Ultra low-dose single photon emission computed tomography myocardial perfusion imaging

Background: Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) provides excellent diagnostic and prognostic information. A primary limitation of SPECT is radiation exposure. New cadmium zinc telluride (CZT) technology has allowed for reduced radiation exposure. Methods: A cohort of 414 consecutive patients undergoing very low-dose SPECT MPI utilizing CZT technology was analyzed. Patients received rest/stress dosing strategies of 111/333, 148/444, 222/666, 296/888, 370/1110 Megabecquerels (MBq) (3/9, 4/12, 6/18, 8/24, 10/30 millicuries) depending on their weight and body mass index. Image quality was visually assessed by the reading cardiologist (scale: 1 = poor; 2 = fair; 3 = good; 4 = excellent). Results: 58% of patients received 111/333MBq, 22% received 148/444MBq, 13% received 222/666MBq, 6% received 296/888MBq, and 1% received 370/1110MBq. The estimated radiation dose was 3.6, 4.8, 7.2, 9.6, and 12 millisieverts respectively. The average image quality for the cohort was 3.3 ± 0.7. The rest/stress counts (103) for 111/333 and 148/444 groups were 532 ± 212/1718 ± 525 and 545 ± 177/1748 ± 399, while the rest/stress counts (103) for the 222/666 and 296/888 groups were 673 ± 178/2235 ± 923 and 764 ± 249/2588 ± 788 respectively. The 111/333 and 148/444 groups had significantly lower counts than the 222/666 and 296/888 groups, but only the 296/888 group had a significant difference in image quality when compared to the 111/333 group, with the 111/333 group having better image quality. Conclusion: CZT technology permits rapid, very low-dose MPI studies to be performed, thus, reducing the radiation exposure for patients, while still providing high quality, diagnostic perfusion results. The majority of our patients were imaged at less than 4mSv.