Investigating the Association of Carotid Atherosclerotic Plaque MRI Features and Silent Stroke After Carotid Endarterectomy

BACKGROUND

The predictive value of carotid plaque characteristics for silent stroke (SS) after carotid endarterectomy (CEA) is unclear.

OBJECTIVE

To investigate the associations between carotid plaque characteristics and postoperative SS in patients undergoing CEA.

STUDY TYPE

Prospective.

POPULATION

One hundred fifty-three patients (mean age: 65.4 ± 7.9 years; 126 males) with unilateral moderate-to-severe carotid stenosis (evaluated by CT angiography) referred for CEA.

FIELD STRENGTH/SEQUENCE

3 T, brain-MRI:T2-PROPELLER, T1-/T2-FLAIR, diffusion weighted imaging (DWI) and T2*, carotid-MRI:black-blood T1-/T2W, 3D TOF, Simultaneous Non-contrast Angiography intraplaque hemorrhage.

ASSESSMENT

Patients underwent carotid-MRI within 1-week before CEA, and brain-MRI within 48-hours pre-/post-CEA. The presence and size (volume, maximum-area-percentage) of carotid lipid-rich necrotic core (LRNC), intraplaque hemorrhage (Type-I/Type-II IPH) and calcification were evaluated on carotid-MR images. Postoperative SS was assessed from pre-/post-CEA brain DWI. Patients were divided into moderate-carotid-stenosis (50%-69%) and severe-carotid-stenosis (70%-99%) groups and the associations between carotid plaque characteristics and SS were analyzed.

STATISTICAL TESTS

Independent t test, Mann-Whitney U-test, chi-square test and logistic regressions (OR: odds ratio, CI: confidence interval). P value <0.05 was considered statistically significant.

RESULTS

SS was found in 8 (16.3%) of the 49 patients with moderate-carotid-stenosis and 21 (20.2%) of the 104 patients with severe-carotid-stenosis. In patients with severe-carotid-stenosis, those with SS had significantly higher IPH (66.7% vs. 39.8%) and Type-I IPH (66.7% vs. 38.6%) than those without. The presence of IPH (OR 3.030, 95% CI 1.106-8.305) and Type-I IPH (OR 3.187, 95% CI 1.162-8.745) was significantly associated with SS. After adjustment, the associations of SS with presence of IPH (OR 3.294, 95% CI 1.122-9.669) and Type-I IPH (OR 3.633, 95% CI 1.216-10.859) remained significant. Moreover, the volume of Type-II IPH (OR 1.014, 95% CI 1.001-1.028), and maximum-area-percentage of Type-II IPH (OR 1.070, 95% CI 1.002-1.142) and LRNC (OR 1.030, 95% CI 1.000-1.061) were significantly associated with SS after adjustment. No significant (P range: 0.203-0.980) associations were found between carotid plaque characteristics and SS in patients with moderate-carotid-stenosis.

DATA CONCLUSIONS

In patients with unilateral severe-carotid-stenosis, carotid vulnerable plaque MR features, particularly presence and size of IPH, might be effective predictors for SS after CEA.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Clinical Utility of Intravascular Ultrasound (IVUS) in Carotid Artery Interventions: A Systematic Review and Meta-analysis

BACKGROUND

Carotid plaque morphology plays an important role in determining outcome of carotid artery stenting (CAS). Intravascular ultrasound (IVUS) and its extension VH (Virtual Histology)-IVUS evaluate plaque characteristics in real time and guide decision making during stenting. To date, there is no consensus about indications of IVUS and its validated methods. This systematic review and meta-analysis aims to evaluate the clinical utility of IVUS in carotid artery interventions (CAS) and develop a future consensus for research and practice parameters.

METHODS

A systematic review and meta-analysis was performed of the English literature articles published till February 2021. Studies reporting on IVUS parameters and findings and also its performance compared with other imaging modalities were included in review. Pooled prevalence with 95% confidence intervals (CI) was calculated. The statistical analysis was conducted in R version 3.6.2.

