The Vesical Imaging-Reporting and Data System (VI-RADS) was introduced in 2018 to provide consistency when radiologists use multiparametric MRI (mpMRI) for staging bladder cancer. A team of researchers from China tested the scoring system’s ability to detect detrusor muscle invasion, sharing their findings in Radiology.
“The system provides a five-point VI-RADS score, which can suggest the likelihood of detrusor muscle invasion by bladder cancer,” wrote lead authors Huanjun Wang and Cheng Luo of the First Affiliated Hospital of Sun Yat-Sen University in Guangzhou, and colleagues. “However, to be widely used in clinical practice, VI-RADS must be further tested and validated.”
The authors explored data from 340 bladder cancer patients who underwent mpMRI from November 2011 to August 2018, retrospectively categorizing each patient’s tumor “with the largest burden” according to VI-RADS. Assessments were made by two radiologists, who scored the tumors individually and then together. The final VI-RADS scores were then compared with postoperative pathology.
Of the 340 tumors, 75% were verified as non-muscle-invasive. The overall area under the ROC curve for VI-RADS for detecting detrusor muscle invasion was 0.94. The sensitivity of a VI-RADS score of 3 or greater was 87.1%, while the sensitivity was 96.5%.
In addition, all tumors scored as VI-RADS 4 or 5 were verified as muscle-invasive cancer during postoperative pathology. All receiving a score of VI-RADS 1 were verified as non-muscle-invasive cancer.
“The recommendation of VI-RADS can benefit the standardization of multiparametric bladder MRI both in clinical and research applications, and additionally can help to create a systematic approach to reporting bladder MRI findings as well as defining the risk of muscle invasion,” the authors wrote. “Our study results also suggest that the consistency between two readers in VI-RADS scoring was excellent. The disagreement between the two readers mainly occurred when the tumors were located in the bladder neck (three tumors) and bilateral ureteral orifices (two tumors); further investigation is needed to determine whether this is related to the special anatomic structure for the bladder neck and bilateral ureteral orifices.”
The authors noted the study had certain limitations. An inherent bias may be present due to the retrospective nature of their research, for example, and the fact that all patients were treated at the same institution. Also, since only the largest tumor from each patient’s imaging results was scored using VI-RADS, there may be a selection bias present.
The team ultimately concluded, however, that they do recommend the use of VI-RADS for predicting detrusor muscle invasion in patients with untreated bladder cancer.
In a related editorial, also published in Radiology, the authors described these findings as “very promising.”
“It should stimulate practices not currently using MRI for bladder cancer staging to consider it,” wrote Daniel J. A. Margolis, MD, and Jim C. Hu, MD, MPH, Weill Cornell Medical College in New York City. “Hopefully, it will also kindle enthusiasm for prospective multicenter trials to confirm these encouraging findings. If this method for staging bladder cancer is validated, it would be a powerful prognostic tool for the management of this common disease.”