Cerebral microbleeds and cognition in cerebrovascular disease: an update

Disrupted brain structural networks associated with depression and cognitive dysfunction in cerebral small vessel disease with microbleeds

Emerging evidence highlights cerebral microbleeds (CMBs) as hallmarks of cerebral small vessel disease (CSVD) underlying depression and cognitive dysfunction. This study aimed to reveal how depression and cognition-related white matter (WM) abnormalities are topologically presented, and the network-level structural disruptions associated with CMBs in CSVD. We used probabilistic diffusion tractography and graph theory to investigate brain WM network topology in CSVD patients with (n = 64, CSVD-c) and without (n = 138, CSVD-n) CMBs and 90 healthy controls. Then we evaluated the Pearson's correlations between disrupted network metrics and neuropsychological parameters. For global topology, the CSVD-c group exhibited significantly decreased global (Eglob) and local (Eloc) efficiency and increased shortest path length compared with the controls, while no significant difference was found between the CSVD-c and CSVD-n groups. For regional topology, although all groups showed highly similar hub distributions, compare with control group, the CSVD-c group exhibited significantly decreased nodal efficiency mainly in the bilateral supplementary motor area (SMA), median cingulate gyrus (DCG) and right orbital middle frontal gyrus, while the CSVD-n group showed significantly decreased nodal efficiency only in the right SMA. Notably, Eglob, Eloc and nodal efficiency of the right anterior cingulate gyrus, DCG, middle temporal gyrus and left insula showed significantly negative correlations with depression score, significantly positive correlations with Rey auditory verbal learning test and symbol digit modalities test scores in CSVD-n group, as well as significantly negative correlations with Stroop color-word test scores in CSVD-c group. The WM networks of CSVD patients are characterized by decreased global integration and local specialization, and decreased nodal efficiency highly related to depression and cognitive dysfunction in the attention, default mode network and sensorimotor regions. These findings provide new insight into the neurobiological mechanisms of CSVD and concomitant affective and cognitive disorders.

Association between triglyceride glucose index and all-cause mortality in patients with cerebrovascular disease: a retrospective study

BACKGROUND

Triglyceride glucose (TyG) is associated with stroke, atherosclerosis, and adverse clinical outcomes. However, its correlation with cerebrovascular disease (CVD) mortality remains unclear. This study aimed to investigate the relationship between TyG index and mortality in patients with CVD.

METHODS

Patient data sourced from the Medical Information Mart for Intensive Care -IV database were categorized based on TyG quartiles. Kaplan-Meier survival analysis was used to estimate survival disparities among the TyG subgroups. Cox proportional risk modeling was used to examine the association between the TyG index and mortality. Generalized summation models were applied to fit the smoothed curves. log-likelihood ratio test were used to analyze the non-linear relationship.

RESULTS

The study comprised 1,965 patients (50.18% were male). The 28-day and 90-day mortality rates were 20.10% and 24.48%, respectively. The TyG index exhibited a linear relationship with the 28-day mortality (Hazards ratio (HR), 1.16; 95% confidence interval (CI), 0.99-1.36) and the 90-day mortality (HR, 1.18; 95% CI, 1.02-1.37). In the TyG Q4 group, each 1 mg/dl increase was linked to a 35% rise in the risk of 28-day mortality and a 38% increase in the risk of 90-day mortality. Subgroup analyses highlighted a more substantial association between TyG index and 90-day mortality in the diabetic group.

CONCLUSION

Our findings underscore the positive association between TyG and the 28- and 90-day mortality rates in patients with CVD. This insight may prove pivotal for identifying at-risk populations and enhancing risk prediction in the clinical management of CVD.

Engineered inhaled nanocatalytic therapy for ischemic cerebrovascular disease by inducing autophagy of abnormal mitochondria

Mitochondrial dysfunction and subsequent accumulation of reactive oxygen species (ROS) are key contributors to the pathology of ischemic cerebrovascular disease. Therefore, elimination of ROS and damaged mitochondria is crucial for the effective treatment of this disease. For this purpose, we designed an inhalation nanotherapeutic agent, P/D@Mn/Co3O4, to treat ischemic cerebrovascular disease. Mn/Co3O4 effectively removed excess ROS from cells, reduced acute cellular oxidative stress, and protected neural cells from apoptosis. Furthermore, it depleted the H+ surrounding mitochondria and depolarized the mitochondrial membrane potential, inducing mitophagy and eliminating abnormal mitochondria, thereby avoiding the continuous overproduction of ROS by eliminating the source of ROS regeneration. On intranasal administration, Mn/Co3O4 encapsulated by platelet membranes and 2,3-(dioxy propyl)-trimethylammonium chloride can bypass the blood-brain barrier, enter the brain through the trigeminal and olfactory pathways, and target inflammatory regions to remove ROS and damaged mitochondria from the lesion area. In rat models of stroke and vascular dementia, P/D@Mn/Co3O4 effectively inhibited the symptoms of acute and chronic cerebral ischemia by scavenging ROS and damaged mitochondria in the affected area. Our findings indicate that the nanotherapeutic agent developed in this study can be used for the effective treatment of ischemic cerebrovascular disease.

A bibliometric analysis of cerebral microbleeds and cognitive impairment

BACKGROUND AND OBJECTIVES

Cerebral microbleeds (CMBs) are imaging markers for small cerebral vascular diseases, which can accumulate and impact the corresponding brain networks. CMBs can affect cognitive function, including executive function, information processing speed, and visuospatial memory. Bibliometrics is a scientific and innovative method that can analyze and visualize the scientific field quantitatively. In this study, we aimed to use bibliometric analysis to demonstrate the relationship and mechanisms between CMBs and cognitive impairment. Furthermore, we reviewed the relationship between CMBs and different cognitive disorders. The use of bibliometrics can help further clarify this relationship.

METHODS

We retrieved articles on CMBs and cognitive impairment from the Web of Science Core Collection. The keywords (such as stroke, dementia, and cerebral amyloid angiopathy), authors, countries, institutions and journals, in the field were visually analyzed using VOSviewer software and bibliometric websites.

RESULTS

This bibliometric analysis reveals the related trends of CMBs in the field of cognitive impairment. CMBs, along with other small vascular lesions, constitute the basis of cognitive impairment, and studying CMBs is essential to understand the mechanisms underlying cognitive impairment.

CONCLUSION

This bibliometric analysis reveals a strong link between CMBs and cognitive impairment-related diseases and that specific brain networks were affected by CMBs. This provides further insights into the possible mechanisms and causes of CMBs and cognitive impairment. The direct and indirect damage (such as oxidative stress and neuroinflammation) to the brain caused by CMBs, destruction of the frontal-subcortical circuits, elevated Cystatin C levels, and iron deposition are involved in the occurrence and development of cognitive impairment. CMBs may be a potential marker for detecting, quantifying, and predicting cognitive impairment.

Prospective Assessment of Cerebral Microbleeds with Low-Field Magnetic Resonance Imaging (0.55 Tesla MRI)

PURPOSE

Accurate detection of cerebral microbleeds (CMBs) on susceptibility-weighted (SWI) magnetic resonance imaging (MRI) is crucial for the characterization of many neurological diseases. Low-field MRI offers greater access at lower costs and lower infrastructural requirements, but also reduced susceptibility artifacts. We therefore evaluated the diagnostic performance for the detection of CMBs of a whole-body low-field MRI in a prospective cohort of suspected stroke patients compared to an established 1.5 T MRI.

