Magnetic resonance fingerprinting–derived T1 and T2 relaxation times achieved an area under the receiver operating characteristic curve of 0.89 for differentiating indolent vs aggressive renal neoplasms in an exploratory analysis of a prospective study of patients with suspected renal cell carcinoma, according to recent a study.
Researchers evaluated whether kidney magnetic resonance fingerprinting (MRF) alone and in combination with diffusion-weighted imaging and arterial spin labeling could differentiate indolent vs aggressive renal tumors using noninvasive imaging.
The prospective proof-of-concept study enrolled 24 adult patients with renal neoplasms confirmed by histopathologic grading following surgical resection. The tumors were classified as indolent (low-grade or benign; n = 14) or aggressive (high-grade or unclassified; n = 10) based on biologic behavior.
All of the patients underwent imaging at 3 T using noncontrast protocols. MRF generated quantitative T1 and T2 maps in approximately 15 seconds per imaging section using a breath-hold acquisition. Diffusion-weighted imaging and arterial spin labeling magnetic resonance imaging (MRI) were used to derive apparent diffusion coefficient and renal blood flow measurements, respectively. Region-of-interest analysis was performed by a blinded abdominal radiologist.
In univariable analysis, T2 relaxation time provided the strongest discrimination between the tumor groups, with higher values observed in indolent vs aggressive neoplasms (86 ms vs 61 ms). T2 achieved an area under the curve of 0.83 compared with 0.62 for renal blood flow, 0.39 for T1, and 0.38 for apparent diffusion coefficient.
Multivariable modeling showed that combining MRF–derived T1 and T2 values improved classification performance, yielding an area under the curve of 0.89 with sensitivity of 86% and specificity of 93%. Adding diffusion or perfusion parameters to the model didn't result in a statistically significant improvement in performance.
No between-group differences were observed for T1, apparent diffusion coefficient, or renal blood flow. Tumor size also didn't differ between indolent and aggressive groups.
The researchers noted that T1 and T2 relaxation times were affected by tissue properties, including cellular density, water content, and macromolecule concentration. MRF enabled simultaneous acquisition of T1 and T2 in a single breath hold with inherent coregistration, overcoming the limitations of conventional quantitative MRI techniques.
However, the findings were based on a small sample size, and the analysis was exploratory. Additional limitations included potential selection bias toward surgically treated tumors, single-reader region-of-interest analysis, and technical challenges in aligning diffusion and perfusion maps with MRF data.
“MRF-derived T1 and T2 relaxation times may provide complementary information in the differentiation of indolent versus aggressive renal masses,” wrote lead study author Sree Harsha Tirumani, MD, of the Department of Radiology at Case Western Reserve University as well as the Department of Radiology at University Hospitals Cleveland Medical Center, and colleagues.
Full disclosures can be found in the study.
Source: Radiology
