PURE-MRI: An international study assessing physician accuracy in delineating the prostate and urethra on prostate MRI.
Academic Article
Overview
abstract
PURPOSE: Precise delineation of genitourinary structures during prostate cancer (PCa) care is critical to optimize treatment delivery while minimizing toxicity and injury. The Prostate and UREthra on MRI (PURE-MRI) study is an international, prospective study to assess physicians' accuracy segmenting prostate and urethra on MRI. METHODS: Physicians who diagnose or treat PCa were invited to contour prostate and urethra on patient cases using standard T2-weighted MRI (all planes). We compared these contours to reference consensus segmentations produced by a multidisciplinary panel of experts. We also evaluated performance of validated auto-segmentation AI tools. Accuracy was assessed with spatial and volumetric analyses. A mixed effects model was used to evaluate potential factors influencing contour performance. RESULTS: 62 specialists from 11 countries created 114 prostate and 110 urethra contours. Prostate median (min, max) accuracy for physicians [vs. AI] was Dice: 0.92 (0.62, 0.95) [vs. 0.95 (0.94, 0.96)], maximum deviation inside prostate: 3.4 mm (1.0, 12.4) [vs. 3.0 mm (3.0, 3.0)], maximum deviation beyond prostate: 5.3 mm (2.4, 17.3) [vs. 3.9 mm (3.1, 4.9)], mean deviation (per case) from the reference prostate: 1.6 mm (0.9, 3.9) [vs. 1.2 mm (1.1, 1.6)]. Urethra accuracy was Dice: 0.33 (0.03, 0.69) [vs. 0.41 (0.35, 0.48)], coverage: 36 % (3 %, 96 %) [vs. 81 % (80 %, 91 %)], maximum (2D) deviation beyond urethra: 1.6 mm (1.0, 2.3) [vs. 1.8 mm (1.3, 2.1)]. CONCLUSION: Physicians contour the prostate on MRI with overall Dice >0.9, though typical cases still include at least one error >5 mm and sometimes >10 mm. Physician urethra contours were less accurate, with typical coverage of <40 % of the reference urethra (compared to >80 % for AI). Physician trainees performed similarly to experienced clinicians. AI tools give comparable accuracy to practicing physicians for prostate contours and achieve better coverage of the urethra.
