The most serious controversy regarding the application of transaxial SPECT technology to /sup 201/Tl myocardial perfusion imaging is the choice between 360/sup 0/ compared with 180/sup 0/ data sampling techniques. The present study utilized the original 360/sup 0/ sampled raw data of 25 patients who had both SPECT /sup 201/Tl myocardial perfusion imaging and coronary angio/ventriculography for back projection reprocessing to accomplish the 360/sup 0//180/sup 0/ comparison. The results show a high incidence, 36% (9/25), of false-positive segmental perfusion abnormality and a high incidence, 24% (6/25), of moderate to severe degree of image distortion with the 180/sup 0/ data sampled reconstructed images. These were not observed in the 360/sup 0/ data sampled reconstructed images. The above findings confirmed our previous preliminary conclusion that even though the 180/sup 0/ data sampling technique has the advantage of providing improved image contrast and reduction in acquisition time it is not a reliable technique and should be abandoned.