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 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

Non-invasive Vascular Structure and Pathology Using Very-high Resolution Ultrasound

Very-high resolution ultrasound (VHRU, 25-55MHz) is a recently developed method for non-invasive assessment of vascular structures. With its increased ultrasound frequency, the method allows for noninvasive examination of the vascular wall in vivo with an axial resolution in the range of tens of micrometers. These characteristics make it a feasible method to determine vascular dimensions of superficial arteries and arteries in the pediatric population. The aim of this thesis was the following: 1. To study the application of a semi-automatic border detection software to improve measurement characteristics of the arterial wall layers, 2. To assess accuracy, precision and feasibility of the VHRU method in assessing superficial arterial wall layers in preterm and term neonates, 3. To validate the VHRU method to assess age-related intimal thickening of the arterial wall, and 4. To determine the potential to implement the method as a noninvasive tool in the bedside diagnosis of giant-cell arteritis of the temporal artery. This Thesis shows that there is no significant difference in the technical precision or bias of arterial wall layer dimension measurements using a semi-automated border detection software compared to electronical calipers, but time of analysis is significantly shorter using the automated border detection software. VHRU is feasible, accurate and precise in the measurement of arterial layer thickness (intima-media and intima-media-adventitia thickness) of proximal conduit arteries, such as carotid, brachial and femoral, in preterm and term neonates. The resolution of VHRU is insufficient in the assessment of more peripheral conduit arteries such as the radial artery. VHRU is feasible and able to detect a thickened intimal layer, seen as a four-line pattern of the arterial far wall in the ultrasound image, in superficial peripheral muscular conduit arteries with intima thickness >0.06mm. Measurements leading-to-leading edge of the intimal layer are accurate compared with histological thickness. VHRU is feasible, accurate and precise in assessing transmural inflammation related intimal thickening in patients with giant-cell arteritis of the temporal artery. The method was however not useful in patients with inflammation limited to the adventitia or without inflammation on histology. In conclusion, very-high resolution ultrasound is an emerging method for the assessment of superficial vascular wall layer structures. The harmless and non-invasive method can detect near-microscopical changes in the vascular wall in human subjects from the newborn stage to old age. Very-high resolution ultrasound has a clinical potential in the non-invasive assessment of vascular health and disease related pathology.Kajoamaton korkeataajuusultraääni (VHRU, very-high resolution ultrasound, 25-55MHz) on 2000-luvulla kehitetty ultraäänimenetelmä valtimonseinämän kuvantamiseen. Korkeammilla ultraäänitaajuuksilla kuvan erottelukyky on parempi, lähes mikroskooppitasoa, mutta kuvausalue on rajoittunut lähellä anturia oleviin rakenteisiin. Tässä väitöskirjassa arvioidaan puoliautomaattisen analyysiohjelman käyttöä valtimoseinämän eri kerrosten mittaamisessa. Lisäksi kirjassa selvitetään menetelmän soveltuvuutta vastasyntyneiden lasten valtimoseinämän arvioinnissa, menetelmän käyttöä valtimon sisäkalvon (tunica intima) paksuuden mittauksessa ikääntyneillä, sekä menetelmän hyötyjä jättisoluarteriitin diagnostiikassa. Tutkimme puoliautomaattisen ohjelmankäyttöä kymmenen henkilön eri verisuonista otettujen kuvien arvioinnissa vertailemalla analyysiaikaa ja mittauksien luotettavuutta käsin tehtyihin yksittäismittauksiin. Emme löytäneet eroa menetelmien luotettavuudessa, mutta puoliautomaattisen menetelmän analyysiaika oli merkittävästi lyhyempi. VHRU-menetelmä pystyi luotettavasti ja tarkasti mittaamaan suurten ja keskisuurten valtimoiden seinämän kerrospaksuudet. VHRU-menetelmällä tutkittiin 78 ikääntynyttä potilasta, jotka oli lähetetty ohimovaltimon koepalan ottoon jättisoluarteriittiepäilyn takia. Niiden potilaiden joukossa, joilla ei ollut tulehdusmuutoksia suonen seinämässä, 76 %:lla oli histologisesti paksuuntunut valtimon sisäkalvo joka oli tarkasti ja luotettavasti mitattavissa VHRU-menetelmällä. Jättisoluarteriittipotilailla ohimovaltimon seinämä oli histologiassa selkeästi paksuntunut. VHRU-menetelmällä mitattu yli 0,3 mm:n valtimon sisäkalvo oli tarkka ja herkkä mittari jättisoluarteriitille. Kajoamaton korkeataajuusultraääni on uusi menetelmä, jolla pinnallisten valtimoiden seinämän kerrosten paksuudet voidaan tarkasti ja luotettavasti mitata. Puoliautomaattisella ohjelmalla valtimoseinämän kerroksen paksuuden mittaamista voidaan nopeuttaa. Menetelmän parempi erottelukyky mahdollistaa pienten vastasyntyneiden valtimoseinämän kuvantamisen ja ikääntyvien valtimon sisäkalvon paksuuden mittaamisen. Ohimovaltimon jättisoluarteriitissa suonenseinämä turpoaa tulehduksen seurauksena ja tämä näkyy VHRU-kuvissa paksuuntuneena sisäkalvona. Menetelmä voisi tulevaisuudessa soveltua kliiniseen käyttöön pinnallisten verisuonisairauksien tutkimuksessa ja diagnostiikassa

