MRI detection of new hemorrhages: potential marker of progression in cerebral amyloid angiopathy

Arteriolar degeneration and stiffness in cerebral amyloid angiopathy are linked to β-amyloid deposition and lysyl oxidase

Cerebral amyloid angiopathy (CAA) is a vasculopathy characterized by vascular β-amyloid (Aβ) deposition on cerebral blood vessels. CAA is closely linked to Alzheimer's disease (AD) and intracerebral hemorrhage. CAA is associated with the loss of autoregulation in the brain, vascular rupture, and cognitive decline. To assess morphological and molecular changes associated with the degeneration of penetrating arterioles in CAA, we analyzed post-mortem human brain tissue from 26 patients with mild, moderate, and severe CAA end neurological controls. The tissue was optically cleared for three-dimensional light sheet microscopy, and morphological features were quantified using surface volume rendering. We stained Aβ, vascular smooth muscle (VSM), lysyl oxidase (LOX), and vascular markers to visualize the relationship between degenerative morphological features, including vascular dilation, dolichoectasia (variability in lumenal diameter) and tortuosity, and the volumes of VSM, Aβ, and LOX in arterioles. Atomic force microscopy (AFM) was used to assess arteriolar wall stiffness, and we identified a pattern of morphological features associated with degenerating arterioles in the cortex. The volume of VSM associated with the arteriole was reduced by around 80% in arterioles with severe CAA and around 60% in cases with mild/moderate CAA. This loss of VSM correlated with increased arteriolar diameter and variability of diameter, suggesting VSM loss contributes to arteriolar laxity. These vascular morphological features correlated strongly with Aβ deposits. At sites of microhemorrhage, Aβ was consistently present, although the morphology of the deposits changed from the typical organized ring shape to sharply contoured shards with marked dilation of the vessel. AFM showed that arteriolar walls with CAA were more than 400% stiffer than those without CAA. Finally, we characterized the association of vascular degeneration with LOX, finding strong associations with VSM loss and vascular degeneration. These results show an association between vascular Aβ deposition, microvascular degeneration, and increased vascular stiffness, likely due to the combined effects of replacement of VSM by β-amyloid, cross-linking of extracellular matrices (ECM) by LOX, and possibly fibrosis. This advanced microscopic imaging study clarifies the association between Aβ deposition and vascular fragility. Restoration of physiologic ECM properties in penetrating arteries may yield a novel therapeutic strategy for CAA.

[Current findings on the coincidence of cerebral amyloid angiopathy and Alzheimer's disease]

Die zerebrale Amyloidangiopathie (CAA) tritt trotz verschiedener Pathomechanismen häufig koinzident zur Alzheimer-Demenz auf. Sie moduliert kognitive Defizite im Rahmen der Alzheimer-Erkrankung (AD) annehmbar durch additive Effekte, auch wenn die diesbezüglichen Zusammenhänge komplex sind. Die pathophysiologische Gemeinsamkeit beider Erkrankungen besteht in einem gestörten Amyloidmetabolismus, distinkt ist jedoch die pathologische Prozessierung von Amyloidvorläuferproteinen. Die CAA mit ihren verschiedenen Subtypen ist eine pathomechanistisch heterogene Gefäßerkrankung des Gehirns. Vaskuläre und parenchymatöse Amyloidablagerungen kommen gemeinsam, aber auch isoliert und unabhängig voneinander vor. Um den spezifischen Beitrag der CAA zu kognitiven Defiziten im Rahmen der AD zu untersuchen, bedarf es daher geeigneter diagnostischer Methoden, die der Komplexität der histopathologischen bzw. bildmorphologischen Charakteristika der CAA gerecht werden, sowie differenzierender testpsychometrischer Verfahren, anhand derer der Beitrag der CAA zu kognitiven Defiziten deskriptiv erfasst und damit ätiologisch besser zuordenbar wird.

Incidental De Novo Cerebral Microhemorrhages are Predictive of Future Symptomatic Macrohemorrhages After Surgical Revascularization in Moyamoya Disease

BACKGROUND

Patients with moyamoya disease who develop incidental cerebral microhemorrhages (CMHs) on magnetic resonance imaging (MRI) have higher risk of developing subsequent symptomatic repeat macro hemorrhages.

OBJECTIVE

To evaluate the effect of surgical revascularization on development of de novo CMHs and assess its correlation with repeat hemorrhage rates and functional outcome in hemorrhagic onset moyamoya disease (HOMMD).

METHODS

We retrospectively reviewed a prospectively managed departmental database of all patients presenting with HOMMD treated between 1987 and 2019. The search yielded 121 patients with adequate MRI follow-up for inclusion into the study.

RESULTS

In total, 42 preoperative CMHs were identified in 18 patients (15%). Patients presenting with preoperative CMH were more likely to develop de novo CMH after surgical revascularization. 7 de novo CHMs were identified in 6 patients (5%) on routine postoperative MRI at distinct locations from previous sites of hemorrhage or CMH. Symptomatic repeat macro hemorrhage was confirmed radiographically in 15 patients (12%). A total 5 (83%) of 6 patients with de novo CMHs later suffered symptomatic repeat macro hemorrhage with 4 of 5 (80%) hemorrhages occurring at sites of previous CMH. On univariate and multivariate analysis, de novo CMHs was the only significant variable predictive for developing repeat symptomatic hemorrhage. Development of delayed repeat symptomatic hemorrhage was prognostic for higher modified Rankin Score and therefore poorer functional status, whereas preoperative functional status was predictive of final outcome.

CONCLUSION

De novo CMHs after surgical revascularization might serve as a radiographic biomarker for refractory disease and suggest patients are at risk for future symptomatic macro hemorrhage.

