Ultra-high-field arterial spin labelling MRI for non-contrast assessment of cortical lesion perfusion in multiple sclerosis

Abstract

ObjectivesTo assess the feasibility of using an optimised ultra-high-field high-spatial-resolution low-distortion arterial spin labelling (ASL) MRI acquisition to measure focal haemodynamic pathology in cortical lesions (CLs) in multiple sclerosis (MS).MethodsTwelve MS patients (eight female, mean age 50 years; range 35–64 years) gave informed consent and were scanned on a 7 Tesla Philips Achieva scanner. Perfusion data were collected at multiple post-labelling delay times using a single-slice flow-sensitive alternating inversion recovery ASL protocol with a balanced steady-state free precession readout scheme. CLs were identified using a high-resolution Phase-Sensitive Inversion Recovery (PSIR) scan. Significant differences in perfusion within CLs compared to immediately surrounding normal appearing grey matter (NAGMlocal) and total cortical normal appearing grey matter (NAGMcortical) were assessed using paired t-tests.ResultsForty CLs were identified in PSIR scans that overlapped with the ASL acquisition coverage. After excluding lesions due to small size or intravascular contamination, 27 lesions were eligible for analysis. Mean perfusion was 40 ± 25 ml/100 g/min in CLs, 53 ± 12 ml/100 g/min in NAGMlocal, and 53 ± 8 ml/100 g/min in NAGMcortical. CL perfusion was significantly reduced by 23 ± 9% (mean ± SE, p = 0.013) and 26 ± 9% (p = 0.006) relative to NAGMlocal and NAGMcortical perfusion, respectively.ConclusionThis is the first ASL MRI study quantifying CL perfusion in MS at 7 Tesla, demonstrating that an optimised ASL acquisition is sensitive to focal haemodynamic pathology previously observed using dynamic susceptibility contrast MRI. ASL requires no exogenous contrast agent, making it a more appropriate tool to monitor longitudinal perfusion changes in MS, providing a new window to study lesion development.Key Points• Perfusion can be quantified within cortical lesions in multiple sclerosis using an optimised high spatial resolution arterial spin Labelling MRI acquisition at ultra-high-field.• The majority of cortical lesions assessed using arterial spin labelling are hypo-perfused compared to normal appearing grey matter, in agreement with dynamic susceptibility contrast MRI literature.• Arterial spin labelling MRI, which does not involve the injection of a contrast agent, is a safe and appropriate technique for repeat scanning of an individual patient.

Imaging cortical multiple sclerosis lesions with ultra-high field MRI

“…Eight articles were included in the field strength comparison (one post-mortem , seven in vivo ), eight publications in the sequence comparison (three post-mortem , five in vivo ) and five articles that validated UHF MRI data against histology. An overview of all included studies and relevant study parameters is provided in Appendix A , Bluestein et al, 2012a , Cohen-Adad et al, 2011 , Dury et al, 2019 , Fan et al, 2015 , Gaitan et al, 2013 , Herranz et al, 2020 , Jonkman et al, 2016a , Jonkman et al, 2016b , Kangarlu et al, 2007 , Kolber et al, 2017 , Kollia et al, 2009 , Metcalf et al, 2010 , Mistry et al, 2014 . Among the 25 in vivo studies, sample size ranged from 8 to 90 patients, mean age from 36 to 54 years and female proportion from 33 to 81%.…”

Development of Cortical Lesion Volumes on Double Inversion Recovery MRI in Patients With Relapse-Onset Multiple Sclerosis

“…Recent clinical trials, neuropathological investigations and MRI imaging studies have drawn growing attention to the relevance of gray matter (GM) lesions and particularly cortical lesions (CL) in Multiple Sclerosis (MS) patients (1–3). In contrast to earlier assumptions (4, 5), recent studies reported that neuroinflammation is present in CLs, suggesting that active immune mechanisms and focal demyelination are present inside the cortical layer (6–8).…”