Comparison of sampling angle between 6deg and 8deg in 360deg myocardial SPECT images

The sampling angle of myocardial single photon emission computed tomography (SPECT) by 360deg data sampling was changed from 6deg (60 frames) to 8deg (45 frames), and phantom images and clinical images were compared. By this method, calculation is performed by addition between opposite frames using even number projections in reverse projection with filter correction used for SPECT image constitution, but this process simultaneously constitutes aliasing artifacts. We, therefore, attemped to reduce the artifacts utilizing two methods. Firstly, we projected the odd number. Secondly, we utilizing the off set reconstruction which projected reversely in 360deg grades. The lattice of a hot spot phantom was delineated more clearly, the homogeneity and quantitative representation of defects were improved, and changes in the image quality associated with the liver uptake were reduced in SPECT images at a sampling angle of 6deg as compared with 8deg. Images of good quality were obtained also by resting Tl-201 myocardial scintigraphy in normal subjects. (author)