RESULTS

A total of 2015 patients from 29 studies were included. Proportional meta-analysis was performed on 1566 patients from 11 studies. In 9 studies, stroke/transient ischemic attack (TIA) had a pooled prevalence of 4% (95% CI 3%-5%) while asymptomatic stroke had a pooled prevalence of 46% (95% CI 31%-62%) in 4 studies following IVUS. Two studies reported that IVUS detected more plaque protrusion compared with angiography (n=33/396 vs 11/396). IVUS led to stent type or size change in 8 of 48 cases which were missed on angiography in 3 other studies. Concordance between VH-IVUS and true histology was good at 80% to 85% reported in 2 studies.

CONCLUSIONS

This systematic review and meta-analysis showed, though IVUS fared better to computed tomography (CT)/magnetic resonance (MR) angiography for better stent selection during CAS, with low to moderate risk of bias in the studies included. However, large scale, preferably randomized controlled studies are needed to predict its role in determining clinical outcome.

Risk factors for new ischemic cerebral lesions after carotid artery stenting: A systematic review and meta-analysis

BACKGROUND

New ischemic cerebral lesions (NICL) are commonly occur after carotid artery stenting (CAS) with an incidence rate ranging from 18-58% and are detected by diffusion-weighted imaging-magnetic resonance imaging (DWI-MRI). Numerous studies have reported that NICL could increase the risk of future cerebrovascular events and cognitive impairment. This systematic review and meta-analysis aimed to identify risk factors for NICL after CAS.

METHODS

Relevant literature reporting risk factors for NICL after CAS were searched. Randomized controlled trials, case-control studies, or cohort studies were included in accordance with the pre-specified eligibility criteria. The risk of bias was assessed using the Cochrane Collaboration criteria and the quality of evidence was assessed with the corresponding scale. Data were analyzed using the RevMan V. 5.3 analysis software.

RESULTS

The final analyses included a total of 21 studies and 1907 participants, including 764 NICL-positives and 1143 NICL-negatives. Determinants for NICL-positivity were age (mean deviation (MD): 2.60; 95% confidence interval (CI): [1.53-3.68]), symptomatic carotid lesions (odds ratio (OR): 1.77; 95% CI: [1.39-2.25]) and smoking (OR: 0.74; 95% CI: [0.58-0.94]). For symptomatic patients, risk factors for NICL-positive included diabetes mellitus (OR: 1.76; 95% CI: [1.09-2.82]), but smoking (OR: 0.54; 95% CI: [0.31-0.93]) was a protective factor. Risk factors for centers with high NICL incidence were age (MD: 2.05; 95% CI: [0.93-3.17]) and symptomatic carotid lesions (OR: 1.77; 95% CI: [1.29-2.45]).

CONCLUSIONS

Older age and symptomatic carotid lesions are associated with an increased risk of post-CAS NICL whereas smoking is associated with a decreased risk. Risk factors for NICL in symptomatic patients is diabetes mellitus, while those for patients at centers with high incidence are age and symptomatic carotid lesions. Systematic review registration: CRD42019121129.

Circumferential degree of carotid calcification is associated with new ischemic brain lesions after carotid artery stenting

Background

The relationship between plaque calcification and new ischemic brain lesions after carotid artery stenting (CAS) remains controversial. The purpose of this study was to determine if the circumferential degree of carotid calcification is associated with new ischemic brain lesions on diffusion-weighted imaging (DWI) after CAS.

Methods

A total of 96 patients with carotid stenosis of ≥50% who underwent CAS were enrolled in the study. All patients underwent preoperative carotid computed tomography (CT), and preoperative and postoperative brain MRI. The brain MRI sequences included T1WI, T2WI, T2-fluid-attenuated inversion recovery (FLAIR), and DWI. The location, circumferential degree, volume, percentage volume, maximum density, mean density, Agatston score of carotid calcification, and total plaque volume were assessed and compared between patients with and without new ischemic brain lesions after CAS. Univariate and multivariate analyses were performed to evaluate predictors of new ischemic brain lesions.

