The role of DWI MRI for differential diagnostic of solid renal tumors

Introduction. Currently, CT and MRI do not reliably differentiate oncocytoma, angiomyolipoma with minimal fat and renal cell carcinoma, and therefore most patients with localized solid renal tumors undergo surgical treatment. Identification of differential signs of benign formations according to imaging methods would make it possible to change the therapeutic tactics in more than a third of cases in patients with newly diagnosed small renal masses (less than 4 cm).Purpose. The aim of the study was to evaluate the diagnostic efficacy of diffusion-weighted MRI (DWI) in the differential diagnosis of solid renal masses.Materials and methods. А prospective study, which included 90 patients aged 34 to 79 years with primary solid renal masses who were examined and treated at the Hertsen Moscow Oncology Research Institute – Branch of the National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation was conducted in the period from February 2019 to October 2021. Before surgery, all patients underwent MRI of the retroperitoneal organs using DWI with b-factors of 0–800 s/mm2 and 0–1000 s/mm2. The diffusion coefficient was quantified on two ADC maps for renal masses of various histological types and the obtained values were compared with each other.Results. According to the results of the statistical analysis, the values of the diffusion coefficient for benign tumors were significantly higher than for RCC (p < 0.05). There was no statistically significant difference between clear cell, chromophobe and papillary types of RCC in terms of diffusion coefficient both at b-factors of 0–800 s/mm2 and at 0–1000 s/mm2.Conclusion. Using DWI we can suggest a benign genesis of a solid renal mass. Differential signs for RCC of various histological types according to diffusion-weighted images were not identified.