Intra- and inter-operator reproducibility of automated cloud-based carotid lumen diameter ultrasound measurement

Background: Common carotid artery lumen diameter (LD) ultrasound measurement systems are either manual or semi-automated and lack reproducibility and variability studies. This pilot study presents an automated and cloud-based LD measurements software system (AtheroCloud) and evaluates its: (i) intra/inter-operator reproducibility and (ii) intra/inter-observer variability. Methods: 100 patients (83 M, mean age: 68 ± 11 years), IRB approved, consisted of L/R CCA artery (200 ultrasound images), acquired using a 7.5-MHz linear transducer. The intra/inter-operator reproducibility was verified using three operator's readings. Near-wall and far carotid wall borders were manually traced by two observers for intra/inter-observer variability analysis. Results: The mean coefficient of correlation (CC) for intra- and inter-operator reproducibility between all the three automated reading pairs were: 0.99 (P < 0.0001) and 0.97 (P < 0.0001), respectively. The mean CC for intra- and inter-observer variability between both the manual reading pairs were 0.98 (P < 0.0001) and 0.98 (P < 0.0001), respectively. The Figure-of-Merit between the mean of the three automated readings against the four manuals were 98.32%, 99.50%, 98.94% and 98.49%, respectively. Conclusions: The AtheroCloud LD measurement system showed high intra/inter-operator reproducibility hence can be adapted for vascular screening mode or pharmaceutical clinical trial mode

The Ultrasound Window Into Vascular Ageing: A Technology Review by the VascAgeNet COST Action

Arteriosclerosis; Ultrasound; Vascular ageingArteriosclerosi; Ecografia; Envelliment vascularArteriosclerosis; Ecografía; Envejecimiento vascularNon-invasive ultrasound (US) imaging enables the assessment of the properties of superficial blood vessels. Various modes can be used for vascular characteristics analysis, ranging from radiofrequency (RF) data, Doppler- and standard B/M-mode imaging, to more recent ultra-high frequency and ultrafast techniques. The aim of the present work was to provide an overview of the current state-of-the-art non-invasive US technologies and corresponding vascular ageing characteristics from a technological perspective. Following an introduction about the basic concepts of the US technique, the characteristics considered in this review are clustered into: 1) vessel wall structure; 2) dynamic elastic properties, and 3) reactive vessel properties. The overview shows that ultrasound is a versatile, non-invasive, and safe imaging technique that can be adopted for obtaining information about function, structure, and reactivity in superficial arteries. The most suitable setting for a specific application must be selected according to spatial and temporal resolution requirements. The usefulness of standardization in the validation process and performance metric adoption emerges. Computer-based techniques should always be preferred to manual measures, as long as the algorithms and learning procedures are transparent and well described, and the performance leads to better results. Identification of a minimal clinically important difference is a crucial point for drawing conclusions regarding robustness of the techniques and for the translation into practice of any biomarker.This article is based upon work from COST Action CA18216 VascAgeNet, supported by COST (European Cooperation in Science and Technology, www.cost.eu). A.G. has received funding from “La Caixa” Foundation (LCF/BQ/PR22/11920008). R.E.C is supported by the National Health and Medical Research Council of Australia (reference: 2009005) and by a National Heart Foundation Future Leader Fellowship (reference: 105636). J.A. acknowledges support from the British Heart Foundation [PG/15/104/31913], the Wellcome EPSRC Centre for Medical Engineering at King's College London [WT 203148/Z/16/Z], and the Cardiovascular MedTech Co-operative at Guy's and St Thomas' NHS Foundation Trust [MIC-2016-019]

