Periventricular and deep white matter leukoaraiosis have a closer association with cerebral microbleeds than age

A nomogram for predicting cerebral white matter lesions in elderly men

Objective

This study aimed to develop a nomogram tool to predict cerebral white matter lesions (WMLs) in elderly men.

Methods

Based on a retrospective cohort from January 2017 to December 2019, a multivariate logistic analysis was performed to construct a nomogram for predicting WMLs. The nomogram was further validated using a follow-up cohort between January 2020 and December 2022. The calibration curve, receiver operating characteristics (ROC) curves, and the decision curves analysis (DCA) were used to evaluate discrimination and calibration of this nomogram.

Result

A total of 436 male patients were enrolled in this study, and all 436 patients were used as the training cohort and 163 follow-up patients as the validation cohort. A multivariate logistic analysis showed that age, cystatin C, uric acid, total cholesterol, platelet, and the use of antiplatelet drugs were independently associated with WMLs. Based on these variables, a nomogram was developed. The nomogram displayed excellent predictive power with the area under the ROC curve of 0.951 [95% confidence interval (CI), 0.929-0.972] in the training cohort and 0.915 (95% CI, 0.864-0.966) in the validation cohort. The calibration of the nomogram was also good, as indicated by the Hosmer-Lemeshow test with p-value of 0.594 in the training cohort and 0.178 in the validation cohort. The DCA showed that the nomogram holds good clinical application value.

Conclusion

We have developed and validated a novel nomogram tool for identifying elderly men at high risk of WMLs, which exhibits excellent predictive power, discrimination, and calibration.

The analysis of association between single features of small vessel disease and stroke outcome shows the independent impact of the number of microbleeds and presence of lacunes

The impact of small vessel disease (SVD) on stroke outcome was investigated either separately for its single features in isolation or for SVD sum score measuring a qualitative (binary) assessment of SVD-lesions. We aimed to investigate which SVD feature independently impacts the most on stroke outcome and to compare the continuous versus binary SVD assessment that reflects pronouncement and presence correspondingly. Patients with a first-ever anterior circulation ischemic stroke were retrospectively investigated. We performed an ordered logistic regression analysis to predict stroke outcome (mRS 3 months, 0-6) using age, stroke severity, and pre-stroke disability as baseline input variables and adding SVD-features (lacunes, microbleeds, enlarged perivascular spaces, white matter hyperintensities) assessed either continuously (model 1) or binary (model 2). The data of 873 patients (age 67.9 ± 15.4, NIHSS 24 h 4.1 ± 4.8) was analyzed. In model 1 with continuous SVD-features, the number of microbleeds was the only independent predictor of stroke outcome in addition to clinical parameters (OR 1.21; 95% CI 1.07-1.37). In model 2 with the binary SVD assessment, only the presence of lacunes independently improved the prediction of stroke outcome (OR 1.48, 1.1-1.99). In a post hoc analysis, both the continuous number of microbleeds and the presence of lacunes were independent significant predictors. Thus, the number of microbleeds evaluated continuously and the presence of lacunes are associated with stroke outcome independent from age, stroke severity, pre-stroke disability and other SVD-features. Whereas the presence of lacunes is adequately represented in SVD sum score, the microbleeds assessment might require another cutoff and/or gradual scoring, when prediction of stroke outcome is needed.

The iron burden of cerebral microbleeds contributes to brain atrophy through the mediating effect of white matter hyperintensity

The goal of this work was to explore the total iron burden of cerebral microbleeds (CMBs) using a semi-automatic quantitative susceptibility mapping and to establish its effect on brain atrophy through the mediating effect of white matter hyperintensities (WMH). A total of 95 community-dwelling people were enrolled. Quantitative susceptibility mapping (QSM) combined with a dynamic programming algorithm (DPA) was used to measure the characteristics of 1309 CMBs. WMH were evaluated according to the Fazekas scale, and brain atrophy was assessed using a 2D linear measurement method. Histogram analysis was used to explore the distribution of CMBs susceptibility, volume, and total iron burden, while a correlation analysis was used to explore the relationship between volume and susceptibility. Stepwise regression analysis was used to analyze the risk factors for CMBs and their contribution to brain atrophy. Mediation analysis was used to explore the interrelationship between CMBs and brain atrophy. We found that the frequency distribution of susceptibility of the CMBs was Gaussian in nature with a mean of 201 ppb and a standard deviation of 84 ppb; however, the volume and total iron burden of CMBs were more Rician in nature. A weak but significant correlation between the susceptibility and volume of CMBs was found (r = -0.113, P < 0.001). The periventricular WMH (PVWMH) was a risk factor for the presence of CMBs (number: β = 0.251, P = 0.014; volume: β = 0.237, P = 0.042; total iron burden: β = 0.238, P = 0.020) and was a risk factor for brain atrophy (third ventricle width: β = 0.325, P = 0.001; Evans's index: β = 0.323, P = 0.001). PVWMH had a significant mediating effect on the correlation between CMBs and brain atrophy. In conclusion, QSM along with the DPA can measure the total iron burden of CMBs. PVWMH might be a risk factor for CMBs and may mediate the effect of CMBs on brain atrophy.

Clinical Prediction Model for Screening Acute Ischemic Stroke Patients With More Than 10 Cerebral Microbleeds

Background

Hemorrhagic transformation is one of the most serious complications in intravenous thrombolysis. Studies show that the existence of more than 10 cerebral microbleeds is strongly associated with hemorrhagic transformation. The current study attempts to develop and validate a clinical prediction model of more than 10 cerebral microbleeds.

Methods

We reviewed the computed tomography markers of cerebral small vessel diseases and the basic clinical information of acute ischemic stroke patients who were investigated using susceptibility weighted imaging from 2018 to 2021. A clinical prediction model of more than 10 cerebral microbleeds was established. Discrimination, calibration, and the net benefit of the model were assessed. Finally, a validation was conducted to evaluate the accuracy and stability of the model.

Results

The multivariate logistic regression model showed hypertension, and some computed tomography markers (leukoaraiosis, lacunar infarctions, brain atrophy) were independent risk factors of more than 10 cerebral microbleeds. These risk factors were used for establishing the clinical prediction model. The area under the receiver operating characteristic curve (AUC) was 0.894 (95% CI: 0.870–0.919); Hosmer–Lemeshow chi-squared test yielded χ² = 3.946 (P = 0.862). The clinical decision cure of the model was higher than the two extreme lines. The simplified score of the model ranged from 0 to 12. The model in the internal and external validation cohort also had good discrimination (AUC 0.902, 95% CI: 0.868–0.937; AUC 0.914, 95% CI: 0.882–0.945) and calibration (P = 0.157, 0.247), and patients gained a net benefit from the model.

Conclusions

We developed and validated a simple scoring tool for acute ischemic stroke patients with more than 10 cerebral microbleeds; this tool may be beneficial for paradigm decision regarding intravenous recombinant tissue plasminogen activator therapy of acute ischemic stroke.

Cerebral Microbleeds With Atrial Fibrillation After Ablation Therapy

Background

The prevalence of cerebral microbleeds (CMBs) is significantly higher in patients with atrial fibrillation (AF) than in those without AF. CMBs in patients with AF have been reported to be primarily of the lobar type, but the exact cause of this remains unknown. We investigated the possibility that hemorrhagic transformation of embolic microinfarction can account for de novo lobar CMBs.

Methods

A total of 101 patients who underwent ablation therapy for AF were prospectively registered, and 72 patients completed the assessment with MRI 6 months after catheter ablation. Brain MRI, including diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI), were examined at 1–3 days (baseline) and 6 months after catheter ablation. We quantitatively evaluated the spatial and temporal distribution of embolic microinfarctions and de novo CMBs.

Results

Of the 101 patients, 68 were enrolled in this study. Fifty-nine patients (86.8%) showed embolic microinfarctions on baseline DWI immediately after catheter ablation. There were 137 CMBs in SWI, and 96 CMBs were of the lobar type. Six months later, there were 208 CMBs, including 71 de novo CMBs, and 60 of 71 (84.5%) were of the lobar type. Of the 71 de novo CMBs, 56 (78.9%) corresponded to the location of previous embolic microinfarctions found on baseline DWI. The platelet count was significantly lower and hematocrit/hemoglobin and Fazekas score were higher in the group with de novo CMBs than in the group without de novo CMBs.

Conclusion

De novo CMBs frequently appeared after catheter ablation therapy. Our results suggest that embolic microinfarction can cause lobar CMBs.

