Dear Editor,

We read the article titled “Prospective assessment of VI-RADS score in multiparametric MRI in bladder cancer: accuracy and the factors affecting the results” by Oğuz et al.¹, published online in Diagnostic and Interventional Radiology. We congratulate the authors on this prospective magnetic resonance imaging (MRI) study in patients with bladder cancer. We want to make a few contributions and comments on this research article.

First, it is noteworthy that the number of cases accepted on the Vesical Imaging Reporting and Data System (VI-RADS) 3, according to the MRI evaluation in this study, was considerably higher than the studies in the current literature.^2,3,4,5,6 The proportion of patients with a VI-RADS score of 3 in Oğuz et al.’s¹ study was 38.75%. However, in prospective studies in the current literature, the proportion of patients with a VI-RADS score of 3 was 13.4% in Del Giudice et al.’s² study, 18.2% in Erkoc et al.’s³ study, 6.9% in Metwally et al.’s⁴ study, 19.2%–20.5% in Akcay et al.’s⁵ study, and 8.8%–18.7% in Ueno et al.’s⁶ study. Moreover, Oğuz et al.¹ reported that 93.5% (29/31) of the patients with a score of VI-RADS 3 had histopathologically non-muscle invasive bladder cancer, which is quite different from the literature. Many studies have shown that bladder tumors with a VI-RADS 3 score are in the gray zone and can indicate muscle-invasive and non-muscle-invasive bladder cancer at a similar rate. For example, Metwally et al.⁴ reported that of the 24 patients with a VI-RADS score of 3, 13 (54.2%) had histopathologically non-muscle invasive bladder cancer, while 11 (45.8%) had muscle-invasive bladder cancer. Similarly, Akcay et al.⁵ reported that of the 15 patients with a VI-RADS score of 3, 7 (46.7%) had histopathologically non-muscle invasive bladder cancer, while 8 (53.3%) had muscle-invasive bladder cancer. We suggest that this difference between the literature and Oguz et al.’s¹ study may be due to an MRI assessment error.

Second, Oğuz et al.¹ reported that the second observer for interobserver agreement evaluated only 20 random patients. However, the VI-RADS scores of these 20 patients were not specified. According to our clinical practice, the VI-RADS scores of the tumors are very important in terms of the interobserver agreement. For example, an excellent interobserver agreement is expected in evaluating tumors with a VI-RADS score of 1 or 5. In contrast, a significant decrease in the agreement is scheduled for those with a VI-RADS score of 3. Therefore, the authors need to indicate the VI-RADS scores of the 20 patients they evaluated.¹

Finally, the authors noted that patients without muscle tissue in the transurethral resection of bladder tumor (TUR-BT) sample underwent a second TUR-BT after the first resection but did not specify the number or proportion of these patients. Akcay et al.⁵ reported that 10 of 83 patients (12%) had insufficient TUR-BT. We suggest that reporting the number of inadequate TUR-BT procedures in this study will contribute to the literature.¹

Conflict of interest disclosure

The authors declared no conflicts of interest.