Reproducibility of renal perfusion MR imaging in native and transplanted kidneys using non‐contrast arterial spin labeling

Purpose: To examine both inter‐visit and intra‐visit reproducibility of a MR arterial spin labeling (ASL) perfusion technique in native and transplanted kidneys over a broad range of renal function. Materials and Methods: Renal perfusion exams were performed at 1.5 T in a total of 24 subjects: 10 with native and 14 with transplanted kidneys. Using a flow‐sensitive alternating inversion recovery (FAIR) ASL scheme, 32 control/tag pairs were acquired and processed using a single‐compartment model. Two FAIR‐ASL MR exams were performed at least 24 h apart on all the subjects to assess inter‐visit reproducibility. ASL perfusion measurements were also repeated back‐to‐back within one scanning session in 8 native subjects and in 12 transplant subjects to assess intra‐visit reproducibility. Intra‐class correlations (ICCs) and coefficients of variation (CVs) were calculated as metrics of reproducibility. Results: Intra‐visit ICCs ranged from 0.96 to 0.98 while CVs ranged from 4.8 to 6.0%. Inter‐visit measurements demonstrated slightly more variation with ICCs from 0.89 to 0.94 and CVs from 7.6 to 13.1%. Medullary perfusion demonstrated greater variability compared with cortical blood flow: intra‐visit ICCs from 0.72 to 0.78 and CVs from 16.7 to 26.7%, inter‐visit ICCs from 0.13 to 0.63 and CVs from 19.8 to 37%. Conclusion: This study indicates that a FAIR‐ASL perfusion technique is reproducible in the cortex of native and transplanted kidneys over a broad range in renal function. In contrast, perfusion measurements in the medulla demonstrated moderate to poor reproducibility for intra‐visit and inter‐visit measures respectively. J. Magn. Reson. Imaging 2011;33:1414–1421. © 2011 Wiley‐Liss, Inc.