Comparative study of thallium emission myocardial tomography with 180 degrees and 360 degrees data collection.

Basic and clinical evaluation of thallium single-photon emission computed tomography (SPECT) using a rotating gamma camera with 180 degrees (LPO to RAO) data collection was carried out and compared with the full 360 degrees rotation. No attenuation correction was used. In a phantom study the reconstructed image from the 180 degrees scan revealed better resolution. Although the 180 degrees scan, when compared with the 360 degrees scan, showed great photon attenuation in the deep location of a line source in water, this problem was not significant in the clinical study of six normal hearts. In 11 cases with myocardial infarction, the perfusion defect was more clearly visualized in the 180 degrees scan. The defect-to-normal (D/N) wall-count ratio was lower in the 180 degrees scan (0.48 +/- 0.16; mean +/- s.d.) than in the 360 degrees scan (0.61 +/- 15, p less than 0.05), indicating superior lesion contrast in the former. These results suggest that for myocardial SPECT the 180 degrees collection method is a more effective technique in the clinical evaluation of coronary artery disease.