The myocardial count distribution and the stresssol;rest ratio distribution were compared between prone and supine Tc-99m MIBI myocardial SPECT acquisitions. Ninety-nine male patients with a low stress supine inferior wall count underwent stress and rest acquisitions in the supine and prone positions successively. For each study, values depicting the inferior, anterior, septal, and lateral wall counts were extracted from a medioventricular normalized circumferential profile and underwent a statistical analysis (Student's pairedt-test). On prone imaging, when compared to supine imaging, counts showed a highly significant mean relative increase of 11percnt; plusmn; 1percnt; in the inferior wall and of 7percnt; plusmn; 1percnt; in the septum. Conversely, these counts showed a significant mean relative decrease of 4percnt; plusmn; 1percnt; in the anterior wall and of 3percnt; plusmn; 1percnt; in the lateral wall. Moreover, the inferior wall stresssol;rest ratio showed a highly significant mean relative increase (6percnt; plusmn; 2percnt;). The prone position is probably preferable for interpreting the inferior wall and septum, where relative counts are enhanced, as with TI-201, and because the inferior stress-rest discrepancies are reduced in that position. But 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-99m MIBI, in order to prevent a misleading interpretation.
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