Neural stem cell therapy for neurovascular injury in Alzheimer's disease

Alzheimer's disease (AD), the most common form of dementia, is characterized by progressive neurodegeneration leading to severe cognitive decline and eventual death. AD pathophysiology is complex, but neurotoxic accumulation of amyloid-β (Aβ) and hyperphosphorylation of Tau are believed to be main drivers of neurodegeneration in AD. The formation and deposition of Aβ plaques occurs in the brain parenchyma as well as in the cerebral vasculature. Thus, proper blood-brain barrier (BBB) and cerebrovascular functioning are crucial for clearance of Aβ from the brain, and neurovascular dysfunction may be a critical component of AD development. Further, neuroinflammation and dysfunction of angiogenesis, neurogenesis, and neurorestorative capabilities play a role in AD pathophysiology. Currently, there is no effective treatment to prevent or restore loss of brain tissue and cognitive decline in patients with AD. Based on multifactorial and complex pathophysiological cascades in multiple Alzheimer's disease stages, effective AD therapies need to focus on targeting early AD pathology and preserving cerebrovascular function. Neural stem cells (NSCs) participate extensively in mammalian brain homeostasis and repair and exhibit pleiotropic intrinsic properties that likely make them attractive candidates for the treatment of AD. In the review, we summarize the current advances in knowledge regarding neurovascular aspects of AD-related neurodegeneration and discuss multiple actions of NSCs from preclinical studies of AD to evaluate their potential for future clinical treatment of AD.

Increased cerebral microbleeds and cortical superficial siderosis in pediatric patients with Down syndrome

BACKGROUND

Patients with Down syndrome carry a third copy of the amyloid precursor protein gene, which is localized on chromosome 21. Consequently, these patients are prone to develop early-onset Alzheimer disease and cerebral amyloid angiopathy. Post-mortem studies suggest increased amyloid deposition to be already detectable in children with Down syndrome. The aim of our study was to evaluate if amyloid-related changes in pediatric Down syndrome patients can be detected in vivo using MRI biomarkers of cerebral microbleeds and cortical superficial siderosis.

MATERIALS AND METHODS

This retrospective study included 12 patients with Down syndrome (mean age = 5.0 years) and 12 age-matched control subjects (mean age = 4.8 years). Frequency and location of microbleeds and siderosis were assessed on blood-sensitive MRI sequences in a consensus reading by two radiologists applying a modified Microbleed Anatomical Rating Scale.

RESULTS

Down syndrome patients showed a significantly higher mean microbleeds count and likelihood of siderosis than age-matched controls. Across groups, the highest microbleeds count was found in lobar regions (gray and white matter of frontal, parietal, temporal, and occipital lobes, and the insula), while fewer microbleeds were located in subcortical and infratentorial regions. The number of microbleeds increased over time in all three Down syndrome patients with a follow-up exam.

CONCLUSION

In vivo MRI biomarkers can support the diagnosis of early-onset cerebral amyloid angiopathy, which might already be present in pediatric Down syndrome patients. This might contribute to clinical decision-making and potentially to the development of therapeutic and prophylactic approaches, as cerebral amyloid angiopathy increases the risk for intracranial hemorrhage and may be associated with increased risk of developing Alzheimer disease.

Fine Particulate Matter, Residential Proximity to Major Roads, and Markers of Small Vessel Disease in a Memory Study Population

BACKGROUND

Long-term exposure to ambient air pollution has been associated with impaired cognitive function and vascular disease in older adults, but little is known about these associations among people with concerns about memory loss.

OBJECTIVE

To examine associations between exposures to fine particulate matter and residential proximity to major roads and markers of small vessel disease.

METHODS

From 2004-2010, 236 participants in the Massachusetts Alzheimer's Disease Research Center Longitudinal Cohort participated in neuroimaging studies. Residential proximity to major roads and estimated 2003 residential annual average of fine particulate air pollution (PM2.5) were linked to measures of brain parenchymal fraction (BPF), white matter hyperintensities (WMH), and cerebral microbleeds. Associations were modeled using linear and logistic regression and adjusted for clinical and lifestyle factors.

RESULTS

In this population (median age [interquartile range] = 74 [12], 57% female) living in a region with median 2003 PM2.5 annual average below the current Environmental Protection Agency (EPA) standard, there were no associations between living closer to a major roadway or for a 2μg/m3 increment in PM2.5 and smaller BPF, greater WMH volume, or a higher odds of microbleeds. However, a 2μg/m3 increment in PM2.5 was associated with -0.19 (95% Confidence Interval (CI): -0.37, -0.005) lower natural log-transformed WMH volume. Other associations had wide confidence intervals.

CONCLUSIONS

In this population, where median 2003 estimated PM2.5 levels were below the current EPA standard, we observed no pattern of association between residential proximity to major roads or 2003 average PM2.5 and greater burden of small vessel disease or neurodegeneration.

Implications of CHA2DS2-VASc Score in Stroke Patients with Atrial Fibrillation: An Analysis of 938 Korean Patients

BACKGROUND AND AIMS

The aim of this study was to investigate the stroke mechanisms and associated conditions influencing the decision regarding stroke thromboprophylaxis in patients with atrial fibrillation (AF) plus ischemic stroke, according to the CHA2DS2-VASc score.

METHODS

We evaluated 938 consecutive patients with a diagnosis of AF plus transient ischemic attack/ischemic stroke. Based on the CHA2DS2-VASc scores, patients were stratified as score 0 or 1 (n = 151), score 2 (n = 146), score 3 (n = 213), score 4 (n = 185), or score ≥5 (n = 243).

RESULTS

Patients with a higher CHA2DS2-VASc score were more likely to have noncardioembolic stroke mechanism (p = 0.001). Large-artery atherosclerosis causing stenosis >50% was more frequently observed in the high CHA2DS2-VASc group (p < 0.001). Coronary artery disease and the use of antiplatelet agents were more prevalent in the higher group (p < 0.001). A high CHA2DS2-VASc score was associated with a higher frequency of cerebral microbleeds and a higher Fazekas grade for leukoaraiosis (p < 0.001). The HAS-BLED score was correlated with the CHA2DS2-VASc score (γ = 0.650; p < 0.001).

CONCLUSIONS

A higher CHA2DS2-VASc score is associated with noncardioembolic mechanisms of stroke and with a higher risk of bleeding. Strategies to treat macro/microangiopathy such as use of statin for plaque stabilization, as well as oral anticoagulants with a lower bleeding risk, are needed in these patients.