Results

All of the 96 patients (67.8±6.8 years of age, 83.3% men) were included in the analysis. New ischemic brain lesions on DWI were observed in 40 patients (41.7%). Patients with new ischemic brain lesions after CAS had a larger circumferential degree of calcification than those without new ischemic brain lesions (P<0.001). There was only a possible trend toward significance for the percentage volume of calcification between the two groups with and without new brain ischemic lesions (P=0.07). No significant differences were found regarding the location (P=0.18), volume (P=0.37), maximum density (P=0.44), mean density (P=0.39), Agatston score (P=0.28), and total plaque volume (P=0.33) of carotid calcification between the DWI+ and DWI- groups. In the multivariate analysis, an increased risk of new ischemic brain lesions was observed in patients with a high score for the circumferential degree of calcification [score 3; odds ratio (OR): 10.7, P<0.001; score 4, OR: 11.7, P=0.038].

Conclusions

The circumferential degree of carotid calcification was associated with new ischemic brain lesions after CAS. CAS should be avoided if possible for carotid stenosis with large circumferential calcified plaques.

The predictive value of CHADS2 score for subclinical cerebral ischemia after carotid artery stenting (from the PREVENT-CAS trial)

BACKGROUND

Carotid artery stenting (CAS) is being increasingly used as an alternative revascularization procedure to carotid endarterectomy; however, subclinical ischemic cerebral lesions after CAS remain as a matter of concern. Hence, we aimed to assess the clinical utility of the CHADS₂ score in predicting subclinical ischemic events after CAS.

METHODS

We prospectively evaluated 107 patients (mean age: 70.4 ± 6.6 years, male:77) who underwent CAS for carotid artery revascularization. The patients having symptomatic transient ischemic attack or stroke after CAS were excluded. The presence of new hyperintense lesion on diffusion-weighted imaging (DWI) without any neurological findings was considered as silent ischemia. Patients were classified into two groups as DWI-positive and DWI-negative patients.

RESULTS

Among study population, 28 patients (26.2%) had subclinical embolism. The DWI-positive group had a significantly higher CHADS2 scores, older age, more frequent history of stroke, higher proportion of type III aortic arch, and longer fluoroscopy time than the DWI-negative group. Increased CHADS₂ score was identified as one of the independent predictors of silent embolism (OR = 5.584; 95%CI: 1.516-20.566; p = .010), and CHADS₂ score higher than 2.5 predicted subclinical cerebral ischemia with a sensitivity of 72% and a specificity of 71% (AUC: 0.793; 95% CI: 0.696 - 0.890; p < .001).

CONCLUSIONS

CHADS₂ score was able to predict the risk of periprocedural subclinical ischemic events in CAS and might be of clinical value in the management of patients with carotid artery stenosis.

Age and the risk of new ischemic lesions on diffusion weighted imaging after carotid artery stenting: A systematic review and meta-analysis

To perform a systematic review and meta-analysis to show the association between age and the risk of new ischemic lesions on diffusion-weighted magnetic resonance imaging (DWI) after carotid artery stenting in patients with carotid artery stenosis. We searched PubMed and EMBASE from their dates of inception to March 14, 2019 for eligible studies. Standardized mean difference (SMD) and pooled odds ratio (OR) with 95% confidence interval (CI) was used to evaluate the association between age and new DWI lesions. Sensitivity analysis was performed to detect the possible source of heterogeneity. Twenty-three studies enrolling 2127 patients were included. The incidence of new DWI lesions was 62% in older patients and 41% in younger patient (OR 2.44, 95%CI 1.57-3.79; p < 0.0001). The patients with new DWI lesions were older than those without (SMD 0.24, 95% CI 0.08-0.39; p = 0.003). The risk of new DWI lesions increased by 1.07 per added year (95%CI 1.04-1.11, p < 0.0001). The results remained stable in sensitivity analyses and after adjusting for publication bias. It was concluded that older age was at higher risk of new DWI lesions after stenting in patients with carotid artery stenosis.

