STANDARDIZED UPTAKE VALUE OF 99mTc-SESTAMIBI IN MYOCARDIAL PERFUSION SPECT/CT

Abstract

The standardized uptake value (SUV) of 99mTc SESTAMIBI in myocardial perfusion imaging is the measured activity normalized for surface area and injected dose. As a reference, if the dose were uniformly distributed over the entire body, the value everywhere would be one. The purpose of this study is to determine the standardized uptake value in myocardial perfusion imaging patients using quantitative SPECT/ CT protocol. The materials in this study include SPECT/CT system, 99mTc SESTAMIBI, one hollow cylindrical phantom, two anthropomorphic phantoms with inserts, twenty patients with normal myocardial perfusion scan and twenty-seven abnormal patients who underwent coronary angiogram. Conversion Factor and recovery coefficient were calculated using the above phantoms and then applied to the patients. The average conversion factor and recovery coefficient were 4875 CPM/MBq and 0.565 respectively. In using the e-soft reconstruction algorithm, the SUV for mean and SD in normal myocardial perfusion scan for rest and stress studies were 8.15±1.21 and 8.00±1.5 respectively. Using Image J software method, the average SUV for three vessels of the heart, LAD, LCX and RCA, in normal myocardial perfusion imaging were 7.70±1.2, 8.15±1.1, 7.61±1.3 in rest scan and 7.67±1.2, 8.04±1.5, 7.56±1.2 in stress scan. By comparing the two methods with T-test, the SUV for normal patients were not significantly different. For abnormal scan, z scoring method is used to define the cut off score between normal SUV and abnormal SUV from image J segmentation method. Coronary angiography result was used as a gold standard to define diagnostic index. The score result on each segment of left ventricle had been compared with MPI retrospective report. The results showed that SUV had higher negative predictive value for eliminating perfusion defects. Specificity of 74%, sensitivity of 58% and accuracy of 67% of SUV study for the heart were higher than conventional myocardial perfusion imaging (51%,52%,51%), respectively. The severity of defect can be observed by looking at the negative score level. The benefit of this study is to obtain absolute quantification for myocardium perfusion measurement in SUV values.