Evaluation of renal masses with CEST MRI: Protocol optimization and preliminary results

Abstract Purpose This study investigates the application of CEST MRI in human kidneys, with the overarching goal of developing CEST MRI for renal mass characterization. Here, the focus is on the development of a protocol and the proof‐of‐principle evaluation of CEST for the characterization of clear cell renal cell carcinoma (ccRCC). Methods Ten healthy volunteers and five patients diagnosed with ccRCC underwent CEST MRI scans at 3 T. The sequence performance was characterized in healthy volunteers and tested using three saturation power levels, B 1rms = 0.7, 1.2, and 1.6 μT. We compared the magnetization transfer ratio asymmetry (MTR asym ) values at 1.0, 2.0, and 3.5 ppm between the kidney cortex of healthy volunteers and the cortex/renal masses of renal cell carcinoma (RCC) patients. We also investigated the correlation of CEST with tumor characteristics, such as volume, necrosis percentage, and histopathological grade. Results Significant differences in MTR asym values were observed between ccRCC tumor regions and healthy kidney cortex in all three compared frequency offset ranges ( p < 0.05). At the same time, MTR asym values in the cortex of the contralateral kidney in RCC patients were not significantly different when compared with the values of healthy kidney cortex values ( p > 0.7). Conclusion CEST MRI demonstrates considerable potential as a non‐invasive imaging tool for the characterization of renal masses.