Cerebral blood flow in a tri-ethnic population: insights from pCASL perfusion MRI

Abstract

Objectives: Arterial transit artefacts (ATAs) on pseudo-continuous arterial spin labelling (pCASL) MRI represent visual markers of delayed arterial transit. This study aimed to investigate their prevalence and distribution and to evaluate the effects of sex, ethnicity, intracranial arterial anatomy, and cardiovascular parameters in a subgroup of the UK tri-ethnic population-based Southall and Brent REvisited (SABRE) study.

Materials and methods: We analysed 360 participants-120 each of White European, South Asian, and African Caribbean origin-from the prospective SABRE cohort who underwent 3.0-T brain MRI and clinical assessment between 2014 and 2018. ATAs were visually rated across 40 predefined brain regions on pCASL perfusion images and summarised as percentage ATA scores. Intracranial arterial anatomy was classified on time-of-flight MR angiography, and cardiovascular parameters were obtained from clinical assessment. ATAs were compared by sex and ethnicity, and associations with demographic, anatomical, and cardiovascular factors were analysed using multivariable regression.

Results: Of 360 participants, 284 (78.89%; mean age 70.12 ± 6.58 years; range 49-89; 139 women) had usable pCASL data. ATA prevalence varied across vascular territories and between women and men. African Caribbean participants showed a higher frequency of ATAs in the posterior circulation, whereas in most anterior territories they had fewer ATAs than White Europeans or South Asians.

Conclusion: Visual rating of ATAs revealed sex- and ethnicity-specific differences in ATA distribution, reflecting variations in arterial transit time influenced by intracranial vascular anatomy and cardiovascular parameters. These findings highlight the potential of ATAs as imaging markers for personalised cerebrovascular assessment and risk stratification.

Key points: Question Prevalence and distribution of arterial transit artefacts (ATAs) on arterial spin labelling MRI, and their relationship to sex, ethnicity, vascular anatomy, and cardiovascular parameters, have not been systematically investigated. Findings ATAs were most prevalent in African Caribbeans, particularly in MCA-PCA borderzones and PCA territories; no significant differences were found between White Europeans and South Asians. Clinical relevance Visual rating revealed substantial differences in the ATA distribution among ethnic populations, as well as between women and men. Recognising these specific patterns can help distinguish physiological from pathological perfusion, thereby enhancing diagnostic accuracy and treatment planning.

Keywords: Artefacts; Brain; Cerebrovascular circulation; Ethnicity; Spin labels.