METHODS

A prospective scanner comparison was performed including 27 patients, of whom 3 patients were excluded because the time interval was >1 h between acquisition of the 1.5 T and 0.55 T MRI. All SWI sequences were assessed for the presence, number, and localization of CMBs by two neuroradiologists and additionally underwent a Likert rating with respect to image impression, resolution, noise, contrast, and diagnostic quality.

RESULTS

A total of 24 patients with a mean age of 74 years were included (11 female). Both readers detected the same number and localization of microbleeds in all 24 datasets (sensitivity and specificity 100%; interreader reliability ϰ = 1), with CMBs only being observed in 12 patients. Likert ratings of the sequences at both field strengths regarding overall image quality and diagnostic quality did not reveal significant differences between the 0.55 T and 1.5 T sequences (p = 0.942; p = 0.672). For resolution and contrast, the 0.55 T sequences were even significantly superior (p < 0.0001; p < 0.0003), whereas the 1.5 T sequences were significantly superior (p < 0.0001) regarding noise.

CONCLUSION

Low-field MRI at 0.55 T may have similar accuracy as 1.5 T scanners for the detection of microbleeds and thus may have great potential as a resource-efficient alternative in the near future.

The effects of imaging markers on clinical trajectory in cerebral amyloid angiopathy: a longitudinal study in a memory clinic

BACKGROUND

We investigated the relevance of various imaging markers for the clinical trajectory of cerebral amyloid angiopathy (CAA) patients in a memory clinic.

METHODS

A total of 226 patients with probable CAA were included in this study with a mean follow-up period of 3.5 ± 2.7 years. Although all had more than one follow-up visit, 173 underwent follow-up Mini-Mental Status Examination (MMSE) and Clinical Dementia Rating Sum of Boxes (CDR-SB) ranging from 2 to 15 time points. Among 226, 122 patients underwent amyloid-β (Aβ) PET imaging. The prevalence of intracerebral hemorrhage (ICH) and its imaging predictors was investigated. The effects of CAA imaging markers and Aβ PET positivity on longitudinal cognition based on the MMSE and CDR-SB were evaluated using mixed effects models.

RESULTS

During the follow-up, 10 (4.4%) patients developed ICH: cortical superficial siderosis (cSS; hazard ratio [HR], 6.45) and previous lobar ICH (HR, 4.9), but lobar cerebral microbleeds (CMBs) were not predictors of ICH development. The presence of CMIs (p = 0.045) and Aβ positivity (p = 0.002) were associated with worse MMSE trajectory in CAA patients. Regarding CDR-SB trajectory, only Aβ positivity was marginally associated with worse longitudinal change (p = 0.050).

CONCLUSION

The results of the present study indicated that various imaging markers in CAA patients have different clinical relevance and predictive values for further clinical courses.

Impact of white-matter mask selection on DTI histogram-based metrics as potential biomarkers in cerebral small vessel disease

OBJECTIVE

Histogram-based metrics extracted from diffusion-tensor imaging (DTI) have been suggested as potential biomarkers for cerebral small vessel disease (SVD), but methods and results have varied across studies. This work aims to assess the impact of mask selection for extracting histogram-based metrics of fractional anisotropy (FA) and mean diffusivity (MD) on their sensitivity as SVD biomarkers.

METHODS

DTI data were collected from 17 SVD patients and 12 healthy controls. FA and MD maps were estimated; from these, histograms were computed on two whole-brain white-matter masks: normal-appearing white-matter (NAWM) and mean FA tract skeleton (TBSS). Histogram-based metrics (median, peak height, peak width, peak value) were extracted from the FA and MD maps. These were compared between groups and correlated with the patients' cognitive scores (executive function and processing speed).

RESULTS

White-matter mask selection significantly impacted FA and MD histogram metrics. In particular, significant interactions were found between Mask and Group for FA peak height (p = 0.027), MD Median (p = 0.035) and MD peak width (p = 0.047); indicating that the mask used affected their ability to discriminate between groups. In fact, MD peak width showed a significant 8.8% increase in patients when using TBSS (p = 0.037), but not when using NAWM (p = 0.69). Moreover, the mask may have an effect on the correlations with cognitive measures. Nevertheless, MD peak width (TBSS: r = - 0.75, NAWM: r = - 0.71) and MD peak height (TBSS: r = 0.65, NAWM: r = 0.62) remained significantly correlated with executive function, regardless of the mask.

CONCLUSION

The impact of the processing methodology, in particular the choice of white-matter mask, highlights the need for standardized MRI data-processing pipelines.

Automated detection of cerebral microbleeds via segmentation in susceptibility-weighted images of patients with traumatic brain injury

Cerebral microbleeds (CMBs) are a recognised biomarker of traumatic axonal injury (TAI). Their number and location provide valuable information in the long-term prognosis of patients who sustained a traumatic brain injury (TBI). Accurate detection of CMBs is necessary for both research and clinical applications. CMBs appear as small hypointense lesions on susceptibility-weighted magnetic resonance imaging (SWI). Their size and shape vary markedly in cases of TBI. Manual annotation of CMBs is a difficult, error-prone, and time-consuming task. Several studies addressed the detection of CMBs in other neuropathologies with convolutional neural networks (CNNs). In this study, we developed and contrasted a classification (Patch-CNN) and two segmentation (Segmentation-CNN, U-Net) approaches for the detection of CMBs in TBI cases. The models were trained using 45 datasets, and the best models were chosen according to 16 validation sets. Finally, the models were evaluated on 10 TBI and healthy control cases, respectively. Our three models outperform the current status quo in the detection of traumatic CMBs, achieving higher sensitivity at low false positive (FP) counts. Furthermore, using a segmentation approach allows for better precision. The best model, the U-Net, achieves a detection rate of 90% at FP counts of 17.1 in TBI patients and 3.4 in healthy controls.

Lobar Cerebral Microbleeds Are Associated With Cognitive Decline in Patients With Type 2 Diabetes Mellitus

Purpose

Combined the number, volume, and location of cerebral microbleeds (CMBs), this study aimed to explore the different features of CMBs and their correlation with cognitive ability in patients with type 2 diabetes mellitus (T2DM).

Methods

This study recruited 95 patients with T2DM and 80 healthy control (HC) individuals. AccuBrain^®, an automated tool, was used to obtain the number and volume of CMBs. The scores on global cognition and five cognitive domains were derived from a battery of cognitive tests. The logistic regression and multivariate linear regression were conducted to determine the relationship between the CMBs (number, volume, and location) and cognitive ability in patients with T2DM.

Results

After adjusting for several variables, the total volume of CMBs (OR = 0.332, 95%CI: 0.133–0.825, and p = 0.018) was independent risk factor for cognitive impairment, whereas the total number of CMBs was not (OR = 0933, 95%CI: 0.794–1.097, and p = 0.400). Furthermore, the volume of CMBs in lobar regions was independently associated with working memory (β = −0.239, 95%CI: −0.565 to −0.035, and p = 0.027). However, no significant correlation between the number of CMBs (both lobar and deep/infratentorium) and any cognitive domains was observed.

Conclusions

Lobar CMBs was related with cognitive impairment in patients with T2DM and might be a potential early warning signal. Compared with the counting analysis, the quantitative method offered a more sensitive and objective measurement for studying imaging features of CMBs.

Cerebral Microbleeds Are Associated with Impairments in Executive Function and Processing Speed

BACKGROUND

Cerebral microbleed (CMB) is an increasingly important risk factor for cognitive impairment due to population aging. Controversies, however, remain regarding the exact association between CMB and cognitive dysfunction.

