Late evaluation of silent cerebral ischemia detected by diffusion-weighted MR imaging after filter-protected carotid artery stenting

Clinical and subclinical microemboli following neuroangiography in children

BACKGROUND

To assess the frequency, imaging appearances, and risk factors of brain microemboli following pediatric neuroangiography, as assessed by early diffusion-weighted MRI imaging (DWI).

METHODS

This single-center, retrospective analysis investigated early DWI post-pediatric neuroangiography. Patients aged 0-18 years who had diagnostic neuroangiography and DWI within a week postprocedure were included. Data on clinical and procedural parameters and MRI findings were recorded. Univariate and multivariate analyses were performed on the following risk factors: age, weight, vasculopathy, antiplatelet drug use, access type, intraprocedural heparin, procedure duration, neck arteries catheterized, and angiographic runs. A p-value<0.05 indicated statistical significance.

RESULTS

Eighty-two children were included (40.2% female), mean age 10.1±4.5 years (range: 7 months-17 years). There were no intraprocedural thromboembolic complications recognized. DWI positivity was seen following 3.6% (3/82) procedures: two with transient symptoms, and one instance of silent microemboli. There were no territorial infarcts or clinical stroke. Children with underlying vasculopathy had a higher risk of microemboli from angiography than children without vasculopathy (OR 31.6, p=0.02), and the OR of microemboli following transradial angiography was 79.1 (p=0.005) as compared with transfemoral angiography. Univariate and multivariate analysis showed a significant association between microemboli and number of angiographic runs (p=0.004). Follow-up MRI in all three patients showed no residual abnormal signal.

CONCLUSIONS

Cerebral microemboli are unusual following uncomplicated neuroangiography in children. However, in the presence of underlying vasculopathy and with transradial technique, the incidence approaches that reported in the adult literature. An increased association with the number of angiographic runs is an important and controllable factor.

Changes in Cognitive Functions after Carotid Endarterectomy and Carotid Stenting: A Decade-Apart Comparison

BACKGROUND

This study investigates changes in cognitive function in patients with severe carotid stenosis who underwent carotid endarterectomy (CEA) and carotid stenting (CAS) over two decades.

METHODS

We compared cognitive function within 30 days after the procedure in 267 patients (first 100 each for CEA and CAS in two periods: 2008-2012 and 2018-2022) in a single institution. Assessments used Adenbrooke's Cognitive Examination-Revised (ACE-R), the Mini-Mental State Examination (MMSE), Speech Fluency Test (SFT), and Clock Drawing Test (CDT), conducted before and 30 ± 2 days after surgery.

RESULTS

Patients (mean age 67.2 years, 70%+ carotid stenosis) exhibited different cognitive changes over periods. In 2008-2012, significant declines in MMSE (CEA, p = 0.049) and CDT (CAS, p = 0.015) were observed among asymptomatic patients. On the contrary, in 2018-2022, improvements were observed in ACE-R and MMSE for symptomatic and asymptomatic patients undergoing CEA and CAS.

CONCLUSION

Over a decade, advances in interventional techniques and patient management have reduced risks of cognitive decline in patients with asymptomatic carotid stenosis and also have improved cognitive functions in both symptomatic and asymptomatic individuals.

Recovery of Hypoxic Regions in a Rat Model of Microembolism

OBJECTIVES

Endovascular treatment (EVT) has become the standard of care for acute ischemic stroke. Despite successful recanalization, a limited subset of patients benefits from the new treatment. Human MRI studies have shown that during removal of the thrombus, a shower of microclots is released from the initial thrombus, possibly causing new ischemic lesions. The aim of the current study is to quantify tissue damage following microembolism.

MATERIALS AND METHODS

In a rat model, microembolism was generated by injection of a mixture of polystyrene fluorescent microspheres (15, 25 and 50 µm in diameter). The animals were killed at three time-points: day 1, 3 or 7. AMIRA and IMARIS software was used for 3D reconstruction of brain structure and damage, respectively.

CONCLUSIONS

Microembolism induces ischemia, hypoxia and infarction. Infarcted areas persist, but hypoxic regions recover over time suggesting that repair processes in the brain rescue the regions at risk.

