Feasibility of renal perfusion quantification by Fourier decomposition MRI

Purpose: To evaluate the feasibility of perfusion measurements in the human kidney by Fourier decomposition MRI (FD-MRI).

Methods: Renal perfusion measurements by FD-MRI and arterial spin labeling (ASL) were performed using a 1.5 T whole-body MR-scanner (Magnetom Avanto, Siemens Healthineers AG, Germany) in 15 healthy volunteers (mean age 33.0 ± 13.6 years). Five healthy volunteers were measured twice to evaluate the reproducibility. Besides, five patients with renal artery stenosis (RAS) (mean age 58.4 ± 16.2 years) were included in the study to evaluate potential clinical use of the FD-MRI for evaluating renal perfusion. For renal FD-MRI, coronal 2D-TrueFisp sequence (1 section; section thickness: 10 mm; FOV: 400 × 400 mm 2; TR/TE: 2.06/0.89 ms; 250 images; 0,36 s/image), for renal ASL, coronal FAIR-TrueFisp sequence (1 section; section thickness: 10 mm; FOV: 400 × 400 mm2; TR/TE 4.0/2.0 ms, TI 1200 ms, 30 averages; 8,32 s/average) were acquired without any triggering. Perfusion parameter maps of the kidneys were calculated for both methods. After manual segmentation, ROI-based analysis (whole kidney, cortex and medulla, respectively) was performed and the results were subsequently compared using the Student t-test.

Results: The acquisition times were 1.30 min and 4.16 min, for renal FD-MRI and ASL, respectively. No significant difference in global renal perfusion (RBF) between both methods was detected (mean RBF in the right kidney: 308.4 ± 31.5 mL/100 mL/min for FD-MRI; 315.2 ± 41.1 for ASL; in the left kidney: 315.6 ± 32.8 mL/100 mL/min for FD-MRI; 310.2 ± 39.1 mL/100 mL/min for ASL, respectively). The results indicated good reproducibility of both considered methods. However, cortico-medullar differentiation was not possible by FD-MRI, probably due to lower SNR compared to ASL. Significant difference in the side-separated RBF were measured by FD-MRI as well as by ASL (p < 0.05) in patients with RAS.

Conclusions: FD-MRI is a novel, rapid approach for contrast-free perfusion quantification in the human kidney. Main advantage of this new method compared to ASL perfusion is the significant shorter acquisition time and lower dependency on patient's compliance. However, lower SNR of FD-MRI needs further improvement to make FD-MRI a competitive alternative to ASL.