Intravascular ultrasound-guided internal carotid artery stenting

AIM

The study was aimed at demonstrating efficacy and feasibility of intravascular ultrasound during internal carotid artery stenting for assessment of atheromatous plaque protrusion through a stent.

PATIENTS AND METHODS

Over the period from October to December 2018, the specialists of our Centre performed a total of 90 internal carotid artery stenting procedures in 83 patients (of these, 7 patients underwent bilateral staged stenting of both internal carotid arteries) using intravascular ultrasound in order to assess intraoperative protrusion of an atherosclerotic plaque through the implanted stent. The patients' age varied from 42 to 87 (mean 68.6±6.9) years. Symptomatic lesions of internal carotid arteries were revealed in 14 (16.9%) operated patients and asymptomatic lesions in 69 (83.1%). The degree of stenosis varied from 60% to 90% according to the findings of preliminary duplex ultrasonography and was subsequently confirmed by the results of multislice computed tomography or selective angiography. The assessment of the patients' neurological status, as well as duplex ultrasonography of brachiocephalic arteries were performed at a scheduled follow-up visit on day 30 after discharge from hospital.

RESULTS

The technical success of stenting was achieved in 100% of patients. According to the findings of intravascular ultrasound, plaque protrusion was observed in eight (8.8%) stented patients. Among them, six (6.6%) were free from angiographic signs of protrusion and only two (2.2%) had apparent angiographic signs of protrusion. During the early postoperative period, transient ischaemic attack was identified in four (4.4%) cases. One (1.1%) patient was found to develop ST-segment elevation acute myocardial infarction 24 hours after internal carotid artery stenting, followed by large hemispheric stroke on the side of stenting revealed on postoperative day 3. Nine (10%) patients according to the findings of intravascular ultrasound were diagnosed as having incomplete stent apposition after postdilatation, with the absence of such signs on angiography.

CONCLUSION

Intravascular ultrasound during carotid stenting provides a more accurate assessment of such an event as atherosclerotic plaque protrusion through a stent's cells. At the same time, IVUS-guided assessment of the intraoperative outcome may prevent the risk for the development of stroke in the early postoperative period. Besides, intravascular ultrasound allows a more detailed assessment of stent apposition and the degree of stent expansion in order to optimize and improve the remote results of the operation.

Risk factors associated with microembolization after carotid intervention

BACKGROUND

Microembolization after carotid artery stenting (CAS) and carotid endarterectomy (CEA) has been documented and may confer risk for neurocognitive impairment. Patients undergoing stenting are known to be at higher risk for microembolization. In this prospective cohort study, we compare the microembolization rates for patients undergoing CAS and CEA and perioperative characteristics that may be associated with microembolization.

METHODS

Patients undergoing CAS and CEA were prospectively recruited under local institutional review board approval from an academic medical center. All patients also received 3T brain magnetic resonance imaging with a diffusion-weighted imaging sequence preoperatively and within 24 hours postoperatively to identify procedure-related new embolic lesions. Preoperative, postoperative, procedural factors, and plaque characteristics were collected. Factors were tested for statistical significance with logistic regression.

RESULTS

A total of 202 patients were enrolled in the study. There were 107 patients who underwent CAS and 95 underwent CEA. Patients undergoing CAS were more likely to have microemboli than patients undergoing CEA (78% vs 27%; P < .0001). For patients undergoing CAS, patency of the external carotid artery (odds ratio [OR], 11.4; 95% confidence interval [CI], 1.11-117.6; P = .04), lesion calcification (OR, 5.68; 95% CI, 1.12-28.79; P = .04), and lesion length (OR, 0.29; 95% CI, 0.08-1.01; P = .05) were all found to be independent risk factors for perioperative embolization. These factors did not confer increased risk to patients undergoing CEA.

CONCLUSIONS

Patients undergoing CAS are at higher risk for perioperative embolization. The risk for perioperative embolization is related to the length of the lesion and calcification. Identifying the preoperative risk factors may help to guide patient selection and, thereby, reduce embolization-related neurocognitive impairment.

