Sietske Rozie

Erasmus Universiteit Rotterdam, Rotterdam, South Holland, Netherlands

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Publications (24)48.04 Total impact

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    ABSTRACT: The distensibility of a blood vessel is a marker of atherosclerotic disease. In this paper we investigate the feasibility of measuring carotid artery distensibility on 4D CTA, both manually and using a new automatic method. On 4D CTA datasets manual (n=38) and automatic (n=76) measurements of the carotid distensibility were performed. A subset (n=10) of the manual annotations were repeated by a second observer. The interobserver variability was assessed using a Bland-Altman analysis and appeared to be too large to reliably measure the distensibility using manual annotation. We compared two versions of the automatic method: one using 3D registration and one using a 4D registration method. The latter resulted in a more smooth deformation over time. The automatic method was evaluated using a synthetic deformation and by investigating whether known relations with cardiovascular risk factors could be reproduced. The relation between distensibility and cardiovascular risk factors was tested with a Mann-Whitney U test. Automatic measurements revealed an association with hypertension whereas the manual measurements did not. This relation has been found by other studies too. We conclude that carotid artery distensibility measurements should be performed automatically and that the method described in this paper is suitable for that. All CTA datasets and related clinical data used in this study can be downloaded from our website (http://ctadist.bigr.nl).
    Medical image analysis 03/2013; 17(5):515-524. · 3.09 Impact Factor
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    ABSTRACT: The purpose of this study was to validate automated atherosclerotic plaque measurements in carotid arteries from CT angiography (CTA). We present an automated method (three initialization points are required) to measure plaque components within the carotid vessel wall in CTA. Plaque components (calcifications, fibrous tissue, lipids) are determined by different ranges of Hounsfield Unit values within the vessel wall. On CTA scans of 40 symptomatic patients with atherosclerotic plaque in the carotid artery automatically segmented plaque volume, calcified, fibrous and lipid percentages were 0.97 ± 0.51 cm(3), 10 ± 11%, 63 ± 10% and 25 ± 5%; while manual measurements by first observer were 0.95 ± 0.60 cm(3), 14 ± 16%, 63 ± 13% and 21 ± 9%, respectively and manual measurement by second observer were 1.05 ± 0.75 cm(3), 11 ± 12%, 61 ± 11% and 27 ± 10%. In 90 datasets, significant associations were found between age, gender, hypercholesterolemia, diabetes, smoking and previous cerebrovascular disease and plaque features. For both automated and manual measurements, significant associations were found between: age and calcium and fibrous tissue percentage; gender and plaque volume and lipid percentage; diabetes and calcium, smoking and plaque volume; previous cerebrovascular disease and plaque volume. Significant associations found only by the automated method were between age and plaque volume, hypercholesterolemia and plaque volume and diabetes and fibrous tissue percentage. Significant association found only by the manual method was between previous cerebrovascular disease and percentage of fibrous tissue. Automated analysis of plaque composition in the carotid arteries is comparable with the manual analysis and has the potential to replace it.
    The international journal of cardiovascular imaging 05/2011; 28(4):877-87. · 2.15 Impact Factor
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    ABSTRACT: Intracranial arterial stenosis (ICAS) in patients with recent ischemic stroke is associated with a high risk of recurrent stroke. More insight into the pathophysiology of ICAS could help identify patients at high risk requiring more aggressive secondary prevention. We evaluated the prevalence, distribution, calcification, and the risk factors predisposing ICAS in a European stroke population. Consecutive patients with a transient ischemic attack or ischemic stroke (n=786) were evaluated for the presence and distribution of ICAS (≥30% luminal narrowing) by CT angiography. ICAS were categorized as symptomatic or asymptomatic, and the presence of calcification was assessed. The association of traditional cerebrovascular risk factors and the erythrocyte sedimentation rate with ICAS was analyzed. In 178 of 786 patients (23%), 288 ICAS were observed. Most stenoses (n=194/288; 67%) were located in the posterior circulation arteries. In 59 of 786 patients (8%), ICAS were considered symptomatic. ICAS in the basilar artery and arteries beyond the circle of Willis were mainly noncalcified. In addition to age, gender, and several traditional cerebrovascular risk factors, erythrocyte sedimentation rate was independently associated with the presence of ICAS (OR, 1.20; 95% CI, 1.06-1.36) and with the presence of noncalcified ICAS in particular (OR, 1.20; 95% CI, 1.05-1.37). ICAS was observed in a noteworthy number of European stroke patients. Particularly, the majority of ICAS was observed in the posterior circulation, possibly conferring worse prognosis. ICAS in distal arteries were mainly noncalcified. Association of noncalcified ICAS and erythrocyte sedimentation rate may indicate a prominent role for inflammatory factors in intracranial atherosclerotic disease.
