Characterisation of symptomatic intracranial plaque without substantial stenosis using high-resolution vessel wall MRI

AIM

To characterise symptomatic intracranial plaque without substantial stenosis using three-dimensional (3D) high-resolution contrast-enhanced black-blood magnetic resonance imaging (BBMRI) and to determine plaque features associated with recent cerebrovascular events.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. The case notes from patients with evidence of intracranial atherosclerosis in a large intracranial artery with preceding BBMRI were reviewed retrospectively. Symptomatic and asymptomatic plaques with substantial luminal stenosis (<50%) were matched by plaque location and patient age. All MRI images were de-identified and interpreted by two neuroradiologists who were blinded to the history of symptoms. Qualitative analyses including the presence of intraplaque haemorrhage (IPH), eccentricity, surface irregularity, and grade of plaque enhancement were recorded. Quantitative analyses including normal wall index and degree of contrast enhancement were calculated. Multivariate regression analysis was performed to identify the association with cerebrovascular ischaemic events.

RESULTS

A total of 38 pairs of symptomatic and asymptomatic plaques from 74 patients were analysed. Compared to asymptomatic plaques, symptomatic plaques demonstrated higher degree of contrast enhancement (29.77 ± 19.23 versus 18.21 ± 12.18%, p=0.039) and presence of IPH (26% versus 8%, p=0.032). No significant differences were detected regarding eccentricity, surface irregularity, and normal wall index. Events were associated with contrast enhancement (OR, 1.212; 95% confidence interval [CI], 1.086–1.352) after controlling for age, sex, cardiovascular risk factors, and stenosis degree. IPH was not associated with events.

CONCLUSION

Contrast enhancement in the intracranial plaque without substantial stenosis is associated with previous events, and may serve as the vulnerable feature, thereby stratifying stroke risk not achievable by luminal stenosis.