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

Abstract

Objectives We investigated the feasibility and reproducibility of free-breathing motion-corrected multiple inversion time (multi-TI) pulsed renal arterial spin labelling (PASL), with general kinetic model parametric mapping, to simultaneously quantify renal perfusion (RBF), bolus arrival time (BAT) and tissue T 1 . Methods In a study approved by the Health Research Authority, 12 healthy volunteers (mean age, 27.6 ± 18.5 years; 5 male) gave informed consent for renal imaging at 3 T using multi-TI ASL and conventional single-TI ASL. Glyceryl trinitrate (GTN) was used as a vasodilator challenge in six subjects. Flow-sensitive alternating inversion recovery (FAIR) preparation was used with background suppression and 3D-GRASE (gradient and spin echo) read-out, and images were motion-corrected. Parametric maps of RBF, BAT and T 1 were derived for both kidneys. Agreement was assessed using Pearson correlation and Bland-Altman plots. Results Inter-study correlation of whole-kidney RBF was good for both single-TI (r 2 = 0.90), and multi-TI ASL (r 2 = 0.92). Single-TI ASL gave a higher estimate of whole-kidney RBF compared to multi-TI ASL (mean bias, 29.3 ml/min/100 g; p <0.001). Using multi-TI ASL, the median T 1 of renal cortex was shorter than that of medulla (799.6 ms vs 807.1 ms, p = 0.01), and mean whole-kidney BAT was 269.7 ± 56.5 ms. GTN had an effect on systolic blood pressure (p < 0.05) but the change in RBF was not significant. Conclusions Free-breathing multi-TI renal ASL is feasible and reproducible at 3 T, providing simultaneous measurement of renal perfusion, haemodynamic parameters and tissue characteristics at baseline and during pharmacological challenge. Key points • Multiple inversion time arterial spin labelling (ASL) of the kidneys is feasible and reproducible at 3 T.• This approach allows simultaneous mapping of renal perfusion, bolus arrival time and tissue T 1 during free breathing.• This technique enables repeated measures of renal haemodynamic characteristics during pharmacological challenge.

Consensus-based technical recommendations for clinical translation of renal ASL MRI

“…Issues such as repeatability and validation of ASL with alternative methods to measure renal perfusion were extensively addressed therewith and, therefore, will not be covered in the present manuscript. The previous literature review [8] as well as 12 studies published in the intervening period [11][12][13][14][15][16][17][18][19][20][21][22], the results of a series of surveys and the discussions that took place at the in-person meetings form the basis for the final recommendations presented here.…”

“…Standardizing patient preparation with the aim of achieving more reproducible renal perfusion measurements may be desirable. Renal ASL perfusion estimates have shown significant variation when subjects were challenged with water loading, protein load, adenosine, and furosemide [20,[38][39][40].…”

“…For each, single time point acquisitions, defined to be at a given TI for FAIR and PLD for PCASL, are recommended for simplicity of acquisition and data analysis [R3.2]. Multiple time point acquisitions, in which data are collected at a number of TIs [20,43,44] or PLDs [45], require a longer acquisition time and more complicated processing. However, it was agreed that a multiple time point method can be useful if delayed arrival time is suspected in a clinical population, as this provides a measurement of arterial transit time (ATT) which can facilitate more accurate quantification of renal perfusion [R3.3].…”

Image registration in dynamic renal MRI—current status and prospects

“…Shirvani et al, showed recently the feasibility of multiparametric renal arterial spin labeling (3 T, 3D GRASE, FAIR, background suppression, and PD image acquired as the reference) with free-breathing acquisition [94]. The control and labeled images were motion-corrected by performing retrospective 2D elastic registration.…”

Robust pCASL perfusion imaging using a 3D Cartesian acquisition with spiral profile reordering (CASPR)

“…3D GRASE has been increasingly used for perfusion imaging, both in the brain and kidneys . However, because of the linear or low‐high view ordering that is currently used, 3D GRASE images also suffer from signal variations and are often acquired using multiple signal averages .…”