Cerebral Microbleeds Remain for Nine Years: A Prospective Study with Yearly Magnetic Resonance Imaging

BACKGROUND

Cerebral microbleeds (CMBs) are refined neuroimaging findings detected on T2*-weighted gradient echo (GRE) magnetic resonance imaging (MRI) and are widely accepted as an important marker of the vulnerability of cerebral small vessels. It is necessary to further clarify the natural history of CMBs by a longitudinal study. This study aimed to reveal the natural history of CMBs and find a better way to track CMBs by a prospective long-term observation.

METHODS

We performed yearly brain MRI assessments for 7 or more years in 8 nonvalvular atrial fibrillation Japanese outpatients with CMBs detected in the baseline MRI. We began to use a 3.0T MRI scanner from 2012 as well.

RESULTS

We followed up 3 patients for 9 years, 2 for 8 years, and 3 for 7 years. In all patients, the CMBs at baseline did not disappear during the follow-up period. Importantly, the CMB in 1 patient seemed to disappear during the sixth imaging using 1.5T T2*-weighted GRE but was detected again during the seventh imaging with 3.0T susceptibility weighted imaging and ninth imaging with 3.0T T2* GRE. Moreover, in a patient implanted with a pacemaker, which is only applicable for 1.5T MRI at present, the CMB seemed to disappear and appeared once again with a 1.5T T2*-weighted GRE at a slice thickness of 2.5 mm instead of 5 mm.

CONCLUSIONS

From this prospective study, we obtained 2 absolutely new findings that CMBs remained for as long as 9 years and a high-field or thin-slice MRI can detect concealed CMBs.

Relationship between white matter connectivity loss and cortical thinning in cerebral amyloid angiopathy

Patients with cerebral amyloid angiopathy (CAA) show loss of white matter connectivity and cortical thinning on MRI, primarily in posterior brain regions. Here we examined whether a potential causal relationship exists between these markers of subcortical and cortical brain injury by examining whether changes in cortical thickness progress in tandem with changes in their underlying connections. Thirty-one patients with probable CAA with brain MRI at two time points were included (follow-up time: 1.3 ± 0.4 years). Brain networks were reconstructed using diffusion MRI-based fiber tractography. Of each network node, we calculated the change in fractional anisotropy-weighted connectivity strength over time and the change in cortical thickness. The association between change in connectivity strength and cortical thickness was assessed with (hierarchical) linear regression models. Our results showed that decline in posterior network connectivity over time was strongly related to thinning of the occipital cortex (β = 0.65 (0.35-0.94), P < 0.001), but not to thinning of the other posterior or frontal cortices. However, at the level of individual network nodes, we found no association between connectivity strength and cortical thinning of the corresponding node (β = 0.009 ± 0.04, P = 0.80). Associations were independent of age, sex, and other brain MRI markers of CAA. To conclude, CAA patients with greater progressive loss of posterior white matter connectivity also have greater progression of occipital cortical thinning, but our results do not support a direct causal relationship between them. The association can be better explained by a shared underlying mechanism, which may form a potential target for future treatments. Hum Brain Mapp 38:3723-3731, 2017. © 2017 Wiley Periodicals, Inc.

Mapping the Connectome Following Traumatic Brain Injury

There is a paucity of accurate and reliable biomarkers to detect traumatic brain injury, grade its severity, and model post-traumatic brain injury (TBI) recovery. This gap could be addressed via advances in brain mapping which define injury signatures and enable tracking of post-injury trajectories at the individual level. Mapping of molecular and anatomical changes and of modifications in functional activation supports the conceptual paradigm of TBI as a disorder of large-scale neural connectivity. Imaging approaches with particular relevance are magnetic resonance techniques (diffusion weighted imaging, diffusion tensor imaging, susceptibility weighted imaging, magnetic resonance spectroscopy, functional magnetic resonance imaging, and positron emission tomographic methods including molecular neuroimaging). Inferences from mapping represent unique endophenotypes which have the potential to transform classification and treatment of patients with TBI. Limitations of these methods, as well as future research directions, are highlighted.

Density heterogeneity and fluid-blood levels in patients aged over 55 with lobar hematoma

BACKGROUND

Density heterogeneity and fluid-blood levels (FBLs) are frequently seen on acute CT scans of deep brain hemorrhage. Our aim was to analyze the density heterogeneity and FBLs seen on acute/subacute CT in patients aged>55 with lobar haemorrhage (LH), and to study the relationship of these brain abnormalities with other parameters, including cerebral amyloid angiopathy (CAA)-related abnormalities.

METHODS

This was an observational study and retrospective analysis of early CT scans (<7 days) in patients aged>55 years with acute lobar hemorrhage who, between 2012 and 2015, were entered into our stroke database. A total of 37 LH episodes (without trauma, abnormal coagulation/platelet counts, vascular malformation, tumor or vasculitis) in 35 patients were analyzed. Other studied parameters were gender, age, history of hypertension, blood pressure on admission, prior antiplatelet treatment, aPTT, PTT, platelet count, hematocrit, timing of first CT, LH volume, involved lobe, cortical superficial siderosis, microbleeds, chronic LH and CAA (classic and modified Boston) criteria. CAA-related abnormalities seen on MRI were also scored.

RESULTS

Overall, in 26 LH episodes (70%), CT was performed within 24h. Density heterogeneity and FBLs were seen in 19 (51%) and 9 (24%) LH episodes, respectively. Also, according to classic and modified Boston criteria, 18 (51%) and 24 (69%) patients, respectively, fulfilled criteria for probable/definite CAA. As for the presence of FBLs, a statistically significant association was found with both the presence of probable/definite CAA according to modified Boston criteria (P=0.033) and the presence of superficial siderosis (P=0.019).

CONCLUSION

Density heterogeneity and, to a lesser degree, FBLs are frequently seen in patients aged>55 with LH. FBLs may also be associated with CAA-related hemorrhage.

