Quantification of Myocardial Blood flow using Dynamic N-13 Ammonia PET and factor Analysis

Choi, Yong; Kim, Joon Young; Im, Ki Chun; Kim, Jong Ho; Woo, Sang Keun; Lee, Kyung Han; Kim, Sang Eun; Choe, Yearn Seong; Kim, Byung Tae

Abstract

PURPOSE: We evaluated the feasibility of extracting pure left ventricular blood pool and myocardial time-activity curves (TACs) and of generating factor images from human dynamic N-13 ammonia PET using factor analysis. The myocardial blood flow (MBF) estimates obtained with factor analysis were compared with those obtained with the user drawn region-of-interest (ROI) method.
MATERIALS AND METHODS
Stress and rest N-13 ammonia cardiac PET imaging was acquired for 23 min in 5 patients with coronary artery disease using GE Advance tomograph. Factor analysis generated physiological TACs and factor images using the normalized TACs from each dixel. Four steps were involved in this algorithm: (a) data preprocessing; (b) principal component analysis; (c) oblique rotation with positivity constraints; (d) factor image computation. Area under curves and MBF estimated using the two compartment N-13 ammonia model were used to validate the accuracy of the factor analysis generated physiological TACs. The MBF estimated by factor analysis was compared to the values estimated by using the ROI method.
RESULTS
MBF values obtained by factor analysis were linearly correlated with MBF obtained by the ROI method (slope=0.84, r=0.91). Left ventricular blood pool TACs obtained by the two methods agreed well (Area under curve ratio: 1.02 (0~1 min), 0.98 (0~2 min), 0.86 (1~2 min)).
CONCLUSION
: The
RESULTS
of this study demonstrates that MBF can be measured accurately and noninvasively with dynamic N-13 ammonia PET imaging and factor analysis. This method is simple and accurate, and can measure MBF without blood sampling, ROI definition or spillover correction. KW: N-13 ammonia, PET, Myocardial blood flow, Factor analysis