Risk factors for new ischaemic cerebral lesions after carotid artery stenting: protocol for a systematic review and meta-analysis

INTRODUCTION

New ischaemic cerebral lesions (NICL) detected by diffusion-weighted imaging MRI are common after carotid artery stenting (CAS), with an occurrence rate ranging from 18% to 57%. Many studies reported occurrence of NICL could increase risk of future cerebrovascular events and cognitive impairment. However, controversies about determinants for occurrence of NICL after CAS exist among studies, and one risk factor embodied in an article may not be in another. Aim of this study is to introduce a protocol for a systematic review and meta-analysis to identify risk factors associated with occurrence of NICL after CAS.

METHODS AND ANALYSIS

All relevant literature referring to risk factors for occurrence of NICL after CAS will be searched on the major databases, such as PubMed, Embase, Web of Science and the Cochrane Library until 31 December 2018. Literature, which must be randomised controlled trials, case-control studies or cohort studies, will be included in accordance with the prespecified eligibility criteria. The risk of bias will be assessed using the Cochrane Collaboration criteria and the quality of evidence will be assessed with the corresponding scale. Data will be extracted with a form prepared before and analysed using RevMan V.5.3 analyses software. Heterogeneity will be assessed using I² statistic. Our systematic review will be performed according to the guidance from the Cochrane Handbook for Systematic Reviews of Interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

ETHICS AND DISSEMINATION

There is no need for ethical approval because primary data will not be attained. The systematic review will be presented at international conferences and published in peer-reviewed journals.

PROSPERO REGISTRATION NUMBER

CRD42019121129.

Silent brain infarcts on diffusion-weighted imaging after carotid revascularisation: A surrogate outcome measure for procedural stroke? A systematic review and meta-analysis

Aim

To investigate whether lesions on diffusion-weighted imaging (DWI+) after carotid artery stenting (CAS) or endarterectomy (CEA) might provide a surrogate outcome measure for procedural stroke.

Materials and Methods

Systematic MedLine® database search with selection of all studies published up to the end of 2016 in which DWI scans were obtained before and within seven days after CAS or CEA. The correlation between the underlying log odds of stroke and of DWI+ across all treatment groups (i.e. CAS or CEA groups) from included studies was estimated using a bivariate random effects logistic regression model. Relative risks of DWI+ and stroke in studies comparing CAS vs. CEA were estimated using fixed-effect Mantel-Haenszel models.

Results

We included data of 4871 CAS and 2099 CEA procedures (85 studies). Across all treatment groups (CAS and CEA), the log odds for DWI+ was significantly associated with the log odds for clinically manifest stroke (correlation coefficient 0.61 (95% CI 0.27 to 0.87), p = 0.0012). Across all carotid artery stenting groups, the correlation coefficient was 0.19 (p = 0.074). There were too few CEA groups to reliably estimate a correlation coefficient in this subset alone. In 19 studies comparing CAS vs. CEA, the relative risks (95% confidence intervals) of DWI+ and stroke were 3.83 (3.17-4.63, p < 0.00001) and 2.38 (1.44-3.94, p = 0.0007), respectively.

Discussion

This systematic meta-analysis demonstrates a correlation between the occurrence of silent brain infarcts on diffusion-weighted imaging and the risk of clinically manifest stroke in carotid revascularisation procedures.

Conclusion

Our findings strengthen the evidence base for the use of DWI as a surrogate outcome measure for procedural stroke in carotid revascularisation procedures. Further randomised studies comparing treatment effects on DWI lesions and clinical stroke are needed to fully establish surrogacy.

Utilization of Intravascular Ultrasound during Carotid Artery Stenting

For patients at high risk for surgery, carotid artery stenting (CAS) is a viable alternative to help reduce risk of stroke for patients with high-grade carotid artery stenosis; however, a higher incidence of perioperative stroke has been observed in patients undergoing stenting compared to those undergoing open surgery. Intravascular ultrasound (IVUS) is commonly used during coronary artery procedures to help evaluate lesions and to guide stent placement. Multiple groups have sought to determine whether IVUS could also be used during CAS. While IVUS has been shown to be both feasible and safe during CAS, there is limited evidence that demonstrates direct improvement in procedural outcomes. Further studies focusing on clinical outcomes should be conducted in order to justify routine use of this technology during CAS.

