To systematically review and compare the diagnostic capability of CTA and MRA in identifying vulnerable carotid plaque characteristics, such as intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), and ulceration.

Accurate diagnosis of vulnerable carotid plaque is crucial for stroke risk stratification. CTA and MRA are key noninvasive imaging modalities, but their comparative accuracy for assessing plaque vulnerability is  unclear.

This review was conducted according to PRISMA 2020 guidelines. A search of PubMed, SCOPUS, and Cochrane Central Register of Controlled Trials (CENTRAL) databases was performed through October, 2024. Studies comparing CTA and MRA for assessing carotid plaque vulnerability in symptomatic or asymptomatic patients were included. The quality of included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) and QUADAS-C tools.

Out of 3302 studies, five comparative studies (377 patients, 695 plaques) were included, with the majority (92.9%) of reported patients being symptomatic. The overall risk of bias was high, primarily due to non-randomized patient selection. Significant heterogeneity precluded a formal meta-analysis, necessitating a descriptive synthesis. The review found that MRA, with its superior soft-tissue contrast, is the preferred modality for directly identifying lipid-rich necrotic core (LRNC). However, several CTA findings showed strong associations with MRA-defined vulnerability: the presence of intraplaque hemorrhage (IPH) on MRA was consistently associated with significantly higher mean plaque density, higher NASCET percentage stenosis, greater soft-plaque thickness, and the presence of the "rim sign" (adventitial calcification with internal soft plaque) on CTA. For ulceration, one study found CTA and MRA to be equivalent.

While MRA provides more detailed direct plaque characterization, CTA offers a widely available alternative. CTA markers—heterogenous plaque density, soft-plaque thickness, plaque ulceration, and stenosis severity—serve as indicators of vulnerable plaque features. Current evidence is limited by heterogeneous studies with a high risk of bias. Standardized, comparative research is needed.