EFFECT OF 360-DEGREES AND 180-DEGREES ROTATION SPET ACQUISITIONS ON MYOCARDIAL POLAR MAP - COMPARISON OF TL-201-LABELED, TC-99(M)-LABELED AND I-123-LABELED RADIOPHARMACEUTICALS

Both 360 degrees and 180 degrees rotation acquisition methods have bee n used in myocardial single photon emission tomography (SPET) studies. We compared both methods using Tl-201, Tc-99(m) and I-123 radiopharma ceuticals with phantoms and clinical models. Myocardial phantom studie s with anterior and inferior defects were performed using Tl-201, Tc-9 9(m) and I-123. Clinical models of 14 typical situations, including no rmal subjects, patients with anterior or inferior defects and a high r ight hemi-diaphragm, were studied. The radiopharmaceuticals were Tl-20 1, Tc-99(m)-sestamibi, I-123-BMIPP and I-123-MIBG. Four sets of 180 de grees anterior rotation data with starting angles of (A) posterior, (B ) LPO 30 degrees, (C) LPO 60 degrees and (D) left lateral direction we re generated and compared with 360 degrees rotation SPET. A polar map display was used for quantification. In phantom studies, the defect co ntrast on the map was higher in the anterior defect with 180 degrees r otation than with 360 degrees rotation. However, it was decreased in t he inferior defect, particularly with Tl-201, because of decreased wal l activity around the defect. In the patient model with anterior or in ferior defects, the defect contrast was improved with 180 degrees SPET by up to 10%. A slight decrease in the normal region was also noted i n the 180 degrees reconstruction. The effect of diffuse liver activity on the inferior region depended on the rotation range. A patient with a high right hemi-diaphragm showed a lower inferior count with 360 de grees SPET. In conclusion, the 360 degrees acquisition was superior to the 180 degrees acquisition in the phantom with defects. Clinically, the quantitative differences in radionuclide types (Tc-99(m), I-123 or Tl-201) were not significant for quantifying a moderate degree (50-60 % of peak count) of defect. However, we note quantitative variation de pending on the rotation range in the 180 degrees method. ((C) 1988 Cha pman & Hall Ltd.).