Association between spontaneous internal carotid artery dissection and perivascular adipose tissue attenuation on computed tomography angiography.

BACKGROUND: Spontaneous cervical artery dissection (sCAD) is a leading cause of ischemic stroke in young patients. Studies using high-resolution magnetic resonance imaging and positron emission tomography have suggested vessel wall inflammation to be a pathogenic factor in sCAD. Computed tomography (CT) attenuation of perivascular adipose tissue (PVAT) is an established non-invasive imaging biomarker of inflammation in coronary arteries, with higher attenuation values reflecting a greater degree of vascular inflammation.

OBJECTIVES: We evaluate the CT attenuation of PVAT surrounding the internal carotid artery (PVATcarotid ) with and without spontaneous dissection.

METHODS: Single-center prospective observational study of 56 consecutive patients with CT-verified spontaneous dissection of the internal carotid artery (ICA). Of these patients, six underwent follow-up computed tomography angiography (CTA). Twenty-two patients who underwent CTA for acute neurological symptoms but did not have dissection formed the control group. Using semi-automated research software, PVATcarotid was measured as the mean Hounsfield unit (HU) attenuation of adipose tissue within a defined volume of interest surrounding the ICA.

RESULTS: PVATcarotid was significantly higher around dissected ICA compared with non-dissected contralateral ICA in the same patients (-58.7 ± 10.2 vs -68.9 ± 8.1 HU, p  < 0.0001) and ICA of patients without dissection (-58.7 ± 10.2 vs -69.3 ± 9.3 HU, p  < 0.0001). After a median follow-up of 89 days, there was a significant reduction in PVATcarotid around dissected ICA (-57.5 ± 13.4 to -74.3 ± 10.5 HU, p  < 0.05), while no change was observed around non-dissected contralateral ICA (-71.0 ± 4.4 to -74.1 ± 4.1 HU, p  = 0.19). ICA dissection was an independent predictor of PVATcarotid following multivariable adjustment for age and the presence of ICA occlusion.

CONCLUSION: PVATcarotid is elevated in the presence of sCAD and may decrease following the acute event.