Characterization of high-grade prostate cancer at multiparametric MRI: assessment of PI-RADS version 2.1 and version 2 descriptors across 21 readers with varying experience (MULTI study)
Florian Di Franco, Rémi Souchon, Sébastien Crouzet, Marc Colombel, A. Ruffion, Amna Klich, Mathilde Almeras, Laurent Milot, Muriel Rabilloud, Olivier Rouvière, on behalf of the MULTI Study Group, Sabine Debeer, Marine Dubreuil-Chambardel, Stéphanie Bravetti, Stéphane Cadot, Bénédicte Cayot, Paul-Hugo Jouve de Guibert, Paul Cezar Moldovan, Gaele Pagnoux, Clément Pernet, Louis Perrier, Nicolas Stacoffe, Sarah Transin, Michel Abihanna, Sébastien Ronze, Alexandre Ben Cheikh, Flavie Bratan, Rémy Rosset, Domitille Cadiot, Leangsing Iv, Jean Champagnac, Nicolas Girouin, Olivier Lopez, Athivada Soto Thammavong
Abstract
OBJECTIVE: To assess PI-RADSv2.1 and PI-RADSv2 descriptors across readers with varying experience. METHODS: Twenty-one radiologists (7 experienced (≥ 5 years) seniors, 7 less experienced seniors and 7 juniors) assessed 240 'predefined' lesions from 159 pre-biopsy multiparametric prostate MRIs. They specified their location (peripheral, transition or central zone) and size, and scored them using PI-RADSv2.1 and PI-RADSv2 descriptors. They also described and scored 'additional' lesions if needed. Per-lesion analysis assessed the 'predefined' lesions, using targeted biopsy as reference; per-lobe analysis included 'predefined' and 'additional' lesions, using combined systematic and targeted biopsy as reference. Areas under the curve (AUCs) quantified the performance in diagnosing clinically significant cancer (csPCa; ISUP ≥ 2 cancer). Kappa coefficients (κ) or concordance correlation coefficients (CCC) assessed inter-reader agreement. RESULTS: At per-lesion analysis, inter-reader agreement on location and size was moderate-to-good (κ = 0.60-0.73) and excellent (CCC ≥ 0.80), respectively. Agreement on PI-RADSv2.1 scoring was moderate (κ = 0.43-0.47) for seniors and fair (κ = 0.39) for juniors. Using PI-RADSv2.1, juniors obtained a significantly lower AUC (0.74; 95% confidence interval [95%CI]: 0.70-0.79) than experienced seniors (0.80; 95%CI 0.76-0.84; p = 0.008) but not than less experienced seniors (0.74; 95%CI 0.70-0.78; p = 0.75). As compared to PI-RADSv2, PI-RADSv2.1 downgraded 17 lesions/reader (interquartile range [IQR]: 6-29), of which 2 (IQR: 1-3) were csPCa; it upgraded 4 lesions/reader (IQR: 2-7), of which 1 (IQR: 0-2) was csPCa. Per-lobe analysis, which included 60 (IQR: 25-73) 'additional' lesions/reader, yielded similar results. CONCLUSIONS: Experience significantly impacted lesion characterization using PI-RADSv2.1 descriptors. As compared to PI-RADSv2, PI-RADSv2.1 tended to downgrade non-csPCa lesions, but this effect was small and variable across readers.