Carotid Artery Wall Imaging: Perspective and Guidelines from the ASNR Vessel Wall Imaging Study Group and Expert Consensus Recommendations of the American Society of Neuroradiology

SUMMARY: Identification of carotid artery atherosclerosis is conventionally based on measurements of luminal stenosis and surface irregularities using in vivo imaging techniques including sonography, CT and MR angiography, and digital subtraction angiography. However, histopathologic studies demonstrate considerable differences between plaques with identical degrees of stenosis and indicate that certain plaque features are associated with increased risk for ischemic events. The ability to look beyond the lumen using highly developed vessel wall imaging methods to identify plaque vulnerable to disruption has prompted an active debate as to whether a paradigm shift is needed to move away from relying on measurements of luminal stenosis for gauging the risk of ischemic injury. Further evaluation in randomized clinical trials will help to better define the exact role of plaque imaging in clinical decision-making. However, current carotid vessel wall imaging techniques can be informative. The goal of this article is to present the perspective of the ASNR Vessel Wall Imaging Study Group as it relates to the current status of arterial wall imaging in carotid artery disease

The Segmentation of Ultrasound Images for Artery Wall Detection and Intima-Media Thickness Measurement

Tato práce je zaměřena na problematiku měření šířky vrstev intima a media (intima media thickness), která se z medicínského pohledu ukazuje jako vhodná pro ohodnocení rizik plynoucích z různých onemocnění kardiovaskulárního systému. Šířka intima media je měřena v ultrazvukovém obraze, který zobrazuje arterii carotis communis v jejím podélném řezu, ve kterém jsou patrné měřené vrstvy intima a media. Práce zahrnuje teoretickou analýzu problematiky z technického i medicínského pohledu a shrnuje současný stav zkoumané problematiky. V práci je popsán návrh nového plně automatického systému pro měření šířky vrstev intima media. Navržený systém zahrnuje i robustní proceduru lokalizace arterie a je tak schopen bez počáteční inicializace či úpravy vstupních dat zpracovávat přímo zdrojová data získaná ultrazvukovou stanicí v B-módu.The thesis focuses on the measurement of intima media thickness, which seems to be a significant marker of the risk of cardiovascular events. Intima media thickness is measured in ultrasound image displaying the common carotid artery in its longitudinal section. In the longitudinal section the intima and media layers are visible. Thesis is discussing both technical and medical background and summarizes state of the art in this field. The main part of the thesis describes the novel automatic system for measurement of intima media thickness. Proposed system includes also robust method for artery localization and therefore is able to process raw B-mode data from ultrasound station without any initialization or manual preprocessing.