    Stroke 03/2011; 42(5):1244-50. · 6.16 Impact Factor
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    ABSTRACT: Symptomatic carotid artery plaque ulceration is associated with distinct plaque components such as a large lipid-rich necrotic core (LR-NC) in ischemic stroke patients with a ≥50% carotid stenosis. We evaluated the associations between carotid artery plaque ulceration and plaque characteristics in ischemic stroke patients with ≥50% stenosis, as well as in those with a low degree of stenosis (0% to 49%). Consecutive patients (n=346) with symptoms in the anterior circulation were evaluated with multidetector CT angiography (MDCTA) for the presence of atherosclerotic plaque, degree of stenosis, and plaque ulceration in the symptomatic carotid artery. Plaque volume and plaque component proportions of LR-NC, fibrous tissue, and calcification were measured. The associations between plaque ulceration and plaque characteristics were analyzed using logistic regression. Atherosclerotic plaque was present in 185 patients. Plaque ulcerations were present in 38 (21%) patients, of which half had a low degree stenosis (0% to 49%). Plaque volume was significantly larger in ulcerated plaques. After adjustment for age, sex, and degree of stenosis, LR-NC proportion was strongly associated with plaque ulceration (odds ratio, 2.21; 95% CI, 1.49 to 3.27), whereas calcification proportion was inversely associated with plaque ulceration (odds ratio, 0.60; 95% CI, 0.40 to 0.89). These associations remained significant in patients with a low degree stenosis (0% to 49%). Plaque volume, degree of stenosis, and LR-NC proportion evaluated noninvasively with MDCTA are associated with carotid artery plaque ulceration, even in patients with a low degree stenosis (0% to 49%). Plaque volume and composition analysis with MDCTA may identify rupture prone plaques and improve risk stratification in ischemic stroke patients.
    Stroke 02/2011; 42(2):367-72. · 6.16 Impact Factor
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    ABSTRACT: Atherosclerotic carotid plaque rupture may lead to thromboembolization, causing transient ischemic attack or ischemic stroke. Carotid plaque ulceration on angiography is associated with plaque rupture. Although healing of ruptured plaques has been described in coronary arteries, little is known about the natural development of plaque ulcerations in carotid arteries. We therefore explored the evolution of carotid plaque surface morphology with serial multidetector CT angiography (MDCTA). From a registry of patients with transient ischemic attack or minor ischemic stroke, we selected 83 patients who had undergone serial MDCTA of the carotid arteries. Arteries subjected to revascularization procedures between the two scans were excluded (n = 11). Plaque surface morphology was classified as smooth, irregular or ulcerated on both baseline and follow-up MDCTA. Progression (i.e. development of irregularities or ulceration) and regression (i.e. disappearance of irregularities or ulceration) in morphology were evaluated. The mean time interval between the MDCTA scans was 21 ± 13 months. At baseline, 28 (18%) arteries were normal, 124 (80%) contained atherosclerotic plaque and 3 (2%) were occluded. Plaque surface morphology was smooth in 86 arteries (55%), irregular in 23 (15%) and ulcerated in 15 (10%). At follow-up, surface morphology was unchanged in 88% of arteries, had progressed in 8% and regressed in 4%. Most importantly, plaque morphology remained unchanged in most ulcerated plaques (10/15; 67%). One ulcerated plaque had progressed, whereas 4 had regressed. New ulcerations had developed in 2 nonulcerated plaques. MDCTA allows evaluation of temporal changes in atherosclerotic carotid plaque morphology. Plaque surface morphology remained unchanged in most arteries. Carotid ulcerations persist for a long time, and may remain a potential source of thromboembolism.
