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Transverse view of the left carotid arteries. a. in the middle third of the neck. b. in the cranial third of the neck. scm: sterno- cleidomastoid muscle. vji: internal jugular vein. acc: common ca- rotid artery. ace: external carotid artery. aci: internal carotid artery.
Source publication
Carotid duplex ultrasonography is a noninvasive technique for hemodynamically significant stenosis detection and cardiovascular risk estimation. Anatomic information of carotid arteries is provided by B-mode scanning. Hemodynamic features are displayed color-flow and pulsed Doppler imaging. Examination technique, normal carotid anatomy and flow pat...
Contexts in source publication
Context 1
... ultrasonography is the initial diagnostic test used to detect atherosclerotic disease of the extracranial carotid arteries allowing the detection of stenosis (symp- tomatic and hemodynamically significant or asympto- matic), or for follow–up after carotid endarterectomy and stenting [1-3]. In the absence of dyspnea or back pain, carotid arter- ies are examined with the patient in the supine position. Hyperextension is ensured by placing a small foam pil- low or a rolled-up towel under the neck. For enhancing neck exposure, the head is turned away from the exam- ined side at about a 45-degree angle from the midline or slightly less. The patient can also be examined in a reclining chair with easily adjustable backrest and head- rest [2,4,5]. Multi frequency linear transducers are preferable: high frequencies (7.5 to 12 MHz) for the distal two-thirds of the common carotid artery (CCA) and for the bifurca- tion region and lower frequency (5 MHz) for the origin of the CCA and the distal portion of the internal carotid artery (ICA) [3]. The most appropriate examination sequence is the two-step method. The first step is represented by a com- plete survey of the carotid arteries with B-mode and color flow imaging in two planes- transverse (anterior, lat- eral, or posterolateral approach) and longitudinal (ante- rolateral, posterolateral, and far-posterolateral approach) [2,4-6]. The second step of the e xamination protocol is represented by the in-depth investigation of the areas of interest using pulsed Doppler in longitudinal plane [3]. The three carotid arteries – CCA, ICA, and the exter- nal carotid artery (ECA) – should be analyzed bilaterally by various parameters – origin, location and course, cal- iber, wall structure and motion, branches, and blood flow pattern [2,4-6]. The CCA usually originates from the innominate ar- tery on the right side, and the aortic arch on the left side. For this reason, only the right CCA origin can be dis- played (fig 1-3) The CCA course is represented by an oblique line ori- ented upward from behind the sternoclavicular joint to the level of the upper border of the thyroid cartilage [6]. The proximal portion of the CCA is more profound. It may move up to 2-3 mm during systole, especially in pa- tients with hypertension and anxiety disorders. The distal two-thirds of the artery are parallel to the skin surface. The principal CCA relations are anterolaterally with the sternocleidomastoid muscle and the internal jugular vein (IJV), and medially with the thyroid (fig 4). The IJV wall is thin and it is usually oval in cross section. Vein move- ments are modulated mainly by the respiratory cycle. Ultrasound texture of the wall consists in three par- allel zones. Internal and external layers are hyperechoic and the middle is hypoechoic. The inner layer is repre- sented by the interface between circulating blood and tunica intima. The middle layer includes the intima and the media and the outer reflection is due to the adventitia. These three layers form the intima-media complex. The intima-media thickness (IMT) is represented by the dis- tance between the two hyperechoic layers. It is displayed in long-axis view at the far wall in the last one centimeter of the CCA (fig 5). The normal IMT values are influenced by age and gender. A value less than 0.9 mm is considered to be normal. Higher values are a marker of subclinical atherosclerosis so that the IMT is one of the factors in- fluencing prognosis in patients with hypertension [1,3,4]. The CCA lumen has an average diameter of 6-7 mm. There are no collateral branches of the CCA. Usu- ally, the CCA divides into the ICA and the ECA at the level of the superior border of the thyroid cartilage. The point of division is slightly dilated and it is known as the carotid bulb or the carotid sinus [2,4,5]. There are many variations in the location of the ICA relative to the ECA so that the display of the two arteries in a single longitudinal plane is possible in only 40-60% of cases. The ICA is located most frequently (49%) pos- terolateral to the ECA [5]. Due to the coronal plane of bifurcation, the ICA is located lateral to the ECA therefore longitudinal section can highlight only one artery (fig 6). The ICA has 6.5-7.5 mm diameter at the carotid si- nus, and 4.3-5.3 mm, beyond the bulb [5]. There are three portions of the ICA: proximal part represented by the ca- rotid sinus; mid ICA where the diameter becomes small- er; and distal ICA located at more than 3 cm above the bifurcation usually with curved course [3]. There are no collateral branches of the ICA in its extracranial course. The IMT can be measured in the proximal ICA and in the mid ICA (fig 7). The ECA has a lower lumen than proximal ICA, equal to the mid and distal