Small vessel disease and cognitive impairment: The relevance of central network connections

Central brain network connections greatly contribute to overall network efficiency. Here we examined whether small vessel disease (SVD) related white matter alterations in central brain network connections have a greater impact on executive functioning than alterations in non-central brain network connections. Brain networks were reconstructed from diffusion-weighted MRI scans in 72 individuals (75 ± 8 years) with cognitive impairment and SVD on MRI. The centrality of white matter connections in the network was defined using graph theory. The association between the fractional anisotropy (FA) of central versus non-central connections, executive functioning, and markers of SVD was evaluated with linear regression and mediation analysis. Lower FA in central network connections was more strongly associated with impairment in executive functioning than FA in non-central network connections (r = 0.41 vs. r = 0.27; P < 0.05). Results were consistent across varying thresholds to define the central subnetwork (>50%-10% connections). Higher SVD burden was associated with lower FA in central as well as non-central network connections. However, only central network FA mediated the relationship between white matter hyperintensity volume and executive functioning [change in regression coefficient after mediation (95% CI): -0.15 (-0.35 to -0.02)]. The mediation effect was not observed for FA alterations in non-central network connections [-0.03 (-0.19 to 0.04)]. These findings suggest that the centrality of network connections, and thus their contribution to global network efficiency, appears to be relevant for understanding the relationship between SVD and cognitive impairment. Hum Brain Mapp 37:2446-2454, 2016. © 2016 Wiley Periodicals, Inc.

Amyloid-related imaging abnormalities-haemosiderin (ARIA-H) in patients with Alzheimer's disease treated with bapineuzumab: a historical, prospective secondary analysis

BACKGROUND

Amyloid-related imaging abnormalities due to haemosiderin deposition (ARIA-H) occur in patients with mild to moderate dementia due to Alzheimer's disease (AD) and have been reported with increased incidence in clinical trials of amyloid-lowering therapies under development for AD.

OBJECTIVE

Our objective was to explore the relationship between the incidences of ARIA-H during treatment with placebo and different doses of bapineuzumab, a humanised monoclonal antibody directed against amyloid β.

METHODS

Two neuroradiologists independently reviewed 2572 GRE/T2* MRI sequences from 262 participants in two phase two clinical trials of bapineuzumab and an open-label extension study. Readers were blinded to the participant's therapy, APOE ε4 genotype and medical history.

RESULTS

Several risk factors for small ARIA-H <10 mm (microhaemorrhages) were identified: APOE ε4, bapineuzumab treatment, pre-existing small ARIA-H and use of antithrombotics. The HR (95%CI) for incident ARIA-H <10 mm associated with the number of APOE ε4 alleles was 11.9 (3.3 to 42.5) for 2 versus no alleles and 3.5 (1.0 to 12.0) for 1 versus no allele. The HR for bapineuzumab therapy was 3.5 (1.0 to 12.0); for the presence of baseline ARIA-H <10 mm, it was 3.5 (1.6 to 7.8), and for the use of antithrombotic agents it was 2.2 (1.0 to 4.8). The incidence rate for ARIA-H <10 mm was elevated only in the initial 6 months of active treatment and declined after this interval to a rate similar to that observed in the group treated with placebo.

CONCLUSIONS

ARIA-H represents a spectrum of MRI findings due to haemosiderin deposition that appears to be related to impaired vascular integrity. The increased risk for ARIA-H associated with APOE ε4 allele frequency, pre-existing ARIA-H, treatment with bapineuzumab and use of antithrombotic agents provides additional support for this hypothesis of loss of integrity of cerebral vessels due to amyloid burden.

TRIAL REGISTRATION

NCT00112073 and NCT00606476.

New Cerebral Microbleeds After Mechanical Thrombectomy for Large-Vessel Occlusion Strokes

The interval appearance of cerebral microbleeds (CMBs) after endovascular treatment has never been described. We investigated the frequency and predictors of new CMBs that developed shortly after mechanical thrombectomy for acute ischemic stroke, and its impact on clinical outcome.We retrospectively analyzed patients with large-vessel occlusion strokes treated with Merci Retriever, Penumbra System, or stent-retriever devices. Serial T2*-weighted gradient-recall echo (GRE) magnetic resonance imaging (MRI) before and 48 h after endovascular thrombectomy were assessed to identify new CMBs. We examined independent factors associated with new CMBs after mechanical thrombectomy. We analyzed the association of the presence, burden, and distribution of new CMBs with clinical outcome.A total of 187 consecutive patients with serial GRE were enrolled in this study. CMBs were evident in 36 (19.3%) patients before mechanical thrombectomy. New CMBs occurred in 41 (21.9%) patients after mechanical thrombectomy. Of the 68 new CMBs, 45 appeared in the lobar location, 18 in the deep location and 5 in the infratentorial location. The presence of baseline CMBs was associated with new CMBs after mechanical thrombectomy (OR 5.38; 95% CI 2.13-13.59; P < 0.001), no matter whether the patients were treated primarily with mechanical thrombectomy or with intravenous thrombolysis followed by mechanical thrombectomy. Patients with new CMBs did not have increased rates of hemorrhagic transformation, in-hospital mortality, and modified Rankin Scale score 4 to 6 at discharge.New CMBs are common after mechanical thrombectomy in one-fifth of patients with acute ischemic stroke. Baseline CMBs before mechanical thrombectomy predicts the development of new CMBs. New CMBs after mechanical thrombectomy do not influence clinical outcome.

Silent New Brain Lesions: Innocent Bystander or Guilty Party?

With the advances in magnetic resonance imaging, previously unrecognized small brain lesions, which are mostly asymptomatic, have been increasingly detected. Diffusion-weighted imaging can identify small ischemic strokes, while gradient echo T2* imaging and susceptibility-weighted imaging can reveal tiny hemorrhagic strokes (microbleeds). In this article, we review silent brain lesions appearing soon after acute stroke events, including silent new ischemic lesions and microbleeds appearing 1) after acute ischemic stroke and 2) after acute intracerebral hemorrhage. Moreover, we briefly discuss the clinical implications of these silent new brain lesions.