Characteristics of Cortical Atrophy and White Matter Lesions Between Dementia With Lewy Bodies and Alzheimer's Disease: A Case-Control Study

Introduction: Currently, there is still clinical overlap between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) patients, which may affect the accuracy of the early diagnosis of DLB. For better diagnosis and prognosis, further exploration of local cortical atrophy patterns and white matter lesions is needed.

Methods: We reviewed the outpatient medical records of 97 DLB patients and 173 AD patients from January 2018 to September 2020 along with 30 matched outpatient clinic normal elderly people. MRI visual rating scales, including medial temporal lobe atrophy (MTA), global cortical atrophy-frontal subscale (GCA-F), posterior atrophy (PA), Fazekas scale, Evans Index and cerebral microbleeds were evaluated and analyzed in DLB and AD patients with different severities and normal controls.

Results: Overall, patients with DLB had higher scores on all visual rating scales than the normal controls. Meanwhile, compared with AD, DLB had lower MTA scores in the mild to moderate groups (both p ≤ 0.001), but the GCA-F and PA scores were similar (all p > 0.05). The Fazekas scores in the moderate to severe DLB group were lower than those in the AD group (p = 0.024 and p = 0.027, respectively). In addition, the diagnostic performance and sensitivity of multiple imaging indicators for DLB were better than that of MTA alone (the combination of MTA, GCA-F, PA, Fazekas visual rating scales, AUC = 0.756, 95%CI: 0.700–0.813, sensitivity = 0.647, specificity = 0.804 and MTA visual rating scale, AUC = 0.726, 95%CI: 0.667–0.785, sensitivity = 0.497, specificity = 0.876, respectively).

Conclusion: The medial temporal lobe of DLB patients was relatively preserved, the frontal and parietal lobes were similarly atrophied to AD patients, and the white matter hyperintensity was lighter than that in AD patients. Combined multiple visual rating scales may provide a novel idea for the diagnosis of early DLB.

Patterns and Predictors of Extra-Corporeal Membrane Oxygenation Related Cerebral Microbleeds

OBJECTIVES

Recent case-reports have described an atypical cerebral microbleed (CMB) topography after extracorporeal membrane oxygenation (ECMO). The objective of this study was to examine the prevalence, radiographic patterns, and clinical correlates of possibly-ECMO-related (PER) CMB.

MATERIALS AND METHODS

We performed a retrospective study of 307 consecutive patients receiving ECMO support at our tertiary-care University Hospital (2013-2018). PER CMB were defined as CMB present in corpus-callosum and/or middle cerebellar peduncle with/without involvement of other lobar/deep structures. Leukoaraiosis was quantified using the Wahlund age-related white matter changes scale. Patient characteristics were compared between cohorts with and without PER CMB.

RESULTS

Forty patients (median age 60 years; 33% vv-ECMO and 67% va-ECMO) received at-least one MRI-brain within 3 months of ECMO support. CMB were present in 77.5% (n = 31) patients with 39% (n = 12), 17% (n = 5), and 44% (n = 14) having low (< 10 CMB), moderate (10-30 CMB), and high (> 30 CMB) burden respectively. Among CMB-positive patients, 71% (n = 22) had PER CMB, with 91% of such cases demonstrating involvement of splenium. Leukoaraiosis did not corelate to PER CMB presence (p = 0.267) or burden (ρ = 0.09). Patients with PER CMB had higher rates of ischemic stroke (50 vs. 33%), intracranial hemorrhage (41 vs. 17%), and all-cause mortality (27 vs. 17%); with survivors demonstrating no differences in their discharge disposition or modified Rankin Score.

CONCLUSIONS

Post-ECMO cerebral microbleeds have a distinct distribution pattern that commonly involves the splenium of corpus-callosum. Their etiopathogenesis may be independent of microvascular lipohyalinosis. This requires further study in a larger sample-size.

Cerebral Microbleeds Load and Long-Term Outcomes in Minor Ischemic Stroke

BACKGROUND AND PURPOSE

The association between the cerebral microbleed (CMB) count and outcomes in ischemic stroke has not been fully clarified. The aim of this study was to investigate the relationship between the CMBs count and functional outcomes in patients with a minor ischemic stroke treated with antiplatelet therapy METHODS: Non-cardiogenic minor ischemic stroke (NIHSS score < 4 on admission) patients who were treated with antiplatelet therapy were enrolled. The patients were divided into four groups based on the number of CMBs (absent, 1, 2-4, and > 4), and their clinical outcomes were compared. A poor outcome was defined as a modified Rankin scale (mRS) score of 3-6 90 days after symptom onset. Logistic regression analysis was performed to evaluate whether the CMBs count contributes to poor outcomes with well-known risk factors such as age, NIHSS score on admission, ischemic stroke recurrence, large artery atherosclerosis stroke subtype, and DWMHs.

RESULTS

A total of 240 patients were enrolled, and their pre mRS scores were matched based on CMB presence. A higher burden of CMBs was linearly correlated with the incidence of poor outcomes (4% in the absent group, 8% in the 1 CMB group, 13% in the 2-4 CMB group, and 20% in the > 4 CMB group, P = 0.002). Multivariate logistic regression analysis showed that CMBs count was one of the independent factor associated with poor outcomes (odds ratio 1.07, 95% confidence interval 1.02-1.12, P = 0.003).

CONCLUSION

The CMBs count contributes independently to poor outcomes in minor ischemic stroke patients treated with antiplatelet therapy.

Coexistence of Cerebral Microbleeds and Amyloid Pathology in Patients with Cognitive Complaints

Background and Purpose

We investigated the prevalence of amyloid positivity and cerebral microbleeds (CMBs) in subjects with cognitive complaints with the aim of identifying differences in clinical parameters and cognitive function according to the pattern of coexistence.

Methods

We retrospectively enrolled 200 subjects with memory impairment and applied both standardized ¹⁸F-florbetaben PET and brain MRI, including susceptibility-weighted imaging. The amyloid burden was visually classified as positive or negative, and the number and location of CMBs were also analyzed visually. Descriptive analysis was performed for the prevalence of amyloid positivity and CMBs. The relationship between the coexisting pattern of those two findings and clinical parameters including the results of neuropsychiatric tests was analyzed.

Results

Positive amyloid PET scans were exhibited by 102 (51.5%) of the 200 patients, and 51 (25.5%) of them had CMBs, which were mostly located in lobar areas in the patients with positive amyloid scans. The patients with CMBs were older and had a higher burden of white-matter hyperintensities than the patients without CMBs. The patients with CMBs also performed worse in confrontation naming and frontal/executive function. When classified by topographical region, parietal CMBs (odds ratio=3.739, p=0.024) were significantly associated with amyloid positivity.

Conclusions

The prevalence of CMBs was higher in patients with cognitive decline than in the general population. CMBs play distinctive roles in affecting clinical parameters and neuropsychological profiles according to the coexistence of amyloid pathology.

The study on analysis of risk factors for severity of white matter lesions and its correlation with cerebral microbleeds in the elderly with lacunar infarction

This study aimed to explore the risk factors for severity of white matter lesions and its correlation with in the elderly with lacunar infarction.Patients (range, 70-85 years) with lacunar infarction treated in a hospital in China from 2016 to 2017were enrolled. Fazekas rating scale (0-6 points) was used to assess severity of white matter lesions. Risk factors for the severity of white matter lesions and correlation between cerebral microbleeds and white matter lesions in the elderly with lacunar infarction were studied.The elderly (81-85 years' old, odds ratio [OR]: 2.423, 95% confidence interval [CI]: 1.795-3.271, P = .018; 76∼80 years' old, OR: 3.113, 95% CI: 1.723-5.625, P = .043), carotid atherosclerosis (OR: 3.062, 95% CI:1.715-5.468, P < .001), history of hypertension (OR: 3.694, 95% CI: 2.031-6.717, P < .001) were risk factors for the severity of white matter lesions. The white matter lesions score increased corresponding to increase in the cerebral microbleeds grade (P < .001). The white matter lesions score was higher in the cerebral microbleeds combined with the white matter lesions group than in the white matter lesions group (P < .01). After correcting the effects of age, there was a correlation between white matter lesions and cerebral microbleeds (P < .001). Logistic analysis revealed that the patients' age (81-85 years' old, OR: 2.722, 95% CI: 1.985-3.734, P = .019; 76∼80 years' old, OR: 1.857, 95% CI: 1.075-3.207, P = .031), history of hypertension (OR: 2.931, 95% CI: 1.136-7.567, P = 0.0.036), systolic blood pressure (OR: 1.049, 95% CI: 1.015-1.084, P = .007), high-sensitivity C-reactive protein (OR: 1.504, 95% CI: 1.254-1.803, P < .001), homocysteine (OR: 1.076, 95% CI: 1.020-1.136, P = .009), and carotid atherosclerosis (OR: 1.389, 95% CI: 1.103-1.748, P = .010) were significant risk factors for combined cerebral microbleeds with white matter lesions in patients with lacunar infarction.The elderly, carotid atherosclerosis, history of hypertension were risk factors for the severity of white matter lesions. Cerebral microbleeds were positively correlated with the severity of white matter lesions.

