Science, art, and artifacts: how important is quantification for the practicing physician interpreting myocardial perfusion studies?

Although considerable efforts have been directed toward improving imaging agents and imaging equipment, relatively little attention has been given to factors that optimize image interpretation. Stress myocardial perfusion images are often interpreted by visual inspection alone. This may introduce considerable inter- and intraobserver variability. Importantly, clinical usefulness of myocardial perfusion imaging may not be consistently reproduced in many laboratories using visual analysis. Relative myocardial distribution of imaging agents on either planar or single-photon emission computed tomographic images can be readily quantified and compared with normal data files by computer processing. Quantification of myocardial perfusion images provides a reproducible measure of the extent of perfusion abnormalities and defect reversibility. The extent of perfusion abnormalities has been shown to have prognostic significance. Computer quantification of myocardial perfusion images improves not only the overall diagnostic yield but also enhances reliability, accuracy, confidence, and reproducibility of interpretation.