OBJECTIVE

We aimed to determine the relationship between CMB burden and cognitive impairment, and also explore the characteristics of cognitive decline in CMB patients for middle-aged and elderly people.

METHODS

The present cross-sectional study included 174 participants (87 CMB patients and 87 controls) who underwent brain magnetic resonance imaging and a battery of neuropsychological test. Global cognitive function was measured using Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Compound z-scores were calculated for three cognitive subdomains: memory, executive function and processing speed.

RESULTS

CMB patients had lower scores of MMSE (p < 0.001) and MoCA (p < 0.001). Patients at each category of CMB count had worse performance in global cognitive function and all three cognitive subdomains (p < 0.001). In multiple linear regression models, CMB patients had significantly greater declines in executive function (p < 0.001), processing speed (p < 0.001), and MoCA (p = 0.003) with increasing number of CMB. We found no relationship between CMB location and cognition (p > 0.05).

CONCLUSION

CMB is associated with impairment in global cognition as well as for all tested subdomains. Strongest effect sizes were seen for tests which rely on executive functioning, where performance deficits increased in proportion to degree of CMB burden. Prospective studies are needed to evaluate whether the association between CMB and executive dysfunction is causal.

Cerebral Microbleeds and White Matter Hyperintensities are Associated with Cognitive Decline in an Asian Memory Clinic Study

BACKGROUND

Cerebral Small Vessel Disease (SVD); lacunes, Cerebral Microbleeds (CMBs), and White Matter Hyperintensities (WMH) have a vital role in cognitive impairment and dementia. SVD in lobar location is related to cerebral amyloid angiopathy, whereas SVD in a deep location with hypertensive arteriopathy. It remains unclear how different locations of SVD affect long-term cognitive decline. The present study aimed to analyse the association between different locations and severity of SVD with global and domain-specific cognitive decline over the follow-up interval of 3 years.

METHODS

We studied 428 participants who had performed MRI scans at baseline and at least 3 neuropsychological assessments. Locations of lacunes and CMBs were categorized into strictly lobar, strictly deep and mixed-location, WMH volume into anterior and posterior. The National Institute of Neurological Disorders and Stroke-Canadian Stroke Network Harmonization Neuropsychological Battery was used to assess cognitive function. To analyse the association between baseline location and severity of SVD with cognitive decline, linear regression models with generalized estimated equations were constructed to calculate the mean difference, 95% confidence interval and two-way interaction factor between time and SVD.

RESULTS

Increased numbers of baseline CMBs were associated with a decline in global cognition as well as a decline in executive function and memory domains. Location-specific analysis showed similar results with strictly lobar CMBs. There was no association with strictly deep and mixed-location CMBs with cognitive decline. Baseline WMH volume was associated with a decline in global cognition, executive function and memory. Similar results were obtained with anterior and posterior WMH volumes. Lacunes and their locations were not associated with cognitive decline.

CONCLUSION

Strictly lobar CMBs, as well as WMH volume in anterior and posterior regions, were associated with cognitive decline. Future research focuses are warranted to evaluate interventions that may prevent cognitive decline related to SVD.

Higher Total Cerebral Small Vessel Disease Burden Was Associated With Mild Cognitive Impairment and Overall Cognitive Dysfunction: A Propensity Score-Matched Case-Control Study

Background and Objective

The combination of neuroimaging and cognition characteristics may provide complementary information for early identification of mild cognitive impairment (MCI). This study aimed to establish the clinical relevance between cerebral small vessel disease (CSVD) burden and MCI and further explored the cognitive characteristics linked to CSVD applying a propensity score matching (PSM) approach.

Methods

The study was designed as a case–control study. All the subjects underwent the standard clinical assessments, neuropsychological testing battery (including global cognition, memory, executive function, and speed and motor control domains), and brain magnetic resonance imaging (MRI). A 1:2 nearest-neighbor matching approach without replacement was employed with a caliper of 0.15 in the PSM approach.

Results

A total of 84 MCI patients and 186 cognitively normal controls were included in this study. After PSM, 74 MCI patients and 129 controls were successfully matched, and the covariate imbalance was well eliminated. Compared with controls, the MCI group had more severe CSVD burden. In the binary logistic regression analysis, CSVD was associated with MCI after adjusting for all confounders. The results of multivariate linear regression analyses showed that higher total MRI CSVD burden was related to the deficit of cognitive performance in global cognition and three important cognitive domains after adjusting for all confounders.

Conclusion

Cerebral small vessel disease was an independent risk factor of MCI. Moreover, higher total MRI CSVD burden was associated with the overall cognitive impairment among middle-aged and elderly Chinese adults.

Cerebral microbleeds in vascular dementia from clinical aspects to host-microbial interaction

Vascular dementia is the second leading cause of dementia after Alzheimer's disease in the elderly population worldwide. Cerebral microbleeds (CMBs) are frequently observed in MRI of elderly subjects and considered as a possible surrogate marker. The number and location of CMBs reflect the severity of diseases and the underlying pathologies may involve cerebral amyloid angiopathy or hypertensive vasculopathy. Accumulating evidence demonstrated the clinicopathological discrepancies of CMBs, the clinical significance of CMBs associated with other MRI markers of cerebral small vessel disease, cognitive impairments, serum, and cerebrospinal fluid biomarkers. Moreover, emerging evidence has shown that genetic factors and gene-environmental interactions might shed light on the underlying etiologies of CMBs, focusing on blood-brain-barrier and inflammation. In this review, we introduce recent genetic and microbiome studies as a cutting-edge approach to figure out the etiology of CMBs through the "microbe-brain-oral axis" and "microbiome-brain-gut axis." Finally, we propose novel concepts, "microvascular matrisome" and "imbalanced proteostasis," which may provide better perspectives for elucidating the pathophysiology of CMBs and future development of therapeutics for vascular dementia using CMBs as a surrogate marker.

Cognitive impact of cerebral microbleeds in patients with symptomatic small vessel disease

BACKGROUND AND AIM

Whether cerebral microbleeds cause cognitive impairment remains uncertain. We analyzed whether cerebral microbleeds are associated with cognitive dysfunction in patients with symptomatic cerebral small vessel disease, and whether this association is independent of other neuroimaging markers of cerebral small vessel disease.

METHODS

We analyzed consecutive patients with MRI-confirmed lacunar stroke included in DNA-Lacunar-2 multicenter study. Cerebral microbleeds were graded using the Brain Observer Microbleed Rating Scale (BOMBS). Neuropsychological assessment was performed using the Brief Memory and Executive Test (BMET). We analyzed the association between cerebral microbleeds, BMET, and the following subdomains: executive function/processing speed and orientation/memory. We also searched for an independent association between cerebral microbleeds and vascular cognitive impairment, defined as BMET ≤ 13.

RESULTS

Out of 688 included patients, cerebral microbleeds were detected in 192 (27.9%). After adjusting for white matter hyperintensities severity, lacune count, and other confounders, both the presence and the number of cerebral microbleeds were significantly associated with impaired cognitive performance [β = -13.0; 95% CI = (-25.3, -0.6) and β = -13.1; 95% CI = (-19.8, -6.4), respectively]. On analysis of specific cognitive domains, associations were present for executive function/processing speed [β = -5.8; 95% CI = (-9.3, -2.2) and β = -4.3; 95% CI = (-6.2, -2.4), respectively] but not for orientation/memory [β = -0.4; 95% CI = (-4.0, 3.2) and β = -2.1; 95% CI = (-4.0, 0.1), respectively]. We also found an independent association between the presence and the number of cerebral microbleeds and vascular cognitive impairment [adjusted OR = 1.48; 95% CI = (1.01, 2.18) and OR = 1.43; 95% CI = (1.15, 1.79), respectively].

