Myocardial single-photon emission computed tomographic quality assurance.

In this era of cost constraints in health care and the growing demand for cost-effective clinical strategies, the nuclear cardiologist is under increasing pressure to show clear evidence that myocardial imaging studies compete favorably with other modalities. This underlines the need for ensuring consistently high image quality and accuracy using optimally chosen standardized protocol. Nuclear medicine imaging has not yet reached the level of standardization, automation, and built-in quality control of imaging modalities such as ultrasound or x-ray computerized tomography, where the press of a button guarantees a consistent high-quality image. This is due to the large number of parameters and other factors affecting image quality that each individual operator still has to choose or be aware of before commencing imaging. Of crucial importance is ensuring the correct collection of the raw data. Processing can be repeated, but errors in the raw data, if detected at all, require repeating the entire study. These errors can cause artifacts that are difficult or impossible to recognize and are the major causes of incorrect reporting. Examples are a poorly prepared radiopharmaceutical, a poor injection, scatter from "hot" areas outside myocardium, an undetected change in the photopeak window, uniformity, or center of rotation, insufficient acquisition time, camera too far from the patient, etc. The first step to guarantee consistent image quality and accuracy is the preparation and strict implementation of a quality assurance program covering all the individual stages of the procedure starting from preparation of the radiopharmaceutical and ending with processing, display, and reporting. The next step is the standardization of optimally chosen protocols with maximization of automation. Rapid built-in automated software-driven equipment quality control checks should be developed. Finally, attenuation and scatter correction, gated single-photon emission computed tomography, and the advent of digital cameras will no doubt improve quantitation and accuracy even further following clinical evaluation in close cooperation with manufacturers who have the incentive to accelerate all the above steps.