Achieving Very-Low-Dose Radiation Exposure in Cardiac Computed Tomography, Single-Photon Emission Computed Tomography, and Positron Emission Tomography

During the past several years, the need to reduce radiation has become a central issue in cardiac imaging. During this time, radiation dose to the patient in cardiac computed tomography (CT), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) has seen significant reductions without compromising image quality, primarily because of new developments in scanner hardware and reconstruction software. Sub-mSv radiation doses have been reported for cardiac CT.1–5 Stress and rest SPECT myocardial perfusion imaging (MPI) traditionally required ≈15 minutes to register the required number of photon events. New SPECT camera instrumentation and software have now enabled acquisition times as short as 2 minutes, to increase counting efficiency by up to a factor of 7.6 These new systems can also be used to reduce radiation exposure to patients during the MPI scan, allowing a corresponding marked reduction in the administered dose of radioactivity when used with the standard imaging time.7 It is important to keep radiation exposure as low as reasonably achievable. In this review, therefore, we briefly summarize recent technical advances in scanner hardware and reconstruction software, as well as the steps recommended to achieve very low radiation dose in cardiac imaging. We also review the current status of radiation in cardiac CT, SPECT, and PET as reported in multicenter studies and registries, as well as current clinical reports of radiation dose reduction, which illustrate the potential of the newest technology.Direct imaging of the coronary arteries is challenging because of their small sizes and rapid motion. Cardiac CT requires high temporal resolution to freeze such motion and therefore has benefited from steadily increasing CT gantry rotation speed. Imaging of the coronary arteries also requires high spatial resolution and reconstruction of submillimeter slices. Multiple transaxial slices need to be acquired simultaneously for complete …