CONCLUSION

In a large cohort of symptomatic cerebral small vessel disease patients, after controlling for other neuroimaging markers of cerebral small vessel disease severity, cerebral microbleeds were associated with cognitive dysfunction. Executive function and processing speed were predominantly impaired. This might suggest a causal role of cerebral microbleeds in determining vascular cognitive impairment.

Association of Trimethylamine N-Oxide and Its Precursor With Cerebral Small Vessel Imaging Markers

Background: High plasma levels of trimethylamine N-oxide (TMAO) and its precursor choline have been linked to stroke; however, their association with cerebral small vessel disease remains unclear. Here we evaluated the association of plasma levels of TMAO and choline with imaging markers of cerebral small vessel disease, including white matter hyperintensities, lacunes, and cerebral microbleeds.

Methods: We performed a baseline cross-sectional analysis of a multicenter hospital-based cohort study from 2015 to 2018. The data were collected from 30 hospitals in China and included 1,098 patients with ischemic stroke/transient ischemic attack aged ≥18 years. White matter hyperintensities, lacunes, and cerebral microbleeds were evaluated with the patients' demographic, clinical, and laboratory information removed. White matter hyperintensities were rated using the Fazekas visual grading scale, while the degree of severity of the lacunes and cerebral microbleeds was defined by the number of lesions.

Results: Increased TMAO levels were associated with severe white matter hyperintensities [adjusted odds ratio (aOR) for the highest vs. lowest quartile, 1.5; 95% confidence interval (CI), 1.0–2.1, p = 0.04]. High TMAO levels were more strongly associated with severe periventricular white matter hyperintensities (aOR for the highest vs. lowest quartile, 1.6; 95% CI, 1.1–2.3, p = 0.009) than deep white matter hyperintensities (aOR for the highest vs. lowest quartile, 1.3; 95% CI, 0.9–1.9, p = 0.16). No significant association was observed between TMAO and lacunes or cerebral microbleeds. Choline showed trends similar to that of TMAO in the association with cerebral small vessel disease.

Conclusions: In patients with ischemic stroke or transient ischemic attack, TMAO and choline appear to be associated with white matter hyperintensities, but not with lacunes or cerebral microbleeds; TMAO and choline were associated with increased risk of a greater periventricular, rather than deep, white matter hyperintensities burden.

Mixed-location cerebral microbleeds as a biomarker of neurodegeneration in a memory clinic population

Cerebral microbleeds (CMBs) in the lobar and deep locations are associated with two distinct pathologies: cerebral amyloid angiopathy and hypertensive arteriopathy. However, the role of mixed-location CMBs in neurodegeneration remains unexplored. We investigated the associations between strictly lobar, strictly deep and mixed-location CMBs with markers of neurodegeneration. This study recruited 477 patients from a memory clinic who underwent 3T MRI scans. CMBs were categorized into strictly lobar, strictly deep and mixed-location. Cortical thickness, white matter volume and subcortical structural volumes were quantified using Free-Surfer. Linear regression models were performed to assess the association between CMBs and cerebral atrophy, and the mean difference (β) and 95% confidence intervals (CIs) were reported. In the regression analyses, mixed-location CMBs were associated with smaller cortical thickness of limbic region [β= -0.01; 95% CI= -0.02, -0.00, p=0.007) as well as with smaller accumbens volume [β= -0.01; 95% CI= -0.02, -0.00, p=0.004) and presubiculum region of hippocampus [β= -0.01; 95% CI= -0.02, -0.00, p=0.002). Strictly lobar CMBs were associated with smaller total white matter volume [β= -0.03; 95% CI= -0.04, -0.01, p<0.001] and with region specific white matter volumes. The underlying mechanism requires further research and may involve shared mechanisms of vascular dysfunction and neurodegeneration.

Invited Review: The spectrum of age-related small vessel diseases: potential overlap and interactions of amyloid and nonamyloid vasculopathies

Deep perforator arteriopathy (DPA) and cerebral amyloid angiopathy (CAA) are the commonest known cerebral small vessel diseases (CSVD), which cause ischaemic stroke, intracebral haemorrhage (ICH) and vascular cognitive impairment (VCI). While thus far mainly considered as separate entities, we here propose that DPA and CAA share similarities, overlap and interact, so that 'pure' DPA or CAA are extremes along a continuum of age-related small vessel pathologies. We suggest blood-brain barrier (BBB) breakdown, endothelial damage and impaired perivascular β-amyloid (Aβ) drainage are hallmark common mechanisms connecting DPA and CAA. We also suggest a need for new biomarkers (e.g. high-resolution imaging) to deepen understanding of the complex relationships between DPA and CAA.

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.

How Do Different Forms of Vascular Brain Injury Relate to Cognition in a Memory Clinic Population: The TRACE-VCI Study

BACKGROUND

Memory clinic patients frequently present with different forms of vascular brain injury due to different etiologies, often co-occurring with Alzheimer's disease (AD) pathology.

OBJECTIVE

We studied how cognition was affected by different forms of vascular brain injury, possibly in interplay with AD pathology.

METHODS

We included 860 memory clinic patients with vascular brain injury on magnetic resonance imaging (MRI), receiving a standardized evaluation including cerebrospinal fluid (CSF) biomarker analyses (n = 541). The cognitive profile of patients with different forms of vascular brain injury on MRI (moderate/severe white matter hyperintensities (WMH) (n = 398), microbleeds (n = 368), lacunar (n = 188) and non-lacunar (n = 96) infarct(s), macrobleeds (n = 16)) was assessed by: 1) comparison of all these different forms of vascular brain injury with a reference group (patients with only mild WMH (n = 205) without other forms of vascular brain injury), using linear regression analyses also stratified for CSF biomarker AD profile and 2) multivariate linear regression analysis.

RESULTS

The cognitive profile was remarkably similar across groups. Compared to the reference group effect sizes on all domains were <0.2 with narrow 95% confidence intervals, except for non-lacunar infarcts on information processing speed (age, sex, and education adjusted mean difference from reference group (β: - 0.26, p = 0.05). Results were similar in the presence (n = 300) or absence (n = 241) of biomarker co-occurring AD pathology. In multivariate linear regression analysis, higher WMH burden was related to a slightly worse performance on attention and executive functioning (β: - 0.08, p = 0.02) and working memory (β: - 0.08, p = 0.04).

CONCLUSION

Although different forms of vascular brain injury have different etiologies and different patterns of cerebral damage, they show a largely similar cognitive profile in memory clinic patients regardless of co-occurring AD pathology.

