Conspicuity and muscle-invasiveness assessment for bladder cancer using VI-RADS: a multi-reader, contrast-free MRI study to determine optimal b-values for diffusion-weighted imaging.

To (1) compare bladder cancer (BC) muscle invasiveness among three b-values using a contrast-free approach based on Vesical Imaging-Reporting and Data System (VI-RADS), to (2) determine if muscle-invasiveness assessment is affected by the reader experience, and to (3) compare BC conspicuity among three b-values, qualitatively and quantitatively.

Thirty-eight patients who underwent a bladder MRI on a 3.0-T scanner were enrolled. The gold standard was histopathology report following transurethral resection of BC. Three sets of images, including T2w and different b-values for DWI, set 1 (b = 1000 s/mm2), set 2 (b = 1500 s/mm2), and set 3 (b = 2000 s/mm2), were reviewed by three differently experienced readers. Descriptive statistics and Intraclass Correlation Coefficient (ICC) were calculated. Comparisons among readers and DWI sets were performed with the Wilcoxon test. Receiver operating characteristic (ROC) analysis was performed. Areas under the curves (AUCs) and pairwise comparison were calculated.

AUCs of muscle-invasiveness assessment ranged from 0.896 to 0.984 (reader 1), 0.952-0.968 (reader 2), and 0.952-0.984 (reader 3) without significant differences among different sets and readers (p > 0.05). The mean conspicuity qualitative scores were higher in Set 1 (2.21-2.33), followed by Set 2 (2-2.16) and Set 3 (1.82-2.14). The quantitative conspicuity assessment showed that mean normalized intensity of tumor was significantly higher in Set 2 (4.217-4.737) than in Set 1 (3.923-4.492) and Set 3 (3.833-3.992) (p < 0.05).

Muscle invasiveness can be assessed with high accuracy using a contrast-free protocol with T2W and DWI, regardless of reader's experience. b = 1500 s/mm2 showed the best tumor delineation, while b = 1000 s/mm2 allowed for better tumor-wall interface assessment.

Abdominal radiology (New York). 2022 Mar 18 [Epub ahead of print]

Andrea Delli Pizzi, Domenico Mastrodicasa, Alessio Taraschi, Nicoletta Civitareale, Erica Mincuzzi, Stefano Censi, Michele Marchioni, Giulia Primiceri, Pietro Castellan, Roberto Castellucci, Giulio Cocco, Piero Chiacchiaretta, Antonella Colasante, Antonio Corvino, Luigi Schips, Massimo Caulo

Department of Innovative Technologies in Medicine & Dentistry, "G. d'Annunzio" University, Chieti, Italy. ., Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA., Unit of Radiology, "Santissima Annunziata" Hospital, Chieti, Italy., Department of Neuroscience, Imaging and Clinical Sciences, "G. d'Annunzio" University, Chieti, Italy., Department of Medical, Oral and Biotechnological Sciences, G. d'Annunzio University of Chieti, Urology Unit, SS Annunziata Hospital, Chieti, Italy., Unit of Ultrasound in Internal Medicine, Department of Medicine and Science of Aging, "G. D'Annunzio" University, Chieti, Italy., Center of Advanced Studies and Technology (CAST), "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy., Surgical Pathology Unit, SS Annunziata Hospital, Chieti, Italy., Motor Science and Wellness Department, University of Naples "Parthenope", Naples, Italy.