Associations between carotid artery wall thickness and cardiovascular risk factors using multidetector CT

Evaluation of Carotid Wall Thickness by using Computed Tomography and Semiautomated Ultrasonographic Software

Purpose

The increased thickness of the carotid artery is associated with the development of coronary and cerebrovascular events. In this study our purpose was to evaluate the carotid artery wall thickness (CAWT) by using multidetector-row computed tomography angiography (MDCTA) and the intima media thickness (IMT) by using semiautomated ultrasonography (SA-US) to evaluate the agreement between the two methods.

Methods

This is a retrospective study, and the institutional review board approval was obtained. Twenty-one patients (age range, 59–81 years) were analyzed with the use of a 16-detector row CT and a sonographic scanner. In total, 14 subjects had shown cerebral ischemic symptoms. The IMT was quantified by the use of specific semiautomated software (ImgTracer™, Global Biomedical Technologies, Roseville, CA) by four expert observers, and the CAWT was measured by use of the MDCTA. Data were compared with the Wilcoxon test for paired samples. Bland–Altman statistics was used to measure the agreement between MDCTA and SA-US. A p value < 0.05 was considered significant.

Results

Forty-two carotids were analyzed, and the CAWT ranged from 0.64 to 2.99 mm, with a mean value of 1.438 mm. By analyzing the Bland–Altman plots, we observed a good agreement between SA-US and correlation coefficient r were 0.9250 (95% confidence interval [CI] 0.864–0.959; p < 0.0001), 0.9265 (95% CI 0.866–0.961; p < 0.0001), 0.9466 (95% CI 0.902–0.971; p < 0.0001), and 0.8621 (95% CI: 0.756–0.924; p < 0.0001) for observer 1, observer 2, observer 3 and observer 4 respectively.

Conclusions

Data of this preliminary study by using SA-US and MDCTA demonstrated a good agreement between in the measurement of CAWT and IMT.

Contrast-enhanced CT imaging in patients with chronic kidney disease

Renal microvascular rarefaction characterizes chronic kidney disease (CKD). In murine models of CKD, micro-CT imaging reflected capillary rarefaction using quantification of renal relative blood volume (rBV). In addition, micro-CT imaging revealed morphological alterations of the intrarenal vasculature including reduced vascular branching and lumen diameter. Here, we retrospectively quantified rBV in contrast-enhanced CT angiography in patients and found that, compared to non-CKD patients, those with CKD and renal fibrosis had significantly reduced rBV in the renal cortex. rBV values closely mirrored capillary rarefaction in the corresponding nephrectomy specimens. In patients with follow-up CT angiography, reduction of renal function was paralleled by a decline in rBV. Using virtual autopsy, i.e., postmortem CT angiography, morphometry of intrarenal arteries in 3D-rendered CT images revealed significantly reduced arterial diameter and branching in CKD compared to non-CKD cases. In conclusion, in CKD patients, contrast-enhanced CT imaging with quantification of rBV correlates with functional renal vasculature, whereas virtual autopsy allows morphometric analyses of macrovascular changes. Importantly, the observed vascular alterations in CKD patients mirror those in animals with progressive CKD, suggesting a high relevance of animal models for studying vascular alterations in CKD and renal fibrosis.

Is there an association between asymmetry of carotid artery wall thickness (ACAWT) and cerebrovascular symptoms?

PURPOSE

Previous publications demonstrated that multi-detector-row computed tomography Angiography (MDCTA) can evaluate the carotid artery wall thickness (CAWT). The purpose of this work was to compare the asymmetry of CAWT between carotids in symptomatic and asymptomatic patients.

MATERIAL AND METHODS

Sixty consecutive symptomatic (males 44; median age 64) and 60 asymptomatic sex- and age-matched patients were analysed by using a 40-detector-row CT system. CAWT was calculated for both carotids in each patient and the ratio between the thicker CAWT and the contra-lateral was calculated to obtain the ACAWT index. Bland-Altman, logistic regression and receiver operating characteristic (ROC) curve analysis were calculated.

RESULTS

The Bland-Altman plot demonstrates a very good agreement between measurements with a mean difference value of 3.4% and 95% CI from -8% to 14.8%. The ACAWT was significantly different between symptomatic and asymptomatic patients (with a p value of 0.0001). The ROC area under the curve was 0.742 (p = 0.001). Logistic regression model indicated that ACAWT, CAWT, stenosis degree, and fatty plaques were independent variables associated with cerebrovascular symptoms (p value, respectively, 0.0108, 0.0231, 0.0002, and 0.013).

CONCLUSION

Results of our study indicated that the index of asymmetry in the CAWT might be used as a further parameter to stratify the risk of symptoms related to carotid artery.

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.

Semiautomated and automated algorithms for analysis of the carotid artery wall on computed tomography and sonography: a correlation study

OBJECTIVES

The purpose of this study was to compare automated and semiautomated algorithms for analysis of carotid artery wall thickness and intima-media thickness on multidetector row computed tomographic (CT) angiography and sonography, respectively, and to study the correlation between them.

METHODS

Twenty consecutive patients underwent multidetector row CT angiographic and sonographic analysis of carotid arteries (mean age, 66 years; age range, 59-79 years). The intima-media thickness of the 40 carotid arteries was measured with novel and dedicated automated software analysis and by 4 observers who manually calculated the intima-media thickness. The carotid artery wall thickness was automatically estimated by using a specific algorithm and was also semiautomatically quantified. The correlation between groups was calculated by using the Pearson ρ statistic, and scatterplots were calculated. We evaluated intermethod agreement using Bland-Altman analysis.