ICA. The artery can be eas- ily recognized because it has a branch, the superior thy- roid artery, which gets off at the level of hyoid bone [2,4-6]. Hemodynamic assessment is the next step of the examination by using color flow mapping and pulsed Doppler technique. ICA and ECA have different pul- satility patterns: low peripheral resistance in ICA with the presence of color throughout the cardiac cycle, in- creasing during the systole and decreasing during the diastole, and high peripheral resistance in ECA with the color decreasing or disappearing at the end of di- astole. Pulsed Doppler examination is performed in longitu- dinal view. The sample volume is placed within the lumen without touching the wall with ultrasound incident angle under 60°. The peak systolic velocity is usually less than 125 cm/s. Two pulsatility patterns of carotid arteries are usually seen: moderate pulsatility in the CCA, with tall and broad systolic peak and low end-diastolic velocity, and low pulsatility in ICA, with broad systolic peaks and significant end-diastolic flow velocity [2,4-6] (fig 8-11). The most common limitations of the ultrasound examinations are the large size of the transducer, left CCA origin, deep location of the CCA, short neck, big beard, involuntary head movements, and important dyspnea. The two principal sources of error are repre- sented by the low level of operator expertise and the lack of time for a complete examination. Ultrasound artifacts, as hyperechoic lumen, marginal acoustic shadow, and aliasing, and hyperkinetic syndrome are other sources of error. Variants of origin, caliber, course (tortuosity, coiling or kinking), and bifurcation (spatial position, absence of carotid bulb) may be po- tential ...
Context 2
... distal two-thirds of the artery are parallel to the skin surface. The principal CCA relations are anterolaterally with the sternocleidomastoid muscle and the internal jugular vein (IJV), and medially with the thyroid (fig 4). The IJV wall is thin and it is usually oval in cross section. ...
Citations
... However, multicontrast MRI has cost and scanning limitations that make its use in daily clinical practice limited, thus remaining largely dedicated for research purposes. In contrast, B-mode ultrasound is widely used for the assessment of atherosclerosis in the carotid artery due to its ease of use, very low costs, and wide availability [20]. Histology-based studies have shown the capability of ultrasound to separate the lipid, fibrous, and calcified tissues in the carotid [21]- [23]. ...
... Histology-based studies have shown the capability of ultrasound to separate the lipid, fibrous, and calcified tissues in the carotid [21]- [23]. Due to these benefits, carotid ultrasound has significant potential as the modality of choice for atherosclerosis assessment in clinical practice [20]. ...
Characterization of carotid plaque composition, more specifically the amount of lipid core, fibrous tissue, and calcified tissue, is an important task for the identification of plaques that are prone to rupture, and thus for early risk estima-tion of cardiovascular and cerebrovascular events. Due to its low costs and wide availability, carotid ultrasound has the potential to become the modality of choice for plaque characterization in clinical practice. However, its significant image noise, coupled with the small size of the plaques and their complex appearance, makes it difficult for automated techniques to discriminate be-tween the different plaque constituents. In this paper, we propose to address this challenging problem by exploiting the unique ca-pabilities of the emerging deep learning framework. More specif-ically, and unlike existing works which require a priori definition of specific imaging features or thresholding values, we propose to build a convolutional neural network that will automatically ex-tract from the images the information that is optimal for the identification of the different plaque constituents. We used ap-proximately 90,000 patches extracted from a database of images and corresponding expert plaque characterizations to train and to validate the proposed convolutional neural network (CNN). The results of cross-validation experiments show a correlation of about 0.90 with the clinical assessment for the estimation of lipid core, fibrous cap, and calcified tissue areas, indicating the poten-tial of deep learning for the challenging task of automatic charac-terization of plaque composition in carotid ultrasound.
In this review, the ultrasound (US) artifacts features such as propagation path, velocity, attenuation, multiple echoes, and resolution are explained. The main restrictions of an axial and lateral resolution are artifacts. However, failure to fix them lead to the lack of details, and adjacent neighboring objects may be observed as one image. This article describes an essential law to control wave movement, and the US artifacts are formed. Thus, it is substantial for the radiologist and sonographer to differentiate between the artifacts and abnormal signs during the diagnostic procedure. Furthermore, the use of enhancing and shadowing artifacts in determining the nature of masses was explained. The comet tail, attenuation, mirror image, refraction, speed displacement, side lobe, and beam width artifacts happened typically in clinical (in-vivo) practice were also discussed. Finally, an estimation and evaluation of these artifacts are necessary to increase the accuracy in diagnosis.
