COMPENSATION FOR DISTANCE-DEPENDENT RESOLUTION IN CARDIAC-PERFUSION SPECT - IMPACT ON UNIFORMITY OF WALL COUNTS AND WALL THICKNESS

We investigated the impact on the uniformity of the polar map of the m aximum wall count, and on the cardiac wall thickness of several method s used to compensate for distance-dependent resolution (DDR) in cardia c perfusion imaging, Compared were: 1) filtered backprojection (FBP) r econstruction with no correction for attenuation and DDR: 2) FBP with Bellini attenuation compensation (AC); 3) FBP with Bellini AC and freq uency distance relationship (FDR) restoration filtering prior to recon struction: 4) ordered-subset maximum likelihood estimation-maximizatio n (OSEM) reconstruction with just AC, and 5) including DDR compensatio n and AC in OSEM reconstruction with 3D postreconstruction Gaussian fi ltering. The best uniformity was obtained with OSEM reconstruction whi ch included just AC. Nearly the same uniformity could he obtained with reconstruction by OSEM which included correction for both AC and DDR when strong 3D post-reconstruction Gaussian filtering was included. Wi th application of this filtering OSEM with compensation for both AC an d DDR achieved significantly better recovery; of the original wall thi ckness at the expense of higher noise magnitude. For the implementatio ns compared herein, it was noted that the modeling of AC and DDR in OS EM yielded a slightly better combination of image quality metrics than FDR restoration. observer detection studies are needed to determine i f compensation for DDR and AC does result in improved lesion detection over just compensation for AC.