Asymptomatic carotid stenosis and concomitant silent brain infarctions

Objectives

This review aims to clarify (1) the definition of silent brain infarct (SBI), (2) the diagnostic criteria of SBI using magnetic resonance imaging (MRI), (3) the prevalence of patients with asymptomatic carotid stenosis and SBI based on MRI assessment, (4) the association of SBI and asymptomatic carotid stenosis and the risk of stroke compared to patients without SBI, (5) the association between development of dementia/cognitive impairment in people with asymptomatic carotid stenosis and SBI, and (6) the evidence for treating patients with carotid stenosis and SBI.

Methods

A systematic search of PubMed and Scopus including all studies published from 2000 to 2018 and written in English.

Results

No consensus of the definition and diagnostic criteria for SBI was found. The prevalence of SBI in asymptomatic carotid patients is 17–33.3%. SBI is a significant risk factor for future stroke, OR 4.6 (95% CI: 3.0–7.2; p < 0.0001). One substudy showed that immediate CEA is beneficial compared to delayed CEA in these patients, showing a 45% reduction in annual stroke rate from 1.5%/year to 0.7%/year.

Conclusion

This review emphasizes the need to standardize the definition and diagnostic criteria of SBI on MRI. Current evidence suggests an increased risk and a small potential benefit of offering carotid endarterectomy to patient with silent brain infarct. Prospective studies are warranted to elucidate these issues further.

The quest for high spatial resolution diffusion-weighted imaging of the human brain in vivo

Diffusion-weighted imaging, a contrast unique to MRI, is used for assessment of tissue microstructure in vivo. However, this exquisite sensitivity to finer scales far above imaging resolution comes at the cost of vulnerability to errors caused by sources of motion other than diffusion motion. Addressing the issue of motion has traditionally limited diffusion-weighted imaging to a few acquisition techniques and, as a consequence, to poorer spatial resolution than other MRI applications. Advances in MRI imaging methodology have allowed diffusion-weighted MRI to push to ever higher spatial resolution. In this review we focus on the pulse sequences and associated techniques under development that have pushed the limits of image quality and spatial resolution in diffusion-weighted MRI.

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.

Serum tumor necrosis factor α levels are associated with new ischemic brain lesions after carotid artery stenting

OBJECTIVE

New diffusion-weighted imaging (DWI) lesions on magnetic resonance imaging (MRI) after carotid artery stenting (CAS) are associated with an increased risk of future cerebrovascular events. Therefore, we evaluated the association between the expression levels of serum inflammatory markers and new DWI lesions after CAS and the presence of intraplaque hemorrhage (IPH). We also explored the mechanisms underlying this association.

METHODS

A total of 225 inpatients with severe carotid artery stenosis were consecutively enrolled in this cohort study. Serum inflammatory marker levels were detected in all patients by enzyme-linked immunosorbent assay. In the final analysis, 128 patients who underwent CAS and received pretreatment and post-treatment MRI scans were enrolled. DWI was performed to detect new ischemia brain lesions. T1-weighted, T2-weighted, and time-of-flight sequences were also conducted to identify IPH.

RESULTS

Serum tumor necrosis factor α (TNF-α) levels were significantly higher in symptomatic patients as well as in IPH+ patients identified by carotid MRI. New DWI lesions were identified in 50% of patients after CAS. Univariate analysis showed that DWI+ patients after CAS exhibited older mean age, higher mean TNF-α levels, and more IPH on preoperative MRI and were less likely to have right carotid stenosis than DWI- patients. Multivariate logistic regression analyses revealed that serum TNF-α concentrations were associated with new DWI lesions after CAS (odds ratio, 1.245; 95% confidence interval, 1.068-1.451; P = .005). Finally, the specificity and sensitivity of serum TNF-α levels in predicting DWI+ patients after CAS were 0.828 and 0.453, respectively.

CONCLUSIONS

Higher serum TNF-α levels are associated with a higher likelihood of new DWI lesions after CAS and the presence of IPH. Therefore, TNF-α is a potentially valuable predictor of acute ischemic cerebral lesions after CAS and the presence of IPH.

