• William Devine, Francesco Giganti, Edward W Johnston, Harbir S Sidhu, Eleftheria Panagiotaki, Shonit Punwani, Daniel C Alexander, and David Atkinson.
• Centre for Medical Imaging, University College London, London, United Kingdom.
• J Magn Reson Imaging. 2019 Sep 1; 50 (3): 910-917.

BackgroundLuminal water imaging (LWI) suffers less from imaging artifacts than the diffusion-weighted imaging used in multiparametric MRI of the prostate. LWI obtains multicompartment tissue information from a multiecho T2 dataset.PurposeTo compare a simplified LWI technique with apparent diffusion coefficient (ADC) in classifying lesions based on groupings of PI-RADS v2 scores. Secondary aims were to investigate whether LWI differentiates between histologically confirmed tumor and normal tissue as effectively as ADC, and whether LWI is correlated with the multicompartment parameters of the vascular, extracellular, and restricted diffusion for cytometry in tumors (VERDICT) diffusion model.Study TypeA subset of a larger prospective study.PopulationIn all, 65 male patients aged 49-79 were scanned.Field Strength/SequenceA 32-echo T2 and a six b-value diffusion sequence (0, 90, 500, 1500, 2000, 3000 s/mm2 ) at 3T.AssessmentRegions of interest were placed by a board-certified radiologist in areas of lesion and benign tissue and given PI-RADS v2 scores.Statistical TestsReceiver operating characteristic and logistic regression analyses were performed.ResultsLWI classifies tissue as PI-RADS 1,2 or PI-RADS 3,4,5 with an area under curve (AUC) value of 0.779, compared with 0.764 for ADC. LWI differentiated histologically confirmed malignant from nonmalignant tissue with AUC, sensitivity, and specificity values of 0.81, 75%, and 87%, compared with 0.75, 83%, and 67% for ADC. The microstructural basis of the LWI technique is further suggested by the correspondence with the VERDICT diffusion-based microstructural imaging technique, with α, A1 , A2 , and LWF showing significant correlations.Data ConclusionLWI alone can predict PI-RADS v2 score groupings and detect histologically confirmed tumors with an ability similar to ADC alone without the limitations of diffusion-weighted MRI. This is important, given that ADC has an advantage in these tests as it already informs PI-RADS v2 scoring. LWI also provides multicompartment information that has an explicit biophysical interpretation, unlike ADC.Level Of Evidence3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:910-917.© 2018 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

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