Follow-up after undersized dilatation of targeted lesions in carotid artery stenting

BACKGROUND AND PURPOSE

We assessed whether intentional undersized dilatation of targeted lesions during carotid artery stenting (CAS) carried a higher risk of in-stent restenosis (ISR) and correlation to subsequent ischemic stroke in qualifying arteries in the follow-up period.

METHODS

Consecutive patients undergoing CAS between April 2003 and May 2010 were retrospectively reviewed. The use of a filter device as a distal embolic protection device (EPD) was first approved by Japanese governmental health insurance in April 2008; previously, transient balloon occlusion was used off-label. Until March 2008 (Group A), the target diameter of balloon dilatation was 80-100% of the normal vessel diameter just distal to the stenotic lesion. Moderately undersized dilatation (70-80% of the normal vessel diameter) using the distal EPD was adopted in April 2008 (Group B) in an attempt to reduce the amount of released plaque debris.

RESULTS

We analyzed 132 CAS procedures (125 patients) in Group A and 53 CAS procedures (52 patients) in Group B. The mean follow-up period was 35.4 months (35.3 months in Group A and 36.0 months in Group B). Eight lesions (4.3%; 7 in Group A and 1 in Group B) developed ISR. None of the patients had symptomatic ISR, and ISR did not increase in Group B (odds ratio, 0.34; 95% confidence interval, 0.04-2.86; p = 0.32).

CONCLUSIONS

Undersized dilatation of targeted lesions did not increase the risk of developing ISR, and we suggest it as a viable treatment option to prevent ischemic events during CAS.

Pathology of embolic debris in carotid artery stenting

BACKGROUND

The relationship between magnetic resonance (MR) plaque imaging and the pathology of distal embolic debris is unknown. We aimed to evaluate the relationship between the pathology of embolic debris in the embolic filter during carotid artery stenting (CAS), MR plaque imaging, and new ischemic lesions on diffusion-weighted imaging (DWI).

METHOD

We prospectively reviewed the 36 patients who underwent CAS using a filter-type embolic protection device. Pathology of debris was categorized into thrombosis, inflammatory cells, elastic fiber, and calcification. We compared the clinical parameters, MR plaque imaging, and pathological characteristics of the embolic debris retained in the filter during CAS on univariate analysis.

RESULTS

Eleven patients had and 25 patients did not have new lesion on DWI. All of DWI-high lesions were identified in affected side middle cerebral artery territory. Embolic debris was microscopically confirmed in 28 patients (78%); thrombosis in 11 (31%), inflammatory cells in 13 (36%), elastic fiber in 12 (33%), and calcification in 9 (25%). Proportion of asymptomatic carotid stenosis, intra-operative bradycardia/hypotension, and inflammatory cells of debris were significantly higher in patients with new DWI-high lesions. There was no significant relationship between the pathological characteristics and MR plaque imaging of distal embolic debris.

CONCLUSIONS

Our study showed that new DWI-high lesions might be influenced by types of debris in the filter. The need for future studies specifically examine the association of pathology of debris and findings of MR plaque imaging with new DWI-high lesions during CAS is emphasized.

CYP2C19 genotype and early ischemic lesion recurrence in stroke patients treated with clopidogrel

BACKGROUND

Early recurrent ischemic lesions detected on diffusion-weighted imaging (DWI) have been proposed as a surrogate marker for clinical recurrence. We hypothesized that cytochrome P450 2C19 (CYP2C19) genotype influences the incidence of early recurrence on DWI in acute stroke patients treated with clopidogrel.

METHODS

We enrolled 76 Korean patients with acute ischemic stroke due to large artery atherosclerosis who were treated with clopidogrel. Early ischemic lesion recurrence was defined as new lesions separate from the index lesion. We compared the rates of early ischemic lesion recurrence on DWI based on the CYP2C19 genotypes.