Nε-(carboxymethyl)lysine Concentration in Debris from Carotid Artery Stenting Correlates Independently with Signal Intensity on T1-Weighted Black-Blood Magnetic Resonance Images

BACKGROUND AND PURPOSE

Because magnetic resonance imaging (MRI) focuses on the morphological characteristics of carotid artery plaques, its diagnostic value with respect to plaque vulnerability is limited. We examined the correlation between N^ε-(carboxymethyl)lysine (CML), a main chemical structure of advanced glycation end-products, and the vulnerability of plaques visualized on MRI scans.

MATERIALS AND METHODS

We enrolled 43 patients who had undergone carotid artery stenting (CAS) for carotid artery stenosis; all underwent MRI studies, including black-blood MRI and diffusion-weighted imaging (DWI). The signal intensity ratio (SIR) of plaques to adjacent sternocleidomastoid muscle (P/M) on T1- and T2-weighted images (T1WI, T2WI) was calculated. Protein samples were extracted from debris trapped by a filter device. The concentrations of CML and myeloperoxidase (MPO) were measured by solid-phase enzyme-linked immunosorbent assay.

RESULTS

The patients were classified into 2 groups based on their SIR-P/M on T1WI and T2WI scans. We observed a higher incidence of post-CAS DWI lesions in patients with a higher than a lower SIR-P/M on T1WI; the CML and MPO concentrations in their CAS debris were also higher. No such differences were seen in patients with a higher or lower SIR-P/M on T2WI scans. The concentration of CML in CAS debris correlated independently with the SIR-P/M on T1WI of the carotid plaques, and was related to the concentration of MPO in CAS debris.

CONCLUSIONS

Our findings suggest CML as a candidate molecular imaging probe for the identification of vulnerable plaques.

Analysis of Risk Factors for Cerebral Microinfarcts after Carotid Endarterectomy and the Relevance of Delayed Cerebral Infarction

Background and Purpose

Carotid endarterectomy (CEA) is performed to prevent cerebral infarction, but a common side effect is cerebral microinfarcts. This study aimed to identify the variables related to the production of microinfarcts during CEA as well as determine their association with delayed postoperative infarction.

Methods

This was a retrospective review of data collected prospectively from 548 patients who underwent CEA. The clinical characteristics of the patients and the incidence rates and causes of microinfarcts were analyzed. Microinfarcts were diagnosed by diffusion-weighted magnetic resonance imaging. The presence of delayed postoperative infarction was compared between microinfarct-positive and microinfarct-negative groups.

Results

In total, 76 (13.86%) patients were diagnosed with microinfarcts. Preoperative neurological symptoms were significantly related to the incidence of microinfarcts [odds ratio (OR)=2.93, 95% confidence interval (CI)=1.72–5.00, p<0.001]. Shunt insertion during CEA was the only significant procedure-related risk factor (OR=1.42, 95% CI=1.00–2.19, p=0.05). The presence of microinfarcts did not significantly increase the incidence of delayed postoperative infarction (p=0.204).

Conclusions

In the present study, risk factors for microinfarcts after CEA included preoperative symptoms and intraoperative shunt insertion. Microinfarcts were not associated with delayed postoperative infarction.

Added Value of MRI over CT of the Brain in Intensive Care Unit Patients

BACKGROUND

Intensive care unit (ICU) patients with neurological impairments often require neuroimaging. However, the relative sensitivity of various imaging modalities of the brain has not yet been explored in this population.

METHODS

In this study, we compare the findings of CT and MRI scans in ICU patients to (1) identify the number and rate of clinically relevant lesion detected by MRI while missed by CT and vice versa and (2) determine specific lesion types for which CT versus MRI discrepancies exist. A review of medical records included CT and MRI reports of patients who underwent these procedures while they were patients in our ICUs between July 2004 and July 2009. MRI and CT were compared regarding their ability to detect clinically relevant abnormalities. Odds ratios with 95% confidence limits were calculated to compare diagnostic categories regarding the rate of discrepant MRI versus CT findings, followed by power analyses to estimate sample sizes necessary to allow for further testing in a larger trial.

RESULTS

MRI revealed clinically relevant additional abnormalities over CT in 129 of 136 patients (95%) that included the detection of additional finding for 15/27 hemorrhagic lesions (55.6%), 33/36 (92%) ischemic strokes, 19/27 (70%) traumatic lesions, 8/14 (57%) infections, 15/24 (62.5%) metabolic abnormalities, and all seven neoplasms. Odds ratio analysis revealed the added sensitivity of MRI to be greater for ischemic and neoplastic lesions than for trauma, metabolic-related abnormalities, infection, or hemorrhage.

