The Development of Cortical Microinfarcts Is Associated with Intracranial Atherosclerosis: Data from the Chinese Intracranial Atherosclerosis Study

Microinfarcts in the Deep Gray Matter on 7T MRI: Risk Factors, MRI Correlates, and Relation to Cognitive Functioning-The SMART-MR Study

BACKGROUND AND PURPOSE

The clinical relevance of cortical microinfarcts has recently been established; however, studies on microinfarcts in the deep gray matter are lacking. We examined the risk factors and MR imaging correlates of microinfarcts in the deep gray matter on 7T MR imaging and their relation to cognitive functioning.

MATERIALS AND METHODS

Within the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study, 213 patients (mean age, 68 [SD, 8] years) had a risk-factor assessment, 7T and 1.5T brain MR imaging, and a cognitive examination. Microinfarcts on 7T MR imaging were defined as lesions of <5 mm. Regression models were used to examine the age-adjusted associations among risk factors, MR imaging markers, and microinfarcts. Cognitive function was summarized as composite and domain-specific z scores.

RESULTS

A total of 47 microinfarcts were found in 28 patients (13%), most commonly in the thalamus. Older age, history of stroke, hypertension, and intima-media thickness were associated with microinfarcts. On 1.5T MR imaging, cerebellar infarcts (relative risk = 2.75; 95% CI, 1.4-5.33) and lacunes in the white (relative risk = 3.28; 95% CI, 3.28-6.04) and deep gray matter (relative risk = 3.06; 95% CI, 1.75-5.35) were associated with microinfarcts, and on 7T MR imaging cortical microinfarcts (relative risk = 2.33; 95% CI, 1.32-4.13). Microinfarcts were also associated with poorer global cognitive functioning (mean difference in the global z score between patients with multiple microinfarcts versus none = -0.97; 95% CI, -1.66 to -0.28, P = .006) and across all cognitive domains.

CONCLUSIONS

Microinfarcts in the deep gray matter on 7T MR imaging were associated with worse cognitive functioning and risk factors and MR imaging markers of small-vessel and large-vessel disease. Our findings suggest that microinfarcts in the deep gray matter may represent a novel imaging marker of vascular brain injury.

Acute Cerebral Microinfarcts in Acute Ischemic Stroke: Imaging and Clinical Significance

BACKGROUND

Limited data exist on the significance of acute cerebral microinfarcts (A-CMIs) in the context of acute ischemic stroke (AIS). We aimed to determine the profile and prognostic significance of A-CMIs on magnetic resonance imaging (MRI) in patients presenting with AIS.

METHODS

A prospective single-center series of patients with AIS who had 3T MRIs between March 2013 and December 2019. The presence, number, and location of A-CMIs on diffusion-weighted imaging, and markers of cerebral small vessel disease (CSVD), macroinfarcts features, and etiology were classified as cardioembolism (CE) or large artery atherosclerosis (LAA) or none.

RESULTS

Among 273 patients, A-CMIs were detected in 130 patients (47.6%), of whom cortical A-CMIs were found in 95 (73.0%) patients. Patients with A-CMIs were significantly older, less likely to have diabetes mellitus, and more likely to have atrial fibrillation and an embolic source (CE or LAA) compared to other patients. Patients with A-CMI had a higher frequency of macroinfarcts (diameter >20 mm), more often multiple and distributed in single or multiple vessel territories than other patients. An embolic source (LAA or CE) was independently associated with cortical A-CMIs (LAA adjusted odds ratio [aOR] 4.0 95% confidence interval [CI] 1.6-9.5; CE aOR 2.5, 95% CI 1.1-5.6), whereas lacunes were independently related to subcortical A-CMIs (aOR 2.6, 95% CI 1.2-5.8).

CONCLUSIONS

We have shown A-CMIs occur in cortical and subcortical regions in nearly half of AIS patients, where microembolism and CSVD are, respectively, the key presumed etiological mechanism.