    Cerebrovascular Diseases 01/2011; 31(3):263-70. · 2.81 Impact Factor
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    ABSTRACT: This paper describes an evaluation framework that allows a standardized and objective quantitative comparison of carotid artery lumen segmentation and stenosis grading algorithms. We describe the data repository comprising 56 multi-center, multi-vendor CTA datasets, their acquisition, the creation of the reference standard and the evaluation measures. This framework has been introduced at the MICCAI 2009 workshop 3D Segmentation in the Clinic: A Grand Challenge III, and we compare the results of eight teams that participated. These results show that automated segmentation of the vessel lumen is possible with a precision that is comparable to manual annotation. The framework is open for new submissions through the website http://cls2009.bigr.nl.
    Medical image analysis 01/2011; 15:477-488. · 3.09 Impact Factor
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    ABSTRACT: This paper presents a level set based method for segmenting the outer vessel wall and plaque components of the carotid artery in CTA. The method employs a GentleBoost classification framework that classifies pixels as calcified region or not, and inside or outside the vessel wall. The combined result of both classifications is used to construct a speed function for level set based segmentation of the outer vessel wall; the segmented lumen is used to initialize the level set. The method has been optimized on 20 datasets and evaluated on 80 datasets for which manually annotated data was available as reference. The average Dice similarity of the outer vessel wall segmentation was 92%, which compares favorably to previous methods.
    Anesthesiology 01/2011; 7962. · 5.16 Impact Factor
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    ABSTRACT: We propose and validate a semi-automatic method for lumen segmentation of the carotid bifurcation in computed tomography angiography (CTA). First, the central vessel axis is obtained using path tracking between three user-defined points. Second, starting from this path, the segmentation is automatically obtained using a level set. The cost and speed functions for path tracking and segmentation make use of intensity and homogeneity slice-based image features. The method is validated on a large data set of 234 carotid bifurcations of 129 ischemic stroke patients with atherosclerotic disease. The results are compared to manually obtained lumen segmentations. Parameter optimization is carried out on a subset of 30 representative carotid bifurcations. With the optimized parameter settings the method successfully tracked the central vessel paths in 201 of the remaining 204 bifurcations (99%) which were not part of the training set. Comparison with manually drawn segmentations shows that the average overlap between the method and observers is similar (for the inter-observer set the results were 92% vs. 87% and for the intra-observer set 94% vs. 94%). Therefore the method has potential to replace the manual procedure of lumen segmentation of the atherosclerotic bifurcation in CTA.
    Medical image analysis 12/2010; 14(6):759-69. · 3.09 Impact Factor
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    ABSTRACT: An accurate spatial relationship between 3D in-vivo carotid plaque and lumen imaging and histological cross sections is required to study the relationship between biomechanical parameters and atherosclerotic plaque components. We present and evaluate a fully three-dimensional approach for this registration problem, which accounts for deformations that occur during the processing of the specimens. By using additional imaging steps during tissue processing and semi-automated non-linear registration techniques, a 3D-reconstruction of the histology is obtained. The methodology was evaluated on five specimens obtained from patients, operated for severe atherosclerosis in the carotid bifurcation. In more than 80% of the histology slices, the quality of the semi-automated registration with computed tomography angiography (CTA) was equal to or better than the manual registration. The inter-observer variability was between one and two in-vivo CT voxels and was equal to the manual inter-observer variability. Our technique showed that the angles between the normals of the registered histology slices and the in-vivo CTA scan direction ranged 6-56 degrees , indicating that proper 3D-registration is crucial for establishing a correct spatial relation with in-vivo imaging modalities. This new 3D-reconstruction technique of atherosclerotic plaque tissue opens new avenues in the field of biomechanics as well as in the field of image processing, where it can be used for validation purposes of segmentation algorithms.