Review And Insights Into The Bleeding Mechanism Incited By Antithrombotic Therapy: Mechanistic Nuances Of Dual Pro-Hemorrhagic Substrate Incorporating Drug-Induced Microvascular Leakage

In patients with atrial fibrillation antithrombotic prophylaxis for stroke is associated with an increased risk of bleeding. Cerebrovascular risk-benefit ratio for oral anticoagulation therapies continues to be debated. Macro and/or microhematomas as well as visible or cryptic ones may appear unexpectedly in any anatomic region. The diagnostic and prognostic value of subcutaneous hematomas (petechia, ecchymosis, bruise) potentially predisposing intracerebral micro- or macrobleeding might be reconsidered. Hypothetically, subcutaneous hemorrhagic events are "transparent" signs and reflect the coexistence of remote vulnerable sites that are potential bleeding sources. Obviously vigilance is needed for early signs of drug-related petechiae evaluation to determine whether it is a local/superficial subtlety or a systemic problem. Any bleeding complication, regardless of its scale and anatomical location, might be treated as a worrisome clinical symptom requiring subtle correction of antithrombotic regimen. The focus of this article is to review the current knowledge of drug-related hemorrhage with special emphasis on underlying mechanisms and links between the visible bleeding (predominantly subcutaneous) and remote (such as cerebral) hemorrhagic sources. To mitigate inappropriate therapy, we should consider new conceptual insights and more individualized approaches to achieve an optimal balance of efficacy and safety. We hypothesize that bleeding complications occur as a result of two factors - impact of antithrombotic drugs and related detrimental effect on microvascular network. Most likely the microvasculature undergoes pro-hemorrhagic medication stress leading to unfavorable vascular wall "fenestration" with ensuing consequences. If so, it suggests the presence of dual substrate responsible for hemorrhagic events.

Cortical localization of microbleeds in cerebral amyloid angiopathy: an ultra high-field 7T MRI study

The extent of cortical involvement of cerebral amyloid angiopathy (CAA)-related microbleeds (CMBs) remains unclear. We examined five consecutive patients with probable CAA and three non-demented elderly subjects with ultra-high field 7T MRI, to identify the precise location of CAA-related CMBs. In five CAA patients, 169 of a total of 170 lobar CMBs were located in cortical areas on 7T MRI, while a precise cortical versus juxtacortical localization was unable to be determined for 50/76 CMBs observed by conventional MRI. 7T MRI demonstrates that nearly all lobar CMBs are located in cortex in CAA.

Diagnostic value of lobar microbleeds in individuals without intracerebral hemorrhage

INTRODUCTION

The Boston criteria are the basis for a noninvasive diagnosis of cerebral amyloid angiopathy (CAA) in the setting of lobar intracerebral hemorrhage (ICH). We assessed the accuracy of these criteria in individuals with lobar microbleeds (MBs) without ICH.

METHODS

We identified individuals aged >55 years having brain magnetic resonance imaging (MRI) and pathological assessment of CAA in a single academic hospital and a community-based population (Framingham Heart Study [FHS]). We determined the positive predictive value (PPV) of the Boston criteria for CAA in both cohorts, using lobar MBs as the only hemorrhagic lesion to fulfill the criteria.

RESULTS

We included 102 individuals: 55 from the hospital-based cohort and 47 from FHS (mean age at MRI 74.7 ± 8.5 and 83.4 ± 10.9 years; CAA prevalence 60% and 46.8%; cases with any lobar MB 49% and 21.3%; and cases with ≥2 strictly lobar MBs 29.1% and 8.5%, respectively). PPV of "probable CAA" (≥2 strictly lobar MBs) was 87.5% (95% confidence interval [CI], 60.4-97.8) and 25% (95% CI, 13.2-78) in hospital and general populations, respectively.

DISCUSSION

Strictly lobar MBs strongly predict CAA in non-ICH individuals when found in a hospital context. However, their diagnostic accuracy in the general population appears limited.

The characteristics of superficial siderosis and convexity subarachnoid hemorrhage and clinical relevance in suspected cerebral amyloid angiopathy

BACKGROUND AND AIMS

Systematic studies of superficial siderosis (SS) and convexity subarachnoid hemorrhage (cSAH) in patients with suspected cerebral amyloid angiopathy (CAA) without lobar intracerebral hemorrhage (ICH) are lacking. We sought to determine the potential anatomic correlation between SS/cSAH and transient focal neurological episodes (TFNE) and whether SS/cSAH is predictor of future cerebral hemorrhagic events in these patients.

METHODS

We enrolled 90 consecutive patients with suspected CAA (due to the presence of strictly lobar microbleeds (CMBs) and/or SS/cSAH) but without the history of symptomatic lobar ICH who underwent brain MRI including T2*-weighted, diffusion-weighted imaging and fluid-attenuated inversion recovery sequences from an ongoing single center CAA cohort from 1998 to 2012. Evaluation of SS, cSAH and CMBs was performed. Medical records and follow-up information were obtained from prospective databases and medical charts. TFNE was defined according to published criteria and electroencephalogram reports were reviewed.

RESULTS

Forty-one patients (46%) presented with SS and/or cSAH. The prevalence of TFNE was significantly higher in those with SS/cSAH (61 vs. 10%; p < 0.001) and anatomically correlated with the location of cSAH, but not SS. The majority of TFNE in patients with SS/cSAH presented with spreading sensory symptoms. Intermittent focal slowing on electroencephalogram was present in the same area as SS/cSAH in 6 patients, but no epileptiform activity was found in any patients. Among those with available clinical follow-up (76/90 patients, 84%), ten patients with SS/cSAH (29%, median time from the scan for all patients with SS/cSAH: 21 months) had a symptomatic cerebral bleeding event on follow up (average time to events: 34 months) compared with only 1 event (2.4%, 25 months from the scan) in patients without SS/​cSAH (time to event: 25 months) (p = 0.001). The location of hemorrhages on follow-up scan was not in the same location of previously noted SS/cSAH in 9 of 10 patients. Follow-up imaging was obtained in 9 of 17 patients with cSAH and showed evidence of SS in the same location as initial cSAH in all these 9 cases.

CONCLUSIONS

SS/cSAH is common in patients with suspected CAA without lobar intracerebral hemorrhage and may have a significantly higher risk of future cerebral bleeding events, regardless of the severity of the baseline CMB burden. The findings further highlight a precise anatomical correlation between TFNE and cSAH, but not SS. Distinct from transient ischemic attack or seizure, the majority of TFNE caused by SS/cSAH appear to present with spreading sensory symptoms.