Association Between Cerebral Cortical Microinfarcts and Perilesional Cortical Atrophy on 3T MRI

BACKGROUND AND OBJECTIVES

Cerebral cortical microinfarcts (CMIs) are a novel MRI-marker of cerebrovascular disease (CeVD) that predicts accelerated cognitive decline. Presence of CMIs is known to be associated with global cortical atrophy, although the mechanism linking the two is unclear. Our primary objective was to examine the relation between CMIs and cortical atrophy and establish possible perilesional atrophy surrounding CMIs. Our secondary objective was to examine the role of cortical atrophy in CMI-associated cognitive impairment.

METHODS

Patients were recruited from two Singapore memory clinics between December 2010 and September 2013 and included if they received the diagnosis no objective cognitive impairment, cognitive impairment (with or without a history of stroke) or Alzheimer's or vascular dementia. Cortical thickness, chronic cortical microinfarcts and MRI-markers of CeVD were assessed on 3T MRI. Patients underwent cognitive testing. Cortical thickness was compared globally between patients with and without CMIs, regionally within individual patients with CMIs comparing brain regions with CMIs to the corresponding contralateral region without CMIs and locally within individuals patients in a 50 mm radius of CMIs. Global cortical thickness was analyzed as mediator in the relation between CMI and cognitive performance.

RESULTS

Of the 238 patients (mean age 72.5 SD 9.1 years) enrolled, 75 had ≥1 CMIs. Patient with CMIs had a 2.1% lower global cortical thickness (B=-.049 mm, 95% CI [.091; -.007] p=.022) compared to patients without CMIs, after correction for age, sex, education and intracranial volume. In patients with CMIs, cortical thickness in brain regions with CMIs was 2.2 % lower than in contralateral regions without CMIs (B=-.048 mm [-.071; -.026] p<.001). In a 20 mm radius area surrounding the CMI-core, cortical thickness was lower than in the area 20-50 mm from the CMI-core (Mean difference -.06 mm 95% CI [-.10; -.02] p=.002). Global cortical thickness was a significant mediator in the relationship between CMI presence and cognitive performance as measure with the Mini-Mental State Examination (B=-.12 [-.22; -.01] p=.025).

DISCUSSION

We found cortical atrophy surrounding CMIs, suggesting a perilesional effect in a cortical area many times larger than the CMI-core. Our findings support the notion that CMIs affect brain structure beyond the actual lesion site.

Cortical Microinfarcts Associated With Worse Outcomes in Patients With Acute Ischemic Stroke Receiving Endovascular Treatment

BACKGROUND AND PURPOSE

We aimed to evaluate the impact of cortical microinfarcts (CMIs) on functional outcome after endovascular treatment in patients with acute ischemic stroke.

METHODS

In a multicenter registration study for RESCUE-RE (a registration study for Critical Care of Acute Ischemic Stroke After Recanalization), eligible patients with large vessel occlusion stroke receiving endovascular treatment, who had undergone 3T magnetic resonance imaging on admission or within 24 hours after endovascular treatment were analyzed. We evaluated the presence and numbers of CMIs with assessment of axial T1, T2-weighted images, and fluid-attenuated inversion recovery images. The primary outcome was functional dependence or death defined as modified Rankin Scale scores of 3 to 6 at 90 days. Secondary outcomes included early neurological improvement, any intracranial hemorrhage, symptomatic intracranial hemorrhage, and mortality. We investigated the independent associations of CMIs with the outcomes using multivariable logistic regression in overall patients and in subgroups.

RESULTS

Among 414 patients (enrolled from July 2018 to May 2019) included in the analyses, 96 (23.2%) patients had at least one CMI (maximum 6). Patients with CMI(s) were more likely to be functionally dependent or dead at 90 days, compared with those without (55.2% versus 37.4%; P<0.01). In multivariable logistic regression analyses, presence of CMI(s) (adjusted odds ratio, 1.78 [95% CI, 1.04-3.07]; P=0.04) and multiple CMIs (CMIs ≥2; adjusted odds ratio, 7.41 [95% CI, 2.48-22.17]; P<0.001) were independently, significantly associated with the primary outcome. There was no significant difference between subgroups in the associations between CMI presence and the primary outcome.

CONCLUSIONS

Acute large vessel occlusion stroke patients receiving endovascular treatment with CMI(s) were more likely to have a poor functional outcome at 90 days, independent of patients' characteristics. Such associations may be dose-dependent. Registration: URL: http://www.chictr.org.cn; Unique identifier: ChiCTR1900022154.

