DETECTION OF CHANGES IN RENAL BLOOD FLOW USING ARTERIAL SPIN LABELING MRI

Abstract

Objective: Alteration in kidney perfusion is an early marker of renal damage. Magnetic resonance imaging (MRI) with arterial spin labeling (ASL) is a noninvasive approach to measure renal blood flow (RBF) without the use of contrast media. The purpose of this study consisting of two experiments was to evaluate whether both acute and short-term changes in RBF could be detected using ASL-MRI technique. Design and method: RBF as assessed by cortical (CRBF), medullary, and total renal blood flow (TRBF) were measured by ASL-MRI using FAIR True-FISP sequence. In the first experiment with 11 normotensive healthy individuals (NT) and 11 hypertensive patients (HT), RBF was measured at baseline and after both feet were covered with cold ice packs (cold pressor test) that activates the sympathetic nervous system. In the second experiment, RBF was measured in patients with chronic kidney disease (CKD) before and after a pharmacological intervention. Results: A significant reduction in CRBF (p = 0.042) and a trend in TRBF (p = 0.053) were observed in response to the activation of the sympathetic nervous system in both NT individuals and HT patients (Table 1). In the second experiment, a trend towards reduction of CRBF (p = 0.051) and TRBF (p = 0.059) has been detected after pharmacological intervention. An evaluation of RBF measurements between three different study populations reveals that TRBF were significantly lower in patients with HT (309.5 ± 17.3 mL/100 g/min) and CKD patients (260.4 ± 29.1 mL/100 g/min) compared to NT individuals (338.7 ± 30.0 mL/100 g/min) (NT vs. HT-p = 0.014, NT vs. CKD-p = 0.004). TRBF was also lower in patients with CKD compared to HT (p = 0.047). Conclusions: Our data indicate that both acute and short-term changes in RBF could be detected using ASL-MRI. Moreover, we were able to detect differences in RBF between healthy and diseased individuals by needing only small sample size per group. Thus, ASL-MRI offers an advantage in conducting clinical trials compared to other technologies.