High incidence of asymptomatic cerebral microbleeds in patients with hemorrhagic onset-type moyamoya disease: a phase-sensitive MRI study and meta-analysis

BACKGROUND

Moyamoya disease is a relatively rare cerebrovascular occlusive disorder. Several studies have reported cerebral microbleeds (CMBs) in moyamoya disease patients using T2*-weighted imaging (T2*WI) and/or susceptibility-weighted imaging (SWI).

PURPOSE

To investigate the incidence, distribution patterns, and influencing factors of asymptomatic CMBs in patients with moyamoya disease.

MATERIAL AND METHODS

Phase-sensitive imaging (PSI) was used to investigate 27 consecutive moyamoya disease patients with a 3-T magnetic resonance imaging system, then a meta-analysis of 245 patients (asymptomatic moyamoya disease, n = 23; ischemic moyamoya disease, n = 161; hemorrhagic moyamoya disease, n = 61) from four previous individual studies and our PSI study was performed. The meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Based on the clinical and radiological data, we divided the studies into different model groups to calculate the incidence of CMBs and discuss the distribution patterns of CMBs.

RESULTS

Thirty-five asymptomatic CMBs were demonstrated in 14 moyamoya disease patients (51.9%) in our PSI study. Of these, 45.7% were located in the periventricular white matter. In the meta-analysis, the pooled incidence of asymptomatic CMBs in moyamoya disease was 46% (95% confidence interval [CI], 28.2-63.8%) on SWI or PSI and 29.6% (95% CI, 17.4-41.7%) on T2*WI. Statistical analysis showed that PSI or SWI offered better detection of CMBs in moyamoya disease than T2*WI, and 3-T T2*WI offered better detection than 1.5-T T2*WI. Furthermore, hemorrhagic onset-type moyamoya disease correlated with a high incidence of asymptomatic CMBs.

CONCLUSION

PSI or SWI can detect CMBs better than T2*WI, and 3-T T2*WI. Hemorrhagic onset-type moyamoya disease seems to correlate with a high incidence of asymptomatic CMBs. The meta-analysis indicates that asymptomatic CMBs may be an important factor for hemorrhagic stroke risk. Long-term evaluation of CMBs using PSI or SWI may contribute to the management of moyamoya disease.

The Significance of Cortical Cerebellar Microbleeds and Microinfarcts in Neurodegenerative and Cerebrovascular Diseases

Background: As cortical microbleeds and microinfarcts in neurodegenerative and cerebrovascular diseases have been studied predominantly at the level of the cerebral hemispheres and linked to the presence of cerebral amyloid angiopathy (CAA), we aimed at determining with 7.0-tesla magnetic resonance imaging (MRI) whether the causes and the frequency of cortical cerebellar microbleeds (CCeMBs) and microinfarcts (CCeMIs) are the same. Materials and Methods: Hundred and four postmortem brains, composed of 29 with pure Alzheimer's disease (AD), 9 with AD associated to CAA, 10 with frontotemporal lobar degeneration, 9 with amyotrophic lateral sclerosis, 10 with Lewy body disease, 12 with progressive supranuclear palsy, 9 with vascular dementia (VaD), and 16 controls, were examined. On a horizontal section of a cerebellar hemisphere examined with 7.0-tesla MRI, the number CCeMBs and CCeMIs were compared between the different disease groups and the control group. The MRI findings were also compared with the corresponding mean values observed on histological examination of a separate standard horizontal section of a cerebellar hemisphere, used for diagnostic purpose. Results: CCeMBs and CCeMIs were only significantly increased in the VaD group. When comparing the diseased patients with and without CAA mutually and with those with arterial hypertension and severe atherosclerotic cerebrovascular disease, only in the latter an increase of CCeMBs and CCeMIs was observed. There was an excellent correlation between the MRI and the neuropathological findings. Conclusions: CCeMBs and CCeMIs are mainly due to atherosclerotic cerebrovascular disease and not due to CAA. Their increased presence cannot be included to the Boston diagnostic criteria for CAA.

Simultaneous imaging of radiation-induced cerebral microbleeds, arteries and veins, using a multiple gradient echo sequence at 7 Tesla

BACKGROUND

The purpose of this study was to implement and evaluate the utility of a multi-echo sequence at 7 Tesla (T) for simultaneous time-of-flight (TOF) MR-angiography (MRA) and susceptibility-weighted imaging (SWI) of radiation-induced cerebral microbleeds (CMBs), intracranial arteries, and veins.

METHODS

A four-echo gradient-echo sequence was implemented on a 7T scanner. The first echo was used to create TOF-MRA images, while the remaining echoes were combined to visualize CMBs and veins on SWI images. The sequence was evaluated on eight brain tumor patients with known radiation-induced CMBs. Single-echo images were also acquired to visually and quantitatively compare the contrast-to-noise ratio (CNR) of small- and intermediate-vessels between acquisitions. The number of CMBs detected with each acquisition was also quantified. Statistical significance was determined using a Wilcoxon signed-rank test.

RESULTS

Compared with the single-echo sequences, the CNR of small and intermediate arteries increased 7.6% (P < 0.03) and 9.5% (P = 0.06), respectively, while the CNR of small and intermediate veins were not statistically different between sequences (P = 0.95 and P = 0.46, respectively). However, these differences were not discernible by visual inspection. Also the multi-echo sequence detected 18.3% more CMBs (P < 0.008) due to higher slice resolution.

CONCLUSION

The proposed 7T multi-echo sequence depicts arteries, veins, and CMBs on a single image to facilitate quantitative evaluation of radiation-induced vascular injury.