RESULTS

By comparing automated carotid artery wall thickness, automated intima-media thickness, semiautomated carotid artery wall thickness, and semiautomated intima-media thickness analyses, a statistically significant association was found, with the highest values obtained for the association between semiautomated and automated intima-media thickness analyses(Pearson ρ = 0.9; 95% confidence interval, 0.82-0.95; P = 0.0001). The lowest values were obtained for the association between semiautomated intima-media thickness and automated carotid artery wall thickness analyses (Pearson ρ = 0.44; 95% confidence interval, 0.15-0.66; P = 0.0047). In the Bland-Altman analysis, the better results were obtained by comparing the semiautomated and automated algorithms for the study of intima-media thickness, with an interval of -16.1% to +43.6%.

CONCLUSIONS

The results of this preliminary study showed that carotid artery wall thickness and intima-media thickness can be studied with automated software, although the CT analysis needs to be further improved.

Computed tomography carotid wall plaque characterization using a combination of discrete wavelet transform and texture features: A pilot study

In 30% of stroke victims, the cause of stroke has been found to be the stenosis caused by plaques in the carotid artery. Early detection of plaque and subsequent classification of the same into symptomatic and asymptomatic can help the clinicians to choose only those patients who are at a higher risk of stroke for risky surgeries and stenosis treatments. Therefore, in this work, we have proposed a non-invasive computer-aided diagnostic technique to classify the detected plaque into the two classes. Computed tomography (CT) images of the carotid artery images were used to extract Local Binary Pattern (LBP) features and wavelet energy features. Significant features were then used to train and test several supervised learning algorithm based classifiers. The Support Vector Machine (SVM) classifier with various kernel configurations was evaluated using LBP and wavelet features. The SVM classifier presented the highest accuracy of 88%, sensitivity of 90.2%, and specificity of 86.5% for radial basis function (RBF) kernel function. The CT images of the carotid artery provide unique 3D images of the artery and plaque that could be used for calculating percentage of stenosis. Our proposed technique enables automatic classification of plaque into asymptomatic and symptomatic with high accuracy, and hence, it can be used for deciding the course of treatment. We have also proposed a single-valued integrated index (Atheromatic Index) using the significant features which can provide a more objective and faster prediction of the class.

Carotid artery wall thickness measured using CT: inter- and intraobserver agreement analysis

SUMMARY

The purpose of this work was to compare inter- and intraobserver agreement in the analysis of CAWT by using MDCTA. The CAWT in 35 patients was quantified by 4 observers. Bland-Altman statistics were used to measure the agreement between observers. The results of our study demonstrated that the CAWT measured by using MDCTA shows a good reproducibility between observers by considering inter- and intraobserver agreement.

Carotid plaque enhancement and symptom correlations: an evaluation by using multidetector row CT angiography

BACKGROUND AND PURPOSE

The identification of plaque characteristics that determine its vulnerability is extremely important. The purpose of this work was to evaluate CPE after administration of contrast material and to assess whether there is a statistical association between CPE and cerebrovascular symptoms.

MATERIALS AND METHODS

Ninety-seven consecutive patients (69 men, 28 women; mean age, 62 years; age range, 39-82 years), studied by using an MDCT scanner, were retrospectively analyzed. Examinations were performed before and after administration of contrast medium. Plaque enhancement was analyzed, and the obtained data were compared with the patient's symptoms. Patients were classified as symptomatic (TIA or stroke with a temporal window of 6 months) or asymptomatic according to neurologic assessment and the TOAST criteria. The ROC curve and Az were calculated, and multiple logistic regression analysis was performed.

RESULTS

Thirty-nine patients were excluded because they had calcified plaques (40.2%). CPE was observed in 74% of the remaining 58 patients. A statistically significant difference was observed between symptomatic and asymptomatic patients for the presence of CPE (P = .0013; OR = 7.5). Moreover, we observed that CPE was higher in fatty plaques (P = .035) than in mixed ones and more frequent in the former (P = .0119). The ROC curve demonstrated that a threshold of 15 HU is associated with a specificity and sensitivity of 83.33% and 76.47%, respectively. Multiple logistic regression showed that CPE and symptoms are associated (P = .0315).

CONCLUSIONS

The results of our study suggest that for noncalcified carotid plaques, the presence of CPE is associated with cerebrovascular symptoms. Fatty plaques are more likely to have CPE compared with mixed plaques.

Comparison between manual and automated analysis for the quantification of carotid wall by using sonography. A validation study with CT

PURPOSE

The purpose of this paper was to compare manual and automated analysis for the quantification of carotid wall obtained with sonography by using the computed tomography as validation technique.

MATERIAL AND METHODS

21 consecutive patients underwent MDCTA and ultrasound analysis of carotid arteries (mean age 68 years; age range 59-81 years). The intima-media-thickness (IMT) of the 42 carotids was measured with novel and dedicated automated software analysis (called AtheroEdge™, Biomedical Technologies, Denver, CO, USA) and by four observers that manually calculated the IMT. The carotid artery wall thickness (CAWT) was also quantified in the CT datasets. Bland-Altman statistics was employed to measure the agreement between methods. A Student's t-test was used to test the differences between the IMT values of AtheroEdge™. The study obtained the IRB approval.

RESULTS

The correlation between automated AtheroEdge™ measurements and those of the human experts were equal to 95.5%, 73.5%, 88.9%, and 81.7%. The IMT coefficient of variation of the human experts was equal to 11.9%. By using a Student's t-test, the differences between the IMT values of AtheroEdge™ and those of the human experts were not found statistically significant (p value=0.02). On comparing AtheroEdge™ (using Ultrasound) with CAWT (using CT), the results suggested a very good concordance of 84.96%.

CONCLUSIONS

Data of this preliminary study indicate that automated software AtheroEdge™ can analyze with precision the IMT of carotid arteries and that the concordance with CT is optimal.