    Journal of biomechanics 05/2010; 43(11):2087-92. · 2.66 Impact Factor
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    ABSTRACT: Atherosclerotic carotid plaque ulceration is considered a marker of previous plaque rupture and subsequent thromboembolism. It can be accurately detected with multidetector CTA. We hypothesized that atherosclerotic plaque ulceration is associated with nonlacunar ischemic stroke rather than lacunar stroke. Prospectively, 750 consecutive patients with transient ischemic attack or ischemic stroke symptoms in the anterior cerebral circulation were evaluated for the presence of atherosclerotic plaque ulceration in the symptomatic carotid artery with multidetector CTA. Patients with stroke attributable to cardiac embolism or other specific etiologies and patients with amaurosis fugax were excluded. Ischemic strokes in the remaining 534 patients were classified as nonlacunar (n=236) or lacunar (n=298) based on clinical symptoms and multidetector CT of the brain. Ulceration was defined as extension of contrast material beyond the vascular lumen into the surrounding plaque. Plaque ulceration in the symptomatic carotid artery was more common in nonlacunar strokes (n=47; 20%) as compared to lacunar strokes (n=20; 7%; P<0.001). After adjustment for age, gender, cardiovascular risk factors, and degree of stenosis, ulcerations were independently associated with nonlacunar stroke compared to lacunar stroke (odds ratio, 2.70; 95% confidence interval, 1.43-5.09). Atherosclerotic carotid plaque ulceration is associated with nonlacunar ischemic stroke, independent of the degree of carotid stenosis. These results suggest that nonlacunar stroke and lacunar stroke are caused by different pathophysiological mechanisms.
    Stroke 04/2010; 41(6):1151-6. · 6.16 Impact Factor
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    ABSTRACT: The distensibility of a blood vessel is a marker of atherosclerotic disease. Manual measurement of the distensibility on CTA images is a difficult task. In this paper we describe a method to automatically determine the distensibility of the carotid artery by locally analyzing the deformation field of a nonrigid registration of a series of ECG-gated CTA images. We evaluate two variants of the method, and compare the results with manually measured distensibilities.
    Proceedings of the 2010 IEEE International Symposium on Biomedical Imaging: From Nano to Macro, Rotterdam, The Netherlands, 14-17 April, 2010; 01/2010
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    ABSTRACT: PURPOSE Plaque vulnerability to rupture is related to the composition and morphology of the atherosclerotic plaque. With multiple contrasts, MRI can provide an effective mean to identify and quantify different components of atherosclerotic plaque in the carotid arteries. METHOD AND MATERIALS The present study is performed within the framework of the Rotterdam study, a large ongoing population-based study performed in healthy subjects aged 45 years and older. Participants with asymptomatic carotid atherosclerosis (defined by ultrasound) were studied. We acquired MRI scans with multiple contrast weightings (PDW-FSE, PDW-EPI, T2W-EPI, 3D-T1W-GRE, 3D-PC-MRA) using a 1.5Tesla MRI scanner and a bilateral surface coil. All images were linear registered. Presence of plaque, presence of different plaque components (calcification, intraplaque hemorrhage, lipid rich necrotic core (LR/NC), fibrous tissue), predominant plaque component and maximal plaque thickness was determined using previously defined MR imaging criteria (figure). RESULTS Five hundred subjects (age range 48,3-98.3 years; 57% men) were studied. Thirty-two studies (6%) were excluded due to low image quality. Hundred-ten carotid arteries were normal. In 826 carotid arteries (88%) a plaque was present with a plaque thickness of 3.3±1.0 mm. Calcifications, intraplaque hemorrhage and LR/NC were respectively seen in 62%, 21% and 22% of the plaques. . Intraplaque hemorrhage and LR/NC were present in respectively 12% and 13% of carotid plaques with a plaque thickness below the median plaque thickness (3.1mm). In plaques with a thickness > 3.1mm these components were present in 30% and 31% of the plaques. The predominant plaque component was fibrous tissue in 55%, calcification in 28%, intraplaque hemorrhage in 9% and LR/NC in 8% of the plaques. CONCLUSION Carotid plaque evaluation in the healthy population is feasible. Different components of the plaque can be identified. Intraplaque hemorrhage and LR/NC, which are considered constituents of the vulnerable plaque, are present predominantly in 26% of asymptomatic participants. CLINICAL RELEVANCE/APPLICATION This study will enhance the understanding of the natural history of carotid atherosclerosis and the relationship between atherosclerosis and cerebrovascular events.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 12/2009
