Imaging modalities to diagnose carotid artery stenosis: progress and prospect

MRI and MR angiography evaluation of pulsatile tinnitus: A focused, physiology-based protocol

BACKGROUND AND PURPOSE

Pulsatile tinnitus (PT) is the subjective sensation of a pulse-synchronous sound, most often due to a cerebrovascular etiology. PT can severely impact quality of life and may indicate a life-threatening process, yet a timely and accurate diagnosis can often lead to effective treatment. Clinical assessment with a history and physical examination can often suggest a diagnosis for PT, but is rarely definitive. Therefore, PT should be evaluated with a comprehensive and targeted radiographic imaging protocol. MR imaging provides a safe and effective means to evaluate PT. Specific MR sequences may be used to highlight different elements of cerebrovascular anatomy and physiology. However, routine MR evaluation of PT must comply with economic and practical constraints, while effectively capturing both common and rarer, life-threatening etiologies of PT.

METHODS

In this state-of-the-art review, we describe our institutional MR protocol for evaluating PT.

RESULTS

This protocol includes the following dedicated sequences: time-of-flight magnetic resonance angiography; arterial spin labeling; spoiled gradient recalled acquisition in the steady state; time-resolved imaging of contrast kinetics; diffusion weighted imaging, and 3-dimensional fluid-attenuated inversion recovery.

CONCLUSIONS

We describe the physiologic and clinical rationale for including each MR sequence in a comprehensive PT imaging protocol, and detail the role of MR within the broader evaluation of PT, from clinical presentation to treatment.

Carotid atherosclerotic disease: A systematic review of pathogenesis and management

Carotid stenosis is an important contributor to ischemic stroke risk with resultant significant impact on neurological disability and death in adults and with worldwide implications. Management of carotid stenosis is impacted by whether there are associated symptoms along with the degree of stenosis. Understanding of the pathogenesis of carotid atherosclerosis or stenosis is important in management of carotid stenosis. Atherosclerotic plaque formation is a chronic insidious process with a number of potential contributors to the formation of such a plaque. The definition of atherosclerosis is not simply limited to abnormal deposition of lipid but also includes a chronic, complex, inflammatory process. Molecularly, in atherosclerosis, there is decreasing nitric oxide (NO) bioavailability, activity and/or expression of endothelial NO synthase, or increasing degradation of NO secondary to enhanced superoxide production. These above changes cause endothelial dysfunction leading to formation of foam cell followed by formation on lipid plaque. After lipid plaque formation, stable or unstable atherosclerotic plaque is formed depending on the calcium deposition over the lipid plaque. It continues to be clearly established that carotid intervention for symptomatic high-grade carotid stenosis is best managed with intervention either by carotid endarterectomy or carotid stenting. However, asymptomatic carotid stenosis is the subject of considerable controversy in terms of optimal management. This review of carotid atherosclerosis is an attempt to incorporate the information provided by more recent studies on pathogenesis and management which may help in the decision-making process for optimal management for protection against stroke.

Identification of Symptomatic Carotid Artery Plaque: A Three-Item Scale Combined Angiography With Optical Coherence Tomography

Introduction: Symptomatic carotid disease conveys a high risk of recurrent stroke. Plaque morphology and specific plaque characteristics are associated with the risk of stroke. This study aimed to evaluate the detailed plaque features by optical coherence tomography (OCT) and develop a simple scale combining clinical indicators, digital subtraction angiography (DSA), and OCT imaging markers to identify symptomatic carotid plaque. Methods: Carotid plaques from consecutive patients who underwent carotid OCT imaging between June 2017 and June 2021 were evaluated. Clinical characteristics, DSA, and OCT data were compared between the symptomatic and asymptomatic groups. Logistic regression was performed to identify the factors associated with symptomatic carotid plaque and to develop a scale. The area under the receiver operating characteristic curve (AUC) was used to evaluate the performance of the scale. Results: A total of 90 carotid plaques from 90 patients were included (symptomatic 35.6%, asymptomatic 64.4%). Three main factors were found to be associated with symptomatic carotid plaque: high-density lipoprotein cholesterol (HDL-C) <0.925 mmol/L (OR, 4.708; 95% CI, 1.640 to 13.517; P = 0.004), irregular plaque (OR, 4.017; 95% CI, 1.250 to 12.910; P = 0.020), and white thrombus (OR, 4.594; 95% CI, 1.141 to 18.487; P = 0.032). The corresponding score of three items produced a scale with good discrimination (AUC, 0.768; 95% CI, 0.665 to 0.871). The optimal cutoff value of the scale was 1.5 points with 59.4% sensitivity and 84.5% specificity. Conclusion: The three-item scale comprising HDL-C <0.925 mmol/L, angiographical irregular plaque, and white thrombus detected by OCT may provide information to identify symptomatic carotid plaque. Further large-scale studies are required to validate whether the symptomatic carotid plaque scale is clinically valuable in recognizing carotid atherosclerosis in the early stages.

