A new approach for improving coronary plaque component analysis based on intravascular ultrasound images

Virtual histology intravascular ultrasound (VH-IVUS) is a clinically available technique for atherosclerosis plaque characterization. It, however, suffers from a poor longitudinal resolution due to electrocardiogram (ECG)-gated acquisition. This article presents an effective algorithm for IVUS image-based histology to overcome this limitation. After plaque area extraction within an input IVUS image, a textural analysis procedure consisting of feature extraction and classification steps is proposed. The pixels of the extracted plaque area excluding the shadow region were classified into one of the three plaque components of fibro-fatty (FF), calcification (CA) or necrotic core (NC) tissues. The average classification accuracy for pixel and region based validations is 75% and 87% respectively. Sensitivities (specificities) were 79% (85%) for CA, 81% (90%) for FF and 52% (82%) for NC. The kappa (kappa) = 0.61 and p value = 0.02 indicate good agreement of the proposed method with VH images. Finally, the enhancement in the longitudinal resolution was evaluated by reconstructing the IVUS images between the two sequential IVUS-VH images

IVUS-based histology of atherosclerotic plaques: improving longitudinal resolution

Although Virtual Histology (VH) is the in-vivo gold standard for atherosclerosis plaque characterization in IVUS images, it suffers from a poor longitudinal resolution due to ECG-gating. In this paper, we propose an image- based approach to overcome this limitation. Since each tissue have different echogenic characteristics, they show in IVUS images different local frequency components. By using Redundant Wavelet Packet Transform (RWPT), IVUS images are decomposed in multiple sub-band images. To encode the textural statistics of each resulting image, run-length features are extracted from the neighborhood centered on each pixel. To provide the best discrimination power according to these features, relevant sub-bands are selected by using Local Discriminant Bases (LDB) algorithm in combination with Fisher’s criterion. A structure of weighted multi-class SVM permits the classification of the extracted feature vectors into three tissue classes, namely fibro-fatty, necrotic core and dense calcified tissues. Results shows the superiority of our approach with an overall accuracy of 72% in comparison to methods based on Local Binary Pattern and Co-occurrence, which respectively give accuracy rates of 70% and 71%

Calcified atherosclerotic plaque: characterization of osteogenic process

Obiettivo è quello di studiare la calcificazione del distretto femorale valutandone istologia e aspetto radiologico, confrontandola anche con l’aspetto radiologico del distretto carotideo. Materiali e metodi. Pazienti con arteriopatia ostruttiva cronica periferica e trattati mediante endoarterectomia della arteria femorale comune da giungo 2015 a giugno 2017 sono stati raccolti prospetticamente. Sono stati raccolti dati demografici, clinici (classificazione di Rutherford). Istologicamente le lesioni aterosclerotiche sono state classificate in due tipi: I)placca aterosclerotica “classica”; II)placca calcifica “atipica”. Altre variabili istologiche raccolte includono: osso metaplastico, noduli calcifici eruttivi. La valutazione della calcificazione è stata effettuata sulla base della tomografia assiale computerizzata utilizzando la classificazione di Babiarz. La comparazione radiologica con il distretto carotideo è stato effettuato con 19 placche carotidee calcifiche. Risultati. Sono state prelevate 38 placche aterosclerotiche in 38 pazienti (età media: 73±8anni; maschi: 79%). Placche aterosclerotiche “classiche” e calcifiche “atipiche” sono state individuate rispettivamente in 12(32%) e 26(68%) casi. Metaplasia ossea e noduli calcifici eruttivi sono stati riscontrati rispettivamente in 15(40%) e 20(53%) casi. La presenza di metaplasie ossee è più frequente con placche calcifiche “atipiche” rispetto a quelle aterosclerotiche “classiche” (rispettivamente 54%vs8%, p=.012). La presenza di noduli calcifici eruttivi è più rara con dislipidemia(p=.004) e con diabete mellito(p=.016). Radiologicamente, la placca femorale è stata classificata come moderatamente calcifica(grado 0-5) e fortemente calcifica(grado 6-8) rispettivamente in 8(21%) e 30(79%) casi. Le placche istologicamente definite calcifiche “atipiche” presentano un aspetto radiologico più calcifico rispetto a quelle ateromasiche “classiche”(p=.007). Le placche femorali sono più calcifiche rispetto alle carotidee, sia in termini di spessore(p=.001) che di circonferenza(p<.001). Conclusione. Le placche istologicamente definite come calcifiche “atipiche” ed i noduli calcifici eruttivi non sembrano essere dipendenti dai fattori di rischio classici per aterosclerosi. Le placche calcifiche “atipiche” risultano radiologicamente più calcifiche delle ateromasiche “classiche”. Le placche femorali risultano essere più calcifiche rispetto al distretto carotideo.Aim is to evaluate histological and radiological aspects of femoral calcification and to compare them with radiological characteristics of carotid district. Methods. Patients treated from June 2015 to June 2017 for peripheral arterial occlusive disease (PAOD) with endarterectomy of common femoral artery and its bifurcation were prospectively collected. Demographics and clinical data, including Rutherford classification, were gathered. According to histology, the arterial plaque was classified in two types: I)“classic” atherosclerotic plaque; II)“atypical” calcific plaque. Presence of osseous metaplasia and eruptive calcified nodule was also registered. Radiological assessment of arterial calcification was performed on the basis of computed tomography angiography (CTA) according to Babiarz classification. Radiological comparison with carotid calcification was performed with 19 calcified carotid plaques. Results. Thirty-eight atherosclerotic plaques in 38 patients (mean age: 73±8years; male: 79%) were collected. “Classic” atherosclerotic and “atypical” calcified plaque were identified in 12 (32%) and 26 (68%) cases, respectively. Osseous metaplasia and eruptive calcified nodule were observed in 15 (40%) e 20 (53%). Osseous metaplasia is more frequent in patient with “atypical” calcified plaque than “classic” atherosclerotic plaque (54% vs 8% respectively; p=.012). Presence of eruptive calcified nodule is more rare in patient with dyslipidemia (p=.004) and diabetes mellitus (p=.016) and insulin-dependent diabetes mellitus (p=.027). Femoral plaque was radiologically classified as moderate (grade 0-5) and heavy calcified (grade 6-8) in 8 (21%) and 30 (79%), respectively. “Atypical” calcified plaques are radiologically more calcified than “classic” atherosclerotic plaque (p=.007). Femoral plaques are more calcified than carotid lesions, both in terms of thickness (p=.001) and circumference (p<.001). Conclusion. Femoral plaques histologically defined as “atypical” calcified plaque and eruptive calcified nodules seems to be not associated with classical atherosclerotic clinical risk factors. “Atypical” calcified plaques are radiologically more calcified than “classic” atherosclerotic plaques. Femoral plaques results to have heavier calcification in comparison with carotid ones

