Differences in plaque morphology and correlation of stenosis at the carotid artery bifurcation and the carotid siphon

Plaque imaging volume analysis: technique and application

The prevention and management of atherosclerosis poses a tough challenge to public health organizations worldwide. Together with myocardial infarction, stroke represents its main manifestation, with up to 25% of all ischemic strokes being caused by thromboembolism arising from the carotid arteries. Therefore, a vast number of publications have focused on the characterization of the culprit lesion, the atherosclerotic plaque. A paradigm shift appears to be taking place at the current state of research, as the attention is gradually moving from the classically defined degree of stenosis to the identification of features of plaque vulnerability, which appear to be more reliable predictors of recurrent cerebrovascular events. The present review will offer a perspective on the present state of research in the field of carotid atherosclerotic disease, focusing on the imaging modalities currently used in the study of the carotid plaque and the impact that such diagnostic means are having in the clinical setting.

Embolic Stroke of Undetermined Source and Carotid Intraplaque Hemorrhage on MRI : A Systemic Review and Meta-Analysis

BACKGROUND

Embolic stroke of undetermined source (ESUS) has traditionally discounted the significance of internal carotid artery stenosis of <50%; however, recent studies have examined the role of carotid artery intraplaque hemorrhage (IPH) as an etiology in nonstenotic carotid arteries. We performed a systemic review of the literature to determine the prevalence of carotid artery IPH on magnetic resonance imaging (MRI) of the vessel wall in patients with ESUS.

METHODS

We used PubMed, Epub ahead of print, Ovid MEDLINE in-process and other non-indexed citations, Ovid MEDLINE, Ovid EMBASE, Ovid Cochrane central register of controlled trials, Ovid Cochrane database of systematic reviews and Scopus. Our study consisted of all case series with >10 patients with IPH and ESUS published through October 2018. Additionally, we included 123 patients from an institutional database from 2015-2019. Random effects meta-analysis was used for pooling across studies. Meta-analysis results were expressed as odds ratio (OR) with respective 95% confidence intervals (CI).

RESULTS

A total of 7 studies with 354 patients were included. The mean age was 67.5 years old. The overall prevalence estimate for prevalence of IPH ipsilateral to the ischemic lesion was 25.8% (95% CI 13.1-38.5). The odds of having IPH on the ipsilateral side versus the contralateral side was 6.92 (95% CI 3.04-15.79).

CONCLUSION

Patients with ESUS have IPH in the carotid artery ipsilateral to the ischemic stroke in 25.8% of cases. Carotid artery vessel wall MRI should be considered as part of the standard work-up in patients with ESUS.

Carotid Intraplaque-Hemorrhage Volume and Its Association with Cerebrovascular Events

BACKGROUND AND PURPOSE

Our aim was to assess the relationship between volume and percentage of intraplaque hemorrhage measured using CT and the occurrence of cerebrovascular events at the time of CT.

MATERIALS AND METHODS

One-hundred-twenty-three consecutive subjects (246 carotid arteries) with a mean age of 69 years who underwent CTA were included in this retrospective study. Plaque volume of components and subcomponents (including intraplaque hemorrhage volume) was quantified with dedicated software.

RESULTS

Forty-six arteries were excluded because no plaque was identified. In the remaining 200 carotid arteries, a statistically significant difference was found between presentation with cerebrovascular events and lipid volume (P = .002), intraplaque hemorrhage volume (P = .002), percentage of lipid (P = .002), percentage of calcium (P = .001), percentage of intraplaque hemorrhage (P = .001), percentage of lipid-intraplaque hemorrhage (P = .001), and intraplaque hemorrhage/lipid ratio (P = .001). The highest receiver operating characteristic area under the curve was obtained with the intraplaque hemorrhage volume with a value of 0.793 (P = .001), percentage of intraplaque hemorrhage with an area under the curve of 0.812 (P = .001), and the intraplaque hemorrhage/lipid ratio with an area under the curve value of 0.811 (P = .001).

CONCLUSIONS

Results of our study suggest that Hounsfield unit values <25 have a statistically significant association with the presence of cerebrovascular events and that the ratio intraplaque hemorrhage/lipid volume represents a strong parameter for the association of cerebrovascular events.

Association between carotid artery plaque inflammation and brain MRI

PURPOSE

To explore the association between presence of inflammatory cells in the carotid plaques surgically treated and brain MRI findings.

MATERIAL AND METHODS

Forty consecutive patients were prospectively analyzed. Brain MRI was performed with a 1.5 Tesla scanner and infacts (lacuna and non-lacunar) pertinence of the anterior circulation were recorded. All patients underwent carotid endarterectomy "en bloc"; carotid plaques histological sections were prepared and immuno-cytochemical analysis was performed to characterize and quantify the presence of inflammatory cells. ROC curve analysis, Pearson Rho correlation and Mann-Whitney test were applied.