Structural network alterations and neurological dysfunction in cerebral amyloid angiopathy

Cerebral amyloid angiopathy is a common form of small-vessel disease and an important risk factor for cognitive impairment. The mechanisms linking small-vessel disease to cognitive impairment are not well understood. We hypothesized that in patients with cerebral amyloid angiopathy, multiple small spatially distributed lesions affect cognition through disruption of brain connectivity. We therefore compared the structural brain network in patients with cerebral amyloid angiopathy to healthy control subjects and examined the relationship between markers of cerebral amyloid angiopathy-related brain injury, network efficiency, and potential clinical consequences. Structural brain networks were reconstructed from diffusion-weighted magnetic resonance imaging in 38 non-demented patients with probable cerebral amyloid angiopathy (69 ± 10 years) and 29 similar aged control participants. The efficiency of the brain network was characterized using graph theory and brain amyloid deposition was quantified by Pittsburgh compound B retention on positron emission tomography imaging. Global efficiency of the brain network was reduced in patients compared to controls (0.187 ± 0.018 and 0.201 ± 0.015, respectively, P < 0.001). Network disturbances were most pronounced in the occipital, parietal, and posterior temporal lobes. Among patients, lower global network efficiency was related to higher cortical amyloid load (r = -0.52; P = 0.004), and to magnetic resonance imaging markers of small-vessel disease including increased white matter hyperintensity volume (P < 0.001), lower total brain volume (P = 0.02), and number of microbleeds (trend P = 0.06). Lower global network efficiency was also related to worse performance on tests of processing speed (r = 0.58, P < 0.001), executive functioning (r = 0.54, P = 0.001), gait velocity (r = 0.41, P = 0.02), but not memory. Correlations with cognition were independent of age, sex, education level, and other magnetic resonance imaging markers of small-vessel disease. These findings suggest that reduced structural brain network efficiency might mediate the relationship between advanced cerebral amyloid angiopathy and neurologic dysfunction and that such large-scale brain network measures may represent useful outcome markers for tracking disease progression.

New microbleeds after thrombolysis: contiguous thin-slice 3T MRI

We aimed to determine the frequency of new microbleeds after intravenous thrombolysis using contiguous thin-slice 3T magnetic resonance imaging. We retrospectively examined clinical and imaging data from 121 consecutive acute ischemic stroke patients who underwent magnetic resonance imaging before and 24 hours after intravenous thrombolysis. Of the included patients, 44 (36.4%) were women, with a median age of 69 years (range, 35-94 years). A total of 363 baseline microbleeds were observed in 57 patients and 8 new microbleeds in 6 patients. Multiple regression analysis indicated that baseline infarct volume (odds ratio, 1.556/10 mL; 95% CI, 1.017-2.379; P = 0.04) and systolic blood pressure (odds ratio, 1.956/10 mm Hg; 95% CI, 1.056-3.622; P = 0.03), but not the presence of baseline microbleeds, were independently associated with new microbleeds. The frequency of neither symptomatic intracranial hemorrhage nor remote hemorrhage or any hemorrhagic transformation was different between patients with and without new microbleeds (0.0% vs 1.7%, P > 0.99; 0.0% vs 1.7%, P > 0.99; 50.0% vs 28.7%, P =0.36). New microbleeds developed rapidly 24 hours after intravenous thrombolysis. The significance of these new microbleeds and their effect on cognitive and functional outcome merits further investigation.

Posterior white matter disease distribution as a predictor of amyloid angiopathy

OBJECTIVES

We sought to examine whether a posterior distribution of white matter hyperintensities (WMH) is an independent predictor of pathologically confirmed cerebral amyloid angiopathy (CAA) and whether it is associated with MRI markers of CAA, in patients without lobar intracerebral hemorrhage.

METHODS

We developed a quantitative method to measure anteroposterior (AP) distribution of WMH. A retrospective cohort of patients without intracerebral hemorrhage and with pathologic evaluation of CAA was examined to determine whether posterior WMH distribution was an independent predictor of CAA (n=59). The relationship of AP distributions of WMH to strictly lobar microbleeds (MBs) (n=259) and location of dilated perivascular spaces (DPVS) (n=85) was examined in a separate cohort of patients evaluated in a memory clinic.

RESULTS

A more posterior WMH distribution was found to be an independent predictor of pathologic evidence of CAA (p=0.001, odds ratio [95% confidence interval]=1.19 [1.07-1.32]), even in the subgroup without lobar MBs (p=0.016, odds ratio [95% confidence interval]=1.18 [1.03-1.36]). In the memory clinic cohort, strictly lobar MBs were independently associated with more posterior WMH distribution (p=0.009). AP distribution of WMH was also associated with location of DPVS (p=0.001), in that patients with predominant DPVS in the white matter over the basal ganglia harbored a more posterior WMH distribution.

CONCLUSIONS

Our results suggest that AP distribution of WMH may represent an additional marker of CAA, irrespective of the presence of lobar hemorrhages.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that there is a significant association between the AP distribution of WMH on MRI with the presence of pathologically confirmed CAA pathology.

Intracerebral hematoma extends via perivascular spaces and perineurium

Intracerebral hemorrhage (ICH) is a devastating disorder associated with high morbidity and mortality. ICH results in the formation of hematoma that affects not only the primary site of injury but also the remote regions. In fact, hematoma can extend via perivascular spaces (also called Virchow-Robin spaces, VRS) and perineurium in an animal model of ICH. In the present study, we used magnetic resonance imaging (MRI) with susceptibility-weighted imaging (SWI) to investigate the characteristics of the perivascular and perineural extensions of hematomas in patients with ICH. A total of 20 ICH patients without secondary subarachnoid and secondary intraventricular hemorrhages were recruited. Brain MRI scans, including SWI, T1, and T2-weighted images, were performed between 17 h to 7 days after the onset of ICH. MRI with SWI revealed that paramagnetic substances spread along the VRS or the perineurium. Such distribution could cause the formation of cerebral microbleeds (CMBs). However, the distribution of remote hemorrhagic lesions varied, depending on the size and location of the original hematoma. The unenhanced CT scans of the 20 patients did not show any hyperdensity around the blood vessels and nerve tracts outside the hematoma. These results indicate the perivascular and perineural extensions of hematomas in patients with ICH, which is formed by the leakage of the original hematoma via the VRS or perineurium. We also provide a new explanation for the series of pathological processes involved in ICH, including the remote effects of hematoma and the formation of CMBs in patients with ICH.

