DWI and PRECISE criteria in men on active surveillance for prostate cancer: A multicentre preliminary experience of different ADC calculations.

The PRECISE score estimates the likelihood of radiological progression in patients on active surveillance (AS) for prostate cancer (PCa) with serial multiparametric magnetic resonance imaging (mpMRI). A PRECISE score of 1 or 2 denotes radiological regression, PRECISE 3 indicates stability and PRECISE 4 or 5 implies progression. We evaluated the inter-reader reproducibility of different apparent diffusion coefficient (ADC) calculations and their relationship to the PRECISE score.

Baseline and follow-up scans (on the same MR systems) of 30 patients with visible lesions from two different institutions were analysed by two radiologists. The PRECISE score was initially assessed in consensus. At least six weeks later, to reduce the likelihood of being influenced by the consensus PRECISE reading, each radiologist independently calculated ADC for the following: lesion, non-cancerous tissue and urine in the bladder. Normalised ADC ratios were calculated with respect to normal prostatic tissue (npADC) and urine. Spearman's correlation (ρ), intraclass correlation coefficients (ICC), differences in ADC and ROC curves were computed.

Interobserver reproducibility was very good (ρ > 0.8; ICC > 0.90). Lesion ADC (0.91 vs 0.73 × 10-3 mm2/s; p=0.025) and npADC ratio (0.68 vs 0.53; p=0.012) at follow-up mpMRI were different between patients with radiological regression or stability vs progression. Cut-offs of 0.77 × 10-3 mm2/s (lesion ADC) and 0.59 (npADC ratio) could differentiate the two groups (area under the curve: 0.74 and 0.77, respectively).

The ADC, npADC ratio and the PRECISE score should be recorded for MRI-based AS.

Magnetic resonance imaging. 2019 Dec 30 [Epub ahead of print]

Francesco Giganti, Martina Pecoraro, Davide Fierro, Riccardo Campa, Francesco Del Giudice, Shonit Punwani, Alex Kirkham, Clare Allen, Mark Emberton, Carlo Catalano, Caroline M Moore, Valeria Panebianco

Department of Radiology, University College London Hospital NHS Foundation Trust, London, UK; Division of Surgery & Interventional Science, University College London, London, UK; Department of Radiological Sciences, Oncology and Pathology, Sapienza University of Rome, Rome, Italy. Electronic address: ., Department of Radiological Sciences, Oncology and Pathology, Sapienza University of Rome, Rome, Italy., Department of Urology, Sapienza University of Rome, Rome, Italy., Department of Radiology, University College London Hospital NHS Foundation Trust, London, UK; Centre for Medical Imaging, University College London, London, UK., Department of Radiology, University College London Hospital NHS Foundation Trust, London, UK., Division of Surgery & Interventional Science, University College London, London, UK; Department of Urology, University College London Hospital NHS Foundation Trust, London, UK.