A local angle compensation method based on kinematics constraints for non-invasive vascular axial strain computations on human carotid arteries

Non invasive vascular elastography (NIVE) was developed to highlight atherosclerotic plaque constituents. However, NIVE motion estimates are affected by artifacts, such as an underestimation of deformations due to projected movement angles with respect to the ultrasound beam, movements of the operator or of the patient during image acquisition. The main objective of this work was to propose a local angle compensation method within small measurement windows for the axial strain based on kinematics constraints, and to introduce a filtering process on the strain time-varying curve to reduce as much as possible the impact of motion artifacts. With such preprocessing, we successfully quantified the strain behavior of near and far walls in longitudinal images of internal carotid arteries without (n = 30) and with (n = 21) significant atherosclerotic disease (greater than 50% stenosis). Maximum strain rates of 4.49% s⁻¹ for the healthy group and of 2.29% s⁻¹ for the atherosclerotic group were calculated on the far wall of internal carotid arteries; significant differences were found between these values (p = 0.001). The minimum strain rates, also on the far wall of internal carotid arteries, of −3.68% s⁻¹ for the healthy group and of −1.89% s⁻¹ for the atherosclerotic group were significantly different as well (p = 8 ×10⁻⁴). The mean systolic, diastolic and cumulated axial strains could also distinguish the two groups after normalization by the pressure gradient between acquired images. To conclude, the proposed techniques allowed to differentiate healthy and atherosclerotic carotid arteries and may help to diagnose vulnerable plaques.     

Fly through ultrasound imaging in assessment of carotid atherosclerosis: a pictorial essay

To assess fly through ultrasound imaging (FTUS) in evaluation of carotid artery atherosclerosis, we prospectively performed conventional sonography and FTUS of the carotid artery on 66 patients with suspicion for atherosclerosis. Characteristics of arterial intima, atherosclerotic plaque, luminal narrowing, and carotid stent graft displayed on FTUS were compared with that on conventional sonography. On FTUS, normal carotid artery wall was smooth in appearance, mild carotid atherosclerosis appeared focal arterial wall irregularity and small plaque formation, arterial luminal reduction resulted from progressive artery plaques, and carotid stent had irregular inner lumen and tight fit against the arterial wall. A total of 38 plaques were detected by conventional sonography, while 48 plaques were depicted by FTUS in 25 patients. Using magnetic resonance angiography as a reference standard, 17 cases with >50% and 3 cases with < 50% luminal reduction measured on FTUS. However, all those 20 cases were measured with >50% luminal reduction on conventional sonography. Compared with conventional sonography, FTUS can dynamically display intraluminal structure on real-time three-dimensional imaging morphologically to improve the accuracy in detecting atherosclerotic plaque and assessing luminal narrowing in the carotid artery.     

Association of carotid atherosclerotic plaque features with acute ischemic stroke: A magnetic resonance imaging study

Background and purpose

It remains unclear whether direct vessel wall imaging can identify carotid high-risk lesions in symptomatic subjects and whether carotid plaque characteristics are more effective indicators for cerebral infarct severity than stenosis. This study sought to determine the associations of carotid plaque characteristics by MR imaging with stenosis and acute cerebral infarct (ACI) sizes on diffusion weighted imaging (DWI).

Materials and methods

One hundred and fourteen symptomatic patients underwent carotid and brain MRI. ACI volume was determined from symptomatic internal carotid artery territory on DWI images. Ipsilateral carotid plaque morphological and compositional characteristics, and stenosis were also determined. The relationships between carotid plaque characteristics, stenosis and ACIs size were then evaluated.

Results

In carotid arteries with 30–49% stenosis, 86.7% and 26.7% were found to have lipid-rich necrotic core (LRNC) and intraplaque hemorrhage, respectively. Furthermore, 45.8% of carotid arteries with 0–29% stenosis developed LRNCs. Carotid morphological measurements, such as % wall volume, and the LRNC size were significantly associated with ipsilateral ACIs volume before and after adjustment for significant demographic factors (age and LDL) or stenosis in patients with carotid plaque (all p < 0.05).

Conclusions

A substantial number of high-risk plaques characterized by vessel wall imaging exist in carotid arteries with lower grade stenosis. In addition, carotid plaque characteristics, particularly the % wall volume and LRNC size, are independently associated with cerebral infarction as measured by DWI lesions. Our findings indicate that characterizing atherosclerotic plaque by MR vessel wall imaging might be useful for stratification of plaque risk and infarction severity.     