Study on the incidence and risk factor of silent cerebrovascular disease in young adults with first-ever stroke

Silent cerebrovascular diseases, including silent brain infarcts (SBI), white matter hyperintensity (WMH), and cerebral microbleed, are closely correlated with stroke progression. The purpose of this study was to investigate the prevalence and potential risk factors of SBI and WMH in young patients with first-ever stroke.A total of 400 young patients with first-ever stroke were included in this study and received magnetic resonance imaging test. The distributions of stroke subtypes were analyzed based on patients' age and gender. The prevalence of SBI and WMH was evaluated in different age groups and stroke subtypes. Independent risk factors for SBI and WMH were identified using logistic regression analysis.The distribution of stroke subtypes was not correlated with patients' age or gender in our study. The incidence of SBI and WMH among all of the young stroke patients was 14.50% and 8.75%, respectively, which showed an upward tendency with age. The percentages of both SBI and WMH were significantly higher in small-vessel disease patients than in cases with other subtype diseases (all P < .05). Hypertension (odds ratio [OR] = 2.645, 95% confidence interval [CI] = 1.429-4.896, P = .002 for SBI; OR = 5.474, 95% CI = 2.319-12.921, P = .000 for WMH; OR = 39.988, 95% CI = 3.988-400.949, P = .002 for SBI and WMH) and homocysteine (OR = 4.033, 95% CI = 2.191-7.425, P = .000 for SBI; OR = 5.989, 95% CI = 2.637-13.602, P = .000 for WMH; OR = 4.068, 95% CI = 1.207-13.715, P = .024 for SBI and WMH) might be potential risk factors for SBI and WMH.The prevalence of silent cerebrovascular disease was elevated with age. Hypertension and elevated homocysteine levels were 2 risk factors for silent cerebrovascular disease in young stroke patients.

Retinal Vascular Imaging in Vascular Cognitive Impairment: Current and Future Perspectives

Vascular cognitive disorders are heterogeneous and increasingly recognized entities with intricate correlation to neurodegenerative conditions. Retinal vascular analysis is a noninvasive approach to study cerebrovascular pathology, with promise to assist particularly during early disease phases. In this article, we have systematically summarized the current understanding, potential applications, and inevitable limitations of retinal vascular imaging in patients with vascular cognitive impairment. In addition, future directions in the field with support from automated technology using deep learning methods and their existing challenges are emphasized.

Remote brain microhaemorrhages may predict haematoma in glioma patients treated with radiation therapy

OBJECTIVES

To evaluate the prevalence of cerebral remote microhaemorrhages (RMH) and remote haematomas (RH) using magnetic resonance susceptibility-weighted imaging (SWI) among patients treated for gliomas during follow-up.

METHODS

We conducted a retrospective single centre longitudinal study on 58 consecutive patients treated for gliomas from January 2009 through December 2010. Our institutional review board approved this study. We evaluated the presence and number of RMH and RH found outside the brain tumour on follow-up MR imaging. We performed univariate and bivariate analyses to identify predictors for RMH and RH and Kaplan-Meier survival analysis techniques.

RESULTS

Twenty-five (43%) and four patients (7%) developed at least one RMH or RH, respectively, during follow-up. The risk was significantly higher for patients who received radiation therapy (49% and 8% versus 0%) (p = 0.02). The risk of developing RH was significantly higher in patients with at least one RMH and a high burden of RMH. The mean age of those presenting with at least one RMH or RH was significantly lower.

CONCLUSIONS

RMH were common in adult survivors of gliomas who received radiation therapy and may predict the onset of RH during follow-up, mainly in younger patients.

KEY POINTS

• Brain RMH and RH are significantly more likely to occur after RT. • RMH occur in almost half of the patients treated with RT. • RMH and RH are significantly more frequent in younger patients. • RH occur only in patients with RMH.

Neuropsychological Features of Microbleeds and Cortical Microinfarct Detected by High Resolution Magnetic Resonance Imaging

BACKGROUND

Lobar microbleeds (MBs) and cortical microinfarct (CMI) are caused by cerebral amyloid angiopathy in the elderly and increase in number in Alzheimer's disease.

OBJECTIVE

The aim of this study is to elucidate the effects of lobar MBs and CMIs on cognitive function.

METHODS

The subjects were outpatients who visited the memory clinic of Mie University Hospital. Among 120 subjects, 109 patients fulfilled the inclusion criteria. We quantitatively estimated MBs and CMIs using double inversion recovery and 3D FLAIR images of 3T MRI. Neuropsychological assessments included intellectual, memory, constructional, and frontal lobe function.

RESULTS

Of the 109 patients, MBs and CMIs were observed in 68 (62%) and 17 (16%) subjects, respectively. Of the 68 patients with MBs, lobar MBs were found in 28, deep MBs in 8 and mixed MBs in 31. In each age group, the number of MBs increased in patients with CMI (CMI+ group) than those without CMI (CMI- group), and MBs and CMIs additively decreased MMSE scores. In psychological screens, the MBs+ group with more than 10 MBs showed significantly lower scores of category- and letter-WF than MB- group. The CMI+ group showed significantly worse scores than CMI- group in Japanese Raven's coloured progressive matrices, Trail Making Test-A, category- and letter-word fluency and copy and drawing of figures.

CONCLUSION

Lobar MBs and CMIs in the elderly frequently coexisted with each other and additively contributed to cognitive impairment, which is mainly predisposed to frontal lobe function.

NSAID Use and Incident Cognitive Impairment in a Population-based Cohort

Nonsteroidal anti-inflammatory drugs (NSAIDs) may prevent dementia, but previous studies have yielded conflicting results. This study estimated the association of prior NSAID use with incident cognitive impairment in the population-based Epidemiology of Hearing Loss Study (EHLS, n=2422 without cognitive impairment in 1998-2000). Prospectively collected medication data from 1988-1990, 1993-1995, and 1998-2000 were used to categorize NSAID use history at the cognitive baseline (1998-2000). Aspirin use and nonaspirin NSAID use were separately examined. Cox regression models were used to estimate the associations between NSAID use history at baseline and incident cognitive impairment in 2003-2005 or 2009-2010. Logistic regression analyses were used to estimate associations with a second outcome, mild cognitive impairment/dementia, available in 2009-2010. Participants using aspirin at baseline but not 5 years prior were more likely to develop cognitive impairment (adjusted hazard ratio=1.77; 95% confidence interval=1.11, 2.82; model 2), with nonsignificant associations for longer term use. Nonaspirin NSAID use was not associated with incident cognitive impairment or mild cognitive impairment/dementia odds. These results provided no evidence to support a potential protective effect of NSAIDs against dementia.

Large Perivascular Spaces Visible on Magnetic Resonance Imaging, Cerebral Small Vessel Disease Progression, and Risk of Dementia: The Age, Gene/Environment Susceptibility-Reykjavik Study

Importance

With advancing age, an increased visibility of perivascular spaces (PVSs) on magnetic resonance imaging (MRI) is hypothesized to represent impaired drainage of interstitial fluid from the brain and may reflect underlying cerebral small vessel disease (SVD). However, whether large perivascular spaces (L-PVSs) (>3 mm in diameter) visible on MRI are associated with SVD and cognitive deterioration in older individuals is unknown.

Objective

To examine whether L-PVSs are associated with the progression of the established MRI markers of SVD, cognitive decline, and increased risk of dementia.

Design, Setting, and Participants

The prospective, population-based Age, Gene/Environment Susceptibility-Reykjavik Study assessed L-PVSs at baseline (September 1, 2002, through February 28, 2006) on MRI studies of the brain in 2612 participants. Participants returned for additional MRI from April 1, 2007, through September 30, 2011, and underwent neuropsychological testing at the 2 time points a mean (SD) of 5.2 (0.2) years apart. Data analysis was conducted from August 1, 2016, to May 4, 2017.

Exposures

The presence, number, and location of L-PVSs.

