CT Attenuation Correction Misregistration in Cardiac SPECT

D. Motion misregistration between CT and SPECT acquisition can create artifactual perfusion defects

CT attenuation correction in cardiac SPECT requires spatial alignment (registration) of the CT map with the SPECT data. If the patient moves between the CT and SPECT acquisitions (e.g., from cardiac motion or patient repositioning), the CT map will not perfectly correspond to the SPECT image, creating artifactual perfusion defects — typically in the anterior or inferior wall. This motion misregistration artifact is a recognized pitfall of AC-corrected cardiac SPECT. It is identified by comparing AC-corrected and non-corrected images side by side; a defect present only on AC images but not on non-corrected images may be an AC artifact.