Characterization of carotid plaque hemorrhage: a CT angiography and MR intraplaque hemorrhage study
Jean Marie U-King-Im1, Allan J Fox, Richard I Aviv
1Division of Neuroradiology, Department of Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
Insights
CT angiography plaque ulceration effectively predicts intraplaque hemorrhage (IPH), unlike plaque density. This finding aids in assessing stroke risk using CT angiography (CTA) for intraplaque hemorrhage (IPH) detection.
Area of Science:
- Vascular imaging
- Radiology
- Cerebrovascular disease
Background:
- Intraplaque hemorrhage (IPH) is a marker of vulnerable atherosclerotic plaques.
- Accurate identification of IPH is crucial for stroke risk stratification.
Purpose of the Study:
- To determine if CT angiographic (CTA) features can predict intraplaque hemorrhage (IPH) as defined by MR-IPH.
- To evaluate the diagnostic performance of CTA plaque ulceration and plaque density for IPH detection.
Main Methods:
- 167 patients underwent both MR-IPH (gold standard) and CTA.
- CTA was assessed for carotid stenosis, plaque density, and plaque ulceration.
- MR-IPH used a 1.5 T scanner with a 3D fat-suppressed acquisition.
Main Results:
- IPH prevalence increased with higher degrees of carotid stenosis.
- Mean CT plaque density was higher in plaques with IPH, but overlap limited its predictive value.
- CTA plaque ulceration demonstrated high sensitivity, specificity, and predictive values for IPH detection.
Conclusions:
- CTA plaque ulceration is a reliable predictor of IPH.
- Mean CTA plaque density is not a useful predictor of IPH.
- CTA plaque ulceration can aid in identifying high-risk carotid plaques for IPH.
Background And Purpose:
The main objective of this study was to evaluate CT angiographic (CTA) features that are able to predict the presence of intraplaque hemorrhage (IPH) as defined by MR-IPH.
Methods:
One hundred sixty-seven consecutive patients (mean age 69 years, SD 12.8; 58 females) underwent both MR-IPH and CTA within 3 weeks. MR-IPH, the gold standard, was performed at 1.5 T using a neurovascular phased-array coil as a coronal T1-weighted 3-dimensional fat-suppressed acquisition. CTA was performed using a 4-slice or a 64-slice CT machine and evaluated, blinded to MR-IPH findings, for carotid stenosis, plaque density, and plaque ulceration. Plaque density was defined as the mean attenuation of plaque at the site of maximum stenosis and 2 sections above and below. Plaque ulceration was defined as outpouching of contrast into the plaque at least 2 mm deep on any single plane.
Results:
Prevalence of IPH increased at higher degrees of carotid stenosis. Mean CT plaque density was higher for plaques with MRI-defined IPH (47 Hounsfield units) compared with without IPH (43 Hounsfield units; P=0.02). However, significant overlap between distributions of plaque densities limited the value of mean plaque density for prediction of IPH. CTA plaque ulceration had high sensitivity (80.0% to 91.4%), specificity (93.0% to 92.3%), positive predictive value (72.0% to 71.8%), and negative predictive value (95.0% to 97.9%) for prediction of IPH. Interobserver agreement for presence/absence of CTA plaque ulceration was excellent (kappa=0.80).
Conclusions:
CTA plaque ulceration, but not mean CTA plaque density, was useful for prediction of IPH as defined by the MR-IPH technique.
