Renal plasma flow (RPF) measured with multiple-inversion-time arterial spin labeling (ASL) and tracer kinetic analysis: Validation against a dynamic contrast-enhancement method

Purpose: To propose and validate a method for accurately quantifying renal plasma flow (RPF) with arterial spin labeling (ASL). Materials and methods: The proposed method employs a tracer-kinetic approach and derives perfusion from the slope of the ASL difference signal sampled at multiple inversion-times (TIs). To validate the method's accuracy, we performed a HIPAA-compliant and IRB-approved study with 15 subjects (9 male, 6 female; age range 2473) to compare RPF estimates obtained from ASL to those from a more established dynamic contrast-enhanced (DCE) MRI method. We also investigated the impact of TI-sampling density on the accuracy of estimated RPF. Results: Good agreement was found between ASL-and DCE-measured RPF, with a mean difference of 9 30 ml/min and a correlation coefficient R = 0.92 when ASL signals were acquired at 16 Tls and a mean difference of 9 +/- 57 ml/min and R = 0.81 when ASL signals were acquired at 5 TIs. RPF estimated from ASL signals acquired at only 2 TIs (400 and 1200 ms) showed a low correlation with DCE-measured values (R = 0.30). Conclusion: The proposed ASL method is capable of measuring RPF with an accuracy that is comparable to DCE MRI. At least 5 TIs are recommended for the ASL acquisition to ensure reliability of RPF measurements. (C) 2016 Elsevier Inc. All rights reserved.