Hepatic arterial spin labelling MRI: an initial evaluation in mice

Abstract

The development of strategies to combat hepatic disease and augment tissue regeneration has created a need for methods to assess regional liver function. Liver perfusion imaging has the potential to fulfil this need, across a range of hepatic diseases, alongside the assessment of therapeutic response. In this study, the feasibility of hepatic arterial spin labelling (HASL) was assessed for the first time in mice at 9.4 T, its variability and repeatability were evaluated, and it was applied to a model of colorectal liver metastasis. Data were acquired using flow-sensitive alternating inversion recovery-arterial spin labelling (FAIR-ASL) with a Look–Locker readout, and analysed using retrospective respiratory gating and a T1-based quantification. This study shows that preclinical HASL is feasible and exhibits good repeatability and reproducibility. Mean estimated liver perfusion was 2.2 ± 0.8 mL/g/min (mean ± standard error, n = 10), which agrees well with previous measurements using invasive approaches. Estimates of the variation gave a within-session coefficient of variation (CVWS) of 7%, a between-session coefficient of variation (CVBS) of 9% and a between-animal coefficient of variation (CVA) of 15%. The within-session Bland–Altman repeatability coefficient (RCWS) was 18% and the between-session repeatability coefficient (RCBS) was 29%. Finally, the HASL method was applied to a mouse model of liver metastasis, in which significantly lower mean perfusion (1.1 ± 0.5 mL/g/min, n = 6) was measured within the tumours, as seen by fluorescence histology. These data indicate that precise and accurate liver perfusion estimates can be achieved using ASL techniques, and provide a platform for future studies investigating hepatic perfusion in mouse models of disease. Copyright © 2014 John Wiley & Sons, Ltd.

MRI-based assessment of liver perfusion and hepatocyte injury in the murine model of acute hepatitis

“…The ASL study showed that perfusion in the liver parenchyma in the control animals was 245 ± 20 ml/min/100 g, which is in good agreement with the previously reported values of 220 ± 30 ml/min/100 g in Balb/c mice obtained using the FAIR-ASL technique with the Look-Locker readout [29]. In our study, perfusion in ALF was impaired by 18 %, likely due to the inflow of activated and therefore inflexible and more viscous leucocytes into the site of inflammation [30–32].…”

“…The T 1 value in the control group was 1249 ± 91 ms, which is comparable to the previously reported 1360 ± 60 ms [29]. The correlation between T 1 and perfusion suggested that the change observed in the value of the relaxation time is linked with the haemodynamics.…”

Combining optical imaging of cleared tissue with mathematical modelling to predict drug delivery and therapeutic response

“…R1(t) was estimated from the theoretical change in spoiled gradient-echo signal magnitude. 55 R10 was the mean, pre-enhancement R1, which was estimated from a Look-Locker multiinversion time acqusition, 56 acquired prior to the dyunamic sequence (TE, 1.18 ms; inversion time spacing, 110 ms; first inversion time, 2.3 ms; 50 inversion recovery readouts).…”

Vascular assessment of liver disease—towards a new frontier in MRI

“…68 Mice liver ASL studies have reported reasonable parenchymal perfusion quantification and changes in perfusion of colorectal liver metastases after administration of vascular disrupting agents. 69 …”