Multi-contrast and three-dimensional assessment of the aortic wall using 3 T MRI

ObjectivesTo develop a 3D-multi-contrast MRI protocol allowing for high resolution imaging of the wall and of atheroma in the thoracic aorta.MethodsEleven healthy volunteers and eleven acute stroke patients with aortic plaques detected by TEE underwent MRI at 3 T. The MRI-protocol consisted of a T1w-bright-blood, a T2w- and a PDw-black-blood sequence (spatial resolution = 1.15 mm³). Image quality was assessed by two blinded investigators using a 3-point score and intra- and inter-rater agreement was tested. In patients, atherosclerotic plaques were graded according to the modified American Heart Association (AHA) classification.ResultsTotal examination time was 35:42 ± 7:48 min in volunteers and 41:07 ± 3:15 min in patients. Image quality was graded with the highest score in 80–94% of T1w, 89–96% of T2w and 79–86% of PDw datasets. Intra- and inter-rater reliability regarding image quality grading was high. Five stroke patients showed AHA type III lesions, three had AHA type VII and two had type VIII plaques. One patient had a vulnerable appearing AHA VI plaque.Conclusions3D-multi-contrast MR-imaging of the aorta was performed with high image quality and in reasonable time. It allows evaluation of atherosclerotic plaque composition throughout the aortic arch and can be used to identify vulnerable plaques in acute stroke patients.     

Impact of advanced modeled iterative reconstruction on interreader agreement in coronary artery measurements

ObjectivesTo evaluate the influence of advanced modeled iterative reconstruction (ADMIRE) on coronary artery computed tomography angiography (cCTA) measurements in comparison to filtered back projection (FBP).Material and methodsPhantom scans and coronary CTA studies of 27 patients were acquired with a third generation dual-source CT scanner. Images were reconstructed using FBP and ADMIRE. Phantom measurements were used as reference standard. In patient studies, representative axial slices of each coronary artery segment without (n = 308) and with coronary plaques (n = 40) were assessed in identical positions for comparison of FBP and ADMIRE reconstructions. Image analyses included quality assessment, phantom and coronary artery measurements, plaque analysis, and interreader agreement of two independent and blinded readers.ResultsMean image noise was lower on ADMIRE reconstructions with 31.3 ± 9.9 HU compared to 55.9 ± 15.7 HU on FBP reconstructions (p < 0.001). Measurement precision and interreader agreement of both observers were assessed satisfactorily on phantom images in comparison to the full width half maximum method. In patients, correlation of lumen diameters of both observers improved using ADMIRE with a Pearson’s r = 0.987 (95% confidence interval [CI], 0.983–0.989; p < 0.001) compared to FBP images with r = 0.939 (95% CI, 0.924–0.951; p < 0.001). Applying ADMIRE, agreement of both observers for lumen diameter measurements significantly increased (p < 0.001). This was also observed for the degree of stenosis (p < 0.001) with r = 0.560 using FBP (95% CI, 0.301–0.742) and with r = 0.818 using ADMIRE (95% CI, 0.680–0.900). Plaque density measurements correlated closely with a Pearson’s r of 0.951 in FBP (95% CI, 0.909–0.974) and 0.967 in ADMIRE (95% CI, 0.939–0.983).ConclusionsAdvanced modeled iterative reconstruction significantly improves coronary artery assessment in coronary CTA in comparison to FBP by improved image quality due to image noise removal. This renders improved interobserver agreement for coronary lumen diameter and degree of stenosis measurements without influencing mean plaque attenuation.     

Angioplastia con stent recuperable como tratamiento del vasoespasmo secundario a la hemorragia subaracnoidea por aneurisma: un estudio multicéntrico de seguridad y eficacia

