Quantification Of Plaque Volume Research Articles

Carotid plaque volume measurement in ischemic stroke: A pilot study

Objectives: Carotid atherosclerosis is a significant risk factor for acute ischemic stroke. Three-dimensional (3D) sonography is a new technique that can be used to analyze carotid plaque both quantitatively and qualitatively. The aim was to study carotid atherosclerosis in stroke patients and healthy controls in terms of plaque volume quantification by 3D ultrasound (US). Materials and Methods: An observational descriptive study was conducted in the stroke unit of a university referral hospital in South India. Patients with ischemic stroke between the ages of 20 and 70 years were studied, along with age- and sex-matched controls. Carotid sonography (2D and 3D) along with Doppler studies was done in all patients, using Philips Affiniti 50 US system. Vascular plaque quantification software was used to assess plaque volume. Results: Twenty-four subjects were recruited, and two were excluded from the study. Twelve were cases, and ten were controls. The mean carotid intima-media thickness (CIMT) (average CIMT in six sites in common carotid artery, three on each side) studied in patients was 0.65 ± 0.10 mm, while that for healthy subjects was 0.62 ± 0.06 mm. The mean plaque volume in patients with stroke or transient ischemic attack was 179.82 ± 310.3 mm3, and that in healthy subjects was 56.75 ± 69.6 mm3. Plaque heterogeneity, surface irregularity, and ulceration were found to be common in symptomatic carotid plaques. Conclusion: The 3D sonography is a non-invasive and simple feasible tool for the analysis of carotid plaque.

3-D Contrast-Enhanced Fusion Ultrasound for Accurate Volume Assessment of Vessel Lumen and Plaque in Carotid Artery Disease as Compared With Computed Tomography Angiography

ObjectiveThree-dimensional contrast-enhanced fusion ultrasound (3D-CEFUS) of atherosclerotic carotid arteries provides spatial visualisation of the vessel lumen, creating a lumenography. As in 3D computed tomography angiography (3D-CTA), 3D-CEFUS outlines the contrast-filled lumen. Plaque and vessel contours are distinguished in 3D-CEFUS, allowing plaque volume quantification as a valid estimate of carotid plaque burden. 3D-CEFUS is unproven in inter-modality studies, vindicating the assessment of 3D-CEFUS applicability and comparing 3D-CEFUS and 3D-CTA lumenography as a proof-of-concept study. MethodsUsing an ultrasound system with magnetic tracking, a linear array transducer, and SonoVue contrast agent generated 3D-CEFUS acquisitions by spatial stitching of serial 2D images. From 3D-CEFUS and 3D-CTA imaging, the atherosclerotic carotid arteries were reconstructed with lumenography in an offline software programme for lumen and plaque volume quantification. Bland-Altman analysis was used for inter-image-modality agreement. ResultsThe study included 39 carotid arteries. Mean lumen and plaque volume in 3D-CEFUS were 0.63 cm3 (SD 0.26) and 0.62 cm3 (SD 0.26), respectively. Lumen volume differences between 3D-CEFUS and 3D-CTA were non-significant, with mean difference of 0.01 cm3 (SD 0.02, p = .26) and limits of agreement range (LoA-range) of ±0.11 cm3. Mean plaque volume difference was -0.12 cm3 (SD 0.19, p = .006) with LoA-range of ±0.39 cm3. ConclusionStrong agreement in lumenography between 3D-CEFUS and 3D-CTA was found. The inter-image-modality difference in plaque volumes was substantial due to challenging vessel wall definition in 3D-CTA. 3D-CEFUS is viable in quantifying carotid plaque volume burden and can potentially monitor plaque development over time.

Early onset of menopause is associated with increased peripheral atherosclerotic plaque volume and progression

Background and aimsCardiovascular disease (CVD) is the leading cause of death in western countries. One risk factor unique to women is the menopausal status. The aim of this study was to analyse the influence of the onset of menopause (MP) on the extent and progression of atherosclerotic plaque volume (PV). MethodsPostmenopausal women with at least one cardiovascular risk factor (CVRF) but without established CVD were included. Quantification of PV was performed in peripheral arteries using a three - dimensional (3D) ultrasound (US) technique. Follow-up examination to assess PV progression was performed after 19 (±8) months. Results110 consecutive postmenopausal women (mean age 65.5) were included. Females with an earlier onset of MP (<45 years) had a significantly higher PV than those with an intermediate (45–52 years) or later onset of menopause (>52 years), irrespective of other CVRF (244 mm³ vs. 193 mm³ vs. 73 mm³, respectively, p = 0.023). In addition, women with an earlier onset of MP had a higher PV progression compared to women with an intermediate or late onset (40 mm³ vs. 35 mm³ vs. 8.5 mm³; p = 0.002, respectively). Moreover, these results were confirmed in multivariate regression, where only onset of MP (OR 0.88; 95%CI 0.81–0.96; p = 0.004) and age (OR 1.06; 95%CI 1.08–1.13; p = 0.025) were significant predictors for a higher atherosclerotic progression. ConclusionsAn earlier onset of MP was associated with an increase in atherosclerotic PV and accelerated progression, independent of other CVRF.

