Understanding external carotid artery collateralisation after cerebral revascularisation in moyamoya disease: insights from quantitative analysis.

Background: This study aims to quantitatively evaluate collateralisation angiogenesis ratio (CAR) of external carotid artery and intracranial arterial residual volumes (ARV) postcerebral revascularisation in moyamoya disease (MMD) and elucidate the factors influencing external carotid artery collateralisation.

Methods: The study retrospectively analysed 297 patients diagnosed with MMD who underwent cerebral revascularisation at our University's Hospital, between January 2015 and May 2023. The clinical data, imaging results and surgical specifics for the patients were collected. Using a newly proposed digital subtraction angiography-based evaluation system, the CAR of external carotid artery and the intracranial ARV were evaluated quantitatively following standardised protocols.

Results: The study included 136 male and 161 female patients. The severity of ischaemic (r=-0.297) and haemorrhagic (r=-0.270) MMD, as assessed by the Suzuki stage, demonstrated a significant negative correlation with intracranial ARV (p<0.001). However, no significant correlation was observed between the intracranial ARV and the modified Rankin Scale scores. Patients with fetal-type posterior cerebral arteries exhibited greater intracranial ARV compared with those without (p=0.003). Additionally, a positive correlation was observed between external carotid artery collateralisation and intracranial ARV post-revascularisation (r=0.340, p<0.001). The CAR of external carotid artery following cerebral revascularisation in patients with MMD remained independent correlation of the intracranial ARV (β=0.385, 95% CI (0.921 to 1.669), p<0.001) and Suzuki stage (β=0.211, 95% CI (0.009 to 0.030), p<0.001).

Conclusions: This study showed a complex association between ARV, the Suzuki stage and the collateralisation of the external carotid artery in patients with MMD who are undergoing revascularisation. These findings provide insights into MMD progression and revascularisation outcomes and may guide clinical decision-making to improve patient care.