CONCLUSIONS

MRI is more sensitive than CT in identifying clinically meaningful lesions in at least a subset of ICU patients, regardless of pathology.

Ischemic brain lesions after carotid artery stenting increase future cerebrovascular risk

Background

Brain lesions on diffusion-weighted imaging (DWI) are frequently found after carotid artery stenting (CAS), but their clinical relevance remains unclear.

Objectives

This study sought to investigate whether periprocedural ischemic DWI lesions after CAS or carotid endarterectomy (CEA) are associated with an increased risk of recurrent cerebrovascular events.

Methods

In the magnetic resonance imaging (MRI) substudy of ICSS (International Carotid Stenting Study), 231 patients with symptomatic carotid stenosis were randomized to undergo CAS (n = 124) or CEA (n = 107). MRIs were performed 1 to 7 days before and 1 to 3 days after treatment. The primary outcome event was stroke or transient ischemic attack in any territory occurring between the post-treatment MRI and the end of follow-up. Time to occurrence of the primary outcome event was compared between patients with (DWI+) and without (DWI–) new DWI lesions on the post-treatment scan in the CAS and CEA groups separately.

Results

Median time of follow-up was 4.1 years (interquartile range: 3.0 to 5.2). In the CAS group, recurrent stroke or transient ischemic attack occurred more often among DWI+ patients (12 of 62) than among DWI– patients (6 of 62), with a cumulative 5-year incidence of 22.8% (standard error [SE]: 7.1%) and 8.8% (SE: 3.8%), respectively (unadjusted hazard ratio: 2.85; 95% confidence interval: 1.05 to 7.72; p = 0.04). In DWI+ and DWI– patients, 8 and 2 events, respectively, occurred within 6 months after treatment. In the CEA group, there was no difference in recurrent cerebrovascular events between DWI+ and DWI– patients.

Conclusions

Ischemic brain lesions discovered on DWI after CAS seem to be a marker of increased risk for recurrent cerebrovascular events. Patients with periprocedural DWI lesions might benefit from more aggressive and prolonged antiplatelet therapy after CAS. (A Randomised Comparison of the Risks, Benefits and Cost Effectiveness of Primary Carotid Stenting With Carotid Endarterectomy: International Carotid Stenting Study; ISRCTN25337470)

Proximal protection with the Gore PAES can reduce DWI lesion size in high-grade stenosis during carotid stenting

AIMS

The aim was to determine the incidence of new ischaemic lesions on diffusion-weighted MR imaging (DWI) in a non-randomised cohort of patients after protected and unprotected carotid artery stent placement using the Parodi Anti-Emboli System (PAES).

METHODS AND RESULTS

A retrospective review was conducted on 269 patients who received DWI prior to, and 24-72 hours after, stent placement. All patients were enrolled in one centre. Forty patients stented with the PAES device were matched with 229 patients stented without protection (control group). New diffusion restriction on DWI was detected in 25.8% (PAES) versus 32.3% (control group); p=0.64. On average there were 0.7 lesions (PAES) versus 0.8 lesions (control group) per patient. The area of lesions was 1.7 (PAES) versus 5.6 mm2. In a subanalysis of patients (32 PAES, 148 non-protected) with >80% stenosis, the area of restricted diffusion was less when proximal protection was used (p<0.05). The number and area of DWI lesions did not differ on the contralateral, non-stented side. When the PAES system was used, patients were more likely not to have any lesion at all (p=0.028).

CONCLUSIONS

In high-grade stenosis, the use of the Gore PAES device significantly reduced the area of new DWI lesions and patients were more likely not to have any new DWI lesion at all.

Nε-(carboxymethyl)lysine in debris from carotid artery stenting: multiple versus nonmultiple postoperative lesions

BACKGROUND

No predictor of postoperative ischemic events has been identified in patients undergoing carotid artery stenting (CAS). We aimed to determine whether N(ε)-(carboxymethyl)lysine (CML) in debris trapped by an embolic protection filter device is a predictor of postoperative ischemic events.