MRI Assessment of Cerebral Small Vessel Disease in Patients with Spontaneous Intracerebral Hemorrhage

PURPOSE

Cerebral small vessel disease (SVD) is known to be associated with ischemic stroke, intracerebral hemorrhage (ICH), and cognitive impairment. In this retrospective observational study, we explored SVD markers on MRI relevant to spontaneous ICH.

MATERIALS AND METHODS

The ICH group consisted of 150 consecutive patients with a first primary parenchymal ICH, and the control group consisted of 271 age- and sex-matched individuals who underwent brain MRI in a health care center. We compared cerebral microbleeds (CMBs), white matter hyperintensities (WMHs), enlarged perivascular space (EPVS), and lacunae in the ICH and control groups.

RESULTS

A total of 1278 CMB lesions were identified in 121 of the 150 patients in the ICH group (80.6%), while 77 CMB lesions were found in 32 of the 271 individuals in the control group (11.8%). WMH and EPVS were more severe and lacunae were more frequent in the ICH patients than in the control group. When receiver operating characteristic (ROC) curves were plotted, number of CMBs most significantly predicted ICH. All imaging markers were significantly associated with ICH in every age group. The location of CMBs coincided with the location of ICH, and ICH volume correlated with CMB count.

CONCLUSION

All MRI markers for SVD were worse in ICH patients than in healthy controls, and these markers were prominent even in young ICH patients. Lacunae, WMH, EPVS, and CMB should be considered as factors related with spontaneous ICH.

The relationship between deep medullary veins score and the severity and distribution of intracranial microbleeds

Background

Microbleeds are frequently detected in normal elderly population, and their presence is associated with an increased risk of intracerebral hemorrhage, ischemic stroke and cognitive impairment. Previous histopathologic findings mainly focused on arteries and capillaries. Nevertheless, few studies investigated the relationship between venous disruption and microbleeds.

Objective

We aimed to evaluate the extent of venous disruption in vivo and assess the correlation between deep medullary veins (DMVs) disruption and the severity and distribution of intracranial microbleeds in patients with cerebral small vessel disease (cSVD).

Methods

We retrospectively reviewed the clinical, laboratory and imaging data of the patients admitted to our department who received brain MRI and presented with CSVD imaging markers. Susceptibility weighted imaging (SWI) phase images were used to observe characteristics of DMVs and derive a brain region-based DMVs visual score. SWI magnitude images were used to evaluate microbleeds. We recorded the number and distribution (lobar or deep or infratentorial) of microbleeds. One-way ANOVA and logistic-regression analysis were used to examine the association between the DMVs score and microbleeds.

Results

A total of 369 cSVD patients were analyzed, including 177 (48.0%) patients with microbleeds, among whom 81(45.8%) patients had 1–2 microbleeds and 96 (54.2%) patients had ≥3 microbleeds (extensive microbleeds). The patients' DMVs score ranged from 0 to18, with a median score of 8(6–12). Higher DMVs score was independently associated with extensive microbleeds (OR = 1.108, 95%Cl: 1.010–1.215, p = 0.03) after adjusting for gender, hypertension, hyperhomocysteinemia, Fazekas score and number of lacunas. According to the distribution, 38 (21.5%) patients were found with strict lobar microbleeds, while 139 (78.5%) patients had non-strict lobar microbleeds. Higher DMVs score was also independently associated with non-strict lobar microbleeds (OR = 1.106, 95% Cl: 1.019–1.200, p = 0.016) after adjusting for gender, hypertension, hyperhomocysteinemia, Fazekas score and number of lacunas. DMVs score was not associated with strict lobar microbleeds (p = 0.307).

Conclusion

DMVs disruption might be involved in the development of extensive microbleeds, especially non-strict lobar cerebral microbleeds.

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Deep medullary veins disruption was associated with extensive microbleeds.

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Deep medullary veins disruption was associated with non-strict lobar microbleeds.

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Venous insufficiency may be one of the pathogenic mechanisms of microbleeds.

Susceptibility Weighted Imaging (SWI) Recommended as a Regular Magnetic Resonance Diagnosis for Vascular Dementia to Identify Independent Idiopathic Normal Pressure Hydrocephalus Before Ventriculo-Peritoneal (V-P) Shunt Treatment: A Case Study

Idiopathic normal pressure hydrocephalus (INPH) with comorbid vascular dementia (VD) often have poor response to ventriculo-peritoneal (V-P) shunt. Here, three patients over the age of 60 came to the hospital with the similar clinical symptoms, Evan index over 0.3, mini-mental state examination (MMSE) score <27, and cerebrospinal fluid (CSF) pressure under 200 mmH₂O. They accepted conventional brain imaging scanning, followed by magnetic resonance-susceptibility weighted imaging (MR-SWI) scanning. We found that MR-SWI could distinguish INPH from leukoaraiosis (LA) and cerebral amyloid angiopathy (CAA), through cerebral microbleed (CMB) images, sharply. We highly recommended incorporation of MR-SWI into INPH international guidance as a routine pre-operative diagnostic method preceding V-P shunt treatment.

Cerebral microbleeds in patients with ischemic cerebrovascular disease taking aspirin or clopidogrel

Cerebral microbleeds (CMBs) may be markers of intracerebral bleeding risk in patients receiving antithrombotic drugs. This study aimed to analyze CMBs and white matter hyperintensities (WMHs) in patients taking aspirin or clopidogrel.This retrospective study included patients with ischemic cardiovascular disease administered 75 mg/day aspirin (n = 150) or clopidogrel (n = 150, matched for age and gender) for >1 year (Affiliated Hospital of Inner Mongolia Medical University, China, from July, 2010 to July, 2015). Patients underwent T2-weighted imaging, T1-weighted imaging, diffusion-weighted imaging (DWI) and enhanced T2*-weighted angiography (ESWAN) imaging (3.0-Tesla scanner). Baseline vascular risk factors for CMBs and macroscopic bleeding (MB) were evaluated using univariate and multivariate analyses.The aspirin and clopidogrel groups did not differ significantly in baseline characteristics or prevalences of CMBs or MB. The odds of MB were higher in patients with CMBs than in patients without CMBs in both the aspirin (odds ratio, 95% confidence interval: 4.09, 1.93-8.68; P < .001) and clopidogrel (6.42, 2.83-14.57; P < .001) groups. The odds of WMHs were also higher in patients with CMBs in both the aspirin (3.28, 1.60-6.71; P = .001) and clopidogrel (4.09, 1.91-8.75; P < .001) groups. Patients receiving treatment for >5 years showed elevated risk of CMBs in the aspirin (0.17; 0.09-0.36; P < .001) and clopidogrel (0.15, 0.07-0.33; P < .001) groups as well as higher odds of MB in the aspirin (0.34, 0.16-0.71; P = .004) and clopidogrel (0.37, 0.17-0.80; P = .010) groups.The WMHs and MB were associated with CMBs in patients taking aspirin or clopidogrel for >1 year, and long-term use increased the risks of CMB and bleeding.

Cerebral microbleeds: hearing through the silence-a narrative review

OBJECTIVE

The term cerebral microbleed (CMB) refers to lesions documented as unexpected findings during computed tomography or magnetic resonance imaging examination of the brain. Initially, a CMB was thought to represent hemosiderin-laden macrophages marking an area of a tiny hemorrhage. Recently, histopathologic studies have shown that the structure of a CMB can be variable. To aid in dealing with this finding and judging its clinical significance, this review addresses important aspects of a CMB, including the definition, prevalence, and incidence in various populations, end-organ damage, associated conditions, and whether any action or treatment by the clinician might be indicated.

METHODS

PubMed Medline, EMBASE, BIOSIS, Current Contents, and Derwent Drug Files databases were searched for the keywords "microbleeds-detection-damage", "silent bleeds", "microbleeds", or "silent bleeds AND hemophilia" from 2011-2016. References of retrieved articles were also reviewed and included if applicable.