RESULTS

Early recurrence on DWI was observed in 36 patients (47.4%). A total of 76 patients were classified into 3 phenotypic groups: extensive metabolizers (EMs; n = 27, 35.5%), intermediate metabolizers (IMs; n = 36, 47.4%), and poor metabolizers (PMs; n = 13, 17.1%). Early recurrence on DWI was more common in PMs (84.6%), followed by IMs (50.0%), and EMs (25.9%; P < .001). PMs had a significantly higher recurrence rate than EMs (P < .001). In multivariate analysis, CYP2C19 genotypes were independently associated with early DWI recurrence (for PMs: odds ratio, 19.3; 95% confidence interval, 3.15-117.56).

CONCLUSIONS

CYP2C19 genotypes are significantly associated with early lesion recurrence in Korean acute stroke patients treated with clopidogrel.

Dilation of the Internal Carotid Artery at the Entrance to the Carotid Canal following Carotid Artery Stenting Predicts Postprocedural Hyperperfusion

OBJECTIVE

Ischemic stroke and hyperperfusion (HP) are the most frequent and important complications in carotid artery stenosis surgery. Carotid artery stenting (CAS) has replaced carotid endarterectomy in high medical risk patients. Prior to CAS, initial angiographic findings disclose a small caliber internal carotid artery (IC) due to stenosis, but after the stenosis is relieved, the diameter of the IC becomes enlarged. We investigated whether a change in the IC diameter was related to ischemic complication and HP using cerebral blood flow single photon emission computed tomography (SPECT).

METHODS

From February 2008 to December 2009 we consecutively performed 39 CAS on 35 patients. We retrospectively analyzed the relationship between changes at the level before the entry to the petrous bone canal of the IC and stenosis of the etiological artery, improvement in stenosis, HP and postintervention diffusion-weighted image high-intensity lesions. Statistical analyses comprised Wilcoxon/Kruskal-Wallis analysis, analysis of variance and a multivariate logistic analysis.

RESULTS

A total of 9 cases showed HP in SPECT. Severity of IC stenosis and change in the IC at the level before the entry to the petrous bone canal were related with statistical significance to HP. Other factors did not correlate with HP.

CONCLUSION

Procedure-related dilation of the IC at the level before the entry to the petrous bone canal occurred due to release of the etiological stenosis. This finding can also support the prediction of HP.

Intravascular ultrasound as a clinical adjunct for carotid plaque characterization

OBJECTIVE

Virtual histology intravascular ultrasound (VH IVUS) is valuable for estimating minimal lumen diameter and plaque characterization. The clinical use of IVUS in carotid intervention is not well characterized. We aim to evaluate the role of IVUS in carotid plaque characterization and determine whether it could be predictive of procedure-related microemboli.

METHODS

From July 2010, patients with severe carotid stenosis who underwent elective carotid stenting procedures were prospectively enrolled. IVUS evaluation was performed before stent placement. Patient demographics, comorbidities, and preoperative images were recorded. Comparison of pre- and postoperative diffusion-weighted magnetic resonance images was used to identify the number of procedure-related microemboli. IVUS-derived minimal lumen diameter and vessel wall plaque characteristics were collected. Univariate and multivariate logistic regressions were used to search for associations between IVUS-derived VH data and incidence of microemboli.

RESULTS

A total of 38 high-risk patients receiving carotid stenting were enrolled. Among them, 25 patients had type I aortic arches and 17 of the patients were symptomatic (preoperative stroke or transient ischemic attack). VH IVUS data did not show strong associations with microemboli, however, a trend was found between the area of fibrous tissue and median or more incidence of microemboli (P = .099). IVUS-defined vessel diameter maximum was associated with median or more incidence of microemboli (P = .042). In addition, median or more incidence of microemboli showed trends with proximal common carotid artery calcification (P = .056) and with being over the age of 80 (P = .06). Contralateral carotid occlusion or high-grade stenosis was associated with postoperative contralateral microemboli (P = .036).