METHODS

We enrolled 27 patients (73.4 ± 7.2 years; 22 male, 5 female) who underwent CAS for carotid artery stenosis. Diffusion-weighted magnetic resonance imaging was performed before and after the procedure. Protein samples were extracted from the debris. CML and myeloperoxidase were examined by solid phase enzyme-linked immunosorbent assay and Western blot analysis.

RESULTS

Seventeen patients had 0 or 1 new lesion (nonmultiple lesions) postoperatively, whereas 10 patients had 2 or more new lesions postoperatively (multiple lesions). The CML concentration of the protein sample was significantly higher in patients with multiple lesions than in those with nonmultiple lesions (6.26 ± 2.77 ng/mg protein and 3.36 ± 1.57 ng/mg protein, respectively; P = .010). Statin therapy for dyslipidemia was associated with a lower incidence of multiple lesions and a lower concentration of CML in the protein sample (P = .004 and P = .02, respectively). Receiver operating characteristic analysis showed that the area under the curve for CML was significantly greater than .5 (.877; 95% confidence interval, .742-1.00).

CONCLUSIONS

CML derived from debris may distinguish between patients with postoperative multiple ischemic lesions and those with postoperative nonmultiple lesions who undergo CAS.

Predictors of acute and persisting ischemic brain lesions in patients randomized to carotid stenting or endarterectomy

BACKGROUND AND PURPOSE

We investigated predictors for acute and persisting periprocedural ischemic brain lesions among patients with symptomatic carotid stenosis randomized to stenting or endarterectomy in the International Carotid Stenting Study.

METHODS

We assessed acute lesions on diffusion-weighted imaging 1 to 3 days after treatment in 124 stenting and 107 endarterectomy patients and lesions persisting on fluid-attenuated inversion recovery after 1 month in 86 and 75 patients, respectively.

RESULTS

Stenting patients had more acute (relative risk, 8.8; 95% confidence interval, 4.4-17.5; P<0.001) and persisting lesions (relative risk, 4.2; 95% confidence interval, 1.6-11.1; P=0.005) than endarterectomy patients. Acute lesion count was associated with age (by trend), male sex, and stroke as the qualifying event in stenting; high systolic blood pressure in endarterectomy; and white matter disease in both groups. The rate of conversion from acute to persisting lesions was lower in the stenting group (relative risk, 0.4; 95% confidence interval, 0.2-0.8; P=0.007), and was only predicted by acute lesion volume.

CONCLUSIONS

Stenting caused more acute and persisting ischemic brain lesions than endarterectomy. However, the rate of conversion from acute to persisting lesions was lower in the stenting group, most likely attributable to lower acute lesion volumes. Clinical Trial Registration -URL: www.isrctn.org. Unique identifier: ISRCTN25337470.

Flow reversal versus filter protection: a pilot carotid artery stenting randomized trial

BACKGROUND

Carotid artery stenting (CAS) has become an alternative treatment for patients presenting symptomatic carotid artery stenosis. The improvement in clinical outcomes with CAS has been associated with the development of embolic protection devices. The trial aim is to compare flow reversal versus filter protection during CAS through femoral access.

METHODS AND RESULTS

Patients were randomly enrolled in CAS using flow reversal or filter protection. The primary end points were the incidence, number, and size of new ischemic brain lesions after CAS. The secondary end points included major adverse cardiac and cerebrovascular events, transient ischemic attack, and definitive ischemic brain lesions on fluid-attenuated inversion recovery magnetic resonance image at a 3-month follow-up. Ischemic brain lesions were assessed by a 3T magnetic resonance image. Neurological outcomes were evaluated by means of the National Institutes of Health Stroke Scale and the modified Rankin Scale (mRS). Forty consecutive patients were randomly assigned. Compared with flow reversal (n=21), filter protection (n=19) resulted in a significant reduction in the incidence (15.8% versus 47.6%, P=0.03), number (0.73 versus 2.6, P=0.05), and size (0.81 versus 2.23 mm, P=0.05) of new ischemic brain lesions. Two patients, 1 from each group, presented transient ischemic attack at 3-month follow-up. There were no major adverse cardiac and cerebrovascular events in the hospital or at 3-month follow-up.

CONCLUSIONS

In this small sample size trial, filter protection was more effective than flow reversal in reducing ischemic brain lesions during CAS through femoral approach.