RESULTS

The published data are found primarily in the imaging literature and focus on diagnostic techniques. Some publications address relationships with diverse, co-existing clinical conditions and implications for treatment, especially in stroke, intracranial hemorrhage, and antithrombotic therapy.

CONCLUSIONS

It is critical for non-radiologist clinicians (primary care, internists, neurologists, hematologists) to be aware of the potential importance of the finding of a CMB, and the fact that these lesions are not always truly silent or without important clinical consequences. As additional studies appear, clinicians may be able to "hear" more clearly through the silence of the CMB and understand potential clinical implications in patients.

Neuroimaging in aging and neurologic diseases

Neuroimaging biomarkers for neurologic diseases are important tools, both for understanding pathology associated with cognitive and clinical symptoms and for differential diagnosis. This chapter explores neuroimaging measures, including structural and functional measures from magnetic resonance imaging (MRI) and molecular measures primarily from positron emission tomography (PET), in healthy aging adults and in a number of neurologic diseases. The spectrum covers neuroimaging measures from normal aging to a variety of dementias: late-onset Alzheimer's disease [AD; including mild cognitive impairment (MCI)], familial and nonfamilial early-onset AD, atypical AD syndromes, posterior cortical atrophy (PCA), logopenic aphasia (lvPPA), cerebral amyloid angiopathy (CAA), vascular dementia (VaD), sporadic and familial behavioral-variant frontotemporal dementia (bvFTD), semantic dementia (SD), progressive nonfluent aphasia (PNFA), frontotemporal dementia with motor neuron disease (FTD-MND), frontotemporal dementia with amyotrophic lateral sclerosis (FTD-ALS), corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), dementia with Lewy bodies (DLB), Parkinson's disease (PD) with and without dementia, and multiple systems atrophy (MSA). We also include a discussion of the appropriate use criteria (AUC) for amyloid imaging and conclude with a discussion of differential diagnosis of neurologic dementia disorders in the context of neuroimaging.

Detecting cerebrovascular changes in the brain caused by hypertension in atrial fibrillation group using acoustocerebrography

Acoustocerebrography is a novel, non-invasive, transcranial ultrasonic diagnostic method based on the transmission of multispectral ultrasound signals propagating through the brain tissue. Dedicated signal processing enables the estimation of absorption coefficient, frequency-dependent attenuation, speed of sound and tissue elasticity. Hypertension and atrial fibrillation are well known factors correlated with white matter lesions, intracerebral hemorrhage and cryptogenic stroke numbers. The aim of this study was to compare the acoustocerebrography signal in the brains of asymptomatic atrial fibrillation patients with and without hypertension. The study included 97 asymptomatic patients (40 female and 57 male, age 66.26 ± 6.54 years) who were clinically monitored for atrial fibrillation. The patients were divided into two groups: group I (patients with hypertension) n = 75, and group II (patients without hypertension) n = 22. Phase and amplitude of all spectral components for the received signals from the brain path were extracted and compared to the phase and amplitude of the transmitted pulse. Next, the time of flight and the attenuation of each frequency component were calculated. Additionally, a fast Fourier transformation was performed and its features were extracted. After introducing a machine learning technique, the ROC plot of differentiations between group I and group II with an AUC of 0.958 (sensitivity 0.99 and specificity 0.968) was obtained. It can be assumed that the significant difference in the acoustocerebrography signals in patients with hypertension is due to changes in the brain tissue, and it allows for the differentiating of high-risk patients with asymptomatic atrial fibrillation and hypertension.

Uncommon Causes of Cerebral Microbleeds

BACKGROUND

Cerebral microbleeds (CMBs) are small and round perivascular hemosiderin depositions detectable by gradient echo sequences or susceptibility-weighted imaging. Cerebral microbleeds are common among patients with hypertension, cerebral ischemia, or cerebral amyloid angiopathy. In this article, we describe uncommon causes of CMBs.

METHODS

We searched Pubmed with the keyword CMBs for relevant studies and looked for different uncommon causes of CMBs.

RESULTS

CMBs have several uncommon etiologies including posterior reversible encephalopathy syndrome, infective endocarditis, brain radiation therapy, cocaine abuse, thrombotic thrombocytopenic purpura, traumatic brain injury, intravascular lymphomatosis or proliferating angio-endotheliomatosis, moyamoya disease, sickle cell anemia/β-thalassemia, cerebral autosomal dominant arteriopathy subcortical infarcts, and leukoencephalopathy (CADASIL), genetic syndromes, or obstructive sleep apnea.

CONCLUSIONS

Understanding the uncommon causes of CMBs is not only helpful in diagnosis and prognosis of some of these rare diseases, but can also help in better understanding different pathophysiology involved in the development of CMBs.

Gene expression variability and the analysis of large-scale RNA-seq studies with the MDSeq

Rapidly decreasing cost of next-generation sequencing has led to the recent availability of large-scale RNA-seq data, that empowers the analysis of gene expression variability, in addition to gene expression means. In this paper, we present the MDSeq, based on the coefficient of dispersion, to provide robust and computationally efficient analysis of both gene expression means and variability on RNA-seq counts. The MDSeq utilizes a novel reparametrization of the negative binomial to provide flexible generalized linear models (GLMs) on both the mean and dispersion. We address challenges of analyzing large-scale RNA-seq data via several new developments to provide a comprehensive toolset that models technical excess zeros, identifies outliers efficiently, and evaluates differential expressions at biologically interesting levels. We evaluated performances of the MDSeq using simulated data when the ground truths are known. Results suggest that the MDSeq often outperforms current methods for the analysis of gene expression mean and variability. Moreover, the MDSeq is applied in two real RNA-seq studies, in which we identified functionally relevant genes and gene pathways. Specifically, the analysis of gene expression variability with the MDSeq on the GTEx human brain tissue data has identified pathways associated with common neurodegenerative disorders when gene expression means were conserved.

The Presence of Previous Cerebral Microbleeds Has a Negative Effect on Hypertensive Intracerebral Hemorrhage Recovery

Background and Purpose: Cerebral microbleeds are an intracerebral microangiopathy with bleeding tendency found in intracerebral hemorrhage patients. However, studies about cerebral microbleed effects on the prognosis of hypertensive intracerebral hemorrhage patients are rare. We performed a prospective study to discuss not only the risk factors of cerebral microbleed incidence in hypertensive intracerebral hemorrhage patients but also the relevance of cerebral microbleeds with silent brain infarction, hemorrhage and prognosis.

Methods: This study enrolled 100 patients diagnosed with hypertensive intracerebral hemorrhage within 3 days after onset. Magnetic resonance imaging including susceptibility-weighted imaging and diffusion-weighted imaging (DWI) were utilized to examine patients on the fifth day after onset. Regular follow-ups were performed to examine the following clinical cerebrovascular events and vascular deaths in 1 year.

Results: Cerebral microbleeds were observed in 55 (55%) patients. Multiple logistic regression analysis showed that over-aging, elevation of serum creatinine, and leukoaraiosis were independently associated with cerebral microbleeds. In addition, higher silent brain infarction prevalence was observed in patients with cerebral microbleeds. In contrast, none of the cerebral microbleed patients exhibited cerebral microbleeds ≥5, which is an independent risk factor of poor 3-month neurological function recovery. During the 1-year follow-up, 14 subjects presented clinical cerebrovascular events or vascular death. The Cox proportional hazards model implicated that atrial fibrillation, cerebral microbleeds ≥5 and silent brain infarction were independent predictive factors for these events.

Conclusions: Over-aging combined with an elevation of serum creatinine and leukoaraiosis were independent risk factors of cerebral microbleeds. Patients with cerebral microbleeds were more likely to exhibit silent brain infarction. Poor recovery of 3-month neurological function was observed in hypertensive intracerebral hemorrhage patients with cerebral microbleeds ≥5. Cerebral microbleeds ≥5 or silent brain infarction might also indicate an elevated risk of future cerebrovascular events and vascular death.

Use of rivaroxaban in patients with stroke

Rivaroxaban, an inhibitor of Factor Xa, is a direct oral anti-coagulant that has been found to be non-inferior to warfarin in preventing cerebral ischemia in patients with non-valvular atrial fibrillation and in the subgroup of patients with a history of the previous stroke or transient ischemic attack. Vascular neurologists in daily clinical practice may encounter patients taking rivaroxaban or patients who may benefit from its use. In this paper, we review the current clinical indications, contraindications, and clinical management guidelines for rivaroxaban while providing a special focus on neurological aspects and expert opinions on rivaroxaban therapy management in various situations that a neurologist may encounter when treating patients with an ischemic stroke (including those requiring intravenous or intra-arterial reperfusion therapy) and patients with an intracerebral hemorrhage. Since data from clinical trials and real-life data are missing in some clinical situations, strong recommendations are not always available. Nevertheless, practical guidelines should be adopted to maximize benefits from this oral anti-coagulant.

