Assessment of Attenuation in Pericarotid Fat among Patients with Carotid Plaque and Spontaneous Carotid Dissection

Background and purpose: Changes in perivascular fat density (PFD) and its association with inflammation have been topics of interest in both atherosclerotic and nonatherosclerotic vasculopathies. The objective of this study was to assess the PFD in patients with spontaneous internal carotid artery dissection (SICAD) or carotid atherosclerotic plaque, with and without intraplaque hemorrhage (IPH). Materials and methods: A cross-sectional retrospective bicentric analysis of 130 patients (30 with SICAD and 100 with carotid atherosclerotic plaque) who underwent CT angiography was performed. Among the subjects with atherosclerotic plaque, 36 showed the presence of IPH. PFD analysis was performed by 2 radiologists who placed 2 ROIs to identify the perivascular fat tissue attenuation. The Mann-Whitney U test was conducted to evaluate the difference between patient cohorts. Results: Carotid arteries with SICAD and IPH demonstrated an average PFD of -68.97 HU (95% CI, -72.11 to -65.82 HU) and -69.97 HU (95% CI, -73.00 to -66.95 HU), respectively, in comparison with patients without IPH, who showed an average PFD -77.11 HU (95% CI,-78.78 to -75.44 HU) (P < .001 for both). Conversely, no significant differences were found between patients with SICAD and those with carotid plaque with IPH (P = .324). Conclusions: The average PFDs in patients with SICAD and carotid atherosclerosis plaque with IPH were similar and higher than those in patients with carotid plaque without IPH. This finding suggests a shared pathologic inflammatory mechanism in these 2 conditions. Studies comparing pathologic specimens directly with radiologic images may be needed to confirm this indirect hypothesis.