ObjectiveTo determine the safety and efficacy of angioplasty with a retrievable stent in treating vasospasm secondary to subarachnoid hemorrhage (SAH) due to an aneurysm.MethodsWe retrospectively analyzed prospectively collected data from consecutive patients undergoing endovascular angioplasty with a retrievable stent to treat vasospasm related to SAH due to an aneurysm in four neurointerventional radiology departments between January 2018 and July 2019. We included patients aged >18 years with vasospasm >50% of the internal carotid artery (ICA), anterior cerebral artery (ACA), and / or middle cerebral artery (MCA) secondary to SAH due to an aneurysm treated with endovascular angioplasty with a retrievable stent. The variables used to measure safety were complications of the procedure and clinical complications. The variables used to measure radiological efficacy were improvement in the degree of stenosis after endovascular treatment and improvement or normalization of cerebral circulation time CTT).ResultsWe included 16 angioplasty procedures with retrievable stents in 13 patients, in which 33 arterial segments were treated (10 ICA, 15 MCA, and 8 ACA). We observed no complications of the procedure in any patients and no clinical complications in patients who were not intubated. All but one of the patients who had delayed CTT at the beginning of the procedure showed improvements in CTT. The mean improvement in the degree of stenosis was 18% ± 11.65% in the ICA, 30.67% ± 18.45% in the MCA, and 28.38% ± 15.49% in the ACA. No statistically significant associations were observed between endovascular treatment variables and the degree of improvement in stenosis.ConclusionAngioplasty with a retrievable stent is a safe and efficacious treatment for vasospasm secondary to SAH due to an aneurysm, improving CTT and stenosis.     

Magnetic resonance imaging of intracranial atherosclerosis: Comparison of ex vivo 3T MRI and histologic findings

PurposeImaging the lipid-rich necrotic core (LRNC) is very important when evaluating the response of lipid-lowering therapy. The purpose of this study was to assess ex vivo LRNC of intracranial atherosclerosis using 3T MRI.Materials and methodsThirty-one atherosclerotic lesions from 17 specimens were analyzed (basilar artery = 15, middle cerebral artery = 16) using 3T MRI. Specimens were not chemically processed for imaging studies. Reconstructed MRI was matched with histologic sections at corresponding locations.ResultsThe median plaque thickness of intracranial atherosclerosis was 0.6 mm (0.4–2.0 mm). All specimens had a LRNC on histologic findings. Three specimens had plaque calcification on histologic findings. LRNC of 30 specimens (96.8%) appeared as homogeneous isointensity/hypointensity on T1-weighted imaging and hypointensity on T2-weighted imaging compared with T1-weighted imaging.ConclusionsAll specimens with ex vivo intracranial atherosclerosis had LRNC. Intracranial atherosclerosis could be an indication for lipid-lowering therapy, similar to previous carotid MR studies.     

Stent Placement for Treatment of Long Segment (≥80 mm) Carotid Artery Stenosis in Patients with Takayasu Disease

PurposeTo evaluate the effectiveness and safety of carotid artery stent (CAS) placement for treatment of long segment stenosis in patients with Takayasu arteritis.Materials and MethodsBetween January 2002 and February 2012, all patients with Takayasu arteritis found to have long segment (≥80 mm) carotid artery stenoses at a single institution were retrospectively analyzed. Five patients treated by CAS placement with either long or multiple self-expandable stents were included. All patients had focal neurologic symptoms, including three strokes and two transient ischemic attacks (TIAs). Six self-expanding stents were used in five patients. The mean follow-up period was 19.2 months (range, 6–30 mo); all patients had clinical evaluation, laboratory examination, and vascular imaging follow-up.ResultsImprovement in clinical symptoms was shown after successful angioplasty. There were no perioperative or in-hospital deaths. Four patients exhibited persistent relief, and repeated angiography or computed tomography (CT) angiography showed normal flow. One patient stopped taking her medications after CAS placement and became symptomatic 8 months later as a result of a severe in-stent stenosis.ConclusionsCAS placement was shown to be a feasible option for treating long segment (≥80 mm) stenosis of carotid arteries in patients with Takayasu arteritis with encouraging results.     

Dual energy CT of peripheral arteries: Effect of automatic bone and plaque removal on image quality and grading of stenoses

