Evidence-based radiology: how to quickly assess the validity and strength of publications in the diagnostic radiology literature.

The aim of this study was to show how evidence-based medicine (EBM) techniques can be applied to the appraisal of diagnostic radiology publications. A clinical scenario is described: a gastroenterologist has questioned the diagnostic performance of magnetic resonance cholangiopancreatography (MRCP) in a patient who may have common bile duct (CBD) stones. His opinion was based on an article on MRCP published in "Gut." The principles of EBM are described and then applied to the critical appraisal of this paper. Another paper on the same subject was obtained from the radiology literature and was also critically appraised using explicit EBM criteria. The principles for assessing the validity and strength of both studies are outlined. All statistical parameters were generated quickly using a spreadsheet in Excel format. The results of EBM assessment of both papers are presented. The calculation and application of confidence intervals (CIs) and likelihood ratios (LRs) for both studies are described. These statistical results are applied to individual patient scenarios using graphs of conditional probability (GCP). Basic EBM principles are described and additional points relevant to radiologists discussed. Online resources for EBR practice are identified. The principles of EBM and their application to radiology are discussed. It is emphasized that sensitivity and specificity are point estimates of the "true" characteristics of a test in clinical practice. A spreadsheet can be used to quickly calculate CIs, LRs and GCPs. These give the radiologist a better understanding of the meaning of diagnostic test results in any patient or population of patients.