CLINICAL TRIAL REGISTRATION URL

http://portal2.saude.gov.br/sisnep/. Unique identifier: 0538.0.004.000-10.

The influence of anti-platelet resistance on the development of cerebral ischemic lesion after carotid artery stenting

PURPOSE

Cerebral ischemic lesions are frequently observed after carotid artery stenting (CAS), and anti-platelet agents are used to prevent stent thrombosis and peri-procedural complications. However, despite the premedication, cerebral ischemic lesions are observed, suggesting that they may rather be related to anti-platelet resistance. We, therefore, investigated the effects of anti-platelet resistance on the development of cerebral ischemic lesions after CAS.

MATERIALS AND METHODS

We retrospectively reviewed patients who received CAS and selected patients for whom brain MRI was performed within 24 hours after CAS and for whom anti-platelet resistance was checked. Anti-platelet resistance was examined by the VerifyNow system. We analyzed the correlation between anti-platelet resistance and cerebral ischemic lesions detected on follow-up MRI.

RESULTS

Among 76 patients, 45 (59.2%) developed new ischemic lesions after CAS. Twelve (15.8%) patients showed aspirin resistance and 50 (65.8%) patients showed clopidogrel resistance. Patients with a new ischemic lesion demonstrated a significantly greater frequency of clopidogrel resistance than those who had no new ischemic lesion (82.2% versus 41.9%, p=0.001). The frequency of aspirin resistance was not significantly different between the groups of patients with and without new ischemic lesions (20.0% versus 9.7%, p=0.340). In multivariate analysis, clopidogrel resistance was a significant risk factor for post-procedural cerebral ischemia.

CONCLUSION

Anti-platelet resistance can be used to predict new ischemic lesions after CAS. Anti-platelet resistance should be evaluated in all patients prior to CAS to prevent ischemic complications related to CAS.

Assessment of reverse flow as a means of cerebral protection during carotid artery stent placement with diffusion-weighted and transcranial Doppler imaging

PURPOSE

To assess the effectiveness of flow reversal as an alternative means of cerebral protection by using transcranial Doppler recordings and diffusion-weighted imaging (DWI) as surrogate markers of brain injury.

MATERIALS AND METHODS

Eighteen patients with symptomatic carotid artery disease were recruited. Magnetic resonance imaging was performed before the intervention and at 3 and 24 hours and 30 days after the intervention to detect new ischemic lesions with DWI. Transcranial Doppler recordings were made during the procedure to assess for microembolic signals (MESs). Data were compared against data from a historical control cohort of patients who underwent CAS placement with or without filter protection (n = 15 each) under the same protocol in a different study.

RESULTS

There were fewer periprocedural new lesions on DWI in the reverse-flow cohort compared with the historical control cohort with filter protection (P = .084). Reverse flow revealed significantly fewer MESs during the whole procedure compared with the filter-protected group (P = .01) but not the unprotected group (P = .55). There was a marked decrease in MES counts for reverse flow protection during the embologenic stages of the procedure (P = .004).

CONCLUSIONS

Use of the reverse flow device was associated with fewer overall lesions on DWI and proportionately fewer positive scans compared with the use of filter-type devices (P = .08, not significant). Transcranial Doppler recordings demonstrated a significant reduction in embolization to the brain during carotid artery stent placement with the use of reverse-flow cerebral protection.

Characteristics of Ischemic Brain Lesions After Stenting or Endarterectomy for Symptomatic Carotid Artery Stenosis

Background and Purpose—

In a substudy of the International Carotid Stenting Study (ICSS), more patients had new ischemic brain lesions on diffusion-weighted magnetic resonance imaging (MRI) after stenting (CAS) than after endarterectomy (CEA). In the present analysis, we compared characteristics of diffusion-weighted MRI lesions.

Methods—

Number, individual and total volumes, and location of new diffusion-weighted MRI lesions were compared in patients with symptomatic carotid stenosis randomized to CAS (n=124) or CEA (n=107) in the ICSS-MRI substudy.