Quantitative and Qualitative Coronary Plaque Assessment Using Computed Tomography Coronary Angiography: A Comparison With Intravascular Ultrasound

To compare computed tomography coronary angiography (CTCA) with intravascular ultrasound (IVUS) in quantitative and qualitative plaque assessment. Patients who underwent IVUS and CTCA within 3 months for suspected coronary artery disease were retrospectively studied. Plaque volumes on CTCA were quantified manually and with automated-software and were compared to IVUS. High-risk plaque features were compared between CTCA and IVUS. There were 769 slices in 32 vessels (27 patients). Manual plaque quantification on CTCA was comparable to IVUS per slice (mean difference of 0.06±0.07, p=0.44; Bland-Altman 95% limits of agreement -2.19-2.08 mm3, bias of -0.06mm3) and per vessel (3.1mm3 ± -2.85mm3, p=0.92). In contrast, there was significant difference between automated-software and IVUS per slice (2.3±0.09mm3, p<0.001; 95% LoA -6.78 to 2.25mm3, bias of -2.2mm3) and per vessel (33.04±10.3 mm3, p<0.01). The sensitivity, specificity, positive and negative predictive value of CTCA to detect plaques that had features of echo-attenuation on IVUS was 93.3%, 99.6%, 93.3% and 99.6% respectively. The association of ≥2 high-risk plaque features on CTCA with echo attenuation (EA) plaque features on IVUS was excellent (86.7%, 99.6%, 92.9% and 99.2%). In comparison, the association of high-risk plaque features on CTCA and plaques with echo-lucency on IVUS was only modest. Plaque volume quantification by manual CTCA method is accurate when compared to IVUS. The presence of at least two high-risk plaque features on CTCA is associated with plaque features of echo attenuation on IVUS.

Plaque quantification by coronary computed tomography angiography using intravascular ultrasound as a reference standard: a comparison between standard and last generation computed tomography scanners.

The emerging role of coronary computed tomography angiography (CCTA) as a non-invasive tool for atherosclerosis evaluation is supported by data reporting a good correlation between CCTA and intravascular ultrasound (IVUS) for plaque volume quantification. Aim of the present study was to evaluate whether a last generation CT-scanner may improve coronary plaque volume assessment using IVUS as standard-of-reference. From a registry of 1915 consecutive, all-comers, patients who underwent a clinically indicated IVUS evaluation we enrolled 59 patients who underwent CCTA with a 64-slice CT (Group 1) and 59 patients who underwent CCTA with whole-heart coverage CT scanner (Group 2). Patients who underwent CCTA with unfavourable heart rhythm were not excluded from the analysis. Image quality (4-point Likert scale) focused on plaque analysis was evaluated. Plaque volume quantification by CCTA was compared to IVUS. No difference in clinical characteristics was found between Group 1 and Group 2. Plaque volume quantification by CCTA was considered not feasible in 11 plaques of Group 1 and in 4 plaques of Group 2 (P = 0.09). Higher correlation for plaque volume quantification by CCTA vs. IVUS was demonstrated in Group 2 when compared with Group 1 (r = 0.9888 vs. 0.9499; P < 0.0001). The Bland-Altman analysis showed plaque volume overestimation by CCTA of 11.9 mm3 in Group 1 and 4 mm2 in Group 2 (P < 0.001). Effective radiation dose of CCTA was significantly lower in Group 2 vs. Group 1 (2.7 ± 0.9 vs. 8.1 ± 3.6 mSv, respectively; P < 0.001). CCTA using a new scanner generation showed to be an accurate non-invasive tool to assess and quantify coronary plaque volume.

