Receiver operating characteristic analysis: a tool for the quantitative evaluation of observer performance and imaging systems.

Receiver operating characteristic (ROC) analysis provides the most comprehensive description of diagnostic accuracy available to date, because it estimates and reports all of the combinations of sensitivity and specificity that a diagnostic test is able to provide. After sketching the 6 levels at which diagnostic efficacy can be assessed, this paper explains the conceptual foundations of conventional ROC analysis, describes a variety of indices that can be used to summarize ROC curves, and describes several forms of generalized ROC analysis that address situations in which more than 2 decision alternatives are available. Key issues that arise in ROC curve fitting and statistical testing are addressed in an intuitive way to provide a basis for judging the validity of ROC studies reported in the literature. A list of sources for free ROC software is provided. Receiver operating characteristic methodology has reached a level of maturity at which it can be recommended broadly as the approach of choice for radiologic imaging system comparisons.