Serum Biomarkers in Carotid Artery Disease

Carotid artery disease is considered a major cause of strokes and there is a need for early disease detection and management. Although imaging techniques have been developed for the diagnosis of carotid artery disease and different imaging-based markers have been proposed for the characterization of atherosclerotic plaques, there is still need for a definition of high-risk plaques in asymptomatic patients who may benefit from surgical intervention. Measurement of circulating biomarkers is a promising method to assist in patient-specific disease management, but the lack of robust clinical evidence limits their use as a standard of care. The purpose of this review paper is to present circulating biomarkers related to carotid artery diagnosis and prognosis, which are mainly provided by statistical-based clinical studies. The result of our investigation showed that typical well-established inflammatory biomarkers and biomarkers related to patient lipid profiles are associated with carotid artery disease. In addition to this, more specialized types of biomarkers, such as endothelial and cell adhesion, matrix degrading, and metabolic biomarkers seem to be associated with different carotid artery disease outputs, assisting vascular specialists in selecting patients at high risk for stroke and in need of intervention.

Symptom Status of Patients Undergoing Carotid Endarterectomy in Canada and United States

BACKGROUND

Previous studies have demonstrated significant geographic variations in the management of carotid artery stenosis despite standard guidelines. To further characterize these practice variations, we assessed differences in patient selection, operative technique, and outcomes for carotid endarterectomy (CEA) in Canada vs. United States.

METHODS

The Vascular Quality Initiative (VQI) was used to identify all patients who underwent CEA between 2010 and 2019 in Canada and United States. Demographic, clinical, and procedural characteristics were recorded and differences between countries were assessed using independent t-test and chi-square test. The primary outcome was the percentage of CEA performed for asymptomatic versus symptomatic disease. The secondary outcomes were 30-day and long-term stroke or death. Associations between country and outcomes were assessed using univariate/multivariate logistic regression and Cox proportional hazards analysis.

RESULTS

During the study period, 131,411 US patients and 701 Canadian patients underwent CEA in VQI sites. Patients from the US were older with more comorbidities including hypertension, diabetes, congestive heart failure, and chronic kidney disease. The use of a shunt, patch, drain, or protamine was less common in the US. Most patients had 70 - 99% stenosis, with no difference between regions. The percentage of CEA performed for asymptomatic disease was significantly higher in the US even after adjusting for demographic, clinical, and procedural characteristics (72.4% vs. 30.7%, adjusted OR 3.91 [95% CI 3.21 - 4.78], p < 0.001). Thirty-day stroke/death was low (1.8% vs. 1.9%) and 1-year stroke/death was similar between groups (HR 0.98 [95% CI 0.69 - 1.39], P = 0.89). The similarities in 1-year stroke/death persisted in asymptomatic patients (HR 0.70 [95% CI 0.37 - 1.30], P = 0.26) and symptomatic patients (HR 1.14 [95% CI 0.74 - 1.73], P = 0.56).

CONCLUSIONS

There are significant variations in CEA practice between Canada and US. In particular, most US patients are treated for asymptomatic disease, whereas most Canadian patients are treated for symptomatic disease. Furthermore, adjunctive procedures including shunting, patch use, and protamine administration are performed less commonly in the US. Despite these differences, perioperative and 1-year stroke/death rates are similar between countries. Future studies should investigate reasons for these variations and quality improvement projects are needed to standardize care.

A Review of Carotid Artery Phantoms for Doppler Ultrasound Applications

Ultrasound imaging systems need tissue-mimicking phantoms with a good range of acoustic properties. Many studies on carotid artery phantoms have been carried out using ultrasound; hence this study presents a review of the different forms of carotid artery phantoms used to examine blood hemodynamics by Doppler ultrasound (DU) methods and explains the ingredients that constitute every phantom with their advantages and disadvantages. Different research databases were consulted to access relevant information on carotid artery phantoms used for DU measurements after which the information were presented systematically spanning from walled phantoms to wall-less phantoms. This review points out the fact that carotid artery phantoms are made up of tissue mimicking materials, vessel mimicking materials, and blood mimicking fluid whose properties matched those of real human tissues and vessels. These materials are a combination of substances such as water, gelatin, glycerol, scatterers, and other powders in their right proportions.