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    ABSTRACT: PURPOSE Atherosclerotic plaque ulceration is a marker for previous plaque rupture, which is related to the composition of the atherosclerotic plaque (which may lead to thromboembolism). We studied the relationship of ulcerated plaques with plaque volume and plaque composition. METHOD AND MATERIALS We included 351 patients (60% male, mean age 61.70 ± 13.78 years) with ischemic cerebrovascular symptoms in the anterior circulation who underwent MDCT Angiography of the carotid bifurcation. In 210 patients (165 with bilateral plaque, 45 with unilateral plaque) plaque was present an analyzed. Plaque volume and plaque components (lipid, fibrous, calcium) were measured using a custom-made software tool (PV en PC). Plaque ulceration was assessed with MPRs. Two observers performed the volume measurements and scored the presence of ulcerated plaques. RESULTS Atherosclerotic plaque was present in 375 arteries. Plaque ulceration was present in 66 out these atherosclerotic arteries. The mean PV of the 66 ulcerated plaques was 1320 ± 822 mm3 and the mean PV of the 309 non-ulcerated plaques was 775 ± 557 mm3, which was significantly different (p<0.001).The ulcerated plaques had a significantly larger contribution (%) of lipid than the non-ulcerated plaques (26 ± 11 % vs 18 ± 10 %; p<0.001). The contribution of calcium was not significantly different between the ulcerated and the non-ulcerated plaques. (12 ± 11 % vs 15 ± 14 % ; p<0.001). CONCLUSION Plaque ulceration is more frequently present in larger plaques and plaque with a lipid core. CLINICAL RELEVANCE/APPLICATION Multidetector CT angiography allows classification of atherosclerotic carotid plaque surface and plaque volume and plaque composition and plaque rupture can be predicted based on plaque composition.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 11/2009
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    ABSTRACT: PURPOSE Whereas lacunar strokes are associated with local occlusive disease of the deep perforating arteries, cortical strokes are supposed to be caused by thromboembolism from the heart, and stenotic atherosclerotic disease in the extracranial and intracranial arteries. The current study aimed to explore the prevalence of symptomatic intracranial arterial stenosis in patients with ischemic strokes of different etiological mechanisms. METHOD AND MATERIALS Prospectively, 408 consecutive patients (55% male, mean age 62±14 years) with hemispherical ischemic cerebrovascular symptoms in the anterior circulation were included. Based on clinical symptoms and brain imaging, strokes were classified into cortical and lacunar strokes. Patients with cardiac embolism (N=52) and other stroke etiology (N=9) were excluded. Cardiovascular risk factors were registered. Presence of intracranial stenosis was assessed using MDCT Angiography, in the intracranial internal carotid artery, the anterior cerebral artery up to the A2 segment and the medial cerebral artery until segment M3. In addition, degree of stenosis and the presence of atherosclerotic plaque ulceration were evaluated in the symptomatic extracranial carotid artery. The association between cortical strokes and intracranial stenosis was studied in a logistic regression model with lacunar strokes as a control group. RESULTS Symptomatic intracranial arterial stenoses were present in 21 out of 144 patients with cortical stroke (15%) and 24 out of 203 patients with lacunar stroke (12%) (p=0.75). After correction for cardiovascular risk factors and race in a multivariate model, no association between cortical stroke and intracranial stenosis was found. However, independent associations between cortical stroke and degree of extracranial carotid stenosis (OR = 1.0; 95%CI 1.0 -1.02) and plaque ulceration (OR = 2.4; 95%CI 1.2-5.0) were confirmed. CONCLUSION In contrast to atherosclerotic plaque ulceration and degree of stenosis in the extracranial carotid artery, intracranial stenoses are not independently associated with ischemic cortical strokes. CLINICAL RELEVANCE/APPLICATION Evidence of an etiological relationship between intracranial stenoses in the symptomatic territory and cortical stroke remains uncertain.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 11/2009
