Soft tissue attenuation patterns in stress myocardial perfusion SPECT images: A comparison between supine and upright acquisition systems

Background. Soft tissue attenuation patterns and their interaction with body habitus and gender in Single Photon Emission Computed Tomography (SPECT)-myocardial perfusion imaging (MPI) of upright patient-position acquisition systems are not well described. Methods. In a retrospective cross-sectional study, we compared the prevalence and patterns of soft tissue attenuation in two groups of normal SPECT-MPI studies acquired by supine (n = 263) vs upright (n = 212) acquisition systems. Results. Attenuation patterns observed in the study population were: anterior (22.3%), inferior (51.6%) and lateral (18.1%). Anterior attenuation was significantly less in those imaged upright (6.1% vs 35.4%), P < .001; particularly among women (9.5% vs 50.7%), P < .001. Inferior attenuation was more common among women imaged upright (49.5% vs 13.5%), P < .001; but was not affected by imaging position among men. Lateral attenuation was more prevalent in the upright group (24.1% vs 13.3%), P = .002; and had a strong association with female gender (P < .001) and BMI ≥ 30 (P < .001). Conclusions. Upright SPECT-MPI acquisition is associated with a unique attenuation pattern which is vastly different than the supine position. Female gender strongly impacted this attenuation pattern, particularly obese women. Our study is the first to describe, in details, the attenuation patterns with upright imaging and is critical for the accurate interpretation of SPECT-MPI acquired with upright systems.