MicroRNA-375-3p is implicated in carotid artery stenosis by promoting the cell proliferation and migration of vascular smooth muscle cells

Background

Atherosclerosis is the main cause of carotid artery stenosis (CAS) which mostly occurs in the elderly. In this paper, the expression level of miR-375-3p in asymptomatic CAS patients and its diagnostic value for asymptomatic CAS were investigated, and the effects of miR-375-3p on the cell proliferation and migration of vascular smooth muscle cells (VSMCs) was further explored.

Methods

98 healthy subjects and 101 asymptomatic CAS patients were participated in this study. qRT-PCR was used to measure the expression level of serum miR-375-3p, and the ROC curve was established to evaluate the predictive value of miR-375-3p for asymptomatic CAS. After transfection with miR-375-3p mimic or inhibitor in vitro, cell proliferation and migration were detected by CCK-8 assay, colony formation assay, and Transwell assay, respectively. The levels of TNF-α, IL-1β, IL-6 were detected by ELISA. Western blot was used to detect the protein expression of XIAP. Finally, luciferase reporter gene assay was applied to assess the interaction of miR-375-3p with target genes.

Results

The expression level of serum miR-375-3p in asymptomatic CAS patients was significantly higher than that in healthy controls, and the AUC value of ROC curve was 0.888. The sensitivity and specificity were 80.2 and 86.7%, respectively, indicating that miR-375-3p had high diagnostic value for asymptomatic CAS. In vitro cell experiments showed that up-regulation of miR-375-3p significantly promoted the proliferation and migration of VSMCs, and also promoted the generation of inflammatory factors and phenotypic transformation of VSMCs. Luciferase reporter gene assay confirmed that XIAP was a target gene of miR-375-3p and was negatively regulated by miR-375-3p.

Conclusions

In this study, miR-375-3p may have a clinical diagnostic value for asymptomatic CAS patients which need further validation. Increased miR-375-3p levels in CAS may be associated with increased proliferation and migration of VSMCs via downregulation of the apoptosis inducing gene XIAP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02326-6.

Carotid Artery Calcification: What We Know So Far

Carotid artery calcification (CAC) is a well-known marker of atherosclerosis and is linked to a high rate of morbidity and mortality. CAC is divided into two types: intimal and medial calcifications, each with its own set of risk factors. Vascular calcification is now understood to be an active, enzymatically regulated process involving dystrophic calcification and endothelial dysfunction at an early stage. This causes a pathogenic inflammatory response, resulting in calcium phosphate deposition in the form of microcalcifications, which causes plaque formation, ultimately becoming unstable with sequelae of complications. If the inflammation goes away, hydroxyapatite crystal formation takes over, resulting in macro-calcifications that help to keep the plaque stable. As CAC can be asymptomatic, it is critical to identify it early using diagnostic imaging. The carotid artery calcification score is calculated using computed tomography angiography (CTA), which is a confirmatory test that enables the examination of plaque composition and computation of the carotid artery calcification score. Magnetic resonance angiography (MRA), which is sensitive as CTA, duplex ultrasound (DUS), positron emission tomography, and computed tomography (PET-CT) imaging with (18) F-Sodium Fluoride, and Optical Coherence Tomography (OCT) are some of the other diagnostic imaging modalities used. The current therapeutic method starts with the best medical care and is advised for all CAC patients. Carotid endarterectomy and carotid stenting are two treatment options that have mixed results in terms of effectiveness and safety. When patient age and anatomy, operator expertise, and surgical risk are all considered, the agreement is that both techniques are equally beneficial.