PurposeTo evaluate the effect of automatic bone and plaque removal on image quality and grading of steno-occlusive lesions in patients undergoing dual energy CT angiography (CTA) of lower extremity.Materials and methodsDual energy (DE) runoff CTA was performed in 50 patients using the following parameters: collimation 2 × 32 × 0.6; tube potentials, 80 kV and 140 kV; reconstructed slice thickness 1 mm. 100 mL iomeprol 400 and 50 mL saline were injected at 4 mL/s. Separate datasets were calculated for each of the two tubes and used to generate automatically bone-subtracted images (ABS) as well as bone and plaque subtracted images (ABPS). Residual bone in the ABS dataset was removed manually (=ABS-B dataset). In addition, a weighted average dataset from both dual energy acquisitions resembling a routine 120 kV CT acquisition was used for standard manual bone subtraction (MBS). Operator time for bone removal was measured. Effectiveness of bone subtraction and presence of vessel erosions was assessed by two readers in consensus. Stenosis grading in plaque subtracted and unsubtracted images was assessed and correlated.ResultsResidual bone fragments (ribs: 46%, patella: 25%, spine: 4%, pelvis: 2%, tibia 2% of patients) were only observed with ABS. The time needed to manually remove these residual bones was 2.1 ± 1.1 min and was significantly lower than the duration of manual bone removal (6.8 ± 2.0 min, p < 0.0001, paired t-test). A total of 1159 arteries were analyzed. Compromising vessel erosions were observed less frequently in the ABS-B dataset (10.6%) than in the MBS dataset (15.2%, p < 0.001, wilcoxon’s signed rank test). A total of 817 steno-occlusive lesions were assessed. While the agreement of grading of steno-occlusive lesions was good at the levels of the aorta and the pelvic arteries (κ = 0.70 in both, Cohen’s kappa statistics), it was moderate at the level of the thigh arteries (κ = 0.57) and poor at the level of the calf (κ = 0.16).ConclusionDE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.     

Calcified carotid atherosclerotic plaque is associated less with ischemic symptoms than is noncalcified plaque on MDCT

OBJECTIVE: Risk assessment based on plaque vulnerability would be valuable in the management of asymptomatic carotid stenosis. The purpose of this study was to compare plaque morphology in symptomatic and asymptomatic patients with significant extracranial carotid artery stenosis using MDCT angiography. MATERIALS AND METHODS: We identified 31 patients with greater than 60% carotid artery stenosis on MDCT angiography using the criteria of the North American Symptomatic Carotid Endarterectomy Trial Collaborators. We analyzed plaque density by blinded review in Hounsfield units in the atherosclerotic plaques of 15 symptomatic and 21 asymptomatic stenotic vessels for classification as soft, intermediate, or calcified. Data were analyzed using multiple logistic regression. RESULTS: Even with age, traditional cardiovascular risk factors, and treatment taken into account, we found that calcified plaques were 21 times less likely to be symptomatic than noncalcified plaques (95% confidence interval for odds ratio, 0.003, 0.749; p = 0.030). No significant predictive value was found between soft (p = 0.23) or intermediate (p = 0.18) plaque morphology for the occurrence of symptoms. CONCLUSION: MDCT angiography may help risk-stratify patients with asymptomatic carotid artery stenosis. Extracranial carotid artery calcified plaques causing stenosis are significantly less likely to be symptomatic and thus may be more stable than noncalcified plaques. This finding may have implications for the interpretation of calcification of atherosclerotic plaque in other vascular beds.     

Predictive value of the coronary artery calcium score and advanced plaque characteristics: Post hoc analysis of the PREDICT registry

BackgroundWhether coronary plaque characteristics assessed in coronary computed tomography angiography (CCTA) in association with the coronary artery calcium score (CACS) have predictive value for coronary events is unclear. We aimed to examine the predictive value of the CACS and plaque characteristics for the occurrence of coronary events.MethodsAmong 2802 patients who were analyzed in the PREDICT registry, 2083 with suspected coronary artery disease (CAD) were studied using post hoc analysis. High-risk plaques were defined as having ≥2 adverse characteristics, such as low computed tomographic attenuation, positive remodeling, spotty calcification, and napkin-ring sign. An adjudicative composite of coronary events (cardiac death, nonfatal acute coronary syndrome, and coronary revascularization ≥3 months after indexed CCTA) were analyzed.ResultsSeventy-three (3.5%) patients had coronary events and 313 (15.0%) had high-risk plaques. Multivariate Cox proportional hazard analysis showed that high-risk plaques remained an independent predictor of coronary events (adjusted hazard ratio [HR] 1.95, 95% confidence interval [CI] 1.13–3.34, P ?= ?0.0154), as well as the log-transformed CACS (adjusted HR 1.24, 95% CI 1.11–1.39, P ?= ?0.0002) and the presence of obstructive stenosis (adjusted HR 5.63, 95% CI 3.22–10.12, P 0.0001). In subgroup analyses, high-risk plaques were independently predictive only in the low CACS class (<100).ConclusionThis study shows that assessment of adverse features by coronary plaque imaging independently predicts coronary events in patients with suspected CAD and a low CACS. Our findings suggest that the clinical value of high-risk plaques to CACS and stenosis assessment appears marginal.     

