Stress-only imaging in patients with prior SPECT MPI: A simulation study

Abstract

The aim of this study was to determine if omitting the repeat resting scan in patients who had prior single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) would have an impact on the interpretation of the stress test. Current guidelines recommend stress and rest imaging for SPECT MPI studies. Stress-only imaging has also entered the guidelines as a feasible option in low-risk patients but has not been studied in high-risk patients. Two independent readers interpreted 47 consecutive MPIs with prior images to determine if the repeat resting scan had an impact on interpretation of the stress test images. In this retrospective analysis, we compared interpretation of stress-only SPECT images using the old rest image for comparison versus conventional rest-stress SPECT imaging. Both readers were blinded to study results. The primary end point of this study was a comparison of summed difference scores (SDS) from stress-only interpretation compared to standard rest-stress interpretation. In this study, 36% (98/272) of patients had previous SPECT MPI. Of these patients, 48% (n = 47) were eligible for stress-only imaging. There was strong agreement between the SDS from the new stress versus old rest image compared with the new stress versus new rest image (r = 0.866, P < .001) with a mean difference in SDS of 0.6 ± 1.7. In this population, 41 of the 47 studies (87%) could have been performed with a stress-only SPECT MPI with comparison with the prior resting study. Starting with the stress-only protocol would have reduced the radiation in this population by 76%. Very similar data is obtained with stress-only imaging in patients who have a prior resting study. Our study suggests that the stress-only imaging may possibly be expanded to populations who have been studied previously or are at higher risk, reserving the option to add a resting study if the interpretation of the stress-only study is unclear.