Main Outcomes and Measures

Incident subcortical infarcts, cerebral microbleeds, and progression of white matter hyperintensities detected on MRI; cognitive decline defined as composite score changes between baseline and follow-up in the domains of memory, information processing speed, and executive function; and adjudicated incident dementia cases diagnosed according to international guidelines.

Results

Of the 2612 study patients (mean [SD] age, 74.6 [4.8] years; 1542 [59.0%] female), 424 had L-PVSs and 2188 did not. The prevalence of L-PVSs was 16.2% (median number of L-PVSs, 1; range, 1-17). After adjusting for age, sex, and interval between baseline and follow-up scanning, the presence of L-PVSs was significantly associated with an increased risk of incident subcortical infarcts (adjusted risk ratio, 2.54; 95% CI, 1.76-3.68) and microbleeds (adjusted risk ratio, 1.43; 95% CI, 1.18-1.72) and a greater 5-year progression of white matter hyperintensity volume. The presence of L-PVSs was also associated with a steeper decline in information processing speed and more than quadrupled the risk of vascular dementia. All associations persisted when further adjusted for genetic and cerebrovascular risk factors. The associations with cognitive outcomes were independent of educational level, depression, and other SVD MRI markers.

Conclusions and Relevance

Large PVSs are an MRI marker of SVD and associated with the pathogenesis of vascular-related cognitive impairment in older individuals. Large PVSs should be included in assessments of vascular cognitive impairment in the older population and as potential targets for interventions.

Initial Investigation into Microbleeds and White Matter Signal Changes following Radiotherapy for Low-Grade and Benign Brain Tumors Using Ultra-High-Field MRI Techniques

BACKGROUND AND PURPOSE

External beam radiation therapy is a common treatment for many brain neoplasms. While external beam radiation therapy adheres to dose limits to protect the uninvolved brain, areas of high dose to normal tissue still occur. Patients treated with chemoradiotherapy can have adverse effects such as microbleeds and radiation necrosis, but few studies exist of patients treated without chemotherapy.

MATERIALS AND METHODS

Ten patients were treated for low-grade or benign neoplasms with external beam radiation therapy only and scanned within 12-36 months following treatment with a 7T MR imaging scanner. A multiecho gradient-echo sequence was acquired and postprocessed into SWI, quantitative susceptibility mapping, and apparent transverse relaxation maps. Six patients returned for follow-up imaging approximately 18 months following their first research scan and were imaged with the same techniques.

RESULTS

At the first visit, 7/10 patients had microbleeds evident on SWI, quantitative susceptibility mapping, and apparent transverse relaxation. All microbleeds were within a dose region of >45 Gy. Additionally, 4/10 patients had asymptomatic WM signal changes evident on standard imaging. Further analysis with our technique revealed that these lesions were venocentric, suggestive of a neuroinflammatory process.

CONCLUSIONS

There exists a potential for microbleeds in patients treated with external beam radiation therapy without chemotherapy. This finding is of clinical relevance because it could be a precursor of future neurovascular disease and indicates that additional care should be taken when using therapies such as anticoagulants. Additionally, the appearance of venocentric WM lesions could be suggestive of a neuroinflammatory mechanism that has been suggested in diseases such as MS. Both findings merit further investigation in a larger population set.

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.

Space and location of cerebral microbleeds, cognitive decline, and dementia in the community

OBJECTIVE

To assess the association of the number and anatomic location of cerebral microbleeds (CMBs), visible indicators of microvascular damage on MRI, with incident cognitive disease in the general population of older people.

METHODS

In the longitudinal population-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, 2,602 participants 66 to 93 years of age and free of prevalent dementia underwent brain MRI and cognitive testing of verbal memory, processing speed, and executive function at baseline and a mean of 5.2 years later. Adjudicated incident dementia cases were diagnosed according to international guidelines.

RESULTS

In the multiple linear regression models adjusted for demographic, genetic, cardiovascular risk, and other cerebrovascular MRI markers, the presence of CMBs located in deep or mixed (deep and lobar) areas was associated with a greater decline in all 3 cognitive domains. Mixed CMBs were the strongest correlate for decline in memory and speed. Compared to those with no CMBs, participants with ≥3 CMBs had a steeper decline in a composite measure of global cognitive function, memory, and speed. Among those with ≥3 deep or mixed CMBs, associations were strongest for memory; the association with speed was strongest in those having ≥3 strictly lobar CMBs. People with ≥3 CMBs, regardless of their locations, had a higher incidence of all-cause dementia and vascular dementia.

CONCLUSIONS

Mixed or a higher load of CMBs, with some specificity for location, is associated with accelerated cognitive decline in older people. These findings suggest a role for hypertensive vasculopathy and the combined effect of hypertensive and cerebral amyloid angiopathy in the pathogenesis of cognitive deterioration.

Vascular Contributions to Cognitive Impairment in Late Life

Cerebrovascular disease (CVD) is the second leading cause of cognitive impairment in late life. Structural neuroimaging offers the most sensitive and specific biomarkers for hemorrhages and infarcts, but there are significant limitations in its ability to detect microvascular disease, microinfarcts, dynamic changes in the blood-brain barrier, and preclinical cerebrovascular disease. Autopsy studies disclose the common co-occurrence of vascular and neurodegenerative conditions, suggesting that in late life, a multifactorial approach to cognitive impairment may be more appropriate than traditional dichotomous classifications. Management of vascular risk factors remains a proven and practical approach to reducing acute and progressive cognitive impairment and dementia.

Susceptibility-weighted imaging: current status and future directions

Susceptibility-weighted imaging (SWI) is a method that uses the intrinsic nature of local magnetic fields to enhance image contrast in order to improve the visibility of various susceptibility sources and to facilitate diagnostic interpretation. It is also the precursor to the concept of the use of phase for quantitative susceptibility mapping (QSM). Nowadays, SWI has become a widely used clinical tool to image deoxyhemoglobin in veins, iron deposition in the brain, hemorrhages, microbleeds and calcification. In this article, we review the basics of SWI, including data acquisition, data reconstruction and post-processing. In particular, the source of cusp artifacts in phase images is investigated in detail and an improved multi-channel phase data combination algorithm is provided. In addition, we show a few clinical applications of SWI for the imaging of stroke, traumatic brain injury, carotid vessel wall, siderotic nodules in cirrhotic liver, prostate cancer, prostatic calcification, spinal cord injury and intervertebral disc degeneration. As the clinical applications of SWI continue to expand both in and outside the brain, the improvement of SWI in conjunction with QSM is an important future direction of this technology. Copyright © 2016 John Wiley & Sons, Ltd.

Cerebral microbleeds and risk of incident dementia: the Framingham Heart Study

Cerebral microbleeds (CMBs) are MRI markers attributed to the most common cerebral angiopathies in the elderly and in patients with dementia: hypertensive and cerebral amyloid angiopathy. CMB detection in asymptomatic persons may help identify those at risk for dementia and may influence preventive strategies and design of clinical trials testing treatments for dementia. We studied the association of CMB with risk of incident dementia in community dwelling individuals. A total of 1296 dementia-free Framingham Heart Study participants (mean age 72 years; 54% women) with available brain MRI and incident dementia data during a mean follow-up period of 6.7 years were included. Using Cox proportional hazards models, we related CMB presence to incident dementia. Multivariable models were adjusted for age, sex, APOE status, and education, with additional models adjusting for vascular risk factors and MRI markers of ischemic brain injury. CMBs were observed in 10.8% and incident dementia in 85 participants (6.6% over study period). Participants with any CMB had 1.74 times higher risk of dementia (hazard ratio [HR] 1.74, 95% confidence interval [CI] 1.00-3.01), whereas those with deep and mixed CMB had a three-fold increased risk (HR 2.99, 95% CI 1.52-5.90). The associations were independent of vascular risk factors, and for deep and mixed CMB also independent of MRI markers of ischemia (HR 2.44, 95% CI 1.22-4.88). Purely lobar CMBs were not associated with incident dementia. Our findings support a role for hypertensive vasculopathy and the interplay of hypertensive and cerebral amyloid angiopathy in risk of dementia and suggest that CMB presence can identify individuals at risk of dementia.

