Quantification of renal perfusion: Comparison of arterial spin labeling and dynamic contrast‐enhanced MRI

Abstract

Purpose: To provide the first comparison of absolute renal perfusion obtained by arterial spin labeling (ASL) and separable compartment modeling of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). Moreover, we provide the first application of the dual bolus approach to quantitative DCE-MRI perfusion measurements in the kidney. Materials and Methods:Consecutive ASL and DCE-MRI acquisitions were performed on six rabbits on a 1.5 T MRI system. Gadolinium (Gd)-DTPA was administered in two separate injections to decouple measurement of the arterial input function and tissue uptake curves. For DCE perfusion, pixel-wise and mean cortex region-of-interest tissue curves were fit to a separable compartment model. Results:Absolute renal cortex perfusion estimates obtained by DCE and ASL were in close agreement: 3.28 6 0.59 mL/g/min (ASL), 2.98 6 0.60 mL/g/min (DCE), and 3.57 6 0.96 mL/g/min (pixel-wise DCE). Renal medulla perfusion was 1.53 6 0.35 mL/g/min (ASL) but was not adequately described by the separable compartment model. Conclusion:ASL and DCE-MRI provided similar measures of absolute perfusion in the renal cortex, offering both noncontrast and contrast-based alternatives to improve current renal MRI assessment of kidney function.

Renal Arterial Spin Labeling Magnetic Resonance Imaging

“…A good repeatability of the perfusion measurements (reported as coefficient of variation, CV) was found over the cortex [29,32,33,34] (CV = 4-16%) and the whole kidney [33,34] (CV = 3-7%), while the data for the renal medulla are sparse [34]. A good correlation of the cortical renal blood flow (RBF) was found for ASL and DSC MRI [29,35] in healthy volunteers. Measurements in an animal model showed that the ASL seems to underestimate the perfusion as compared to RBF measurements performed with fluorescent microspheres [36].…”

Motion-corrected multiparametric renal arterial spin labelling at 3 T: reproducibility and effect of vasodilator challenge

“…ASL uses a radiofrequency (RF) pulse to magnetically label water protons in blood, so that they act as a diffusible tracer. Subtraction of the labelled images from control images allows perfusion maps to be quantified by fitting a kinetic model to the data [9]. In standard single-inversion time (TI) ASL techniques, a single inversion labelling pulse is applied, and a perfusion value is calculated using a simplified model which neglects variations in renal tissue T 1 and makes assumptions concerning the bolus arrival characteristics and blood T 1 [10,11].…”

Fast imaging strategies for mouse kidney perfusion measurement with pseudocontinuous arterial spin labeling (pCASL) at ultra high magnetic field (11.75 tesla)

“…7T), thus resulting in long longitudinal relaxation time (T 1 ) and, therefore, enhanced the sensitivity of ASL techniques. Concerning the ASL scheme strategy, it has been recently demonstrated that, despite modest inversion efficiency, 9 the pCASL approach 2 provides several advantages compared with the widely used pulsed FAIR 14 technique 10,11,13 for mouse kidney perfusion measurement. For the readout strategy, several options are offered, among them EPI (echo planar imaging), RARE (rapid acquisition with relaxation enhancement), TrueFISP (true fast imaging with steady state precession), GRASE (gradient and spin echo), 15 UFLARE (ultra fast low angle rate) 16 or even spiral imaging.…”