MRI Quantitative Mapping Sequences of Renal Masses: Preliminary Results and its Potential Usefulness

Purpose: The goal of this monocentric prospective study consisted in recording T1 (T1m) and T2 (T2m) mapping relaxation times of common renal masses to evaluate the potential usefulness of such biomarkers to discriminate between several types of renal masses. Materials and Methods: We recorded the T1m and T2m values of 62 patients with renal masses on a clinical 3T MR unit using the consensus-based technical recommendations. For the quantitative evaluation, measurements were performed by carefully delineating Regions of Interest (ROIs). Interobserver agreement for the qualitative analysis of image quality was assessed using quadratic Cohen's weighted kappa statistics (k). Student's paired t-test was used to compare pairs of datasets in terms of T1m and T2m values. Data from our three subgroups with renal masses were compared using a non-parametric Kruskal-Wallis test. Results: For renal masses, mean T1m and T2m values were 1,727±97ms and 125±18ms; 1,621±96ms and 117±6ms, and 1,453±75ms and 95±10ms for renal cell carcinomas, angiomyolipomas, and oncocytomas, respectively. For T1m values, there was no significant difference (p=0.42) among the three types of renal masses. However, we have found a statistically significant difference for the T2m value (p=0.001). Conclusion: T1 and T2 mapping are promising sequences, which are not time-consuming and have a rather good interobserver agreement. Moreover, despite a small cohort, those sequences could play a role in the differential diagnosis between benign and malignant renal tumoral masses. This needs to be confirmed by further studies.