Can Carotid Bulb Plaque Assessment Rule Out Significant Coronary Artery Disease? A Comparison of Plaque Quantification by Two- and Three-Dimensional Ultrasound

Screening tools for the detection of coronary artery disease (CAD) are of considerable interest in light of skyrocketing risk factors. Recent work suggests that carotid plaque has a relatively unexplored role in CAD risk prediction but has previously been limited by the difficulty in quantifying its irregular architecture using two-dimensional (2D) ultrasound. The aim of this study was to investigate the utility of a novel automated three-dimensional (3D) ultrasound-based carotid plaque volume quantification technique as a negative predictor of CAD. In this prospective study, 70 consecutive patients referred for coronary angiography underwent same-day 2D and 3D carotid ultrasound scans for the purpose of plaque quantification in the carotid bulbs. Two-dimensional plaque thickness was measured in its maximal value perpendicular to the vessel wall. Total 3D plaque volume was quantified using a stacked-contour method. Luminal narrowing of coronary arteries was analyzed using the established 16-segment model for coronary arteries to produce an overall angiographic score. Receiver operating characteristic curves, negative predictive value, and sensitivity of 2D and 3D plaque quantification relative to coronary angiography were determined. The novel 3D carotid ultrasound method resulted in a higher negative predictive value and sensitivity relative to 2D carotid ultrasound at their optimal thresholds as determined by Youden indices of receiver operating characteristic curves. In particular, total 3D plaque volumes less than the threshold of 0.09 mL accurately predicted the absence of significant CAD in 93.3% of patients (98.0% sensitivity), whereas maximal 2D plaque thickness less than the threshold of 1.35 mm provided significantly lower negative predictability at 75% (93.9% sensitivity). Using the determined threshold of 0.09 mL for plaque volumes, this feasibility study suggests that automated 3D ultrasound-based carotid plaque quantification may serve as an important clinical screening tool to help identify patients who are at low risk for significant CAD.

Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT)

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC) and carotid intimal medial thickness (C-IMT) provide information about the burden of disease. However, despite multiple validation studies of CAC, and C-IMT, these modalities do not accurately assess plaque characteristics, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events. [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity, an important source of cellular inflammation in vessel walls. More recently, we and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors and is also highly associated with overall burden of atherosclerosis. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy as well as longer term therapeutic lifestyle changes (16 months). The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.

3D Quantitative Evaluation of Atherosclerotic Plaque Based on Rotational Angiography

Atherosclerosis is a systemic disease that has been shown to cause various cardiovascular diseases and stroke. However, technologies to evaluate the volume of atherosclerotic plaque are limited. We present a method for determination of 3D plaque volume based on RA. 3DRA images obtained from patients were used to evaluate the plaque. Six patients who were diagnosed with atherosclerotic lesions were included. The PR model developed for 3DRA was applied to analyze the geometry of the vessel and calculate the plaque volume. To validate the present method, we tested computer-generated phantoms with different degrees of stenosis. Application of PR to clinical cases allowed the estimation of plaque morphology and quantification of plaque volume. Technique validation showed that on average, PR can rebuild 92% of the plaque and provide satisfactory determination of plaque volume. A new approach to obtain plaque volume based on 3DRA is presented. The initial tests in 6 clinical cases and validation with different phantoms showed that this method is feasible. Further validation in a larger clinical series is required to assess the ultimate value of the present technique.

Reproducibility of coronary artery plaque volume and composition quantification by 64-detector row coronary computed tomographic angiography: An intraobserver, interobserver, and interscan variability study

Interscan variability of coronary arterial plaque volume and composition quantification with coronary computed tomographic angiography (CCTA), an important attribute when considering CCTA as a serial modality, has not been examined. We sought to systematically determine intraobserver- and interobserver-interscan reproducibility of these measures. Two blinded, experienced readers independently evaluated proximal coronary segments on CCTAs from 30 patients who underwent 2 scans within 200 days (median, 124 days; interquartile range, 49-155 days) without experiencing an interim acute coronary event. Readers recorded number of plaques and, in plaques that met a preset minimal length criterion, quantified total, calcified plaque (CP), and noncalcified plaque (NCP) volumes and percentage of total plaque volume occupied by NCP. Of 89 total segments studied, 36 contained detectable plaque, and 26 met criterion for quantification. Intraobserver, interobserver, and interscan agreements for normal segments were 100%. Intraobserver-interscan correlations of total, CP, and NCP volumes and percentage of NCP were excellent (r=0.93-0.97, P values<0.001). Interobserver-interscan correlations for all measures were also very good (r=0.81-0.96, P values<0.001). Variability in plaque volume quantification was significant, exceeding 60% of the averaged paired plaque volumes in the best-case scenario (interobserver-interscan CP volume). Quantification of percentage of NCP composition by volume was more consistent, with <24% variation in the worst-case scenario (interobserver-interscan). CCTA shows promise for quantifying serial coronary plaque change. Currently, the most robust measure seems to be percentage of plaque composition, rather than plaque volume. For smaller plaques, volume quantification remains challenging.

