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A study of apparent apical defects in cardiac SPECT images when performing attenuation compensation

A variety of effects may make the apical region appear colder than it actually is when performing cardiac SPECT image reconstructions. For some of the patient data, the apical regions of the images reconstructed with only attenuation correction have lower relative intensities to the rest of the heart than those of the images reconstructed without attenuation correction. In this paper, simulations were performed using MCAT phantom to study the effects of geometric point response correction and attenuation correction on cardiac SPECT images in terms of the relative intensity of the apical region to the rest of the heart. A Jaszczak torso/cardiac phantom, to which a bottle of the same activity concentration as the heart insert was bound, was scanned using a Picker PRISM 2000XP dual head SPECT system. Images were reconstructed using the iterative ordered-subset expectation maximization (OS-EM) algorithm. The effect of post filtering with a Wiener filter was studied.