Results—

CAS patients had higher lesion numbers than CEA patients (1 lesion, 15% vs 8%; 2–5 lesions, 19% vs 5%; >5 lesions, 16% vs 4%). The overall risk ratio for the expected lesion count with CAS versus CEA was 8.8 (95% confidence interval, 4.4–17.5; P <0.0001) and significantly increased among patients with lower blood pressure at randomization, diabetes mellitus, stroke as the qualifying event, left-side stenosis, and if patients were treated at centers routinely using filter-type protection devices during CAS. Individual lesions were smaller in the CAS group than in the CEA group ( P <0.0001). Total lesion volume per patient did not differ significantly. Lesions in the CAS group were more likely to occur in cortical areas and subjacent white matter supplied by leptomeningeal arteries than lesions in the CEA group (odds ratio, 4.2; 95% confidence interval, 1.7–10.2; P =0.002).

Conclusions—

Compared with patients undergoing CEA, patients treated with CAS had higher numbers of periprocedural ischemic brain lesions, and lesions were smaller and more likely to occur in cortical areas and subjacent white matter. These findings may reflect differences in underlying mechanisms of cerebral ischemia.

Clinical Trial Registration—

URL: http://www.isrctn.org . Unique identifier: ISRCTN25337470.

Silent Brain Infarction – A Review of Recent Observations

Silent brain infarction is a cerebral ischaemic event evident on brain imaging without any clinical symptom. Silent brain infarction is often detected in apparently healthy, elderly people and in different selected patient groups as well. Lately, several studies were carried out in order to identify the clinical conditions leading to silent brain infarction. A large number of clinical and paraclinical parameters were found to increase silent brain infarction prevalence, and the continuously growing list of risk factors revealed that the majority of them are similar to those related to stroke. Accordingly, some consider silent brain infarction the preclinical stage of clinically overt stroke. This point of view emphasizes the early recognition and management of silent brain infarction-related risk factors, and a great need for comparative studies, which could elicit the most sensitive indicators of the increased silent brain infarction risk, especially the ones that could be cost-effectively screened in the large populations as well.

Insight into the periprocedural embolic events of internal carotid artery angioplasty. A report of four cases and literature review

Thromboembolism is a major risk of carotid angioplasty and stenting (CAS). Although the incidence of distal embolism has been documented by MRI and TCD studies, the mechanisms and management of this complication are rarely reported. Here we describe four patients with periprocedural embolic events to demonstrate the mechanisms of thromboembolism in CAS. Different remedies were applied to these patients according to the underlying mechanisms of thromboembolism and good clinical outcomes were achieved.

Carotid artery stenting without angioplasty and cerebral protection: a single-center experience with up to 7 years' follow-up

BACKGROUND AND PURPOSE

The use of cerebral protection during CAS in the treatment of carotid artery disease is matter of controversy. The purpose of this study was to evaluate the outcome of CASWBAP in a large cohort of patients, with ≤7 years' follow-up.

MATERIALS AND METHODS

Two hundred thirty-six patients with 255 symptomatic carotid stenoses and/or with high-risk-morphology plaques of >50% and asymptomatic plaques of >70% were prospectively identified. Patients underwent neurologic and carotid US examination before the procedure and during follow-up at 1, 3, 6, and 12 months and annually thereafter. Plain films of the neck were obtained immediately after the procedure and then at 1 and 3 months.

RESULTS

Technical success was achieved in 253/255 (99%) patients. Primary stent placement was successful in 248/253 (98%) patients. Neurologic periprocedural complications within 30 days included 1 (0.4%) nondisabling stroke, 1 (0.4%) disabling stroke, 11 (4.3%) TIAs, and 1 (0.4%) death. The mean duration of follow-up was 23 ± 1.4 months (range, 3-84 months). During the follow-up period, there were 9 additional deaths (7 unrelated to the carotid disease and 2 stroke-related) and 2 strokes (in other vascular territories). The degree of stenosis decreased from a mean of 82% before the procedure to a mean of 30% immediately after. During follow-up, 38 (14.8%) angioplasties were performed due to restenosis in 19 (7.4%) patients, lack of stent expansion in 14 (5.4%), or both in 5 (1.9%).

CONCLUSIONS

CASWBAP is effective and safe with a low incidence of periprocedural complications, providing satisfactory long-term clinical results.