[Not Available]

Zusammenfassung. Zerebrale Mikroangiopathien umfassen eine Gruppe neuropathologischer Prozesse, die die kleinen Perforationsarterien, Arteriolen und Kapillaren beeinflussen. Neuroimaging-Merkmale der Einengung der kleinen Koronararterienäste (Small Vessel Disease) sind ischämische und hämorrhagische Marker: jüngster kleiner subkortikaler Infarkt, Lakune vermuteten vaskulären Ursprungs, Hyperintensität der weissen Masse, perivaskuläre Räume, zerebrale Mikroblutungen, Hirnatrophie, kortikale oberflächliche Siderose und akute subarachnoidale Blutungen. Diese Läsionen gelten als der Hauptrisikofaktor der vaskulären kognitiven Störungen. Die zerebrale Mikroangiopathie wird typischerweise in zwei Hauptformen kategorisiert: die nicht-amyloide Angiopathie, die auch als «hypertensive Arteriopathie» bezeichnet wird, die oft mit fortgeschrittenem Alter und vaskulären Risikofaktoren und der zerebralen Amyloidangiopathie zusammenhängt. Die zerebrale Amyloidangiopathie ist klinisch charakterisiert durch kognitive Beeinträchtigungen, intrazerebrale Blutungen und durch transiente Episoden fokal-neurologischer Defizite aufgrund von Subarachnoidalblutungen.

Oral Cnm-positive Streptococcus Mutans Expressing Collagen Binding Activity is a Risk Factor for Cerebral Microbleeds and Cognitive Impairment

Cerebral microbleeds (CMBs) are an important risk factor for stroke and dementia. We have shown that the collagen binding surface Cnm protein expressed on cnm-positive Streptococcus mutans is involved in the development of CMBs. However, whether the collagen binding activity of cnm-positive S. mutans is related to the nature of the CMBs or to cognitive impairment is unclear. Two-hundred seventy nine community residents (70.0 years) were examined for the presence or absence of cnm-positive S. mutans in the saliva by PCR and collagen binding activity, CMBs, and cognitive function were evaluated. Cnm-positive S. mutans was detected more often among subjects with CMBs (p < 0.01) than those without. The risk of CMBs was significantly higher (odds ratio = 14.3) in the group with S. mutans expressing collagen binding activity, as compared to the group without that finding. Deep CMBs were more frequent (67%) and cognitive function was lower among subjects with cnm-positive S. mutans expressing collagen binding activity. This work supports the role of oral health in stroke and dementia and proposes a molecular mechanism for the interaction.

Microbleeds on MRI are associated with microinfarcts on autopsy in cerebral amyloid angiopathy

OBJECTIVES

To identify in vivo MRI markers that might correlate with cerebral microinfarcts (CMIs) on autopsy in patients with cerebral amyloid angiopathy (CAA).

METHODS

We included patients with neuropathologic evidence of CAA on autopsy and available antemortem brain MRI. Clinical characteristics and in vivo MRI markers of CAA-related small vessel disease were recorded, including white matter hyperintensities, cerebral microbleeds, cortical superficial siderosis, and centrum semiovale perivascular spaces. In addition, the presence of intracerebral hemorrhage on MRI was assessed. Evaluation of the presence and number of CMIs was performed in 9 standard histology sections.

RESULTS

Of 49 analyzed patients with CAA, CMIs were present in 36.7%. The presence of ≥1 CMIs on autopsy was associated with higher numbers of microbleeds on antemortem MRI (median 8 [interquartile range 2.5-33.0] vs 1 [interquartile range 0-3], p = 0.003) and with the presence of intracerebral hemorrhage (44.4% vs 16.1%, p = 0.03). No associations between CMIs and other in vivo MRI markers of CAA were found. In a multivariable model adjusted for severe CAA pathology, higher numbers of microbleeds were independent predictors of the presence of CMIs on pathology.

CONCLUSIONS

CMIs are a common finding at autopsy in patients with CAA. The strong association between MRI-observed microbleeds and CMIs at autopsy may suggest a shared underlying pathophysiologic mechanism between these lesions.

A Novel Imaging Marker for Small Vessel Disease Based on Skeletonization of White Matter Tracts and Diffusion Histograms

OBJECTIVE

To establish a fully automated, robust imaging marker for cerebral small vessel disease (SVD) and related cognitive impairment that is easy to implement, reflects disease burden, and is strongly associated with processing speed, the predominantly affected cognitive domain in SVD.

METHODS

We developed a novel magnetic resonance imaging marker based on diffusion tensor imaging, skeletonization of white matter tracts, and histogram analysis. The marker (peak width of skeletonized mean diffusivity [PSMD]) was assessed along with conventional SVD imaging markers. We first evaluated associations with processing speed in patients with genetically defined SVD (n = 113). Next, we validated our findings in independent samples of inherited SVD (n = 57), sporadic SVD (n = 444), and memory clinic patients with SVD (n = 105). The new marker was further applied to healthy controls (n = 241) and to patients with Alzheimer's disease (n = 153). We further conducted a longitudinal analysis and interscanner reproducibility study.

RESULTS

PSMD was associated with processing speed in all study samples with SVD (p-values between 2.8 × 10(-3) and 1.8 × 10(-10) ). PSMD explained most of the variance in processing speed (R(2) ranging from 8.8% to 46%) and consistently outperformed conventional imaging markers (white matter hyperintensity volume, lacune volume, and brain volume) in multiple regression analyses. Increases in PSMD were linked to vascular but not to neurodegenerative disease. In longitudinal analysis, PSMD captured SVD progression better than other imaging markers.

INTERPRETATION

PSMD is a new, fully automated, and robust imaging marker for SVD. PSMD can easily be applied to large samples and may be of great utility for both research studies and clinical use. Ann Neurol 2016;80:581-592.

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.

Automatic Detection of Cerebral Microbleeds From MR Images via 3D Convolutional Neural Networks

Cerebral microbleeds (CMBs) are small haemorrhages nearby blood vessels. They have been recognized as important diagnostic biomarkers for many cerebrovascular diseases and cognitive dysfunctions. In current clinical routine, CMBs are manually labelled by radiologists but this procedure is laborious, time-consuming, and error prone. In this paper, we propose a novel automatic method to detect CMBs from magnetic resonance (MR) images by exploiting the 3D convolutional neural network (CNN). Compared with previous methods that employed either low-level hand-crafted descriptors or 2D CNNs, our method can take full advantage of spatial contextual information in MR volumes to extract more representative high-level features for CMBs, and hence achieve a much better detection accuracy. To further improve the detection performance while reducing the computational cost, we propose a cascaded framework under 3D CNNs for the task of CMB detection. We first exploit a 3D fully convolutional network (FCN) strategy to retrieve the candidates with high probabilities of being CMBs, and then apply a well-trained 3D CNN discrimination model to distinguish CMBs from hard mimics. Compared with traditional sliding window strategy, the proposed 3D FCN strategy can remove massive redundant computations and dramatically speed up the detection process. We constructed a large dataset with 320 volumetric MR scans and performed extensive experiments to validate the proposed method, which achieved a high sensitivity of 93.16% with an average number of 2.74 false positives per subject, outperforming previous methods using low-level descriptors or 2D CNNs by a significant margin. The proposed method, in principle, can be adapted to other biomarker detection tasks from volumetric medical data.