Multimodal Image Analysis for Carotid Artery Plaque Characterization

Atherosclerosis of the carotid artery is a main cause of ischemic cerebrovascular events. There is evidence that the composition of the vessel wall is more strongly related to plaque vulnerability and subsequent events than luminal stenosis, which is currently used for risk stratification in clinical practice. Noninvasive imaging can characterize the composition of the vessel wall. In order to incorporate measures of plaque composition into clinical practice, accurate and robust image segmentation methods are required. This thesis describes the development and validation of image analysis techniques that aim at the automated characterization of the carotid atherosclerotic vessel wall. The first part of this thesis makes use of a dataset in which ex vivo and in vivo MRI and CT, and annotated histology sections are available and have been spatially aligned. We firstly perform segmentation of plaque components in ex vivo MRI. Voxel classifiers are trained on a ground truth of registered histology and μCT images. We show the importance of different groups of features: intensities, Gaussian filters and wall distances, and use these features in subsequent work on in vivo data. Here we address the problems that arise in training and evaluation of segmentation methods when misregistration between histology and in vivo

Inflammatory Markers Associated With Subclinical Coronary Artery Disease: The Multicenter AIDS Cohort Study.

BackgroundDespite evidence for higher risk of coronary artery disease among HIV+ individuals, the underlying mechanisms are not well understood. We investigated associations of inflammatory markers with subclinical coronary artery disease in 923 participants of the Multicenter AIDS Cohort Study (575 HIV+ and 348 HIV- men) who underwent noncontrast computed tomography scans for coronary artery calcification, the majority (n=692) also undergoing coronary computed tomography angiography.Methods and resultsOutcomes included presence and extent of coronary artery calcification, plus computed tomography angiography analysis of presence, composition, and extent of coronary plaques and severity of coronary stenosis. HIV+ men had significantly higher levels of interleukin-6 (IL-6), intercellular adhesion molecule-1, C-reactive protein, and soluble-tumor necrosis factor-α receptor (sTNFαR) I and II (all P&lt;0.01) and a higher prevalence of noncalcified plaque (63% versus 54%, P=0.02) on computed tomography angiography. Among HIV+ men, for every SD increase in log-interleukin-6 and log&nbsp;intercellular adhesion molecule-1, there was a 30% and 60% increase, respectively, in the prevalence of coronary stenosis ≥50% (all P&lt;0.05). Similarly, sTNFαR I and II in HIV+ participants were associated with an increase in prevalence of coronary stenosis ≥70% (P&lt;0.05). Higher levels of interleukin-6, sTNFαR I, and sTNFαR II were also associated with greater coronary artery calcification score in HIV+ men (P&lt;0.01).ConclusionsHigher inflammatory marker levels are associated with greater prevalence of coronary stenosis in HIV+ men. Our findings underscore the need for further study to elucidate the relationships of inflammatory pathways with coronary artery disease in HIV+ individuals