Prevalence of Brain MRI Markers of Hemorrhagic Risk in Patients with Stroke and Atrial Fibrillation

Background and purpose

Cerebral microbleeds (CMBs), cortical superficial siderosis, white matter lesions (WML), and cerebral atrophy may signify greater bleeding risk particularly in patients in whom anticoagulation is to be considered. We investigated their prevalence and associations with stroke type in patients with stroke and atrial fibrillation (AF).

Materials and Methods

Cross-sectional sample, Monash Medical Centre (Melbourne, Australia) between 2010 and 2013, with brain MRI. MRI abnormalities were rated using standardized methods. Logistic regression was used to study associations adjusting for age and sex.

Results

There were 170 patients, mean age 78 years (SD 9.8), 154 (90.6%) with ischemic stroke. Prevalence of MRI markers were any microbleed 49%, multiple (≥2) microbleeds 30%, confluent WMLs 18.8%, siderosis 8.9%, severe cerebral atrophy 37.7%. Combinations of the severe manifestations of these markers were much less prevalent (2.9–12.4%). Compared with ischemic stroke, those with hemorrhagic stroke were more likely to have ≥10 microbleeds (OR 5.50 95% CI 1.46–20.77, p = 0.012) and siderosis (OR 6.24, 95% CI 1.74–22.40, p = 0.005). Siderosis was associated with multiple microbleeds (OR 8.14, 95% CI 2.38–27.86, p = 0.001). Patients admitted with hemorrhagic stroke and multiple microbleeds were more frequently anticoagulated prior to stroke (6/7, 85.7%) than in those with single (1/2, 50%) or no microbleeds (4/7, 57%).

Conclusion

Multiple CMBs, severe WML, and severe cerebral atrophy were common individually in hospitalized patients with stroke and AF, but less so in combination. A higher burden of CMBs may be associated with intracerebral hemorrhage in stroke patients with AF.

Evaluating the Role of Reduced Oxygen Saturation and Vascular Damage in Traumatic Brain Injury Using Magnetic Resonance Perfusion-Weighted Imaging and Susceptibility-Weighted Imaging and Mapping

The cerebral vasculature, along with neurons and axons, is vulnerable to biomechanical insult during traumatic brain injury (TBI). Trauma-induced vascular injury is still an underinvestigated area in TBI research. Cerebral blood flow and metabolism could be important future treatment targets in neural critical care. Magnetic resonance imaging offers a number of key methods to probe vascular injury and its relationship with traumatic hemorrhage, perfusion deficits, venous blood oxygen saturation changes, and resultant tissue damage. They make it possible to image the hemodynamics of the brain, monitor regional damage, and potentially show changes induced in the brain's function not only acutely but also longitudinally following treatment. These methods have recently been used to show that even mild TBI (mTBI) subjects can have vascular abnormalities, and thus they provide a major step forward in better diagnosing mTBI patients.

Leukoaraiosis, Cerebral Hemorrhage, and Outcome After Intravenous Thrombolysis for Acute Ischemic Stroke: A Meta-Analysis (v1)

BACKGROUND AND PURPOSE

We performed a meta-analysis to assess whether leukoaraiosis on brain computed tomographic scans of acute ischemic stroke patients treated with intravenous thrombolysis is associated with an increased risk of symptomatic intracerebral hemorrhage (sICH) or poor functional outcome at 3 to 6 months after stroke, or both.

METHODS

We searched PubMed and pooled relevant data in meta-analyses using random effects models. Using odds ratios (OR), we quantified the strength of association between the presence and severity of leukoaraiosis and post-thrombolysis sICH or 3- to 6-month modified Rankin Score >2.

RESULTS

Eleven eligible studies (n=7194) were pooled in meta-analysis. The risk of sICH was higher in patients with leukoaraiosis (OR, 1.55; 95% confidence interval [CI], 1.17-2.06; P=0.002) and severe leukoaraiosis (OR, 2.53; 95% CI, 1.92-3.34; P<0.0001) compared with patients without leukoaraiosis. Leukoaraiosis was an independent predictor of sICH in 6 included studies (n=4976; adjusted OR, 1.75; 95% CI, 1.35-2.27; P<0.0001). OR for leukoaraiosis and poor 3- to 6-month outcome was 2.02 (95% CI, 1.54-2.65; P<0.0001), with significant statistical heterogeneity (I(2), 75.7%; P=0.002). In adjusted analyses, leukoaraiosis was an independent predictor of poor outcome (n=3688; adjusted OR, 1.61; 95% CI, 1.44-1.79; P<0.0001). In post hoc analyses, including only leukoaraiosis patients in randomized controlled trials (IST-3 [third International Stroke Trial], NINDS [National Institute of Neurological Disorders and Stroke], ECASS-1-2 [European Cooperative Acute Stroke Study]; n=2234), tissue-type plasminogen activator versus control was associated with higher sICH risk (OR, 5.50; 95% CI, 2.49-12.13), but lower poor outcome risk (OR, 0.75; 95% CI, 0.60-0.95).

CONCLUSIONS

Leukoaraiosis might increase post-intravenous thrombolysis sICH risk and poor outcome poststroke. Despite increased sICH risk, intravenous tissue-type plasminogen activator treatment has net clinical benefit in patients with leukoaraiosis. Given the risk of bias/confounding, these results should be considered hypothesis-generating and do not justify withholding intravenous thrombolysis.

Cerebral microbleeds in patients with mild cognitive impairment and small vessel disease: The Vascular Mild Cognitive Impairment (VMCI)-Tuscany study

BACKGROUND AND OBJECTIVES

Cerebral microbleeds (CMBs) are a neuroimaging expression of small vessel disease (SVD). We investigated in a cohort of SVD patients with mild cognitive impairment (MCI): 1) the reliability of the Microbleed Anatomical Rating Scale (MARS); 2) the burden and location of CMBs and their association with cognitive performances, independent of other clinical and neuroimaging features.

METHODS

Patients underwent clinical, neuropsychological (4 cognitive domains), and MRI assessments. CMBs were assessed by three raters.

RESULTS

Out of the 152 patients (57.2% males; mean age±SD: 75.5±6.7years) with gradient-echo (GRE) sequences, 41 (27%) had at least one CMB. Inter-rater agreement for number and location of CMBs ranged from good to very good [multi-rater Fleiss kappa (95%CI): 0.70-0.95]. Lacunar infarcts and some clinical variables (e.g., hypertension and physical activity) were associated with CMBs in specific regions. Total number of CMBs and of those in deep and lobar regions were associated with attention/executive and fluency domains.

DISCUSSION

MARS is a reliable instrument to assess CMBs in SVD patients with MCI. Nearly one third of these patients had at least one CMB. Total CMBs burden was associated with attention/executive functions and fluency domains impairment, lacunar infarcts, and with some potentially modifiable risk factors.

Cerebral blood flow and metabolism associated with cerebral microbleeds in small vessel disease

OBJECTIVE

Cerebral microbleeds (CMBs), probably reflecting microangiopathy, have not yet sufficiently been examined in association with cerebral blood flow (CBF) and metabolism. We investigated the relationships between CMBs, and CBF and metabolism in symptomatic small vessel disease.

METHODS

We enrolled 22 patients with symptomatic small vessel disease without severe stenosis (>50 %) in major cerebral arteries. Volumes of white matter lesions (WMLs) and number of CMBs were assessed on images of fluid-attenuated inversion recovery and gradient-echo T2*-weighted magnetic resonance imaging, respectively. Patients were divided into two groups according to the median number of CMBs (group I <5, n = 10; group II ≥5, n = 12). Parametric images of CBF, cerebral metabolic rate of oxygen (CMRO2), oxygen extraction fraction and cerebral blood volume were estimated using positron emission tomography and (15)O-labeled gases. The functional values in the cortex-subcortex, basal ganglia, and centrum semiovale were compared between the two groups.

RESULTS

Volumes of WMLs of group II were larger than those of group I (median: 38.4; range: 25.1-91.5 mL vs. median: 11.3; range: 4.2-73.4 mL, p = 0.01). In the centrum semiovale, the mean CBF of group II was significantly lower than that of group I (12.6 ± 2.6 vs. 15.6 ± 3.3 mL/100 g/min, p = 0.04). In the other regions, there were no significant differences in either CBF or CMRO2 between the two groups.

