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

An experimental phantom study was performed to evaluate cardiac uniformity, contrast and SNR for two clinical cardiac SPECT imaging protocols: adjacent dual-head 180° and triple-head 360° scans. One head of a SPECT camera was used to acquire 180° and 360° projections with different times per step to simulate the clinical case where dual-head 180° and triple-head 360° each takes a total of 20 minutes. Scans were acquired with no lesion, anterior lesion and posterior lesion in the myocardium. Maximum a posteriori (MAP) reconstruction was done by Iterative Coordinate Descent (ICD) algorithm using a quadratic convex prior. The L-curve method was used to obtain the prior strength. Images both with attenuation and scatter correction (ASC) and without ASC were compared. The 180° scan shows an intensity decrease in anterior apical and posterior basal regions. The 360° scan shows an intensity decrease in the posterior wall. For the anterior lesion the 180° scan has slightly better contrast while for the posterior lesion the 360° scan has slightly better contrast. In conclusion, the difference between the 180° and 360° scans is subtle and the comparison results depend on the lesion position and the view angle of the heart. A receiver operating characteristic (ROC) study of 180° vs. 360° acquisition designed based on these characterizations of contrast, uniformity and noise will be necessary to evaluate overall performance