Predictors of future stroke in adults 60-64 years living in the community

AIM: To investigate predictors of incident stroke in a large epidemiological sample of cognitively healthy individuals in their early 60’s.

METHODS: Cardiovascular (systolic and diastolic blood pressure, hypertension status and medication, body mass index, lung forced vital capacity), lifestyle (alcohol intake, smoking, physical activity), mental health (anxiety and depression status, medication and symptomatology), cognition (executive function, processing speed, working memory, sensorimotor skills), and personality measures (behavioural inhibition and activation, positive and negative affect, neuroticism, psychoticism, extraversion) were investigated as predictors of incident stroke in 1774 participants from the Personality and Total Health Through Life Project over an 8-year follow-up. Logistic regression analyses controlled for age, gender, and education were conducted in the whole cohort as well as in case-control sub-analyses including precisely matched controls to identify factors associated with stroke incidence.

RESULTS: The cohort selected had a mean age of 62.5 years (SD = 1.5) and was 48.6% female with an average of 14.1 years of education (SD = 2.6). When 28 individuals with incident stroke were compared to 1746 cognitively healthy individuals in multivariate logistic regression analyses the only significant predictors of stroke across the five domains considered (cardiovascular, lifestyle, mental health, cognition, personality) and after controlling for gender, age, and education were systolic blood pressure (per unit above 140 mmHg: OR = 1.04, 95%CI: 1.01-1.07, P = 0.002), smoking (trend OR = 2.28, 95%CI: 0.99-5.24, P = 0.052), and sensorimotor skills (purdue pegboard: OR = 0.80, 95%CI: 0.62-0.96, P = 0.037). Similarly, in matched-control analyses significant group differences were found for systolic blood pressure (P = 0.001), smoking (P = 0.036), and sensorimotor skills (P = 0.028).

CONCLUSION: Identified predictors of incident stroke in community-living individuals included high systolic blood pressure and smoking - but also, sensorimotor performance, a measure which has not yet been reported in the literature.

Intracerebral hemorrhage and cognitive impairment

Vascular cognitive impairment and vascular dementia are composed of cognitive deficits resulted from a range of vascular lesions and pathologies, including both ischemic and hemorrhagic. However the contribution of spontaneous intracerebral hemorrhage presumed due to small vessel diseases on cognitive impairment is underestimated, in contrast to the numerous studies about the role of ischemic vascular disorders on cognition. In this review we summarize recent findings from clinical studies and appropriate basic science research to better elucidate the role and possible mechanisms of intracerebral hemorrhage in cognitive impairment and dementia. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

Novel imaging techniques in cerebral small vessel diseases and vascular cognitive impairment

Dementia is a global growing concern, affecting over 35 million people with a global economic impact of over $604 billion US. With an ageing population the number of people affected is expected double over the next two decades. Vascular cognitive impairment can be caused by various types of cerebrovascular disease, including cortical and subcortical infarcts, and the more diffuse white matter injury due to cerebral small vessel disease. Although this type of cognitive impairment is usually considered the second most common form of dementia after Alzheimer's disease, there is increasing recognition of the vascular contribution to neurodegeneration, with both pathologies frequently coexisting. The aim of this review is to highlight the recent advances in the understanding of vascular cognitive impairment, with a focus on small vessel diseases of the brain. We discuss recently identified small vessel imaging markers that have been associated with cognitive impairment, namely cerebral microbleeds, enlarged perivascular spaces, cortical superficial siderosis, and microinfarcts. We will also consider quantitative techniques including diffusion tensor imaging, magnetic resonance perfusion imaging with arterial spin labelling, functional magnetic resonance imaging and positron emission tomography. As well as potentially shedding light on the mechanism by which cerebral small vessel diseases cause dementia, these novel imaging biomarkers are also of increasing relevance given their ability to guide diagnosis and reflect disease progression, which may in the future be useful for therapeutic interventions. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease

We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis.

Imaging of Cerebral Microbleeds

Cerebral microbleeds (CMBs) are defined as small, rounded, or ovoid, homogeneous hypointense lesions on T2*-weighted gradient-echo and other susceptibility-sensitive magnetic resonance imaging (MRI) sequences. They must be differentiated from other causes of focal hypointensities on these sequences. Although CMBs can be caused by a variety of diseases, they are most frequently associated with different forms of cerebral small vessel diseases. This review summarizes the MRI characteristics of CMBs including methodological considerations, as well as prevalence, differential diagnosis, mimics, and clinical relevance of CMBs.

Carotid arterial stiffness and risk of incident cerebral microbleeds in older people: the Age, Gene/Environment Susceptibility (AGES)-Reykjavik study

OBJECTIVE

Age and high blood pressure are major risk factors for cerebral microbleeds (CMBs). However, the underlying mechanisms remain unclear and arterial stiffness may be important. We investigated whether carotid arterial stiffness is associated with incidence and location of CMBs.

APPROACH AND RESULTS

In the prospective, population-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik study, 2512 participants aged 66 to 93 years underwent a baseline brain MRI examination and carotid ultrasound in 2002 to 2006 and returned for a repeat brain MRI in 2007 to 2011. Common carotid arterial stiffness was assessed using a standardized protocol and expressed as carotid arterial strain, distensibility coefficient, and Young elastic modulus. Modified Poisson regression was applied to relate carotid arterial stiffness parameters to CMB incidence. During a mean follow-up of 5.2 years, 463 people (18.4%) developed new CMBs, of whom 292 had CMBs restricted to lobar regions and 171 had CMBs in a deep or infratentorial region. After adjusting for age, sex, and follow-up interval, arterial stiffness measures were associated with incident CMBs (risk ratio per SD decrease in carotid arterial strain, 1.11 [95% confidence interval, 1.01-1.21]; per SD decrease in natural log-transformed distensibility coefficient, 1.14 [1.05-1.24]; and per SD increase in natural log-transformed Young elastic modulus, 1.13 [1.04-1.23]). These measures were also significantly associated with incident deep CMBs (1.18 [1.02-1.37]; 1.24 [1.08-1.42]; and 1.23 [1.07-1.42]) but not with lobar CMBs. When further adjusted for blood pressure and other baseline vascular risk factors, carotid plaque, prevalent CMBs, subcortical infarcts, and white matter hyperintensities, the associations persisted.

CONCLUSIONS

Our findings support the hypothesis that localized increases in carotid arterial stiffness may contribute to the development of CMBs, especially in a deep location attributable to hypertension.

Magnetic resonance imaging appearance of hypertensive encephalopathy in a dog

A 16-year-old female spayed English Staffordshire terrier was presented for evaluation of a 10-month history of intermittent myoclonic episodes, and a one weeks history of short episodes of altered mentation, ataxia and collapse. Magnetic resonance imaging identified subcortical oedema, predominately in the parietal and temporal lobes and multiple cerebral microbleeds.

Serum biochemistry, indirect blood pressure measurements and magnetic resonance imaging abnormalities were consistent with hypertensive encephalopathy secondary to chronic kidney disease.