Atherosclerotic plaque volume and composition in symptomatic carotid arteries assessed with multidetector CT angiography; relationship with severity of stenosis and cardiovascular risk factors

The purpose of this study was to examine the volume and the composition of atherosclerotic plaque in symptomatic carotid arteries and to investigate the relationship between these plaque features and the severity of stenosis and the presence of cardiovascular risk factors. One hundred patients with cerebrovascular symptoms underwent CT angiography. We measured plaque volume (PV) and the relative contribution of plaque components (calcifications, fibrous tissue, and lipid) in the symptomatic artery. The contribution of different components was measured as the number of voxels within defined ranges of HU values (calcification >130 HU, fibrous tissue 60–130 HU, lipid core <60 HU). Fifty-seven patients had atherosclerotic plaque in the symptomatic carotid artery. The severity of stenosis and PV were moderately correlated. Age and smoking were independently related to PV. Patients with hypercholesterolemia had significantly less lipid and more calcium in their plaques than patients without hypercholesterolemia. Other cardiovascular risk factors were not significantly related to PV or plaque composition. Luminal stenosis of the carotid artery partly reflects the amount of atherosclerotic carotid disease. Plaque volume and plaque composition are associated with cardiovascular risk factors.     

Spiral CT angiography and selective digital subtraction angiography of internal carotid artery stenosis.

PURPOSETo determine whether spiral CT angiography allows accurate, quantitative evaluation of anatomic abnormalities, including detection of additional lesions, delineation of plaque morphology, and estimation of degree of internal carotid artery stenosis.METHODSSpiral CT angiography with a maximum intensity projection technique was compared with selective digital subtraction angiography (DSA) in 92 carotid arteries. The category of stenosis was determined according to the North American Symptomatic Carotid Endarterectomy Trial: mild (0% to 29%), moderate (30% to 69%), severe (70% to 99%), and occlusion (100%).RESULTSIn 78 (85%) of the 92 cases, spiral CT angiography and selective DSA demonstrated the same degree of stenosis. All occlusions (n = 19) were diagnosed correctly with spiral CT angiography. Spiral CT angiography agreed with selective DSA in the classification of stenosis in 59% of the group with mild stenosis, in 82% of the group with moderate stenosis, and in 90% of the group with severe stenosis. In the groups with mild (n = 13), moderate (n = 9), and severe (n = 27) stenosis, correlation of spiral CT angiography with selective DSA was significant. Calcified plaques were readily diagnosed with the use of spiral CT angiography but delineation of ulcers was poor. Tandem lesions were not visible owing to the limited coverage.CONCLUSIONSpiral CT angiography is useful for the detection of proximal internal carotid stenoses that are greater than 30%. Depiction of mild stenoses appears to be limited. CT is superior for the detection of calcified plaques but it is not useful for the detection of ulcers.     

Carotid Intraplaque Hemorrhage and Stenosis: At What Stage of Plaque Progression Does Intraplaque Hemorrhage Occur,and When is It Most Likely to Be Associated with Symptoms?

BACKGROUND AND PURPOSE:The relationship between carotid intraplaque hemorrhage and luminal stenosis severity is not well-established. We sought to determine whether intraplaque hemorrhage is related to carotid stenosis and at what degree of stenosis intraplaque hemorrhage most likely contributes to ischemic symptoms.MATERIALS AND METHODS:Consecutive patients who underwent MR carotid plaque imaging with MPRAGE sequences to identify intraplaque hemorrhage were retrospectively reviewed. Degrees of stenoses were categorized as minimal (<30%), moderate (30%–69%), and severe (>70%). Arteries were categorized into 2 groups: symptomatic (ipsilateral to a cerebral ischemic event) and asymptomatic (from a patient without an ischemic event). Multiple regression analyses were used to determine independent associations between the degree of stenosis and intraplaque hemorrhage and the presence of intraplaque hemorrhage with symptoms among categories of stenosis.RESULTS:We included 449 patients with 449 carotid arteries: Two hundred twenty-five (50.1%) were symptomatic, and 224 (49.9%) were asymptomatic. An increasing degree of stenosis was independently associated with the presence of intraplaque hemorrhage (OR = 1.02; 95% confidence interval, 1.01–1.03). Intraplaque hemorrhage was independently associated with ischemic events in arteries with <30% stenosis (OR = 5.68; 95% CI, 1.49–21.69). No such association was observed in arteries with >30% stenosis. Of symptomatic arteries with minimal stenosis, 8.7% had intraplaque hemorrhage versus 1.7% of asymptomatic arteries (P = .02). No differences in intraplaque hemorrhage prevalence were found between symptomatic and asymptomatic groups with moderate (P = .18) and severe stenoses (P = .99).CONCLUSIONS:The presence of intraplaque hemorrhage on high-resolution plaque imaging is likely most useful in identifying symptomatic plaques in cases of minimal stenosis.

