ON THE GENERATION OF SHORT-AXIS AND RADIAL LONG-AXIS SLICES IN TL-201MYOCARDIAL PERFUSION SINGLE-PHOTON EMISSION TOMOGRAPHY

We tried to develop fully automatic reorientation algorithms in thalli um-201 myocardial perfusion single-photon emission tomography, and tes ted a method to evaluate the quality of reorientation. The left ventri cle was automatically segmented using count density information, conto urs generated with Laplacian operators in both transaxial and sagittal slices, and morphological and positional characteristics of the conto urs. Reorientation was automatically performed based on knowledge of t he long axis of a second degree surfac Fitted to the myocardial wall. We tried to achieve improvement in reorientation without relying on an y functional description of left ventricular shape. Quality of reorien tation was evaluated and improved using interactive tools in combinati on with radial long-axis slices. Two groups of 50 patients, after stre ss and rest, were analysed using the traditional manual and the fully automatic procedures. Automatic segmentation was successful in 98 out of 100 cases, and automatic reorientation was of reasonable quality. R eorientation obtained with the radial long-axis slices tool was better than after traditional manual or automatic reorientation. Automatic r eorientation based on second degree surface fitting was in our hands l ess successful than reported in the literature. The tool using radial long-axis slices provides a better standard for testing reorientation algorithms than the traditional manual method.