Evaluation of carotid plaque composition by computed tomography angiography and black blood magnetic resonance image

Carotid Plaque Composition Assessed by CT Predicts Subsequent Cardiovascular Events among Subjects with Carotid Stenosis

BACKGROUND AND PURPOSE

Currently, the characteristics of carotid plaques are considered important factors for identifying subjects at high risk of stroke. This study aimed to test the hypothesis that carotid plaque composition assessed by CTA is associated with an increased risk of future major adverse cardiovascular events among asymptomatic subjects with moderate-to-severe carotid artery stenosis.

MATERIALS AND METHODS

This single-center, retrospective cohort study included 194 carotid plaques from 176 asymptomatic subjects with moderate-to-severe carotid artery stenosis. The association of CTA-determined plaque composition with the risk of subsequent adverse cardiovascular events was analyzed.

RESULTS

During a median follow-up of 41 months, the adverse cardiovascular event incidence among 194 carotid plaques was 19.6%. There were significant differences in plaque Hounsfield units (P < .001) and spotty calcium presence (P < .001) between carotid plaques from subjects with and without subsequent adverse cardiovascular events. Multivariable analysis revealed carotid plaque Hounsfield unit density (P < .001) and spotty calcium (P < .001) as independent predictors of subsequent adverse cardiovascular events. In association with moderate carotid artery stenosis, the plaque Hounsfield unit values were significantly lower among carotid plaques from subjects who experienced subsequent adverse cardiovascular events (P = .002), strokes (P = .01), and cardiovascular deaths (P = .04); the presence of spotty calcium was significantly associated with the occurrence of adverse cardiovascular events (P = .001), acute coronary syndrome (P = .01), and cardiovascular death (P = .04).

CONCLUSIONS

Carotid plaque Hounsfield unit density and spotty calcium were independent predictors of a greater risk of adverse cardiovascular event occurrence.

Quantitative assessment of carotid plaque morphology (geometry and tissue composition) using computed tomography angiography

OBJECTIVE

Quantification of carotid plaque morphology (geometry and tissue composition) may help stratify risk for future stroke and assess plaque progression or regression in response to medical risk factor modification. We assessed the feasibility and reliability of morphologic measurements of carotid plaques using computed tomography angiography (CTA) and determined the minimum detectable change in plaque features by this approach.

METHODS

CTA images of both carotid arteries in 50 patients were analyzed by two observers using a semiautomatic image analysis program, yielding 93 observations per user (seven arteries were excluded because of prior stenting). One observer repeated the analyses 4 weeks later. Measurements included total plaque volume; percentage stenosis (by diameter and area); and tissue composition for calcium, lipid-rich necrotic core (LRNC), and intraplaque hemorrhage (IPH). Reliability of measurements was assessed by intraclass and interclass correlation and Bland-Altman plots. Dice similarity coefficient (DSC) and modified Hausdorff distance (MHD) assessed reliability of geometric shape measurements. We additionally computed the minimum amount of change in these features detectable by our approach.

RESULTS

The cohort was 51% male (mean age, 70.1 years), and 56% had a prior stroke. The mean (± standard deviation) plaque volume was 837.3 ± 431.3 mm³, stenosis diameter was 44.5% ± 25.6%, and stenosis area was 58.1% ± 29.0%. These measurements showed high reliability. Intraclass correlation coefficients for plaque volume, percentage stenosis by diameter, and percentage stenosis by area were 0.96, 0.87, and 0.83, respectively; interclass correlation coefficients were 0.88, 0.84, and 0.78. Intraclass correlations for tissue composition were 0.99, 0.96, and 0.86 (calcium, LRNC, and IPH, respectively), and interclass correlations were 0.99, 0.92, and 0.92. Shape measurements showed high intraobserver (DSC, 0.95 ± 0.04; MHD, 0.16 ± 0.10 mm) and interobserver (DSC, 0.94 ± 0.05; MHD, 0.19 ± 0.12 mm) luminal agreement. This approach can detect a change of at least 3.9% in total plaque volume, 1.2 mm³ in calcium, 4.3 mm³ in LRNC, and 8.6 mm³ in IPH with the same observer repeating measurements and 9.9% in plaque volume, 1.9 mm³ in calcium, 7.9 mm³ in LRNC, and 6.8 mm³ in IPH for two different observers.

CONCLUSIONS

Carotid plaque geometry (total volume, diameter stenosis, and area stenosis) and tissue composition (calcium, LRNC, and IPH) are measured reliably from clinical CTA images using a semiautomatic image analysis program. The minimum change in plaque volume detectable is ∼4% if the same observer makes both measurements and ∼10% for different observers. Small changes in plaque composition can also be detected reliably. This approach can facilitate longitudinal studies for identifying high-risk plaque features and for quantifying plaque progression or regression after treatment.

Subcutaneous hematoma associated with manual cervical massage during carotid artery stenting. A case report

We describe a patient with subcutaneous hematoma associated with manual cervical massage during carotid artery stenting.A 73-year-old man with left cervical carotid artery stenosis presented with left amaurosis fugax. We performed carotid artery stenting using distal embolic protection with balloon occlusion. Dual antiplatelet therapy was maintained in the periprocedural period and an anticoagulant agent was administered during the procedure. Because the aspiration catheter became entrapped by the stent, it did not reach the distal side of the stenotic lesion, and manual compression of the cervical region was therefore performed. Immediately afterwards, a subcutaneous hemorrhage occurred in the cervical region. There was no postoperative dyspnea due to enlargement of the hematoma, which was absorbed spontaneously.Cervical subcutaneous hematoma can occur in the cervical region due to cervical massage in patients who are receiving adjuvant antiplatelet therapy and anticoagulation therapy.