Multispectral optoacoustic tomography of lipid and hemoglobin contrast in human carotid atherosclerosis

Several imaging techniques aim at identifying features of carotid plaque instability but come with limitations, such as the use of contrast agents, long examination times and poor portability. Multispectral optoacoustic tomography (MSOT) employs light and sound to resolve lipid and hemoglobin content, both features associated with plaque instability, in a label-free, fast and highly portable way. Herein, 5 patients with carotid atherosclerosis, 5 healthy volunteers and 2 excised plaques, were scanned with handheld MSOT. Spectral unmixing allowed visualization of lipid and hemoglobin content within three ROIs: whole arterial cross-section, plaque and arterial lumen. Calculation of the fat-blood-ratio (FBR) value within the ROIs enabled the differentiation between patients and healthy volunteers (P = 0.001) and between plaque and lumen in patients (P = 0.04). Our results introduce MSOT as a tool for molecular imaging of human carotid atherosclerosis and open new possibilities for research and clinical assessment of carotid plaques.

Coarse-to-fine multiplanar D-SEA UNet for automatic 3D carotid segmentation in CTA images

PURPOSE

Carotid artery atherosclerotic stenosis accounts for 18-25% of ischemic stroke. In the evaluation of carotid atherosclerotic lesions, the automatic, accurate and rapid segmentation of the carotid artery is a priority issue that needs to be addressed urgently. However, the carotid artery area occupies a small target in computed tomography angiography (CTA) images, which affect the segmentation accuracy.

METHODS

We proposed a coarse-to-fine segmentation pipeline with the Multiplanar D-SEA UNet to achieve fully automatic carotid artery segmentation on the entire 3D CTA images, and compared with other four neural networks (3D-UNet, RA-UNet, Isensee-UNet, Multiplanar-UNet) by assessing Dice, Jaccard similarity coefficient, sensitivity, area under the curve and average hausdorff distance.

RESULTS

Our proposed method can achieve a mean Dice score of 91.51% on the 68 neck CTA scans from Beijing Hospital, which remarkably outperforms state-of-the-art 3D image segmentation methods. And the C2F segmentation pipeline can effectively improve segmentation accuracy while avoiding resolution loss.

CONCLUSION

The proposed segmentation method can realize the fully automatic segmentation of the carotid artery and has robust performance with segmentation accuracy, which can be applied into plaque exfoliation and interventional surgery services. In addition, our method is easy to extend to other medical segmentation tasks with appropriate parameter settings.

Value of transcranial color-code Doppler in evaluating intracranial atherosclerotic stenosis in patients with diabetes mellitus type 2: a comparison of transcranial Doppler and computed tomography angiography

BACKGROUND

There are several imaging assessment methods for intracranial atherosclerotic stenosis (ICAS). This study investigated the most efficient method by which to diagnose ICAS in patients with diabetes mellitus.

METHODS

One hundred seven patients with type 2 diabetes mellitus were enrolled as the experimental group and 68 healthy subjects were designated as the control group. The experimental group was examined with transcranial color-code Doppler (TCCD) and transcranial Doppler (TCD). Sixty-five patients in the experimental group were diagnosed by computed tomography angiography (CTA) on a voluntary basis. The 68 subjects in the control group were examined by TCCD alone.

RESULTS

Based on TCCD examinations, the ICAS positivity rate was 71.0% (76/107) in the experimental group, which was greater than the 42.6% (29/68) in the control group (χ2 = 13.954, P＜0.001). The middle cerebral artery was most frequently affected by ICAS (χ2 = 4.684，P=0.030), with a higher incidence of moderate and severe stenosis (χ2 =4.510，P=0.034). The ICAS positivity rate was 64.6% (42/65) by TCCD, 75.4% (49/65) by CTA, and 53.8% (35/30) by TCD. There was a statistically significant difference between the TCCD and CTA (χ2=1.795, P=0.180) and between the TCD and CTA (χ2=6.594, P=0.010) positivity rates.

CONCLUSIONS

ICAS is expected to occur in patients with diabetes mellitus more often than healthy subjects, and to involve the middle cerebral artery with moderate-to-severe stenosis. The ICAS positivity rate evaluated by TCCD was lower than CTA and higher than TCD.

Viscoelasticity measured by shear wave elastography in a rat model of nonalcoholic fatty liver disease: comparison with dynamic mechanical analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming one of the most common liver diseases. Ultrasound elastography has been used for the diagnosis of NAFLD. However, clinical research on steatosis by elastography technology has mainly focused on steatosis with fibrosis or non-alcoholic steatohepatitis (NASH), while steatosis without fibrosis has been poorly studied. Moreover, the relationship between liver viscoelasticity and steatosis grade is not clear. In this study, we evaluated the degree of liver steatosis in a simple steatosis rat model using shear wave elastography (SWE).

