n SA Journal of Radiology - Reporting of diagnostic accuracy studies in radiology : editorial

Volume 18, Issue 1
  • ISSN : 1027-202X
  • E-ISSN: 2078-6778



The use of technologically based imaging tests to diagnose diseases and lesions is a fundamental function in radiology. Such tests must be evaluated before their introduction, and during their routine use, in clinical practice to ensure that their performance remains constant. One way of measuring the performance of a medical test is by evaluating its accuracy. Accuracy is defined as the ability of a test to correctly distinguish those subjects who have a target condition from those who do not. A target condition can be the presence or stage of a disease or infection. Accuracy is commonly measured by parameters such as sensitivity (the probability of a positive test result amongst those with disease) and specificity (the probability of a negative test result amongst those without disease). Other parameters include predictive values, likelihood ratios and area under the receiver operating characteristic (ROC) curve. In research, the accuracy of a test is estimated by comparing the results of the test of interest (index test) with the results of the best available test (reference test). For instance, one may wish to estimate the accuracy of chest radiographs in detecting a chest lesion. This may be done by subjecting a sample of patients to chest radiography and to computed tomography (CT) scanning, which is the best available test. Chest radiographs can then be compared with CT scans.

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