Purpose: Magnetic resonance imaging (MRI) is a diagnostic imaging method that can be used to assess indeterminate renal masses on computed tomography (CT) scans. We evaluated the diagnostic accuracy of MRI in distinguishing renal cell carcinoma (RCC) from indeterminate renal masses on CT scans and investigated the impact of MRI on clinical decision making.
Methods: A retrospective study was conducted in 120 patients who underwent MRI to distinguish RCC from indeterminate renal masses on CT scans. The diagnostic accuracies of CT and MRI were compared, and factors associated with a final diagnosis of RCC were evaluated using multivariate logistic regression analysis.
Results: Of the 120 patients, 47 (39.2%) had benign masses, including 32 (26.7%) angiomyolipomas, 5 (4.2%) oncocytomas, and 10 (8.3%) complicated cysts. The specificity of MRI was significantly superior to that of CT in diagnosing RCC (68.1 vs. 27.7%, p = 0.001), whereas their sensitivities were equivalent (91.8 vs. 94. 5%, p = 0.754). Multivariate analysis showed that female gender [odds ratio (OR) 0.11, p < 0.001] and MRI diagnosis of RCC (OR 23.35, p < 0.001) were independently associated with a final diagnosis of RCC. MRI results showed that 15 patients (12.5%) thought to have RCC on CT scans could have avoided unnecessary surgery, whereas three patients (2.5%) thought to have benign masses on CT scans could have undergone appropriate surgery.
Conclusions: MRI has incremental benefit to distinguish RCC from indeterminate renal masses on CT scans. MRI may help to decide the most appropriate treatment strategy for patients with indeterminate renal masses on CT scans.