Abstract 3409: Monitoring of Changes in Atheroma Volume by 64-Slice Computed Tomography.

Non-invasive assessment of plaque burden by Multislice Computed Tomography (MDCT) has been recently shown to be feasible. However, to date, there is no data on its accuracy to assess changes in atheroma burden We and others have previously shown that apoA-IMilano (apoA-IM) infusion induces a large plaque regression in a very short period of time The aim of our study was to assess the feasibility of MDCT to accurately quantify the changes in atheroma volume induced by apoA-IM infusion Methods Aortic atherosclerotic lesions were induced in New-Zealand-White Rabbits (n=7) by 9-month atherogenic diet and aortic denudation, as previously reported. Animals were then randomized to receive 2 infusions, 4 days apart, of apoA-IM (ETC-216, Pfizer. n=4) or equal volume of placebo (n=3). All animals underwent 2 imaging studies in a 64-Slice MDCT scanner (Sensation 64, Siemens), pre- and post-treatment (Rx). After last MDCT study, animals were sacrificed and the aorta processed for histological atherosclerotic lesions characterization and volume quantification . Axial MDCT images were reconstructed (3 mm thick, no overlap). Display settings were manipulated according to previous validated studies. For lumen delineation: window width (WW) 1 and level (WL) 65% of lumen attenuation . For outer vessel boundaries: WW 155% and WL 65%. Results MDCT showed that plaque burden regressed by 29% in apoA-IM group (418mm 3 pre-Rx vs. 302mm 3 post-Rx, p=0.031). Conversely, no significant change was observed by MDCT studies done pre- and post-placebo administration. MDCT performed post-Rx showed that mean plaque volume in apoA-IM animals was 11.5% smaller than that of placebo animals (p=0.018). Mean plaque volume in histology showed similar results:plaque volume was 10.6% smaller in the apoA-IM group (p=0.005 vs. placebo). The interobserver variability for plaque volume quantification in MDCT was 10±4%. Conclusion MDCT detects the changes in atherosclerotic plaque volume induced by apoA-IM infusion. Furthermore, an excellent correlation was found between MDCT and histological plaque volumes. These results, combined to the short time of scan and the accessibility to the coronary territory suggest that MDCT could be applied in human studies testing changes in coronary plaque volume.

Imaging of coronary atherosclerosis using computed tomography: Current status and future directions

Computed tomography (CT) imaging of the coronary arteries, using either electron beam tomography (EBT) or multidetector row CT (MDCT), offers two possibilities to assess coronary atherosclerosis. Without injection of contrast agent, coronary calcifications can be detected and quantified. Their presence and extent correlates to the presence and amount of coronary atherosclerotic plaque. Prospective studies have demonstrated a high predictive value concerning the occurrence of coronary artery disease events and overall mortality. An emerging consensus seems to indicate that calcium imaging may be clinically useful in patients at intermediate risk for coronary artery disease events as determined based on traditional risk factors. In addition, recent studies have shown that after injection of contrast agent and using high-resolution scan protocols, the visualization of noncalcified plaque is also possible with CT techniques. However, data on the accuracy of plaque detection, quantification of plaque volume, and characterization of plaque (eg, lipid-rich vs fibrous) is currently limited, and the prognostic significance of noncalcifed coronary atherosclerotic plaque detection is unclear.

Three methods for accurate quantification of plaque volume in coronary arteries.

The coronary atherosclerotic process evolves to an occlusive disease that causes chronic angina and acute coronary syndromes, such as myocardial infarction and sudden death. An important milestone in the understanding of the atherosclerotic process is the development of tools for quantitative assessment of disease progression or regression. A new methodology to analyze the coronary vessel lumen and plaque morphology in 3-D is based on the fusion of intravascular ultrasound (IVUS) and biplane X-ray angiography, which results in a geometrically correct representation of coronary vessels. A comparison of three volume quantification methods: polytope, Watanabe, and Simpson's rule is reported for quantifying the amount of plaque accumulation. The three methods allow local estimation of plaque volume. To determine volumetric indices, the space between the luminal and adventitial surfaces is first subdivided and then each of the volume elements is considered individually to achieve volume quantification. Polyhedral volume elements are employed and the volume of every element is estimated by each of the three approaches. The volume quantification methods were validated in 314 computer-generated shapes. All three methods are highly accurate, providing a mean error of 0.138 +/- 0.049%, 0.139 +/- 0.049%, and 0.832 +/- 0.203% for the polytope, Watanabe, and Simpson-rule methods, respectively. Nevertheless, the polytope and Watanabe methods are statistically significantly more accurate than the Simpson-rule approach (p < 0.001). The volumetric quantification methods were also tested using seven in vivo coronary arterial datasets from seven patients undergoing coronary angioplasty. While the polytope and Watanabe approaches are statistically significantly more accurate compared to the Simpson's rule method, accuracy of either of the tested method is sufficient for all practical purposes. Yet, the methods are not interchangeable and a single technique should be used in comparative volumetric studies.

