HETEROGENEITY OF SPECT BULLS-EYES IN NORMAL DOGS - COMPARISON OF ATTENUATION COMPENSATION ALGORITHMS

In normal dogs, SPECT Tc-99m Sestamibi (MIBI) and Tl-201 myocardial pe rfusion images reconstructed with filtered backprojection (FBP) show a large decrease of counts in the septal wall (S) compared to the later al wall (L). We evaluated the iterative method of Chang at 0 and 1 ite rations (Chang0 and Chang1), and the Maximum Likelihood-Expectation Ma ximization with attenuation compensation (ML-EM-ATN) algorithm on data acquired from 5 normal dogs and from simulated projection data using a homogeneous count-density model of a normal canine myocardium in the attenuation field measured in one dog. Mean counts in the S and L reg ions were calculated from maximum-count circumferential profile arrays . The table shows mean +/- s.d. S/L count ratios. [GRAPHICS] Our resul ts demonstrate that ML-EM-ATN and Chang1 result in improved uniformity , as measured by the S/L ratio.