Investigations into possible causes of hot inferior wall artifacts in attenuation corrected cardiac perfusion images

Through our investigations with simulated images, we have identified several causes of hot inferior wall artifacts in attenuation corrected SPECT cardiac perfusion images. With an insufficient number of iterations, the non-uniform resolution recovered in three dimensions and slow convergence rate of ML-EM reconstruction can cause this artifact when the heart is at a shallow angle (the axis of the heart is close to being horizontal) or when there exists significant background activity. Increasing the number of iterations does not help in correcting this artifact when the attenuation map used has poor resolution or its attenuation coefficients used are not accurate. We also notice that the hot inferior wall artifact is more pronounced when body contouring acquisition or when 180° angular sampling is used