Myocardial perfusion artifacts associated with intermittent arrhythmias during SPECT acquisition

1682 Objectives We have previously reported minor myocardial perfusion artifacts associated with cardiac arrhythmias occurring uniformly throughout SPECT acquisition due to rejected beats resulting in poor summed image counting statistics. However, we have recently noted more marked, localized artifacts when severe arrhythmias and beat rejection occur during only one portion of the SPECT acquisition. Methods To validate this hypothesis, a Data Spectrum® myocardial phantom (with an ECG simulator) with full-thickness septal and half-thickness lateral wall defects was imaged with a 90°-angled dual-headed detector using a 180° (45° RAO to 45° LPO) arc, 72 camera stops, and 8-frame/cardiac cycle gating. The following four SPECT acquisitions were performed: (1) without arrhythmia; (2) with a simulated 50% reduction of beats during each stop (“sustained arrhythmia”); (3) dropping all beats in the first 1/2 of the acquisition (45° RAO - ANT, and 45° LAO - LLAT); and (4) dropping all beats in the last 1/2 of the acquisition (ANT - 45° LAO, and LLAT - 45° LPO). Reconstructed phantom images were compared to the aforementioned clinical cases. Results Both for the clinical cases and the phantom experiments the “sustained arrhythmia” resulted in relatively count-poor tomograms, but no discrete artifactual perfusion defects. The simulated phantom perfusion defects were as extensive and severe as with no arrhythmic beat rejection. Rejection of all beats in the first 1/2 of the acquisition resulted in severe anterolateral/anteroseptal artifactual defects and distortion of the tomograms. Rejection of all beats in the last 1/2 of the acquisition resulted in moderate inferior/inferolateral/apical artifactual defects. Conclusions Intermittent arrhythmias can produce clinically significant myocardial perfusion SPECT artifacts. To anticipate such artifacts inspection of planar projection images, sinograms, and arrhythmic beat quality control curves is recommended. To avoid such artifacts a repeat or simultaneous non-gated acquisition is preferable