RESULTS

The viscoelasticity values of 69 rats with hepatic steatosis were measured quantitatively by SWE in vivo and validated by a dynamic mechanical analysis (DMA) test. Pathological sections were used to determine the steatosis grade for each rat. The results showed that the elasticity values µ obtained by the two methods followed the same trend, and µ is significantly correlated with liver steatosis. The Pearson's correlation coefficients indicate that [Formula: see text] obtained by SWE is positively linear correlated with DMA (r = 0.628, p = 7.85 × 10-9). However, the viscosity values [Formula: see text] obtained by SWE were relatively independent of those obtained by DMA with a correlation coefficient of - 0.01. The combined Voigt elasticity measurements have high validity in the prediction of steatosis (S0 vs. S1-S4), with an AUROC of 0.755 (95% CI 0.6175-0.8925, p < 0.01) and the optimal cutoff value was 2.08 kPa with a sensitivity of 78% and specificity of 63%.

CONCLUSION

SWE might have the feasibility to be introduced as an auxiliary technique for NAFLD patients in clinical settings. However, the viscosity results measured by SWE and DMA are significantly different, because the two methods work in different frequency bands.

High-Frame Rate Vector Flow Imaging Technique: Initial Application in Evaluating the Hemodynamic Changes of Carotid Stenosis Caused by Atherosclerosis

Objective: To investigate the value of high-frame rate vector flow imaging technique (V flow) in evaluating the hemodynamic changes of carotid stenosis caused by atherosclerotic plaques.

Methods and Materials: In this prospective study, patients with stenosis rate (diameter) ≥30% caused by carotid atherosclerotic plaques were included. Degrees of carotid stenosis were graded according to North American Symptomatic Carotid Endarterectomy Trial criteria: moderate (30–69%) or severe (70–99%). Mindray Resona 7s ultrasound machine with a linear array transducer (3–11 MHz) was used for ultrasound examinations. The mean WSS value of carotid arteries was measured at the proximal, narrowest region and distal of carotid stenosis. The mean WSS values were correlated with peak systolic velocity (PSV) measured by color Doppler flow imaging and stenosis degree detected by digital subtraction angiography (DSA). The vector arrows and flow streamline detected by V flow dynamic imaging were analyzed. Imaging findings of DSA in carotid arteries were used as the gold standard.

Results: Finally, 51 patients were included. V flow measurements were performed successfully in 17 patients (100%) with moderate-grade stenosis and in 30 patients (88.2%) with severe-grade stenosis. Dynamic V flow imaging showed yellow or red vectors at the stenotic segment, indicating fast speed blood flow (up to 260.92 cm/s). Changes of streamlines were detected in the stenotic segment. The mean WSS value measured at the narrowest region of the carotid artery had a moderately positive correlation with stenosis degree (r = 0.58, P < 0.05) and PSV value (r = 0.54, P < 0.05), respectively. Significant difference was detected in mean WSS value at the narrowest region of the carotid artery between severe carotid stenosis (1.47 ± 0.97 Pa) and moderate carotid stenosis (0.96 ± 0.44 Pa) (P < 0.05).

Conclusion: The hemodynamic changes detected by V flow of the carotid stenosis might be a potential non-invasive imaging tool for assessing the degree of carotid stenosis.

HYBRID NANOFLUID FLOWS THROUGH A VERTICAL DISEASED CORONARY ARTERY WITH HEAT TRANSFER

Gold nanoparticles (AuNPs) are now widely used because of their synthesis compatibility and less toxicity in several biomedical applications such as cancer treatment. From the fluid mechanics point of view, we examine the behavior of a mixture of gold and Titanium Oxide nanoparticles, which suspended in the blood as a base fluid in the diseased coronary artery. The main goal of this paper is to examine and shed light on the hybrid nanofluid flows through a vertical diseased artery in the presence of the catheter tube with heat transfer. The mathematical model is established and then solved with the Laplace and the finite Hankel transforms. The inverse of the transformed functions has been calculated numerically. The velocity, the pressure, the impedance and the heat transfer are discussed graphically. It is noteworthy to mention that the mixture of the nanoparticles dispersed in the blood needs high pressure to push it. The impedance of blood is proportional to the overall volume concentration of the nanoparticles and Reynolds number.

Carotid Atherosclerosis in Predicting Coronary Artery Disease: A Systematic Review and Meta-Analysis

[Figure: see text].

