Noninvasive Differentiation of Indolent from Aggressive Renal Neoplasms with MR Fingerprinting Combined with Diffusion/Perfusion MRI.

Background Accurate characterization of tumor grade and aggressiveness for renal neoplasms with noninvasive imaging methods is critical for patient management and outcome. Purpose To evaluate kidney MR fingerprinting (MRF) alone and in combination with diffusion-weighted imaging and arterial spin labeling (ASL) MRI for the diagnosis and characterization of renal neoplasms by assessing its performance in differentiating indolent from aggressive tumors. Materials and Methods Adults with suspected renal cell carcinoma (RCC) were recruited between November 2020 and October 2024 for this prospective proof-of-concept study. Histopathologic grading served as the reference standard, and renal masses were classified into indolent (low-grade or benign) and aggressive (high-grade or unclassified RCCs) types according to their natural biologic behavior. Noncontrast coronal T1 and T2 maps were acquired using breath-hold kidney MRF (two to five sections per participant) at 3.0 T. Respiratory-triggered diffusion-weighted imaging and ASL MRI were further applied to measure the apparent diffusion coefficient (ADC) and renal blood flow (RBF), respectively. Univariable and multivariable analyses were performed to identify parameters that differentiated renal neoplasms and correlated with histopathologic findings. Results Renal neoplasms from 24 participants (mean age, 61 years ± 11 [SD]; 16 female) were characterized as indolent (n = 14) and aggressive (n = 10) types. A between-group difference in T2 was observed (indolent, 86 msec ± 22; aggressive, 61 msec ± 14; P = .005), whereas no evidence of between-group differences in T1, ADC, or RBF were observed (P > .05). The area under the receiver operating characteristic curve (AUC) values of T1, T2, ADC, and RBF alone for between-group differentiation were 0.39, 0.83, 0.38, and 0.62, respectively. Multivariable analysis revealed that MRF-derived T1 and T2 provided complementary information in tumor type differentiation, achieving an AUC of 0.89 in this initial exploratory analysis. Conclusion Rapid multiparametric quantitative imaging with kidney MRF improved the ability to assess the grade and aggressiveness of renal neoplasms in 15 seconds per imaging section and without injectable MRI contrast material. © The Author(s) 2026. Published by the Radiological Society of North America under a CC BY 4.0 license. Supplemental material is available for this article.