CONCLUSIONS

Our study indicated that increases in the number of CMBs with larger volumes of WMLs were associated with cerebral ischemia in the deep white matter in patients with symptomatic small vessel disease.

Cerebral microbleeds in idiopathic normal pressure hydrocephalus

Background

A vascular disease could be involved in pathophysiology of normal pressure hydrocephalus (INPH). If so, there should be an association between INPH and cerebral microbleeds (CMB). This study aims to analyze if CMB are associated with INPH.

Methods

In this case-control study we included 14 patients with INPH (mean age 76 years, 60 % female) and 41 healthy controls (HeCo; mean age 71 years, 60 % female). All were investigated with magnetic resonance imaging (MRI) using a T2*-sequence. The MRI exams were reviewed by two neuroradiologists for the presence of CMBs; the prevalence of findings of two or more CMBs was compared between INPH group and control group. After investigation, INPH patients underwent shunt surgery.

Results

Two or more CMB were detected more frequently in the INPH group compared to HeCo (n = 6, 43 % vs. n = 4, 10 %; p = 0.01). Among the participants where MRI revealed CMB, the number of CMB was higher among the INPH patients than the HeCo (median 8; IQR 2-34 vs. median 1; IQR 1–2; p = 0.005).

Conclusions

This study supports a vascular component to the pathophysiology of INPH.

Periventricular hyperintensities are associated with elevated cerebral amyloid

OBJECTIVE

To investigate the association between periventricular white mater hyperintensities (PVWMH) and biomarkers of elevated cerebral β-amyloid (Aβ) in the Alzheimer's Disease Neuroimaging Initiative, a large prospective multicenter observational study.

METHODS

The burden of frontal, parietal, and occipital PVWMH on 3T fluid-attenuated inversion recovery MRI was evaluated in 698 cognitively normal participants and participants with mild cognitive impairment (MCI) using a novel semiquantitative visual rating scale. Results were correlated with CSF-Aβ, florbetapir-PET, and fluorodeoxyglucose (FDG)-PET.

RESULTS

Increased burden of parietal, occipital, and frontal PVWMH was associated with elevated cerebral amyloid evidenced by high florbetapir-PET signal (p < 0.01) and low CSF-Aβ (p < 0.01). In logistic regression models, including PVWMH, age, sex, APOE status, vascular risk factors, pulse pressure, vascular secondary prevention medications, education, ethnicity, and race, parietal, occipital, and frontal PVWMH burden was independently associated with high florbetapir-PET uptake (p < 0.05). In a similar logistic regression model, parietal and occipital (p < 0.05) but not frontal (p = 0.05) PVWMH were independently associated with CSF-Aβ. Weaker associations were found between parieto-occipital PVWMH and elevated CSF-tau (p < 0.05) and occipital PVWMH and elevated CSF-phospho-tau (p < 0.05). PVWMH were associated with cerebral hypometabolism on FDG-PET independent of CSF-Aβ levels (p < 0.05). Absolute and consistency of agreement intraclass correlation coefficients were, respectively, 0.83 and 0.83 for frontal, 0.78 and 0.8 for parietal, and 0.45 and 0.75 for occipital PVWMH measurements.

CONCLUSIONS

Increased PVWMH were associated with elevated cerebral amyloid independent of potential confounders such as age, APOE genotype, and vascular risk factors. The mechanisms underlying the association between PVWMH and cerebral amyloid remain to be clarified.

Computed Tomography--Verified Leukoaraiosis Is a Risk Factor for Post-thrombolytic Hemorrhage

BACKGROUND

Is computed tomography (CT)-verified leukoaraiosis (LA) a risk factor for post-thrombolytic hemorrhagic transformation and symptomatic hemorrhage?

METHODS

(1) Retrospective analysis based on a prospectively planned single-center registry of consecutive tissue plasminogen activator (tPA)-treated patients within 4.5 hours from symptom onset. Standard work-up included baseline noncontrast CT and CT angiography and next day follow-up noncontrast CT. Baseline noncontrast CT LA was graded using Fazekas' score and dichotomized as the absence (Fazekas, 0) or the presence (Fazekas, 1-3). Hemorrhagic transformation was rated using European Cooperative Acute Stroke Study (ECASS) criteria. Symptomatic intracerebral hemorrhage was defined as hemorrhage and deterioration of National Institutes of Health Stroke Scale (NIHSS) of 4 or greater within 36 hours from symptom onset. Endovascularly treated patients were excluded. (2) Pooled analysis with 1312 tPA-treated patients from literature.

RESULTS

In all, 311 tPA-treated patients were included between April 2009 and July 2012. LA was present in 113 (36%). Twenty-three (7%) showed hemorrhagic transformation. LA positive patients had significantly higher hemorrhagic transformation frequency (11.5%, P = .04). LA doubled hemorrhagic transformation risk (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.4-5.8). Only 4 patients developed symptomatic intracerebral hemorrhage, 3 with LA. LA was not an independent risk factor for hemorrhagic transformation (P = .2). Pooled analysis of 1623 patients in total, hereof 479 LA positive patients, showed significantly higher symptomatic intracerebral hemorrhage frequency in 35 (7.3%) LA positive than that in 44 (3.8%) LA negative patients, (P = .005) and doubled symptomatic intracerebral hemorrhage risk in LA positives (OR, 1.97; 95% CI 1.22-3.19).

CONCLUSIONS

LA doubles the risk of post-thrombolytic hemorrhagic transformation and symptomatic hemorrhage; this finding does not support withholding thrombolysis from patients with LA.

Is there an association between cerebral microbleeds and leukoaraiosis?

PURPOSE

Cerebral microbleeds (CMBs) are small dot-like lesions appearing as hyposignals on gradient echo (GRE) T2* magnetic resonance (MR) sequences, whereas the leukoaraiosis (LA) indicates the presence of patchy areas of hypersignal on fluid-attenuated inversion recovery (FLAIR) MR sequences in the periventricular white matter. The purpose of this work was to evaluate the association between LA and CMBs.

MATERIAL AND METHODS

Eighty-five consecutive (men 55; median age 64 years) patients were retrospectively analyzed using a 1.5 T system; CMBs were studied using a T2*-weighted GRE sequence and classified as absent (grade 1), mild (grade 2; total number of microbleeds, 1-2), moderate (grade 3; total number of microbleeds, 3-10), and severe (grade 4; total number of microbleeds, >10). LA was assessed with FLAIR MR sequences and was graded based on the European Task Force on Age-Related White Matter Changes as follows: 1 (no lesions), 2 (focal lesions > 5 mm), 3 (early confluent lesions), and 4 (diffuse involvement of an entire brain region).

RESULTS

We considered 170 cerebral hemispheres. The prevalence of CMBs was 24.7% (42 of 170), whereas the prevalence of LA was 27.1% (46 of 170). A statistically significant correlation was observed between LA and CMBs (correlation rho = .495, P value = .001). Multiple logistic regression analysis showed an association between CMBs and cerebrovascular symptoms (P = .0023).

CONCLUSION

Results of this study suggest an association between CMBs and LA. Moreover, we found that LA is associated with the presence of cerebrovascular symptoms.

Longitudinal relaxographic imaging of white matter hyperintensities in the elderly

Background

Incidental white matter hyperintensities (WMHs) are common findings on T₂-weighted magnetic resonance images of the aged brain and have been associated with cognitive decline. While a variety of pathogenic mechanisms have been proposed, the origin of WMHs and the extent to which lesions in the deep and periventricular white matter reflect distinct etiologies remains unclear. Our aim was to quantify the fractional blood volume (v_b) of small WMHs in vivo using a novel magnetic resonance imaging (MRI) approach and examine the contribution of blood–brain barrier disturbances to WMH formation in the deep and periventricular white matter.

Methods

Twenty-three elderly volunteers (aged 59–82 years) underwent 7 Tesla relaxographic imaging and fluid-attenuated inversion recovery (FLAIR) MRI. Maps of longitudinal relaxation rate constant (R₁) were prepared before contrast reagent (CR) injection and throughout CR washout. Voxelwise estimates of v_b were determined by fitting temporal changes in R₁ values to a two-site model that incorporates the effects of transendothelial water exchange. Average v_b values in deep and periventricular WMHs were determined after semi-automated segmentation of FLAIR images. Ventricular permeability was estimated from the change in CSF R₁ values during CR washout.