The distribution and size of ischemic lesions after carotid artery angioplasty and stenting: evidence for microembolization to terminal arteries

BACKGROUND

Much of the brain is perfused by penetrating arteries that are the "single source" of blood to their surrounding tissues. These tissues should be equally vulnerable to ischemia from embolic occlusion, but there are questions about whether emboli have access to the penetrating arteries serving the deep brain tissues. To examine this issue in humans we recorded the number and distribution of new ischemic lesions on diffusion-weighted magnetic resonance imaging (DWMRI) after carotid artery stenting (CAS), a procedure producing showers of numerous small atheroemboli.

METHODS

Twenty-nine men (aged 62-81) underwent 30 CAS procedures with distal protection in place, and DWMRI 48 hours after the procedure documented new lesions had developed. Thirteen patients were asymptomatic, and 16 had experienced recent symptoms ipsilateral to the treated carotid stenosis. A DWMRI study was done in each patient ≤72 hours before the procedure. All MRI studies were read by the same neuroradiologist.

RESULTS

One patient sustained a minor stroke, which resolved. DWNRI found 131 new lesions (median, 3; range, 1-17; interquartile range, 2-4). Lesion size was <5 mm in 96.6% and 5 to 10 mm in 3.1%. Lesions were ipsilateral in 83.1% and contralateral in 16.9%. Lesions were in the distribution of the middle cerebral artery (91.6%), posterior cerebral artery (6.1%), and superior cerebellar artery subclavian artery (2.0%). Most lesions were in the cortex but at a depth where they were best described as cortical/subcortical (90.8%). The rest were in the periventricular white matter (6.1%) and deep gray matter (3.0%).

CONCLUSIONS

The ischemic areas developing after CAS were predominately in the deeper layers of the cortex in the distribution of the middle cerebral artery, but lesions were seen throughout the brain. The distribution of lesions caused by CAS-induced embolization coincided with estimates of blood flow to the respective areas of the brain. These data add to the evidence implicating microemboli in ischemic pathologies throughout the brain.

Carotid stenting and transcranial Doppler monitoring: indications for carotid stenosis treatment

BACKGROUND

Recently, angioplasty and stenting of carotid arteries (CAS) have taken the place of surgery. The aim of our study is to assess the role of transcranial Doppler (TCD) monitoring during CAS to address the embolic complications during the stages of the procedure, with or without embolic cerebral protection devices.

METHODS

A total of 152 patients were submitted to carotid stenting. All patients were submitted to carotid arteries Duplex scanning.

RESULTS

Neurological complications are related to TCD detection of corpuscolate signals in rapid succession. Even if no reduction of the overall incidence rate of microembolic signals (MES) was observed, a decrease in the number of corpuscolate emboli were recorded when a cerebral protection was working.

CONCLUSIONS

According to our study, even in selected patients on the basis of preoperative diagnostic criteria, CAS is burdened by a nonnegligible risk of subclinical embolic ischemic events detected at TCD and confirmed by diffusion-weighted magnetic resonance imaging (DW-MRI).

Magnetic resonance plaque imaging to predict the occurrence of the slow-flow phenomenon in carotid artery stenting procedures

INTRODUCTION

The purpose is to investigate the feasibility of magnetic resonance (MR) plaque imaging in predicting the arterial flow impairment (slow-flow phenomenon) during carotid artery stenting (CAS) using a filter-type protection device.

METHODS

Thirty-one carotid artery stenotic lesions in 30 patients (28 men and two women; mean age, 71.8 years) were evaluated by MR plaque imaging with black blood T1- and T2-weighted and time-of-flight sequences before CAS. Main plaque components were classified as vulnerable (intraplaque hemorrhage and lipid-rich/necrotic core) or stable (fibrous tissue and dense calcification) from the signal pattern. The plaque classification was statistically compared with the occurrence of slow-flow phenomenon.

RESULTS

The slow-flow phenomenon was observed in ten CAS procedures (five flow arrests and five flow reductions). Flow arrests consisted of four vulnerable and one stable plaque, and flow reductions consisted of four vulnerable and one stable plaque. The slow-flow phenomenon occurred significantly (P<0.01) more frequently in patients with vulnerable plaque.

CONCLUSIONS

Vulnerable carotid plaques have a significantly higher risk of slow-flow phenomenon than stable plaques. The occurrence of the slow-flow phenomenon can be predicted by MR plaque imaging before CAS.