Impact of Prone Position on Myocardial Perfusion SPECT Interpretation in Women with Suspected Coronary Disease

Objectives: Soft tissue attenuation artifacts are the most common cause of false-positives in myocardial perfusion SPECT (MPS). Few studies assessing the value of prone imaging in women have been published. Our study evaluated the impact of prone position imaging on the interpretation of MPS scans of women with suspect coronary artery disease (CAD) and also defined the relationship between breast attenuation, age, bra cup size and body mass index (BMI). Methods: MPS scans of women with suspected CAD (n=431) were retrospectively analyzed by two blinded experts not aware if post-stress images were acquired in supine or prone position. After semi-quantitative analysis summed stress, rest and difference scores (SSS, SRS and SDS, respectively) were calculated and scans were classified as normal, abnormal or equivocal. Results: The SSS and SDS values were distinct and lower for images in prone position (p < 0.01). The analysis of the 17 segments of the left ventricle showed similar findings for most of the anterior (p < 0.01) and inferior (p<0.01) wall segments .One hundred forty-five studies were considered equivocal by the observers, but after the combined analysis with prone images, 70 (48.3%) were reclassified to normal (p < 0.01). Conclusions: Prone position imaging had impact on the interpretation of MPS images. The influence of soft tissue attenuation was reduced and studies initially classified as equivocal were reclassified to normal.