Carotid artery disease is a well-known risk factor for cerebral ischemic events such as stroke, transient ischemic attack, and retinal ischemia. It has been estimated that 18%–25% of all strokes result from carotid artery atherosclerotic disease.¹ Conventional features of carotid atherosclerosis, such as the degree of luminal stenosis and surface irregularities, have been used as predictors of ischemic events.^2-4 The severity of luminal narrowing, specifically, has long served a central role in determining whether medical or surgical intervention is indicated to treat such lesions.^5-7 However, in recent years, attention has been drawn to strokes in patients with mild or moderate carotid artery stenosis, calling into question the reliance on luminal stenosis as the primary prognosticator for ischemic events.^8,9 Instead, interest has turned to the morphologic characteristics of plaques, with the presumption that identifiable vulnerable features may provide crucial information regarding the stability of a plaque.^10,11The advent of high-resolution MR plaque imaging has enabled the detection of various carotid plaque components, including intraplaque hemorrhage (IPH), lipid-rich necrotic core, and various plaque characteristics, including neovascularization and inflammation.¹² Of these, IPH is a particularly well-documented risk factor for stroke.^13-15 Prior studies have found patients with carotid IPH to be at increased risk of thromboembolic events in the context of both mild-to-moderate^13,16,17 and severe arterial stenosis.¹⁵ Nevertheless, the degree of stenosis at which IPH is likely to contribute most to ischemic symptoms remains largely uncertain. This information would provide clinicians with the ability to identify symptomatic IPHs that are likely contributing to ischemic events.The objective of this study was to determine the relationship between IPH and the degree of carotid stenosis by answering following questions: 1) Are increasing degrees of stenosis independently associated with the presence of IPH, and 2) does the prevalence of IPH vary across categories of luminal stenosis? Furthermore, we also sought to determine whether carotid IPH was independently associated with ipsilateral ischemic events among varying degrees of luminal stenosis and to compare the prevalence of IPH between symptomatic and asymptomatic arteries on the basis of the degree of stenosis.     

Carotid artery dissection on non-contrast CT: Does color improve the diagnostic confidence?

PurposeThe purpose of this work was to evaluate if the use of color maps, instead of conventional grayscale images, would improve the observer's diagnostic confidence in the non-contrast CT evaluation of internal carotid artery dissection (ICAD).Materials and methodsOne hundred patients (61 men, 39 women; mean age, 51 years; range, 25–78 years), 40 with and 60 without ICAD, underwent non-contrast CT and were included in this the retrospective study. In this study, three groups of patients were considered: patients with MR confirmation of ICAD, n = 40; patients with MR confirmation of ICAD absence, n = 20; patients who underwent CT of the carotid arteries because of atherosclerotic disease, n = 40. Four blinded observers with different levels of expertise (expert, intermediate A, intermediate B and trainee) analyzed the non-contrast CT datasets using a cross model (one case grayscale and the following case using the color scale). The presence of ICAD was scored on a 5-point scale in order to assess the observer's diagnostic confidence. After 3 months the four observers evaluated the same datasets by using the same cross-model for the alternate readings (one case color scale and the following case using the grayscale). Statistical analysis included receiver operating characteristics (ROC) curve analysis, the Cohen weighted test and sensitivity, specificity, PPV, NPV, accuracy, LR+ and LR−.ResultsThe ROC curve analysis showed that, for all observers, the use of color scale resulted in an improved diagnostic confidence with AUC values increasing from 0.896 to 0.936, 0.823 to 0.849, 0.84 to 0.909 and 0.749 to 0.861 for expert, intermediate A, intermediate B and trainee observers, respectively. The increase in diagnostic confidence (between the AUC areas) was statistically significant (p = 0.036) for the trainee. Accuracy as well as sensitivity, specificity, PPV, NPV, LR+ and LR− were improved using the color scale.ConclusionOur study suggests that the use of a color scale instead the conventional grayscale improves the diagnostic confidence, accuracy and inter-observer agreement of the readers, in particular of junior ones, in the diagnosis of ICAD on non-contrast CT.     