The effects of changes in platelet-to-neutrophil ratios 24 hours after intravenous thrombolysis on prognosis in acute ischemic stroke patients

OBJECTIVE

To investigate the prognostic value of Platelet-to-Neutrophil ratio on admission (PNR on admission) and 24 h after intravenous thrombolysis (24 h PNR) in acute ischemic stroke patients (AIS) patients.

PATIENTS AND METHODS

One hundred fifty-one ischemic stroke patients receiving intravenous thrombolysis were retrospectively recruited in this study. Complete blood count evaluations for PNR were conducted on admission and 24 h after the treatment of thrombolysis. The poor outcome at 3months was defined as the modified Rankin Scale of 3-6.

RESULTS

In multivariate logistic regression, PNR on admission (odds ratio [OR] = 0.967, 95 % confidence interval [CI] = 0.939-0.996; P = 0.028), and 24 h PNR(OR = 0.933, 95 %CI = 0.895-0.972; P = 0.004) were all independent indicators for the 3-month poor prognosis in ischemic stroke patients receiving intravenous thrombolysis. The area under the curve of PNR on admission to predict poor functional outcomes at 3 months was 0.645 (95 %CI = 0.558-0.732; P < 0.001), and the best predictive PNR on admission value was 41.35. After the treatment of thrombolysis, the area under the curve of 24 h PNR to predict poor functional outcomes at 3 months was 0.796 (95 %CI = 0.722-0.858; P < 0.001), and the best predictive 24 h PNR value was 31.03.

CONCLUSIONS

Both the PNR on admission and 24 h PNR were independently associated with poor functional outcomes. Compared with the PNR on admission, 24 h PNR may serve as a more reliable marker for a poor prognosis in ischemic stroke patients receiving intravenous thrombolysis.

Cortical Microinfarcts and White Matter Connectivity in Memory Clinic Patients

Background and purpose: Cerebral microinfarcts (CMIs) are associated with cognitive impairment and dementia. CMIs might affect cognitive performance through disruption of cerebral networks. We investigated in memory clinic patients whether cortical CMIs are clustered in specific brain regions and if presence of cortical CMIs is associated with reduced white matter (WM) connectivity in tracts projecting to these regions.

Methods:164 memory clinic patients with vascular brain injury with a mean age of 72 ± 11 years (54% male) were included. All underwent 3 tesla MRI, including a diffusion MRI and cognitive testing. Cortical CMIs were rated according to established criteria and their spatial location was marked. Diffusion imaging-based tractography was used to reconstruct WM connections and voxel based analysis (VBA) to assess integrity of WM directly below the cortex. WM connectivity and integrity were compared between patients with and without cortical CMIs for the whole brain and regions with a high CMI burden.

Results:30 patients (18%) had at least 1 cortical CMI [range 1–46]. More than 70% of the cortical CMIs were located in the superior frontal, middle frontal, and pre- and postcentral brain regions (covering 16% of the cortical surface). In these high CMI burden regions, presence of cortical CMIs was not associated with WM connectivity after correction for conventional neuroimaging markers of vascular injury. WM connectivity in the whole brain and WM voxels directly underneath the cortical surface did not differ between patients with and without cortical CMIs.

Conclusion:Cortical CMIs displayed a strong local clustering in highly interconnected frontal, pre- and postcentral brain regions. Nevertheless, WM connections projecting to these regions were not disproportionally impaired in patients with compared to patients without cortical CMIs. Alternative mechanisms, such as focal disturbances in cortical structure and functioning, may better explain CMI associated cognitive impairment.

