Comparison of gated SPECT images in 90 .deg. C versus 76 .deg. C dual-head system with variable angle detector

Recently 76 degress with 204 degrees rotation gated SPECT were used with variable angle detector. We have compared 90 degrees with 180 degrees gantry rotation and 76 degrees with 204 degrees rotation gated SPECT images. Twenty patients in stable conditions (M/F=11/9, mean age 54) underwent two MIBI SPECT studies, one with 90 degrees and the other with 76 degrees in the same day. We used dual head system with variable angle detector. (E.CAM: Siemens, USA). Nine patients showed abnormal findings on SPECT images and 11 patients showed normal findings. Automatic quantitation of LVEFs were obtained using previously developed software and visual scoring of motion and thickening was performed using four-point scales in the same 18 segments. Segmental tracer uptake was also evaluated with visual scoring system on 18 segments. The quality of 90 degrees gated MIBI images was ranked as excellent. good, fair and poor in 5%, 75%, 20% and 0%, respectively, compared to 10%, 75%, 15%, 0%. respectively, for 76 degreees gated images. Quantitative-gated MIBI LVEFs with 90 degrees were 40.1% and 41.9% with 76 degrees and there was no significant statistical differences between the two tests. There was exact agreement of visual grading in 331 of 360 segments (92%: tau b=0.837, p<0.01) in 20 patients and 142 of 162 segments (88%: tau b=0.892, p<0.01) in ischemic patients. Exact agreement between 90 degrees and 76 degrees gated MIBI segmental myocardial function in 20 patients was 92% (tau b=0.838) and 91% for motion and thickening socres, respectively. In ischemic patients it was 86% (tau b=0.857) and 83% (tau b=0.873). Although the quality of 76 degrees images were slightly better than the 90 degrees, the tracer uptake wall thickening wall motion and LVEFS were comparable between the two tests