Purpose: Duplex scanning is a useful noninvasive screening tool for the detection of carotid bifurcation disease. Internal carotid artery (ICA) peak systolic velocity (PSV) and ICA/common carotid artery (CCA) PSV ratios are proven metrics determining 70%-99% ICA stenosis. A potential disadvantage of using dramatically increasing systolic velocity measurements in areas of critical arterial stenosis is flow aliasing. Diastolic velocity should be less influenced by this flow artifact. We evaluate ICA and CCA end diastolic velocity (EDV) metrics in predicting severe ICA stenosis and document the prevalence of an aliasing artifact in a population of patients with critical ICA stenosis.
Methods: Consecutive patients undergoing carotid duplex assessments and contrast angiography were compared (n = 140). ICA and CCA PSV and EDV were recorded as was evidence of the flow aliasing of ICA waveforms. ICA/CCA PSV and EDV ratios were calculated. Duplex parameters were compared with angiographic ICA measurements. Receiver-operator characteristic curve (ROC) analysis was used to determine optimal criteria to identify ICA stenosis of 70% to 99%.
Results: Of 256 carotid bifurcation duplex studies, critical angiographic stenosis was present in 105 arteries. Only four completed arterial duplex scans demonstrated flow aliasing. In three of these patients, systolic metrics were non-diagnostic versus ICA/CCA EDV ratios. An ICA/CCA EDV ratio of 2.3 provided the best combination of sensitivity 73.8% and specificity 75.18%.
Conclusion: ICA/CCA diastolic ratios reliably determine 70% or greater ICA stenosis. Flow aliasing infrequently complicates ICA PSV. ARTICLE HISTORY
There is a large clinical requirement for novel vascular grafts; however, the development of novel vascular grafts has not been extremely successful to date. The most successful method for the continuous evaluation of vascular grafts in vivo remains unclear. Therefore, an optimal successive, non-invasive imaging modality is necessary for the study of vascular transplantation. In the present study, a common rabbit model of carotid artery defect was utilized. The patency and hemodynamic characteristics of implanted grafts was examined following surgery by color Doppler ultrasound in three modes, including B-mode, color flow map and pulse-Doppler examination. The results revealed that ultrasound had sufficient spatial resolution to generate clear images of the carotid artery of rabbits with or without the implanted grafts. Color Doppler ultrasound may be applied to evaluate and differentiate the patent, stenosis and occlusion of carotid arteries in rabbits with different vascular grafts implanted. Furthermore, color Doppler ultrasound is an optimal imaging modality for continuous evaluation in vivo. It is also possible for some quantitative analyses to be performed, including measuring the diameter of vascular lumens and the flow velocity of the region of interest. The present study suggests vascular ultrasound as the optimum choice for continuous surveillance of vascular prostheses in vivo, which may provide valuable information about the grafts in order to greatly shorten the experimental period.
En el accidente cerebrovascular (ACV) de causa ateroembólica, las características de la placa de ateroma se correlacionan con el riesgo de isquemia. La compresión extrínseca del vaso puede desencadenar la rotura y la embolización. Dentro de las recomendaciones para la evaluación de pacientes que han presentado un accidente isquémico transitorio o un ACV, se indica la realización de una ecografía Doppler de vasos de cuello (EDVC). Dicha práctica se considera carente de riesgos, aunque durante la misma pueden producirse compresiones bruscas sobre la arteria carótida.
Objective:
To explore the relationship between ambulatory blood pressure and arterial atherosclerosis and provide simple and easy reference indicators for the prediction, prevention and prognosis of cardiovascular events in end-stage renal disease (ESRD) patients.
Method:
This prospective study consecutively collected clinical data of 114 ESRD hospitalized patients in the Department of Nephrology, the First Affiliated Hospital of Nanjing Medical University during August 2012 to December 2012. The data included laboratory data, the ambulatory blood pressure monitoring (ABPM), carotid ultrasound, two-dimensional echocardiography and the prognosis scores of the death risk.
Results:
(1) A series of ABPM parameters were closely associated with atherosclerosis (p ≤ 0.05). Ambulatory Arterial Stiffness Index (AASI) was the most representative parameter of ABPM and also the best indicator for atherosclerosis (logistic regression analysis, p = 0.005). (2) AASI was a comprehensive index of atherosclerosis (p < 0.001), which was associated with the increase of left ventricular diameter (p = 0.028) and the risk of death (p < 0.001). The independent risk factors of AASI were the growth of the age (p < 0.001), elevated serum fibrinogen (p = 0.009) and reduced serum albumin (p = 0.022).
Conclusion:
AASI, as the representative of ABPM parameters, related well to atherosclerosis, which implied a broader application of ABPM in ESRD patients.