Automatic segmentation, feature extraction and comparison of healthy and stroke cerebral vasculature

Accurate segmentation of cerebral vasculature and a quantitative assessment of its morphology is critical to various diagnostic and therapeutic purposes and is pertinent to studying brain health and disease. However, this is still a challenging task due to the complexity of the vascular imaging data. We propose an automated method for cerebral vascular segmentation without the need of any manual intervention as well as a method to skeletonize the binary segmented map to extract vascular geometric features and characterize vessel structure. We combine a Hessian-based probabilistic vessel-enhancing filtering with an active-contour-based technique to segment magnetic resonance and computed tomography angiograms (MRA and CTA) and subsequently extract the vessel centerlines and diameters to calculate the geometrical properties of the vasculature. Our method was validated using a 3D phantom of the Circle-of-Willis region, demonstrating 84% mean Dice similarity coefficient (DSC) and 85% mean Pearson's correlation coefficient (PCC) with minimal modified Hausdorff distance (MHD) error (3 surface pixels at most), and showed superior performance compared to existing segmentation algorithms upon quantitative comparison using DSC, PCC and MHD. We subsequently applied our algorithm to a dataset of 40 subjects, including 1) MRA scans of healthy subjects (n = 10, age = 30 ± 9), 2) MRA scans of stroke patients (n = 10, age = 51 ± 15), 3) CTA scans of healthy subjects (n = 10, age = 62 ± 12), and 4) CTA scans of stroke patients (n = 10, age = 68 ± 11), and obtained a quantitative comparison between the stroke and normal vasculature for both imaging modalities. The vascular network in stroke patients compared to age-adjusted healthy subjects was found to have a significantly (p < 0.05) higher tortuosity (3.24 ± 0.88 rad/cm vs. 7.17 ± 1.61 rad/cm for MRA, and 4.36 ± 1.32 rad/cm vs. 7.80 ± 0.92 rad/cm for CTA), higher fractal dimension (1.36 ± 0.28 vs. 1.71 ± 0.14 for MRA, and 1.56 ± 0.05 vs. 1.69 ± 0.20 for CTA), lower total length (3.46 ± 0.99 m vs. 2.20 ± 0.67 m for CTA), lower total volume (61.80 ± 18.79 ml vs. 34.43 ± 22.9 ml for CTA), lower average diameter (2.4 ± 0.21 mm vs. 2.18 ± 0.07 mm for CTA), and lower average branch length (4.81 ± 1.97 mm vs. 8.68 ± 2.03 mm for MRA), respectively. We additionally studied the change in vascular features with respect to aging and imaging modality. While we observed differences between features as a result of aging, statistical analysis did not show any significant differences, whereas we found that the number of branches were significantly different (p < 0.05) between the two imaging modalities (201 ± 73 for MRA vs. 189 ± 69 for CTA). Our segmentation and feature extraction algorithm can be applied on any imaging modality and can be used in the future to automatically obtain the 3D segmented vasculature for diagnosis and treatment planning as well as to study morphological changes due to stroke and other cerebrovascular diseases (CVD) in the clinic.

In vitro Biomodels in Stenotic Arteries to Perform Blood Analogues Flow Visualizations and Measurements: A Review

Cardiovascular diseases are one of the leading causes of death globally and the most common pathological process is atherosclerosis. Over the years, these cardiovascular complications have been extensively studied by applying in vivo, in vitro and numerical methods (in silico). In vivo studies represent more accurately the physiological conditions and provide the most realistic data. Nevertheless, these approaches are expensive, and it is complex to control several physiological variables. Hence, the continuous effort to find reliable alternative methods has been growing. In the last decades, numerical simulations have been widely used to assess the blood flow behavior in stenotic arteries and, consequently, providing insights into the cardiovascular disease condition, its progression and therapeutic optimization. However, it is necessary to ensure its accuracy and reliability by comparing the numerical simulations with clinical and experimental data. For this reason, with the progress of the in vitro flow measurement techniques and rapid prototyping, experimental investigation of hemodynamics has gained widespread attention. The present work reviews state-of-the-art in vitro macro-scale arterial stenotic biomodels for flow measurements, summarizing the different fabrication methods, blood analogues and highlighting advantages and limitations of the most used techniques.

