Background: Combining exercise and adenosine during the stress phase of myocardial perfusion imaging (MPI) is known to reduce adverse effects and improve image quality. The aim of this study was to assess whether it can also improve the automatic calculation of left ventricular ejection fraction (LVEF) by QGS software package, during the stress phase of Gated SPECT.
Material and methods: One hundred patients who had stress Gated SPECT were retrospectively included in this study. Gated data of those who had adenosine only (50 patients=group A) was compared with those obtained in another group of 50 patients who had added bicycle exercise (Group B). All had identical image acquisition protocol using (99m)Tc-tetrofosmine. Clinical adverse effects, changes in blood pressure (BP), heart rate (HR), and ECG were monitored. Visual assessment of subdiaphragmatic uptake and accuracy of automatic regions of interest (ROI's) drawn by the software were noted. Regions of interest that involved sub-diaphragmatic uptake and resulting in low LVEF were manually adjusted to include the left ventricle only, and the frequency of manual adjustment was noted.
Results: No significant difference was noted in age, sex, baseline BP and HR between groups A and B. Adverse effects occurred less often in group B compared to group A (12% vs. 24%, p=0.118). Maximum HR and BP achieved during stress were significantly higher in group B compared to group A (p=0.025, p=0.001 respectively). The number of patients who had faulty ROI's and low LVEF, who needed manual adjustment of ROI's, were higher in group A compared to group B (16% vs. 6%, p=0.025). The values of LVEF showed significant improvement following manual adjustment of ROI's, increasing from a mean of 19.63+/-15.96 to 62.13+/-7.55 (p=0.0001) and from 17.33+/-9.5 to 49.67+/- 7.7 (p=0.0014) in groups A and B respectively.
Conclusion: The addition of exercise to adenosine significantly improves the automatic calculation of LVEF by QGS software during Gated SPECT and reduces the need for manual adjustment.