3D-Arterial analysis software and CEUS in the assessment of severity and vulnerability of carotid atherosclerotic plaque: a comparison with CTA and histopathology

Purpose

Our purpose is to assess Multiparametric Ultrasound (MPUS) efficacy for evaluation of carotid plaque vulnerability and carotid stenosis degree in comparison with Computed Tomography angiography (CTA) and histology.

Material and methods

3D-Arterial Analysis is a 3D ultrasound software that automatically provides the degree of carotid stenosis and a colorimetric map of carotid plaque vulnerability.

We enrolled 106 patients who were candidates for carotid endarterectomy. Prior to undergoing surgery, all carotid artery plaques were evaluated with Color-Doppler-US (CDUS), Contrast-Enhanced Ultrasound (CEUS), and 3D Arterial analysis (3DAA) US along with Computerized Tomographic Angiography (CTA) to assess the carotid artery stenosis degree. Post-surgery, the carotid specimens were fixed with 10% neutral buffered formalin solution, embedded in paraffin and used for light microscopic examination to assess plaque vulnerability morphological features.

Results

The results of the CTA examinations revealed 91 patients with severe carotid stenoses with a resultant diagnostic accuracy of 82.3% for CDUS, 94.5% for CEUS, 98.4% for 3DAA, respectively. The histopathological examination showed 71 vulnerable plaques with diagnostic accuracy values of 85.8% for CDUS, 93.4% for CEUS, 90.3% for 3DAA, 92% for CTA, respectively.

Conclusions

The combination of CEUS and 3D Arterial Analysis may provide a powerful new clinical tool to identify and stratify “at-risk” patients with atherosclerotic carotid artery disease, identifying vulnerable plaques. These applications may also help in the postoperative assessment of treatment options to manage cardiovascular risks.

     

Haemodynamic analysis of the effect of different types of plaques in the left coronary artery

PurposeCoronary plaque has been shown to directly affect the blood parameters, however, haemodynamic variations based on the plaque configuration has not been studied. In this study we investigate the haemodynamic effects of various types of plaques in the left coronary bifurcation.MethodsEight types of plaque configurations were simulated and located in various positions in the left main stem, the left anterior descending and left circumflex to produce a >50% narrowing of the coronary lumen. We analyse and characterise haemodynamic effects caused by each type of plaque. Computational fluid dynamics was performed to simulate realistic physiological conditions that reveal the in vivo cardiac haemodynamics. Velocity, wall shear stress (WSS) and pressure gradient (PSG) in the left coronary artery were calculated and compared in all plaque configurations during cardiac cycles.ResultsOur results showed that the highest velocity and PSG were found in the type of plaque configuration which involved all of the three left coronary branches. Plaques located in the left circumflex branch resulted in highly significant changes of the velocity, WSS and PSG (p < 0.001) when compared to the other types of plaque configurations.ConclusionOur analysis provides an insight into the distribution of plaque at the left bifurcation, and corresponding haemodynamic effects, thus, improving our understanding of atherosclerosis.     

Transplant renal artery stenosis: Evaluation with contrast-enhanced ultrasound

ObjectiveTo assess the efficacy of contrast-enhanced ultrasound (CEUS) in depicting transplant renal artery stenosis (TRAS).Materials and methodsSeventy-eight patients (56 men and 22 women; aged 36 ± 12.2 years) who were suspected of TRAS due to either Doppler ultrasound (DUS) abnormalities or difficult control of blood pressure and/or persistent deterioration of renal function were enrolled to perform CEUS. The reference standard for the TRAS diagnoses was computed tomography angiography (CTA). The diagnostic performance of DUS and CEUS parameters was assessed by the area under the receiver operating characteristic curve (AUC).ResultsTRAS was diagnosed in 32 out of 78 cases by CTA. The AUC, accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CEUS in predicting TRAS were 0.92, 92.3%, 87.5%, 95.7%, 93.3%, and 91.7%, respectively. CEUS rectified 13 (28.3%) false-positive cases on DUS, which were confirmed by CTA. Compared to DUS parameters, CEUS showed the highest AUC, statistically significant differences of AUC were found (P = 0.006–0.039), except for that of the PSV ratio in the main transplant renal artery to that in interlobar artery (PSV-ratio) (AUC: 0.92 versus 0.86, P = 0.422). However, CEUS showed a significantly higher specificity (95.7% versus 76.1%, P = 0.008) and the same sensitivity compared to PSV-ratio.ConclusionsCEUS is superior to DUS in depicting TRAS. Moreover, our results suggest that CEUS might potentially be used as a noninvasive tool to spare many patients from unnecessary CTA.     