Rapid vessel segmentation and reconstruction of head and neck angiograms using 3D convolutional neural network

The computed tomography angiography (CTA) postprocessing manually recognized by technologists is extremely labor intensive and error prone. We propose an artificial intelligence reconstruction system supported by an optimized physiological anatomical-based 3D convolutional neural network that can automatically achieve CTA reconstruction in healthcare services. This system is trained and tested with 18,766 head and neck CTA scans from 5 tertiary hospitals in China collected between June 2017 and November 2018. The overall reconstruction accuracy of the independent testing dataset is 0.931. It is clinically applicable due to its consistency with manually processed images, which achieves a qualification rate of 92.1%. This system reduces the time consumed from 14.22 ± 3.64 min to 4.94 ± 0.36 min, the number of clicks from 115.87 ± 25.9 to 4 and the labor force from 3 to 1 technologist after five months application. Thus, the system facilitates clinical workflows and provides an opportunity for clinical technologists to improve humanistic patient care.

Manual postprocessing of computed tomography angiography (CTA) images is extremely labor intensive and error prone. Here, the authors propose an artificial intelligence reconstruction system that can automatically achieve CTA reconstruction in healthcare services.

Impact of early diagnosis of carotid artery stenosis by carotid ultrasound: A protocol of systematic review and meta-analysis

BACKGROUND

The purpose of this study is to explore the impact of carotid ultrasound (CU) for early diagnosis of carotid artery stenosis (CAS).

METHODS

Literatures will be sought from the following electronic databases: MEDLINE, EMBASE, Cochrane Library, PSYCINFO, Web of Science, Allied and Complementary Medicine Database, and China National Knowledge Infrastructure. The search will cover from the start of indexing to the present without any limitations of language and publication status. All study quality will be assessed by Quality Assessment of Diagnostic Accuracy Studies tool, and data will be analyzed by RevMan V.5.3 software and Stata V.12.0 software.

RESULTS

This study will investigate the impact of CU for early diagnosis of CAS through sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio.

CONCLUSION

The findings of this study may provide helpful evidence for the impact of CU for early diagnosis of CAS.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019153904.

Skin temperature maps as a measure of carotid artery stenosis

In this study, the effect of carotid artery stenosis on the neck skin temperature maps was investigated. With the presence of stenosis, alterations in the carotid artery hemodynamics bring about changes in the heat transfer to the surrounding tissue. This is expected to be captured in the resulting temperature map over the external neck skin surface; possibly it correlates to the presence of stenosis. A total of twenty carotid artery samples, from ten patients with both sides normal (0% stenosis), stenosis (>50%) on one side, and stenosis (>50%) on both sides, were studied. Duplex Ultrasound and infrared (IR) thermography examinations were performed. A computational study, on an ideal 3-dimensional (3D) carotid artery and jugular vein model encapsulated with a solid neck tissue phantom resembling the human neck, was carried out. Incorporating the patient-specific geometrical (depth of artery and stenosis) and flow (peak systolic and end diastolic inlet velocity) boundary conditions, conjugate bio-heat transfer was studied using a finite volume numerical scheme. Simulation results and in-vivo thermal maps show that the average temperature on the external neck skin surface is significantly higher for normal patients (32.82 ± 0.53 °C versus 32.00 ± 0.37 °C, p < 0.001). Furthermore, the thermal region of interests (TROIs) were extracted from the in-vivo thermal images, which both qualitatively and quantitatively distinguish the normal and diseased cases. This study suggests the potential of thermal feature-based screening of patients with carotid artery stenosis.

Infrared (IR) thermography as a potential screening modality for carotid artery stenosis

In the present study, an infrared (IR) thermal camera was used to map the temperature of the target skin surface, and the resulting thermal image was evaluated for the presence of carotid artery stenosis (CAS). In the presence of stenosis in the carotid artery, abnormal temperature maps are expected to occur on the external skin surface, which could be captured and quantified using IR thermography. A Duplex Ultrasound (DUS) examination was used to establish the ground truth. In each patient, the background-subtracted thermal image, referred to as full thermal image, was used to extract novel parametric cold thermal feature images. From these images, statistical features, viz., correlation, energy, homogeneity, contrast, entropy, mean, standard deviation (SD), skewness, and kurtosis, were calculated and the two groups of patients (control and diseased: a total of 80 carotid artery samples) were classified. Both cut-off value- and support vector machine (SVM)-based binary classification models were tested. While the cut-off value classification model resulted in a moderate performance (70% accurate), SVM was found to have classified the patients with high accuracy (92% or higher). This preliminary study suggests the potential of IR thermography as a possible screening tool for CAS patients.