Value of a Standardized Lexicon for Reporting Levels of Diagnostic Certainty in Prostate MRI

OBJECTIVE. The purpose of this study was to evaluate the usefulness and diagnostic performance of a 5-point standardized diagnostic certainty lexicon for reporting the likelihood of extracapsular extension (ECE) of prostate cancer on routine staging prostate MRI. MATERIALS AND METHODS. This study was a retrospective analysis of routine clinical prostate MRI reports before (254 patients) and after (211 patients) the implementation of a 5-point diagnostic certainty lexicon. Whole-mount step-section pathology of the radical prostatectomy specimens served as the reference standard. The terms used to express diagnostic certainty regarding ECE on standard-of-care MRI and the presence of ECE on pathology were compared between the two periods. ROC analysis was used to evaluate the diagnostic accuracy of the 5-point certainty lexicon for detecting ECE. RESULTS. Before the implementation of the certainty lexicon, radiologists used 38 different terms to express the levels of certainty regarding the presence of ECE on MRI. Afterward, they adhered to the lexicon's predefined 5-point terminology in 85.3% of cases. The 5-point certainty lexicon used on MRI reports had an AUC of 0.852 for diagnosing ECE. CONCLUSION. The implementation of a lexicon of diagnostic certainty dramatically reduced the number of expressions used by radiologists to indicate their levels of diagnostic certainty. The accuracy of the certainty lexicon for diagnosing ECE on standard-of-care prostate MRI is similar to previously reported accuracy values for the diagnosis of ECE by MRI. Thus, the use of such a lexicon might prevent miscommunication and help referring clinicians reliably incorporate radiologists' assessments into clinical decision making.