QUANTITATIVE COMPARISON OF PRONE AND SUPINE MYOCARDIAL SPECT MIBI IMAGES

The myocardial count distribution and the stress/rest ratio distributi on were compared between prone and supine Tc-99m MIBI myocardial SPECT acquisitions, Ninety-nine male patients with a low stress supine inte rior wall count underwent stress and rest acquisitions in the supine a nd prone positions successively. For each study, values depicting the inferior, anterior, septal, and lateral wall counts were extracted fro m a medioventricular normalized circumferential profile and underwent a statistical analysis (Student's paired t-test), On prone imaging, wh en compared to supine imaging, counts showed a highly significant mean relative increase of 11% +/- 1% in the inferior wall and of 7% +/- 1% in the septum, Conversely, these counts showed a significant mean rel ative decrease of 4% +/- 1% in the anterior wall and of 3% +/- 1% in t he lateral wall, Moreover, the inferior wall stress/rest ratio showed a highly significant mean relative increase (6% +/- 2%), The prone pos ition is probably preferable for interpreting the inferior wall and se ptum, where relative counts are enhanced, as with Tl-201, and because the inferior stress-rest discrepancies are reduced in that position, B ut the anterior and lateral wall information is impaired in the prone position, The authors suggest, in case of a low stress supine inferior count, the combination of both positions, which is feasible with Tc-9 9m MIBI, in order to prevent a misleading interpretation.