Quantifying the morphological variations of internal carotid artery in moyamoya angiopathy

Moyamoya angiopathy (MMA) is characterised by the progressive narrowing and subsequent development of collateral blood vessels in the distal internal carotid artery (ICA) and its branches. This study investigates the influence of loss in ICA tortuosity and the role of morphological parameters of ICA subsegments in MMA.

This study utilised the 3D morphometric analysis of ICA models and its subsegments developed from magnetic resonance angiography to evaluate morphological variations in MMA. The investigation compared ICA morphology between MMA cases (40 adults, 33 paediatric patients) and control groups (60 adults, 37 paediatric subjects). Measurements included ICA tortuosity, curvature, and torsion parameters across four ICA subsegments, followed by statistical analysis for both age cohorts.

The Mann-Whitney U-test revealed significantly reduced ICA tortuosity in MMA groups versus controls (p value <.001) for both the adult and paediatric cohorts. In adult MMA group, the subsegments C2, C3, and C4 showed lesser curvature values (p value = .014, <.001, .003), while C5 displayed increased curvature (p = .023) compared to controls. The paediatric MMA cases exhibited significant curvature differences in C2, C3, and C4 (p = .002, <.001, <.001), whereas that of C5 showed no significant variation. In adult MMA cases, the torsion values differed significantly in C2, C3, and C4 (p = .012, .031, .032), while C5 and all of the paediatric subsegments showed little variation. Correlation analysis confirmed the influence of morphological variations of at least three segments on ICA tortuosity for both age groups.

ICA tortuosity is a reliable radiological marker in MMA across age groups. While subsegmental morphological parameters significantly influence overall ICA tortuosity, their impact varies between adult and paediatric cases. These findings suggest ICA tortuosity may have substantial role in the MMA pathogenesis and diagnosis.