Centering Artifacts Manifesting As Anterior Wall Defects On Myocardial SPECT Imaging

Abstract

Purpose: During cardiac SPECT acquisitions in-vitro work has shown that artifacts that may be prospectively interpreted as anterior wall defects can be caused by body centered acquisitions rather than heart centered acquisitions. The purpose of this study was to quantify the effects of center of rotation (COR) placement at the heart, or body centered circular orbits in patients. Methods: 44 patients underwent stress and rest Tc99m-Sestamibi SPECT myocardial scintigraphy using 20-30mCi (740-1070 MBq) and 8-10mCi (259-370 MBq) respectively (64 and 32 views at 30sec/view) using a Siemens Orbiter camera. All image data was evaluated by two radiologists blinded to each others readings. The raw projectional data was rated as body centered, heart centered, or in between using a nominal scale. The SPECT reconstruction data was interpreted for anterior wall defects on rest and stress images. Kappa statistic was calculated between observers and Maentel-Hentzel test for trend between number of anterior wall defects and increasing body centering in the COR of the SPECT acquisition was calculated. Results: Kappa statistics demonstrated good (>0.70) agreement between observers. Analysis demonstrated increasing number of anterior wall defects as the COR moved from heart centered to body centered with an odds ratio of 2.5 [95%CI:1.09-20] for number of anterior wall defects in body centered vs. heart centered acquisitions at rest. In particular 2 cases with anterior wall defects had less cardiac centering on the rest images than the stress images on which these defects were no longer visible. Conclusion: Increasing the distance between the COR of a SPECT acquisition and the anatomic center of the heart causes increasing anterior wall defects to be detected in vivo and may be contributing to artifacts in a daily clinical setting when using 180 degree acquisitions.