Methods: A total of 101 consecutive patients with confirmed diagnosis of total LAD occlusion in our hospital were enrolled. Rest 99mTc-MIBISPECT myocardial perfusion and 18F-FDG PET were performed, in addition all patients received coronary angiography (CAG) at 3 months front and back. Both images were reconstructed in the same machine and QPS software was used to obtain the summed rest score (SRS), abnormal resting total perfusion defect (TPD), viable and non-viable myocardium, LVEDV, LVESV and LVEF in relevant patients. Based on CAG result, the patients were divided into 2 groups: CCC group, n=39 and No CCC group, n=62; according to existing old myocardial infarctionand location of LAD occlusion, the patients were further divided into 4 subgroups. The above parameters were compared among different groups. Results: There were 86 male and 15 female patients with the mean age at (59.92±11.43) years. Relevant parameters in CCC group and No CCC groupwere as in SRS: (21.23±9.68) vs (28.56±8.76), TPD: (30.03±13.69) %vs (40.37±12.50) %, viable myocardium: (21.77±13.12) % vs (13.66±9.23) %, non-viable myocardium (8.28±8.58) %vs (27.40±12.97) %, all P<0.05; in LVEDV: (109.82±30.01) ml vs (173.71±57.69) ml, LVESV: (62.82±22.39) ml vs (122.53±51.66) ml, LVEF: (43.85±8.46) % vs (31.03±8.30) %, all P<0.05. Conclusion: Our preliminary study found that CCC could maintain left ventricular rest perfusion, myocardial viability and protect cardiac function in patients with chronic total LAD occlusion.