Results

In the absence of CR, the total water fraction in both deep and periventricular WMHs was increased compared to normal appearing white matter (NAWM). The v_b of deep WMHs was 1.8 ± 0.6 mL/100 g and was significantly reduced compared to NAWM (2.4 ± 0.8 mL/100 g). In contrast, the v_b of periventricular WMHs was unchanged compared to NAWM, decreased with ventricular volume and showed a positive association with ventricular permeability.

Conclusions

Hyperintensities in the deep WM appear to be driven by vascular compromise, while those in the periventricular WM are most likely the result of a compromised ependyma in which the small vessels remain relatively intact. These findings support varying contributions of blood–brain barrier and brain-CSF interface disturbances in the pathophysiology of deep and periventricular WMHs in the aged human brain.

Cerebral microbleeds in a multiethnic elderly community: demographic and clinical correlates

BACKGROUND

Microbleeds, small perivascular collections of hemosiderin manifested radiologically as hypointensities on gradient-echo magnetic resonance imaging (MRI), are important markers of small vessel pathology. Despite their clinical relevance, little is known about their prevalence and demographic correlates, particularly among ethnically diverse older adults. We examined demographic and clinical correlates of regional microbleeds in a multi-ethnic cohort and examined categorization schemes of microbleed distribution and severity.

METHODS

Between 2005 and 2007, 769 individuals participated in a MRI study as part of the Washington Heights/Inwood Columbia Aging Project. Approximately four years later, 243 out of 339 participants (mean age=84.50) who returned for a repeat MRI had gradient-echo scans for microbleed assessment and comprised the sample. We examined the association of deep and lobar microbleeds with age, sex, education, vascular factors, cognitive status and markers of small vessel disease.

RESULTS

Sixty-seven of the 243 (27%) participants had at least one microbleed. Individuals with microbleeds were more likely to have a history of stroke than individuals without. When categorized as having either no microbleeds, microbleeds in deep regions only, in lobar regions only, and both deep and lobar microbleeds, hypertension, proportion of strokes, and white matter hyperintensity volume (WMH) increased monotonically across the four groups. The number of lobar microbleeds correlated with WMH volume and diastolic blood pressure.

CONCLUSIONS

Microbleeds in deep and lobar locations are associated with worse outcomes than microbleeds in either location alone, although the presence of lobar microbleeds appears to be more clinically relevant.

Cerebral microbleeds in patients with Parkinson's disease

Cerebral microbleeds (CMBs) are known to be associated with cognitive impairments in the elderly and in patients with various diseases; however, the nature of this association has not yet been evaluated in Parkinson's disease (PD). In the present study, we analyzed the incidence of CMBs in PD according to cognitive status, and the impact of CMBs on cognitive performance was also evaluated. The CMBs in PD with dementia (n = 36), mild cognitive impairment (MCI, n = 46), or cognitively normal (n = 41) were analyzed using conventional T2*-weighted gradient-recalled echo images. Additionally, the relationship between the presence of CMBs and cognitive performance on individual tests of cognitive subdomains was analyzed using a detailed neuropsychological test. CMBs occurred more frequently in PD patients with dementia (36.1 %) compared to those with MCI (15.2 %), those who are cognitively normal (14.6 %), and normal controls (12.2 %, p = 0.025). However, the significant association of CMBs with PD dementia disappeared after adjusting white matter hyperintensities (WMHs) as a covariate. The frequencies of deep, lobar, and infratentorial CMBs did not differ among the four groups. After adjusting for age, sex, years of education, and WMHs, PD patients with CMBs had poorer performance in attention domain compared with those without CMBs (34.9 vs 42.6, p = 0.018). The present data demonstrate that even though CMBs were inseparably associated with the presence of WMHs, CMBs occur more commonly in PD patients with dementia than in those without dementia. Additionally, the burden of CMBs may contribute to further cognitive impairment in PD.

Cerebral microbleeds are associated with deep white matter hyperintensities, but only in hypertensive patients

Cerebral microbleeds (CMBs) and white matter hyperintensities (WMH) are the most common manifestations of small vessel disease, and often co-occur in patients with cerebral vascular disease. Hypertension is widely accepted as a risk factor for both CMBs and WMH. However, the effect of hypertension on the association between CMBs and WMH remains unclear. We hypothesized that the relationship between CMBs and WMH is determined by hypertension. One hundred forty-eight patients with acute cerebrovascular disease who were admitted to PLA general hospital in Beijing, China from February 2010 to May 2011 were recruited in this study. CMBs on T2*-weighted angiography (SWAN) were assessed using the Brain Observer Microbleed Rating Scale criteria. The severity of the WMH was separately assessed as either peri-ventricular hyperintensities (PVH) or deep white matter hyperintensities (DWMH). The association among CMBs and the severity of WMH, and hypertension were determined. CMBs were found in 65 (43.9%) patients. The frequency of CMBs was related to the severity of DWMH and PVH. CMBs were more frequently observed in patients with hypertension compared to patients without hypertension (51.3% vs. 20.0%, p = 0.001). Hypertension was an independent risk factor for CMBs (odds ratio 5.239, p = 0.001) and DWMH (odds ratio 2.373, p = 0.040). Furthermore, the relationship between the presence of CMBs and the severity of DWMH was only found in patients with hypertension (r = 0.298, p<0.01). However, CMBs were associated with PVH independently of hypertension. This study demonstrated that hypertension determined the association between CMBs and DWMH.

Neuroimaging in dementia

Over the last few years, advances in neuroimaging have generated biomarkers, which increase diagnostic certainty, provide valuable information about prognosis, and suggest a particular pathology underlying the clinical dementia syndrome. We aim to review the evidence for use of already established imaging modalities, along with selected techniques that have a great potential to guide clinical decisions in the future. We discuss structural, functional and molecular imaging, focusing on the most common dementias: Alzheimer's disease, fronto-temporal dementia, dementia with Lewy bodies and vascular dementia. Finally, we stress the importance of conducting research using representative cohorts and in a naturalistic set up, in order to build a strong evidence base for translating imaging methods for a National Health Service. If we assess a broad range of patients referred to memory clinic with a variety of imaging modalities, we will make a step towards accumulating robust evidence and ultimately closing the gap between the dramatic advances in neurosciences and meaningful clinical applications for the maximum benefit of our patients.

Cerebral microbleeds: a review of clinical, genetic, and neuroimaging associations

Cerebral microbleeds (microbleeds) are small, punctuate hypointense lesions seen in T2* Gradient-Recall Echo (GRE) and Susceptibility-Weighted (SWI) Magnetic Resonance Imaging (MRI) sequences, corresponding to areas of hemosiderin breakdown products from prior microscopic hemorrhages. They occur in the setting of impaired small vessel integrity, commonly due to either hypertensive vasculopathy or cerebral amyloid angiopathy. Microbleeds are more prevalent in individuals with Alzheimer’s disease (AD) dementia and in those with both ischemic and hemorrhagic stroke. However they are also found in asymptomatic individuals, with increasing prevalence with age, particularly in carriers of the Apolipoprotein (APOE) ε4 allele. Other neuroimaging findings that have been linked with microbleeds include lacunar infarcts and white matter hyperintensities on MRI, and increased cerebral β-amyloid burden using ¹¹C-PiB Positron Emission Tomography. The presence of microbleeds has been suggested to confer increased risk of incident intracerebral hemorrhage – particularly in the setting of anticoagulation – and of complications of immunotherapy for AD. Prospective data regarding the natural history and sequelae of microbleeds are currently limited, however there is a growing evidence base that will serve to inform clinical decision-making in the future.

MRI screening for chronic anticoagulation in atrial fibrillation

Anticoagulation is highly effective in preventing stroke due to atrial fibrillation, but numerous studies have demonstrated low utilization of anticoagulation for these patients. Assessment of clinicians' attitudes on this topic indicate that fear of intracerebral hemorrhage (ICH), rather than appreciation of anticoagulation benefits, largely drives clinical decision-making for treatment with anticoagulation in atrial fibrillation. Risk stratification strategies have been used for anticoagulation benefits and hemorrhage risk, but ICH is not specifically addressed in the commonly used hemorrhage risk stratification systems. Cerebral microbleeds are cerebral microscopic hemorrhages demonstrable by brain MRI, indicative of prior microhemorrhages, and predictive of future risk of ICH. Prevalence of cerebral microbleeds increases with age; and cross-sectional and limited prospective studies generally indicate that microbleeds confer substantial risk of ICH in patients treated with chronic anticoagulation. MRI thus is a readily available and appealing modality that can directly assess risk of future ICH in patients receiving anticoagulants for atrial fibrillation. Incorporation of MRI into routine practice is, however, fraught with difficulties, including the uncertain relationship between number and location of microbleeds and ICH risk, as well as cost-effectiveness of MRI. A proposed algorithm is provided, and relevant advantages and disadvantages are discussed. At present, MRI screening appears most appropriate for a subset of atrial fibrillation patients, such as those with intermediate stroke risk, and may provide reassurance for clinicians whose concerns for ICH tend to outweigh benefits of anticoagulation.

