Experience in using the VI-RADS system in assessing the depth of invasion of bladder tumors

Abstract

Introduction. Survival rates and treatment algorithms for patients with bladder cancer (BC) depend on the depth of tumor invasion, in particular on the presence of the bladder muscle layer invasion and extraorganic spread. To assess the depth of bladder invasion, the VI-RADS system was developed in 2018, which is based on multiparametric MRI (mpMRI). According to published studies on the VI-RADS effectiveness, there is a high diagnostic accuracy for identifying formations with probable invasion into the muscle layer. The data on BC extraorganic spread are limited and the issue of assessing the sensitivity and specificity of this system requires further study.Aim of the study. To evaluate the diagnostic performance of mpMRI using the VI-RADS system in detecting muscle invasion and BC extraorganic growth.Materials and methods. A prospective study was conducted in the clinics of the National Medical Research Radiological Centre and included 75 patients aged 19 to 85 years, of which 39 (52%) had been newly diagnosed with BC, 36 (48%) had a relapse or continuous tumor growth. All patients underwent pelvic organs mpMRI on a tomograph with a magnetic field induction of 1.5T, followed by transurethral resection (TUR), TUR-biopsy of the bladder or cystectomy no later than 6 weeks after scanning.. The description of the bladder tumor included its measurements, localization and VI-RADS scale assessment. The data obtained by mpMRI were compared with the results of the morphological study using statistical analysis.Results. According to the results of the study, the overall VI-RADS scale sensitivity for categories above 3 (the presence of muscle invasion is equivocal) was 95.15% [90.11%; 99.95%], above 4 (muscle invasion is likely) – 92.59% [82.11%; 97.94%], specificity was determined at the level of 47.62% [25.71%; 70.22%] and 80.95% [58.09%; 94.55%] respectively. When assessing extraorganic spread in 30 patients, the sensitivity was 83.33% [62.62%; 95.26%], specificity – 83.33% [35.88%; 99.58%]. The accuracy and positive predictive value also had high levels from 80 to 95%, in contrast to the negative predictive value (55.56%).Conclusion. The scale for BC invasion depth assessing VI-RADS is characterized by high rates of sensitivity, specificity and accuracy, in particular when used in determining extraorganic spread.