An evaluation of cardiac uniformity, contrast, and SNR with dual-head 180 degrees and triple-head 360 degrees SPECT scans

An experimental phantom study was performed to evaluate cardiac uniformity, contrast, and signal-to-noise ratio for two clinical cardiac SPECT imaging protocols: adjacent dual-head 180 degrees and triple-head 360 degrees scan s. One head of a SPECT camera was used to acquire 180 degrees and 360 degre es projections with different times per step to simulate the clinical case where dual-head 180 degrees and triple-head 360 degrees each takes a total of 20 min. Scans were acquired with no lesion, anterior lesion, and posteri or lesion in the myocardium. Maximum a posteriori reconstruction was done b y an iterative coordinate descent algorithm using a quadratic convex prior. The L-curve method was used to obtain the prior strength. Some investigati on was done on obtaining the L-curve and on the ways to fit the L-curve and to get the corner point. Images both with attenuation and scatter correcti on (ASC) and without ASC were compared. The 180 degrees scan shows an inten sity decrease in anterior apical and posterior basal regions. The 360 degre es scan shows an intensity decrease in the posterior wall. For the anterior lesion, the 180 degrees scan has slightly better contrast, while for the p osterior lesion, the 360 degrees scan has slightly better contrast. The dif ference between the 180 degrees and 360 degrees scans is subtle, and the co mparison results depend on the lesion position and the view angle of the he art. A receiver operating characteristic study of 180 degrees versus 360 de grees acquisition designed based on these characterizations of contrast, un iformity, and noise will be necessary to evaluate overall performance.