The role of diffusion-weighted imaging on 3 tesla magnetic resonance in the clinical staging and pathological grading of clear cell renal carcinoma

Abstract

Aim: To evaluate the contribution of the apparent diffusion coefficient (ADC) to distinguish between the four clinical stages and pathological grading in patients with clear cell renal cell carcinoma (RCC) on 3T MRI.

Methods: MRI of 93 patients with histopathological diagnosis of clear cell RCC were evaluated retrospectively. Clinical stage was evaluated according to American Joint Committee on Cancer and histopathological examination was evaluated according to the Fuhrman grading system. ADC values were compared for each clinical stage and pathological grade.

Results: Clinical stages were I in 51 patients (54.8%), II in 14 patients (15%), III in 15 patients (16.1%), and IV in 13 patients (13.9%). The Fuhrman grade of the patients were I in 8 (8.6%) patients, II in 55 (59.1%) patients, III in 23 (24.7%) patients and IV in 7 (7.5%) patients. Clinical stage I and Fuhrman grade I had significantly higher ADC values than all groups (p<0.001). The sensitivity was 81% and the specificity was 80.4% when the optimum cut-off value of ADC was taken as 1.41×10⁻³ mm²/s to differentiate between clinical stage I and other stages (II, III, and IV) (AUC:0.910; 95CI:0.855-0.964; p<0.001).  The optimum cutoff value of ADC was taken as 1.67×10⁻³ mm²/s to differentiate between Fuhrman grade I and other grades (II, III and IV), the sensitivity was 88.2% and the specificity was 100% (AUC: 0.927; 95CI: 0.872- 0.983; p<0.001).

Conclusions: In patients with renal mass suggestive of clear cell RCC in imaging studies; The possibility of lymph node or distant metastatic lesion should be considered in patients with an ADC of the primary tumor site less than 1.41×10⁻³ mm²/s, and the presence of distant metastasis in patients with an ADC less than 1.22×10⁻³ mm²/s.