Asymptomatic Cerebral Small Vessel Disease: Insights from Population-Based Studies

Cerebral small vessel disease (CSVD) is a common group of neurological conditions that confer a significant burden of morbidity and mortality worldwide. In most cases, CSVD is only recognized in its advanced stages once its symptomatic sequelae develop. However, its significance in asymptomatic healthy populations remains poorly defined. In population-based studies of presumed healthy elderly individuals, CSVD neuroimaging markers including white matter hyperintensities, lacunes, cerebral microbleeds, enlarged perivascular spaces, cortical superficial siderosis, and cerebral microinfarcts are frequently detected. While the presence of these imaging markers may reflect unique mechanisms at play, there are likely shared pathways underlying CSVD. Herein, we aim to assess the etiology and significance of these individual biomarkers by focusing in asymptomatic populations at an epidemiological level. By primarily examining population-based studies, we explore the risk factors that are involved in the formation and progression of these biomarkers. Through a critical semi-systematic review, we aim to characterize “asymptomatic” CSVD, review screening modalities, and draw associations from observational studies in clinical populations. Lastly, we highlight areas of research (including therapeutic approaches) in which further investigation is needed to better understand asymptomatic CSVD.

Cortical Cerebral Microinfarcts on 3 Tesla MRI in Patients with Vascular Cognitive Impairment

BACKGROUND

Cerebral microinfarcts (CMIs) are small ischemic lesions that are a common neuropathological finding in patients with stroke or dementia. CMIs in the cortex can now be detected in vivo on 3 Tesla MRI.

OBJECTIVE

To determine the occurrence of CMIs and associated clinical features in patients with possible vascular cognitive impairment (VCI).

METHOD

182 memory-clinic patients (mean age 71.4±10.6, 55% male) with vascular injury on brain MRI (i.e., possible VCI) underwent a standardized work-up including 3 Tesla MRI and cognitive assessment. A control group consisted of 70 cognitively normal subjects (mean age 70.6±4.7, 60% male). Cortical CMIs and other neuroimaging markers of vascular brain injury were rated according to established criteria.

RESULT

Occurrence of CMIs was higher (20%) in patients compared to controls (10%). Among patients, the presence of CMIs was associated with male sex, history of stroke, infarcts, and white matter hyperintensities. CMI presence was also associated with a diagnosis of vascular dementia and reduced performance in multiple cognitive domains.

CONCLUSION

CMIs on 3 Tesla MRI are common in patients with possible VCI and co-occur with imaging markers of small and large vessel disease, likely reflecting a heterogeneous etiology. CMIs are associated with worse cognitive performance, independent of other markers of vascular brain injury.

Comparison of Premortem Magnetic Resonance Imaging and Postmortem Autopsy Findings of a Cortical Microinfarct

An 85-year-old woman diagnosed with amyotrophic lateral sclerosis died of pneumonia and was autopsied. Magnetic resonance imaging (MRI) performed 16 days before death revealed an intracortical high-intensity lesion in her right temporal cortex on three-dimensional (3D)-double inversion recovery (DIR) and 3D-fluid-attenuated inversion recovery (FLAIR) images. Histopathological examination indicated a cortical microinfarct (CMI) juxtaposed to cerebral amyloid angiopathy. Recently, in vivo detection of CMIs using 3D-DIR and 3D-FLAIR on 3-tesla MRI has been reported, and postmortem MRI study confirmed the presence of CMIs. This is the first case study to compare CMI findings detected upon premortem MRI to the CMI itself discovered upon postmortem neuropathological examination.

Detection, risk factors, and functional consequences of cerebral microinfarcts

Cerebral microinfarcts are small lesions that are presumed to be ischaemic. Despite the small size of these lesions, affected individuals can have hundreds to thousands of cerebral microinfarcts, which cause measurable disruption to structural brain connections, and are associated with dementia that is independent of Alzheimer's disease pathology or larger infarcts (ie, lacunar infarcts, and large cortical and non-lacunar subcortical infarcts). Substantial progress has been made with regard to understanding risk factors and functional consequences of cerebral microinfarcts, partly driven by new in-vivo detection methods and the development of animal models that closely mimic multiple aspects of cerebral microinfarcts in human beings. Evidence from these advances suggests that cerebral microinfarcts can be manifestations of both small vessel and large vessel disease, that cerebral microinfarcts are independently associated with cognitive impairment, and that these lesions are likely to cause damage to brain structure and function that extends beyond their actual lesion boundaries. Criteria for the identification of cerebral microinfarcts with in-vivo MRI are provided to support further studies of the association between these lesions and cerebrovascular disease and dementia.