RESULTS

The immuno-cytochemical analysis demonstrated that plaques of symptomatic patients (stroke\TIA; n = 25) had more inflammatory cells, mainly macrophages (CD68) compared with plaques of patients without symptoms (Mann-Whitney = P < 0.001, ROC curve area = 0.901). Correlation analysis showed a statistically significant association between the number of brain non-lacunar infarcts and the entity of macrophages (P < 0.001); whereas no association with lacunar infarcts (P = 0.1934) was found.

CONCLUSION

Results of this preliminary study suggest that the presence and amount of inflammatory cells within carotid artery plaque is associated with cerebrovascular events and with the number of MRI brain detectable infarct.

CT Attenuation Analysis of Carotid Intraplaque Hemorrhage

BACKGROUND AND PURPOSE

Intraplaque hemorrhage is considered a leading parameter of carotid plaque vulnerability. Our purpose was to assess the CT characteristics of intraplaque hemorrhage with histopathologic correlation to identify features that allow for confirming or ruling out the intraplaque hemorrhage.

MATERIALS AND METHODS

This retrospective study included 91 patients (67 men; median age, 65 ± 7 years; age range, 41-83 years) who underwent CT angiography and carotid endarterectomy from March 2010 to May 2013. Histopathologic analysis was performed for the tissue characterization and identification of intraplaque hemorrhage. Two observers assessed the plaque's attenuation values by using an ROI (≥ 1 and ≤2 mm²). Receiver operating characteristic curve, Mann-Whitney, and Wilcoxon analyses were performed.

RESULTS

A total of 169 slices were assessed (59 intraplaque hemorrhage, 63 lipid-rich necrotic core, and 47 fibrous); the average values of the intraplaque hemorrhage, lipid-rich necrotic core, and fibrous tissue were 17.475 Hounsfield units (HU) and 18.407 HU, 39.476 HU and 48.048 HU, and 91.66 HU and 93.128 HU, respectively, before and after the administration of contrast medium. The Mann-Whitney test showed a statistically significant difference of HU values both in basal and after the administration of contrast material phase. Receiver operating characteristic analysis showed a statistical association between intraplaque hemorrhage and low HU values, and a threshold of 25 HU demonstrated the presence of intraplaque hemorrhage with a sensitivity and specificity of 93.22% and 92.73%, respectively. The Wilcoxon test showed that the attenuation of the plaque before and after administration of contrast material is different (intraplaque hemorrhage, lipid-rich necrotic core, and fibrous tissue had P values of .006, .0001, and .018, respectively).

CONCLUSIONS

The results of this preliminary study suggest that CT can be used to identify the presence of intraplaque hemorrhage according to the attenuation. A threshold of 25 HU in the volume acquired after the administration of contrast medium is associated with an optimal sensitivity and specificity. Special care should be given to the correct identification of the ROI.

Longitudinal assessment of carotid atherosclerosis after Radiation Therapy using Computed Tomography: A case control Study

OBJECTIVES

To study the carotid artery plaque composition and its volume changes in a group of patients at baseline and 2 years after head and neck radiation therapy treatment (HNXRT).

METHODS

In this retrospective study, 62 patients (41 males; mean age 63 years; range 52-81) who underwent HNXRT and 40 patients (24 males; mean age 65) who underwent surgical resection of neoplasm and did not undergo HNXRT were assessed, with 2-year follow-up. The carotid artery plaque volumes, as well as the volume of the sub-components (fatty-mixed-calcified), were semiautomatically quantified. Mann-Whitney and Wilcoxon tests were used to test the hypothesis.

RESULTS

In the HNXRT group, there was a statistically significant increase in the total volume of the carotid artery plaques (from 533 to 746 mm(3); p = 0.001), in the fatty plaques (103 vs. 202 mm(3); p = 0.001) and mixed plaque component volume (328 vs. 419 mm(3); p = 0.034). A statistically significant variation (from 21.8 % to 27.6 %) in the percentage of the fatty tissue was found.

CONCLUSIONS

Results of this preliminary study suggest that HNXRT promotes increased carotid artery plaque volume, particularly the fatty plaque component.

KEY POINTS

HNXRT increases carotid plaque volume. Plaque volume increase is mainly due to increase.in fatty plaque component. Patients who undergo HNXRT have a progression of carotid artery disease.

Multi-modal CT scanning in the evaluation of cerebrovascular disease patients

Ischemic stroke currently represents one of the leading causes of severe disability and mortality in the Western World. Until now, angiography was the most used imaging technique for the detection of the extra-cranial and intracranial vessel pathology. Currently, however, non-invasive imaging tool like ultrasound (US), magnetic resonance (MR) and computed tomography (CT) have proven capable of offering a detailed analysis of the vascular system. CT in particular represents an advanced system to explore the pathology of carotid arteries and intracranial vessels and also offers tools like CT perfusion (CTP) that provides valuable information of the brain's vascular physiology by increasing the stroke diagnostic. In this review, our purpose is to discuss stroke risk prediction and detection using CT.