Semiconductor Detectors Allow Low-Dose–Low-Dose 1-Day SPECT Myocardial Perfusion Imaging

Abstract

Cadmium zinc telluride (CZT) detectors with linear counting rate response enable count subtraction in sequential scanning. We evaluated whether count subtraction eliminated the need for higher activity doses in the second part of the 1-d stress-rest myocardial perfusion imaging (MPI) protocol. Methods: For 50 patients (mean age 6 SD, 66 6 12 y) with visually abnormal (n 5 42) or equivocal (n 5 8) adenosine-stress MPI (320 MBq of 99m Tc-tetrofosmin) on a CZT camera, rest MPI was performed with a low dose (320 MBq) and repeated after injection of an additional 640 MBq of 99m Tc-tetrofosmin to achieve a standard 3-fold increased dose at rest (960 MBq), compared with stress (320 MBq). Low-dose rest myocardial perfusion images were reconstructed after subtracting the background activity of the preceding stress scan. Segmental percentage tracer uptake of the 2 rest myocardial perfusion images (320 vs. 960 MBq) was compared using intraclass correlation and Bland-Altman limits of agreement. Patient-and coronary territory-based clinical agreement was assessed. Results: The standard protocol revealed ischemia in 34 (68%) and a fixed defect in 8 (16%) patients, of whom 33 (97%) and 8 (100%) were correctly identified by lowdose MPI (clinical agreement, 98%). Segmental uptake correlated well between low-and standard-dose rest scans (r 5 0.94, P , 0.001; Bland-Altman limits of agreement, 211 to 111%). Defect extent was 14.4% (low-dose) versus 13.1% (standard-dose) at rest (P 5 not statistically significant) and 26.6% at stress (P , 0.001 vs. rest scans). Conclusion: These promising results suggest that accurate assessment of ischemic myocardial disease is feasible with a low-dose-low-dose 1-d SPECT MPI protocol using a CZT device.

Nuclear myocardial perfusion imaging with a novel cadmium-zinc-telluride detector SPECT/CT device: first validation versus invasive coronary angiography

“…The ultimate metric may be outcome and with regard to outcome prediction by MPI the added value of attenuation correction has been recently established [18]. The main advancement of the new CZT cameras [19] is the more than 5-fold reduction in scan time [4] or activity [20] at preserved accuracy. Several other applications allow to take even more complete advantage of the refinements offered by the new cameras which may further enhance the clinical importance of MPI.…”

Compared Performance of High-Sensitivity Cameras Dedicated to Myocardial Perfusion SPECT: A Comprehensive Analysis of Phantom and Human Images

“…In particular, it is likely that the image quality parameters of the CZT cameras could have been enhanced using smaller energy windows, with only a limited loss in count sensitivity, but further studies are required to determine the optimal energy windows for CZT SPECT. Additional enhancements might be achieved using cardiac models, such as that available and recommended for the DSPECT camera; by new low-dose protocols (34); and by triggering breathing, especially when using the stationery detectors of the Discovery NM 530c (17).…”

Nuclear cardiology at the door of a new era: better to save mSv or to reduce imaging time?

“…In another study, the patient dose was reduced to 4.3 mSv for stress/rest protocols using a background activity subtraction algorithm [9]. The comparison between standard dose and low-dose background subtracted protocols demonstrated clinical agreement in 98 % of patients, confirming the possibility of significantly reducing radiation exposure while maintaining the diagnostic power of myocardial scintigraphy.…”