Three-dimensional power-mode ultrasound for quantification of the progression of carotid artery atherosclerosis

Elucidation of the dynamic nature of plaque progression has important implications for clinicians. The present study sought to establish an in vivo method for visualizing structural changes in carotid plaques. Three-dimensional reconstruction of parallel two-dimensional gray-scale B-mode ultrasound combined with power-mode examination of 38 carotid artery plaques was performed in a prospective study of 32 patients (18 men, 14 women; mean age 67.5 +/- 7.6 years). Initial mean plaque volume was 391 microl. After a mean of 18.9 months carotid artery plaque progression had occurred in 15% of carotid artery plaques, with plaque volume increasing 59% in these cases. Plaque volume remained constant, within a range of +/- 20% in 85% of cases. Progressive plaques were predominantly hypoechoic (3/5 cases) or had an ulcerated surface in cases of a hyperechoic echogenicity (2/5 cases). Risk factors and drug therapy were unrelated to plaque progression. This study illustrates that the combination of three-dimensional ultrasound with power-mode imaging improves the separation of the intraluminal plaque surface from the vessel lumen. Three-dimensional reconstruction of atherosclerotic carotid artery plaques enables the reproducible quantification of plaque volume and is therefore an excellent technique for longitudinal trials assessing progression or regression of carotid artery disease.

Quantification of plaque volume, shear stress on the endothelium, and mechanical properties of the arterial wall with intravascular ultrasound imaging.

Present intravascular echographic imaging (IVUS) is based on either the mechanically rotated single element catheter or the multi-element phased array catheter principle. In both methods the ultrasonic beam is rotated through 360 degrees and the cross-sectional echo image of plaque and wall structures is visualised. A new development based on intravascular ultrasound is calculation of mechanical properties of the arterial wall. In this so-called elastographic approach, high frequency information obtained at identical positions in the arterial wall is compared under systolic and diastolic pressures. Minute shifts in the echo data indicate local compressibility. It thus becomes possible to indicate areas of high or low strain, which correspond to soft and hard material. Three-dimensional information can be obtained if the position of cross sectional slices is recorded with a pull-back device and slices are united into a 3D image. On the basis of such information it has become possible to view stents in 3D, and with interactive software, to calculate automatically plaque volume. With pull-back information only, the artery is reconstructed as a "straight pipe". Only when the biplane X-ray information is combined with the intravascular pull-back echo information can the true 3D reconstruction of the artery be constructed. Given the true geometric lumen information, it becomes possible, under certain assumptions, to derive the luminal fluid dynamics. From this, shear stress values close to the arterial wall can be calculated. Under the assumption that low values for local shear stress are areas prone to restenosis, predictions of endangered areas can be made.

Three-dimensional ultrasound angiography (power mode) for the quantification of carotid artery atherosclerosis.

Three-dimensional (3D) ultrasound angiography was performed to diagnose carotid artery atherosclerosis. Thirty-five patients (15 women, 20 men) with a history of cerebrovascular disease were examined using conventional color-coded Doppler ultrasound and 3D ultrasound angiography. Carotid stenosis was initially diagnosed using continuous-wave Doppler ultrasound. To determine intraobserver and interobserver reliabilities, 21 patients were evaluated using 3D ultrasound on three occasions. Sixty-five percent of patients were diagnosed with stenosis of more than 50%. Twenty-two percent of plaques had a smooth surface, 72.9% were ulcerated, and 5.1% were indeterminate. Data collection for 3D imaging required 5 minutes per patient, whereas image processing and plaque volume quantification required 30 minutes. Plaque volume ranged from 0.053 to 0.685 ml. The intraobserver and interobserver variabilities were 4.16 and 5.87%, respectively (r = 0.96, p < 0.0001; r = 0.89, p < 0.0001). 3D Color Doppler and 3D ultrasound angiography assessments of plaque volume differed by 8.5%. Plaques were more precisely differentiated using 3D ultrasound, and plaque volume quantification was less affected by echo shadowing after 3D reconstruction. In comparison to other techniques for the quantification of atherosclerotic lesions. 3D ultrasound angiography offers a more precise quantitative method for prospective, clinical studies of atherosclerosis.