Comparison of the diagnostic accuracy and validity of biparametric MRI and multiparametric MRI-based VI-RADS scoring in bladder cancer; is contrast material really necessary in detecting muscle invasion?

Abstract

Purpose (1) To evaluate the accuracy and validity of the biparametric MRI (bp-MRI), including T2-weigthed image (WI) and DWI sequences, and the availability of an alternative to the multiparametric MRI (mp-MRI), for the muscle-invasiveness assessment of bladder cancer (BC). ( 2) To evaluate the diagnostic performance and agreement of readers with different experiences in the abdominal imaging of using both protocols. Methods Preoperative bladder mp-MRI was performed on 128 patients with a initial diagnosis of BC. Two sets of images, set 1 (bp-MRI) and set 2 (mp-MRI), were independently evaluated by both readers. Descriptive statistics, including sensitivity, specificity, accuracy, and area under the curve (AUC), for VI-RADS scores were calculated using ≥ 4 as the cutoff for muscle invasion for each reader and image sets. Inter-reader agreement was evaluated using the Cohen's kappa coefficient. ResultsThe sensitivity ranged between 90.3-93.5% and 87.1-90.3%, specificity ranged between 96.6-99.1% and 91.6-96.6%, accuracy ranged between 96-97.3% and 91.3-94.6%, and AUC ranged between 0.947-0.951 and 0.919-0.921, for bp-MRI and mp-MRI, and reader 1 and reader 2, respectively. No significant differences were shown in diagnostic performance for either reader between both the protocols (p = 0.238 and 0.318). There was excellent agreement among the readers in the VI-RADS scores, using both protocols. Conclusion A bp-MRI protocol has a diagnostic accuracy comparable to an mp-MRI protocol for the detection of muscleinvasive BC using the VI-RADS criteria. Also, in both MRI protocols, the reader's experience does not appear to significantly affect diagnostic performance when using the VI-RADS criteria.

Comparison between biparametric and multiparametric MRI in predicting muscle invasion by bladder cancer based on the VI-RADS

“…DWI and DCE were separated from the same mpMRI images, and VIRADS scoring was performed based on reference to each separated sequence. Two sets of images from the same BCa patients, set 1 (T2 plus DWI) also showed comparable high performance to set 2 (T2 plus DWI plus DCE) (AUC ranged between 0.90 and 0.95 and 0.87–0.95 for bpMRI and mpMRI, P > 0.05) 11 , 14 . In a comparison study between bpMRI and mpMRI comprising 176 different patients (mpMRI, n = 97; and bpMRI, n = 79), the AUCs of VI-RADS using bpMRI and mpMRI were 0.88 and 0.84, respectively 15 .…”

“…However, to the best of our knowledge, only a few studies have compared DWI and DCE sequences for VI-RADS assessment, and most had a small sample size [11][12][13][14][15] . Furthermore, the authors of previous studies only compared the performance of DWI and DCE in the same patients who underwent mpMRI, not contrast-free bpMRI.…”

“…Although a contrast-free protocol is a relatively novel topic in the literature for BCa, our study was prompted by the question of whether the contrast material, considering its side effects, is truly essential in predicting muscle invasion. Only a few studies with a small sample size have compared the diagnostic performance between biparametric MRI (bpMRI) and mpMRI; both imaging modalities had similar sensitivity and specificity 11 – 15 . The present study aimed to validate the use of VI-RADS in patients with BCa and compare its diagnostic performance for predicting muscle invasion between two different protocols: bpMRI and mpMRI.…”