Supine and semi-upright myocardial perfusion imaging (MPI) with a novel dedicated cardiac camera

Objectives D-SPECT (Spectrum-Dynamics, Israel) is a novel solid state cardiac camera Images acquired in a comfortable semi-upright position may produce specific attenuation artifacts, different from the familiar artifacts seen in the supine position. This study compares D-SPECT Tc-MIBI MPI in the supine and semi-upright positions.

Methods 39 patients (59.5+12.5 years, 19 men) injected with 250+850 MBq Tc-MIBI for stress/rest MPI (6 and 4 min) respectively had both supine and semi-upright imaging on D-SPECT. Images were interpreted blindly by 6 reviewers who then re-interpreted the studies side-by-side, noting changes from the original interpretation. Perfusion defects were defined as abnormal when persistent on both positions and as artifact if seen in only one of the positions.

Results Most common artifacts in the semi-upright position were seen in the apical, infero-apical and infero-lateral segments, while in the supine position artifacts were most commonly seen in the infero-apical, apical-lateral and anterior segments. Artifacts were overall more common in the semi-upright position (16-60% of cases) than in the supine position (0-35%) for all reviewers. Additional imaging, supine or semi-upright, changed the final interpretation in 25-48% of cases for the different reviewers.

Conclusions Semi-upright MPI may be subject to specific attenuation artifacts, unfamiliar from previous experience with supine imaging. D-SPECT enables fast MPI and therefore a repeat acquisition in a different position within a short time, which can change the final interpretation in up to 48% of the cases.