Prevalence and clinical implication of microbleeds in dementia with lewy bodies in comparison with microbleeds in Alzheimer's disease

Background

Cerebral microbleeds (MBs) have been well investigated in Alzheimer's disease (AD), but not very extensively in non-AD dementias or in dementia with Lewy bodies (DLB).

Aims

To elucidate the clinical significance of MBs in DLB.

Methods

We compared the prevalence, locations and risk factors for MBs in 59 DLB and 81 AD patients. We visually counted MBs in each of the cortical and subjacent areas (frontal, temporal, parietal and occipital), the basal ganglia and the thalamus, and the brainstem and the cerebellar hemispheres on 1.5-tesla T2*-weighted gradient-recalled-echo MRI images. White matter lesions were semiquantified in fluid-attenuated inversion recovery images according to the Fazekas rating scale.

Results

While the prevalence of MBs was comparable, MBs tended to be more abundant in DLB than in AD in all brain areas with the exception of the occipital lobes. The number of MBs was positively associated with the severity of white matter lesions but not with other vascular risk factors in either AD or DLB. The presence of MBs could be associated with cognitive impairment at onset. MB-positive DLB patients showed less impairment on ¹²³I-metaiodobenzylguanidine myocardial scintigraphy (MIBG scintigraphy) images, supporting the notion of an inverse relationship between vascular lesions and Lewy body pathology.

Conclusion

It was suggested that an intricate association between Lewy body pathology, AD-type pathologies and vascular lesions seems to be related to the initial symptoms and results of MIBG scintigraphy in DLB.

Strictly lobar microbleeds are associated with executive impairment in patients with ischemic stroke or transient ischemic attack

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) are a marker of small vessel diseases, including hypertensive arteriopathy and cerebral amyloid angiopathy, and may be associated with cognitive impairment. The relationship between CMBs and cognitive function in ischemic cerebrovascular disease remains uncertain. We, therefore, investigated the cognitive impact of CMBs in a cohort of patients with ischemic stroke or transient ischemic attack.

METHODS

All patients underwent detailed and comprehensive neuropsychological testing and standardized MRI, including fluid attenuation inversion recovery, T1, T2, and gradient-recalled echo T2*-weighted sequences. CMBs, white matter changes, lacunes, and territorial cortical infarcts (defined by standardized criteria) were identified, and associations with cognition assessed.

RESULTS

Three hundred twenty patients with a diagnosis of ischemic stroke or transient ischemic attack were included. Of these, 72 (22.5%) had at least 1 CMB. Of all the cognitive domains tested, only executive impairment was more prevalent in patients with CMBs than without (38% versus 25%; P=0.039). In univariate analysis, the presence of strictly lobar (but not deep) CMBs was associated with executive impairment (odds ratio, 2.49; 95% confidence interval, 1.16-5.36; P=0.019). In adjusted multivariate analyses, the presence (OR, 2.34; 95% confidence interval, 1.08-5.09; P=0.031) and number (OR, 1.33; 95% confidence interval, 1.04-1.69; P=0.022) of strictly lobar CMBs were significantly associated with executive impairment. CMBs were not associated with impairment in other cognitive domains.

CONCLUSIONS

Strictly lobar CMBs are independently associated with executive dysfunction in patients with ischemic stroke or transient ischemic attack. Our findings suggest that a microangiopathy related to strictly lobar CMBs (eg, cerebral amyloid angiopathy) contributes to cognitive impairment in this population.

Common variants within oxidative phosphorylation genes influence risk of ischemic stroke and intracerebral hemorrhage

BACKGROUND AND PURPOSE

Previous studies demonstrated association between mitochondrial DNA variants and ischemic stroke (IS). We investigated whether variants within a larger set of oxidative phosphorylation (OXPHOS) genes encoded by both autosomal and mitochondrial DNA were associated with risk of IS and, based on our results, extended our investigation to intracerebral hemorrhage (ICH).

METHODS

This association study used a discovery cohort of 1643 individuals, a validation cohort of 2432 individuals for IS, and an extension cohort of 1476 individuals for ICH. Gene-set enrichment analysis was performed on all structural OXPHOS genes, as well as genes contributing to individual respiratory complexes. Gene-sets passing gene-set enrichment analysis were tested by constructing genetic scores using common variants residing within each gene. Associations between each variant and IS that emerged in the discovery cohort were examined in validation and extension cohorts.

RESULTS

IS was associated with genetic risk scores in OXPHOS as a whole (odds ratio [OR], 1.17; P=0.008) and complex I (OR, 1.06; P=0.050). Among IS subtypes, small vessel stroke showed association with OXPHOS (OR, 1.16; P=0.007), complex I (OR, 1.13; P=0.027), and complex IV (OR, 1.14; P=0.018). To further explore this small vessel association, we extended our analysis to ICH, revealing association between deep hemispheric ICH and complex IV (OR, 1.08; P=0.008).

CONCLUSIONS

This pathway analysis demonstrates association between common genetic variants within OXPHOS genes and stroke. The associations for small vessel stroke and deep ICH suggest that genetic variation in OXPHOS influences small vessel pathobiology. Further studies are needed to identify culprit genetic variants and assess their functional consequences.

Severe underweight and cerebral microbleeds

Severely low and/or high body mass index (BMI) has been associated with intracerebral hemorrhage (ICH) risk in several large cohorts. The aim of this study is to assess the relationship between BMI and the presence of cerebral microbleeds. The presence and number of microbleeds were assessed on three-dimensional T2-weighted gradient-recalled-echo sequence on magnetic resonance imaging (MRI). The inclusion criteria were participants aged >40 years old without aneurysmal subarachnoid hemorrhage and any type of cerebral vascular malformations. BMI was categorized into severe underweight (<17.0 kg/m(2)), mild underweight (17.0-18.4 kg/m(2)), normal range (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), and obese (≥ 30.0 kg/m(2)). Multivariate analyses were adjusted for age, sex, hypertension, smoking, alcohol, stroke subtype, severity of periventricular hyperintensities and deep white matter hyperintensities, and dementia. Additionally, we conducted stratification analyses by age, ICH, smoking habit, or history of any kind of cancer, respectively. A total of 384 participants (232 males, 152 females; mean age 67.5 years) met our inclusion criteria. Overall mean BMI was 22.8 ± 3.6 kg/m(2). On multivariate analyses, severe underweight carried a significantly higher risk for cerebral microbleeds (3.48, 1.06-11.4) compared with normal range BMI, even after stratification in the subgroup aged ≥ 60 years (7.23, 1.57-33.2), nonsmokers (4.75, 1.10-20.5), noncancer subgroup (5.66, 1.31-24.5), and non-ICH subgroup (3.81, 1.14-12.7). We found that severe underweight was an independent significant risk factor for presence of cerebral microbleeds, even after effect of aging, smoking, or preexisting illness was eliminated.

Mixed cerebrovascular disease and the future of stroke prevention

Stroke prevention efforts typically focus on either ischemic or hemorrhagic stroke. This approach is overly simplistic due to the frequent coexistence of ischemic and hemorrhagic cerebrovascular disease. This coexistence, termed “mixed cerebrovascular disease”, offers a conceptual framework that appears useful for stroke prevention strategies. Mixed cerebrovascular disease incorporates clinical and subclinical syndromes, including ischemic stroke, subclinical infarct, white matter disease of aging (leukoaraiosis), intracerebral hemorrhage, and cerebral microbleeds. Reliance on mixed cerebrovascular disease as a diagnostic entity may assist in stratifying risk of hemorrhagic stroke associated with platelet therapy and anticoagulants. Animal models of hemorrhagic cerebrovascular disease, particularly models of cerebral amyloid angiopathy and hypertension, offer novel means for identifying underlying mechanisms and developing focused therapy. Phosphodiesterase (PDE) inhibitors represent a class of agents that, by targeting both platelets and vessel wall, provide the kind of dual actions necessary for stroke prevention, given the spectrum of disorders that characterizes mixed cerebrovascular disease.