Magnetic resonance imaging as an adjunct diagnostic tool in computed tomography defined Bosniak IIF-III renal cysts:...

CT imaging is the standard examination for renal cystic lesions and defines the Bosniak category, which dictates further management. Given that Bosniak II/IIF/III renal cystic lesions can potentially harbor renal cell carcinoma (RCC), additional diagnostic modalities may be required in management decision making.

To determine the value of additional magnetic resonance imaging in CT-defined Bosniak IIF-III renal cystic lesions.

This a multicenter retrospective study of 46 consecutive patients, diagnosed with cystic renal lesions between 2009 and 2016. The inclusion criteria were: (1) cystic renal lesion classified as Bosniak IIF-III on CT, (2) a subsequent MRI examination, and (3) documented outcome via surgery for cystic renal mass or follow-up.

46 patients (35 males, 11 females) were included. The mean size of the cystic lesion was 3.92 cm (0.7-10 cm). According to the CT findings, Bosniak IIF and III were found in 12 (26.1%) and 34 (73.9%) cases. Reclassification of Bosniak category was done after MRI examination in 31 cases (67.4%). An upgrade rate of 58.7% (27 cases) to a higher category was made, while the downgrade rate to a lower category was achieved in 4 cases (8.7%). As a result, significant therapeutic management change was made in 12/31 patients (38.7%), of whom 8 underwent subsequent surgery.

MRI study may reduce the use of Bosniak IIF category (in comparison with CT), which has a direct impact on therapeutic management (surgery vs. surveillance) in a significant proportion of patients.