High-Resolution Intracranial Vessel Wall MRI Findings Among Different Middle Cerebral Artery Territory Infarction Types

ObjectiveIntracranial atherosclerotic stroke occurs through various mechanisms, mainly by artery-to-artery embolism (AA) or branch occlusive disease (BOD). This study evaluated the spatial relationship between middle cerebral artery (MCA) plaques and perforating arteries among different MCA territory infarction types using vessel wall magnetic resonance imaging (VW-MRI).Materials and MethodsWe retrospectively enrolled patients with acute MCA infarction who underwent VW-MRI. Thirty-four patients were divided into three groups according to infarction pattern: 1) BOD, 2) both BOD and AA (BOD-AA), and 3) AA. To determine the factors related to BOD, the BOD and BOD-AA groups were combined into one group (with striatocapsular infarction [BOD+]) and compared with the AA group. To determine the factors related to AA, the BOD-AA and AA groups were combined into another group (with cortical infarction [AA+]) and compared with the BOD group. Plaque morphology and the spatial relationship between the perforating artery orifice and plaque were evaluated both quantitatively and qualitatively.ResultsThe plaque margin in the BOD+ group was closer to the perforating artery orifice than that in the AA group (p = 0.011), with less enhancing plaque (p = 0.030). In the BOD group, plaques were mainly located on the dorsal (41.2%) and superior (41.2%) sides where the perforating arteries mainly arose. No patient in the AA group had overlapping plaques with perforating arteries at the cross-section where the perforator arose. Perforating arteries associated with culprit plaques were most frequently located in the middle two-thirds of the M1 segment (41.4%). The AA+ group had more stenosis (%) than the BOD group (39.73 ± 24.52 vs. 14.42 ± 20.96; p = 0.003).ConclusionThe spatial relationship between the perforating artery orifice and plaque varied among different types of MCA territory infarctions. In patients with BOD, the plaque margin was closer and blocked the perforating artery orifice, and stenosis degree and enhancement were less than those in patients with AA.     

Carotid flow pulsatility is higher in women with greater decrement in gait speed during multi-tasking

AimCentral arterial hemodynamics is associated with cognitive impairment. Reductions in gait speed during walking while performing concurrent tasks known as dual-tasking (DT) or multi-tasking (MT) is thought to reflect the cognitive cost that exceeds neural capacity to share resources. We hypothesized that central vascular function would associate with decrements in gait speed during DT or MT.MethodsGait speed was measured using a motion capture system in 56 women (30–80y) without mild-cognitive impairment. Dual-tasking was considered walking at a fast-pace while balancing a tray. Multi-tasking was the DT condition plus subtracting by serial 7′s. Applanation tonometry was used for measurement of aortic stiffness and central pulse pressure. Doppler-ultrasound was used to measure blood flow velocity and β-stiffness index in the common carotid artery.ResultsThe percent change in gait speed was larger for MT than DT (14.1 ± 11.2 vs. 8.7 ± 9.6%, p < 0.01). Tertiles were formed based on the percent change in gait speed for each condition. No vascular parameters differed across tertiles for DT. In contrast, carotid flow pulsatility (1.85 ± 0.43 vs. 1.47 ± 0.42, p = 0.02) and resistance (0.75 ± 0.07 vs. 0.68 ± 0.07, p = 0.01) indices were higher in women with more decrement (third tertile) as compared to women with less decrement (first tertile) in gait speed during MT after adjusting for age, gait speed, and task error. Carotid pulse pressure and β-stiffness did not contribute to these tertile differences.ConclusionElevated carotid flow pulsatility and resistance are characteristics found in healthy women that show lower cognitive capacity to walk and perform multiple concurrent tasks.