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    ABSTRACT: PURPOSE Arterial distensibility is a functional and early marker for atherosclerotic disease.The purpose of this study was to evaluate the feasibility of ECG-gated multidetector CTA (MDCTA) in the assessment of the mechanical properties of the vessel wall in the carotid bifurcation. METHOD AND MATERIALS Patients (n=41; mean ages 63.0 ± 8.7 years, 26 male) with cerebrovascular symptoms were prospectively included. They underwent ECG-gated MDCTA of the carotid artery on a 64-slice DSCT scanner. On the reconstructed 4D datasets we measured lumen area in the common carotid artery (CCA) and in the internal carotid artery (ICA) on images which were reconstructed at every 8% of the RR-interval of the cardiac cycle. Luminal area versus time curves were analysed to illustrate the carotid pulsatile waveforms. Using the change in lumen area (ΔA=Amax - Amin), the relative distension was calculated as [∆A /Amin] * 100. The pulse pressure (ΔP) was used to calculate the distensibility (D) as: ΔA / (Amin x ΔP) (10-3kPa-1). RESULTS Most segments (61%) showed an evident biphasic waveform. The distensibility in the carotid artery was 24.1 ± 12.4 (kPa-1) and was not significantly different for the CCA’s and ICA’s. The distensibility in normal and atherosclerotic carotid arteries was not significantly different. CONCLUSION ECG-gated DSCTA allows the evaluation of distensibility in the carotid arteries. It is feasible to analyze the cross-sectional lumen area changes during a cardiac cycle in different locations along the carotid artery by using an ECG-gated Dual-Source MDCT angiographic protocol. CLINICAL RELEVANCE/APPLICATION Arterial distensibility of the carotid artery can now be evaluated with MDCTA to improve our understanding of the relation between plaque accumulation, plaque composition and morphology.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 11/2009
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    ABSTRACT: PURPOSE Atherosclerotic carotid plaque rupture is thought to lead to thrombus formation with subsequent embolisation of plaque material and/or thrombus and consequently an acute ischemic cerebrovascular event. The purpose of this study was to get insight into the natural history of ulcerated plaques with serial MDCT angiography. METHOD AND MATERIALS In this retrospective study we selected patients with more than one MDCTA of the carotid arteries from our database with patients with ischemic cerebrovascular disease and CTA evaluation. MDCTA images (slice thickness ≤ 1.0 mm, increment 0.6 mm) were evaluated by two blinded observers with multiplanar reformatting software. Plaque surface morphology in the carotid bifurcation was classified as smooth, irregular or ulcerated. Change in surface morphology over time was evaluated. Arteries which were treated in between the two MDCTA scans were excluded. RESULTS We selected 84 patients (63% men, aged 61,8 ± 12,4 years) who had more than one MDCTA of the carotid arteries. The mean time period between the two MDCTA scans was 21 ± 13 months. During the first MDCTA 82% of the patients had symptoms in the carotid circulation and 18% in the vertebrobasilar circulation. Of the 155 arteries available for analysis, 3 (1.9%) were occluded at the first MDCTA and 114 (73,6%), 23 (14,8%) and 15 (9,7%) arteries had smooth, irregular and ulcerated luminal surfaces respectively. On the second MDCTA the surface morphology was unchanged in 91% of the arteries, whereas 5,2% showed progression and 3,9% regression of plaque morphology. Remarkably, the majority (10 out of 15) of the ulcerated plaques showed no changed morphology over a time period of 20 ± 15 months. One ulcerated plaque showed progression (in 21 months), 4 showed regression (in 20 ± 17 months), whereas in two non-ulcerated plaques an ulceration developed (34 ± 9 months). CONCLUSION MDCTA is useful for the evaluation of temporal changes in plaque morphology. On serial MDCTA, atherosclerotic carotid plaque morphology did not change in most cases and healing of ulcerated plaques is not a common phenomenon. CLINICAL RELEVANCE/APPLICATION Atherosclerotic carotid plaque ulceration on MDCTA should be evaluated with clinical and brain imaging data in order to distinguish old, asymptomatic ulcerations from active, symptomatic ulcerations.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 11/2009
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    ABSTRACT: A novel method is presented for carotid artery vessel wall segmentation in computed tomography angiography (CTA) data. First the carotid lumen is semi-automatically segmented using a level set approach initialized with three seed points. Subsequently, calcium regions located within the vessel wall are automatically detected and classified using multiple features in a GentleBoost framework. Calcium regions segmentation is used to improve localization of the outer vessel wall because it is an easier task than direct outer vessel wall segmentation. In a third step, pixels outside the lumen area are classified as vessel wall or background, using the same GentleBoost framework with a different set of image features. Finally, a 2-D ellipse shape deformable model is fitted to a cost image derived from both the calcium and vessel wall classifications. The method has been validated on a dataset of 60 CTA images. The experimental results show that the accuracy of the method is comparable to the interobserver variability.
    IEEE transactions on medical imaging. 07/2009; 29(1):65-76.