Cyclic variation of the common carotid artery structure in relation to prior atherosclerotic burden and physical activity

Background and aims: Cardiovascular disease (CVD) accounts for the most deaths of non-communicable diseases worldwide. It begins with structural and functional changes of the arterial system commonly known as the atherosclerotic process, starting asymptomatically in early childhood, adapting arterial structure and function with advancing age depending on genetic and environmental exposures and finally resulting in CVD events such as myocardial infarction or stroke. CVD risk prediction today is generally based on risk scores, but substantial disadvantages occur since they account only for specific risk factors at one time point. Carotid structure and function (also called carotid stiffness) parameters measured by ultrasound may overcome this disadvantage, since they can provide information on structural and elastic carotid properties and reflect therefore vascular damage accumulated over time. Thus, the aims of this thesis were to summarize the state of the art of ultrasound measurements, to validate the new developed ultrasound analysis system, to assess the variability and reproducibility within the study sample and to investigate the long- and short-term associations of cardiovascular risk factors and carotid stiffness with main focus on physical activity in elderly participants of the SAPALDIA cohort. Methods: The SAPALDIA cohort study is an ongoing multicenter study with a population-based random sample of adults from eight rural and urban areas started in 1991 (SAPALDIA 1), with a first follow-up in 2001-2003 (SAPALDIA 2) and a second follow-up in 2010-2011 (SAPALDIA 3). In SAPALDIA 3, sequential B-mode ultrasound images of the common carotid artery were examined in 3489 participants (51% women) aged between 50-81 years at the time of examination. Expert readers analyzed these ultrasound images with a new analysis system called DYARA (DYnamic ARtery Analysis) according to the state of the art assessed in the review. Thereof, carotid structure parameters were measured and carotid stiffness indices were derived considering blood pressure at time of ultrasound assessment. Validation of the ultrasound analysis program DYARA and reproducibility of carotid parameters were performed in subgroup within the SAPALDIA 3 survey. The presented studies within this thesis comprise cardiovascular risk factor data from the first and second follow-up and therefore, long- and short-term associations with carotid stiffness could be investigated. Results: The intra- and inter-reader results of the validation study were highly consistent with slightly higher bias for analyses with manual interactions compared to the automatic detection. Among the carotid structure parameters, average values across heart cycle showed lower variability than single images in diastole and systole, whereby the relative difference was smaller in lumen diameter values compared to the carotid intima media thickness (CIMT). Based on different statistical approaches, reproducibility values within SAPALDIA 3 were consistently good to excellent for carotid structure and function indices. Findings additionally revealed that subjects itself were the greatest source of variability between two measurements. Multivariate regression analyses suggested that most single cardiovascular risk factors in SAPALDIA 2 were long-termly associated with increased carotid stiffness in SAPALDIA 3 except physical activity and high-density lipoprotein cholesterol (HDL-C). HDL-C was the only protective vascular determinant and no relation was observed for physical activity. Most carotid stiffness parameters were similar strong associated within each cardiovascular risk factor (except compliance showed main deviances among several risk factors). Estimating sex-specific associations of atherosclerotic risk factors and carotid stiffness indicated that increased heart rate was more strongly associated with stiffer arteries across all carotid stiffness parameters in men than in women. Low-density lipoprotein cholesterol (LDL-C) was significantly associated with carotid stiffness only in men and triglyceride only in women. Multifactorial pathway analyses of cardiovascular risk factors in SAPALDIA 3 showed that age was the strongest predictor of carotid stiffness, followed by mean arterial blood pressure and heart rate. Age strongly confounded the association of physical activity and carotid stiffness in multiple regression analyses and therefore, only an univariate association of physical activity and carotid stiffness could be observed. Conclusion: DYARA tackles the challenge of being able to analyze varying ultrasound image qualities with high precision. The high reproducibility and the feasible application in a large sample size suggest that this program can be recommended for epidemiological research, diagnostics and clinical practice. Long- and short-term cardiovascular exposures have added important information to the overall vascular damage assessed by carotid stiffness for both sexes. Although age was the strongest predictor, sex-differences in long-term associations may indicate a certain differentiated susceptibility to cardiovascular risk factors among men and women, which should be investigated in more detail. The presented studies within this thesis provide an important basis towards future investigations targeting the early and late consequences of atherosclerosis, its progression and possible implementations of preventive and/or personalized interventions