Abstract 20162: Baseline and Cumulative Radiation Dose for Intermediate-Risk Individuals Undergoing Coronary Computed Tomography (CCTA) versus Myocardial Perfusion Single Photon Emission Computed Tomography (MPS): A Prospective Multicenter Randomized Trial
Background: Coronary computed tomographic angiography (CCTA) and myocardial perfusion SPECT (MPS) are commonly used tests for individuals with suspected coronary artery disease (CAD), yet both CCTA and MPS expose patients to ionizing radiation. To date, whether CCTA or MPS use Results in differences in baseline and induced radiation dose remains unknown.
Methods: We randomized 180 symptomatic patients with suspected CAD at 2 sites to initial evaluation by CCTA (N=91) vs MPS (N=89). We calculated baseline and downstream radiation dose. Dose for CCTA was calculated using the Dose Length Product multiplied by the conversion factor 0.014, as defined by the European Commission. MPS dose was calculated by the International Commission on Radiation Protection (ICRP) and the Radiation Internal Dose Information Center (RIDIC) methods. Radiation dose for invasive coronary angiography (ICA) was calculated by image-adjusted Dose Area Product values within historically reported ranges.
Results: The average age of the study group was 57.3±9.8 years (50.6% male) with a 40.5% pre-test likelihood of CAD. A coronary artery stenosis >50% was observed in 27 (30%) patients undergoing CCTA, and a perfusion abnormality was detected in 33 (37%) patients undergoing MPS (p=0.29). At a follow-up of 55±34 days, rates were similar between CCTA and MPS patients undergoing downstream CAD imaging studies (14% vs. 11%) and ICA (11% vs. 8%, p=0.38). Baseline median radiation dose to MPS patients by both the ICRP and RIDIC method was more than 2-fold higher than to CCTA patients [13.3 mSv (interquartile range [IQR] 13.1–38.0) for ICRP; 16.89 mSv (IQR 16.4–32.1) for RIDIC vs. 6.1 mSv (IQR 4.9–12.8) for CCTA, p <0.0001] (Figure). Median induced radiation doses were similar amongst CCTA and MPS patients (p=0.32), resulting in a cumulative dose to MPS patients that remained more than 2-fold higher than for CCTA patients [13.3 mSv (IQR 13.1–38.0) per ICRP or 16.9 mSv (IQR 16.47–32.14) per RIDIC vs 7.1 mSv (IQR 4.9–13.3), p<0.0001).
Conclusion: Use of CCTA for evaluation of intermediate-risk symptomatic patients with suspected CAD results in a >50% reduction in cumulative radiation dose, as compared to MPS. Further studies should examine the long-term effects of this differential radiation dose.
- © 2010 by American Heart Association, Inc.