CONCLUSIONS

We demonstrate that periprocedural carotid IVUS is clinically feasible. VH IVUS may be helpful in better understanding plaque morphology and determining optimal stent placement. However, its use in predicting microembolization remains limited.

Carotid plaque characterization by virtual histology intravascular ultrasound related to the timing of carotid intervention

PURPOSE

To determine the incidence of vulnerable plaques characterized by virtual histology intravascular ultrasound (VH IVUS) in patients with severe internal carotid artery (ICA) stenosis and its relationship to the timing of protected carotid artery stenting (CAS).

METHODS

The study included 141 patients (119 men; mean age 66.9 ± 9 years) with severe ICA stenosis undergoing CAS with cerebral protection. Patients were classified in 3 groups: 39 symptomatic early CAS (<14 days from clinical symptoms); 58 symptomatic delayed CAS (range 15-180 days), and 44 asymptomatic CAS. Culprit plaque component was evaluated by VH IVUS. A vulnerable plaque was defined by a thin-cap fibroatheroma and/or calcified thin-cap fibroatheroma.

RESULTS

The composite disabling stroke/mortality was 2.1%. The incidence of vulnerable plaques was significantly higher in the symptomatic early CAS group (25/39, 64.1%) than in the symptomatic delayed CAS group (26/58, 44.8%; p=0.048) or the asymptomatic CAS group (14/44, 31.8%; p=0.003). Symptomatic patients showed a significantly higher incidence of vulnerable plaques (52.6%) than asymptomatic patients (31.8%, p=0.022). There were no significant differences between the symptomatic delayed and asymptomatic groups (p=0.129). By clinical subgroup, a vulnerable plaque was observed in 29 (52.7%) of the patients with 55 transient ischemic attacks, 22 (52.4%) of the 42 minor stroke patients, and 14 (31.8%) of the 44 asymptomatic patients (p=0.152).

CONCLUSION

The incidence of vulnerable plaques was significantly higher in symptomatic patients, increasing as the intravascular study was performed closer to the index ischemic episode.

Quantitative evaluation of high intensity signal on MIP images of carotid atherosclerotic plaques from routine TOF-MRA reveals elevated volumes of intraplaque hemorrhage and lipid rich necrotic core

BACKGROUND

Carotid intraplaque hemorrhage (IPH) and lipid rich necrotic core (LRNC) have been associated with accelerated plaque growth, luminal narrowing, future surface disruption and development of symptomatic events. The aim of this study was to evaluate the quantitative relationships between high intensity signals (HIS) in the plaque on TOF-MRA and IPH or LRNC volumes as measured by multicontrast weighted CMR.

METHODS

Seventy six patients with a suspected carotid artery stenosis or carotid plaque by ultrasonography underwent multicontrast carotid CMR. HIS presence and volume were measured from TOF-MRA MIP images while IPH and LRNC volumes were separately measured from multicontrast CMR.

RESULTS

For detecting IPH, HIS on MIP images overall had high specificity (100.0%, 95% CI: 93.0 - 100.0%) but relatively low sensitivity (32%, 95% CI: 20.8 - 47.9%). However, the sensitivity had a significant increasing relationship with underlying IPH volume (p = 0.033) and degree of stenosis (p = 0.022). Mean IPH volume was 2.7 times larger in those with presence of HIS than in those without (142.8 ± 97.7 mm(3) vs. 53.4 ± 56.3 mm(3), p = 0.014). Similarly, mean LRNC volume was 3.4 times larger in those with HIS present (379.8 ± 203.4 mm(3) vs. 111.3 ± 122.7 mm(3), p = 0.001). There was a strong correlation between the volume of the HIS region and the IPH volume measured from multicontrast CMR (r = 0.96, p < 0.001).

CONCLUSION

MIP images are easily reformatted from three minute, routine, clinical TOF sequences. High intensity signals in carotid plaque on TOF-MRA MIP images are associated with increased intraplaque hemorrhage and lipid-rich necrotic core volumes. The technique is most sensitive in patients with moderate to severe stenosis.