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    ABSTRACT: The purpose of this study was to examine the volume and the composition of atherosclerotic plaque in symptomatic carotid arteries and to investigate the relationship between these plaque features and the severity of stenosis and the presence of cardiovascular risk factors. One hundred patients with cerebrovascular symptoms underwent CT angiography. We measured plaque volume (PV) and the relative contribution of plaque components (calcifications, fibrous tissue, and lipid) in the symptomatic artery. The contribution of different components was measured as the number of voxels within defined ranges of HU values (calcification >130 HU, fibrous tissue 60-130 HU, lipid core <60 HU). Fifty-seven patients had atherosclerotic plaque in the symptomatic carotid artery. The severity of stenosis and PV were moderately correlated. Age and smoking were independently related to PV. Patients with hypercholesterolemia had significantly less lipid and more calcium in their plaques than patients without hypercholesterolemia. Other cardiovascular risk factors were not significantly related to PV or plaque composition. Luminal stenosis of the carotid artery partly reflects the amount of atherosclerotic carotid disease. Plaque volume and plaque composition are associated with cardiovascular risk factors.
    European Radiology 05/2009; 19(9):2294-301. · 4.34 Impact Factor
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    ABSTRACT: A novel, slice-based, semi-automatic method for plaque segmentation and quantification in CTA of carotid arteries is introduced. The method starts with semi-automatic, levelset based, lumen segmentation initialized with three points. Pixel based GentleBoost classification is used to segment the inner and outer vessel wall region using distance from the lumen, intensity and Gaussian derivatives as features. 3D calcified regions located within the vessel wall are segmented using a similar set of features and the same classification method. Subsequently, an ellipse-shaped deformable model is fitted using the inner-outer vessel wall and calcium classification, and plaque components within the wall are characterized using HU ranges. The method is quantitatively evaluated on 5 carotid arteries. Vessel and plaque segmentation are compared to the interobserver variability. Furthermore, correlation of slice-based plaque component quantification with the ground truth values is determined. The accuracy of our method is comparable to the interobserver variability.
    Proceedings of the 2009 IEEE International Symposium on Biomedical Imaging: From Nano to Macro, Boston, MA, USA, June 28 - July 1, 2009; 01/2009
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    ABSTRACT: PURPOSE Calcification of the intracranial segment of the internal carotid artery can be assessed by and quantified with multidetector computed tomography angiography (MDCTA). Intracranial calcification is a marker of intracranial atherosclerosis. We hypothesize that presence of intracranial calcification in the symptomatic artery is related to the presence of infarct on CT in the symptomatic hemisphere. METHOD AND MATERIALS We studied 351 consecutive patients (59.5 male; mean age 62.4 ± 13.1 years), who had cerebrovascular symptoms in the carotid artery territory with MDCTA. Patients with a likely cardioembolic stroke etiology (n=30) or occluded internal carotid artery (n=20) were excluded. CT brain images were reviewed for the presence of recent and old infarcts. We quantified intracranial calcification by manually drawing contours on axial images with a custom-made software tool. The Mann-Whitney U test and Logistic Regression were applied for statistical analysis. RESULTS Intracranial calcification was present in 58% of the symptomatic carotid arteries. Infarcts were present in 43% of the symptomatic hemispheres. The quantity of intracranial calcification was significantly higher in the symptomatic carotid artery of patients with infarcts in the symptomatic hemisphere (36 mm3 ± 78 mm3) than in patients without infarcts in the symptomatic hemisphere (21 mm3 ± 47 mm3) p<0.001). In multivariate analysis after adjustment for age and sex, no independent relationship was found between the quantity of intracranial calcification in the symptomatic artery and infarcts in the symptomatic hemisphere. CONCLUSION The quantity of intracranial calcification was significantly higher in the symptomatic carotid artery of patients with infarcts in the symptomatic hemisphere than in patients without infarcts in the symptomatic hemisphere. However, after adjustment for age and sex, intracranial calcification in the symptomatic artery was not independently associated with infarcts in the symptomatic hemisphere. CLINICAL RELEVANCE/APPLICATION The quantity of intracranial calcification is not an independent predictor of stroke.
    Radiological Society of North America 2008 Scientific Assembly and Annual Meeting; 12/2008

Publication Stats

119 Citations
48.04 Total Impact Points

Institutions

  • 2008–2011
    • Erasmus Universiteit Rotterdam
      • Department of Radiology
      Rotterdam, South Holland, Netherlands
  • 2009–2010
    • Erasmus MC
      • Department of Radiology
      Rotterdam, South Holland, Netherlands