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.

Susceptibility-weighted imaging is more reliable than T2*-weighted gradient-recalled echo MRI for detecting microbleeds

BACKGROUND AND PURPOSE

We investigated the sensitivity and reliability of MRI susceptibility-weighted imaging (SWI) compared with routine MRI T2*-weighted gradient-recalled echo (GRE) for cerebral microbleed (CMB) detection.

METHODS

We used data from a prospective study of cerebral amyloid angiopathy (n=9; mean age, 71±8.3) and healthy non-cerebral amyloid angiopathy controls (n=22; mean age, 68±6.3). Three raters (labeled 1, 2, and 3) independently interpreted the GRE and SWI sequences (using the phase-filtered magnitude image) blinded to clinical information.

RESULTS

In 9 cerebral amyloid angiopathy cases, the raters identified 1146 total CMBs on GRE and 1432 CMBs on SWI. In 22 healthy control subjects, the raters identified ≥1 CMBs in 6/22 on GRE (total 9 CMBs) and 5/22 on SWI (total 19 CMBs). Among cerebral amyloid angiopathy cases, the reliability between raters for CMB counts was good for SWI (intraclass correlation coefficient, 0.87) but only moderate for GRE (intraclass correlation coefficient, 0.52). In controls, agreement on the presence or absence of CMBs in controls was moderate to good on both SWI (κ coefficient ranged from 0.57 to 0.74 across the 3 combinations of rater pairs) and GRE (κ range, 0.31 to 0.70). A review of 114 hypointensities identified as possible CMBs indicated that increased detection and reliability on SWI was related to both increased contrast and higher resolution, allowing better discrimination of CMBs from the background and better anatomic differentiation from pial vessels.

CONCLUSIONS

SWI confers greater reliability as well as greater sensitivity for CMB detection compared with GRE, and should be the preferred sequence for quantifying CMB counts.

Topography of dilated perivascular spaces in subjects from a memory clinic cohort

OBJECTIVE

To investigate whether the topography of dilated perivascular spaces (DPVS) corresponds with markers of particular small-vessel diseases such as cerebral amyloid angiopathy and hypertensive vasculopathy.

METHODS

Patients were recruited from an ongoing single-center prospective longitudinal cohort study of patients evaluated in a memory clinic. All patients underwent structural, high-resolution MRI, and had a clinical assessment performed within 1 year of scan. DPVS were rated in basal ganglia (BG-DPVS) and white matter (WM-DPVS) on T1 sequences, using an established 4-point semiquantitative score. DPVS degree was classified as high (score > 2) or low (score ≤ 2). Independent risk factors for high degree of BG-DPVS and WM-DPVS were investigated.

RESULTS

Eighty-nine patients were included (mean age 72.7 ± 9.9 years, 57% female). High degree of WM-DPVS was more frequent than low degree in patients with presence of strictly lobar microbleeds (45.5% vs 28.4% of subjects). High BG-DPVS degree was associated with older age, hypertension, and higher white matter hyperintensity volumes. In multivariate analysis, increased lobar microbleed count was an independent predictor of high degree of WM-DPVS (odds ratio [OR] 1.53 [95% confidence interval (CI) 1.06-2.21], p = 0.02). By contrast, hypertension was an independent predictor of high degree of BG-DPVS (OR 9.4 [95% CI 1-85.2], p = 0.04).

CONCLUSIONS

The associations of WM-DPVS with lobar microbleeds and BG-DPVS with hypertension raise the possibility that the distribution of DPVS may indicate the presence of underlying small-vessel diseases such as cerebral amyloid angiopathy and hypertensive vasculopathy in patients with cognitive impairment.

Higher ambulatory blood pressure relates to new cerebral microbleeds: 2-year follow-up study in lacunar stroke patients

BACKGROUND AND PURPOSE

Elevated blood pressure (BP) is associated with the presence of cerebral microbleeds (CMBs) in cross-sectional studies. However, longitudinal studies did not show a convincing relationship. We aimed to determine the association between elevated BP levels and the occurrence of new CMBs after a 2-year follow-up in first-ever lacunar stroke patients using ambulatory BP monitoring.

METHODS

Ninety-six first-ever lacunar stroke patients underwent brain MRI and ambulatory BP monitoring at baseline and after 2-year follow-up. We used logistic regression analyses to assess the association of BP levels with new CMBs.

RESULTS

We found new CMBs in 17 patients (18%). Higher 24-hour, day and night systolic BP (odds ratio, 2.69; 95% confidence interval, 1.40-5.21 per SD increase for 24-hour BP) and diastolic BP (odds ratio, 2.13; 95% confidence interval, 1.15-3.90 per SD increase for 24-hour BP) at baseline were associated with the development of new CMBs independent of age and sex. BP levels decreased during follow-up in both patients with and without new CMBs. Unlike BP levels at baseline, there was no difference in BP levels at follow-up between patients with and without new CMBs.

CONCLUSIONS

Both higher systolic and diastolic BP levels were associated with the development of new CMBs in a population of lacunar stroke patients. Decrease of BP levels during follow-up did not halt progression of CMBs; however, it remains to be determined whether (early) intervention with antihypertensive drugs can slow down progression of CMBs.

Computer-aided detection of radiation-induced cerebral microbleeds on susceptibility-weighted MR images

Recent interest in exploring the clinical relevance of cerebral microbleeds (CMBs) has motivated the search for a fast and accurate method to detect them. Visual inspection of CMBs on MR images is a lengthy, arduous task that is highly prone to human error because of their small size and wide distribution throughout the brain. Several computer-aided CMB detection algorithms have recently been proposed in the literature, but their diagnostic accuracy, computation time, and robustness are still in need of improvement. In this study, we developed and tested a semi-automated method for identifying CMBs on minimum intensity projected susceptibility-weighted MR images that are routinely used in clinical practice to visually identify CMBs. The algorithm utilized the 2D fast radial symmetry transform to initially detect putative CMBs. Falsely identified CMBs were then eliminated by examining geometric features measured after performing 3D region growing on the potential CMB candidates. This algorithm was evaluated in 15 patients with brain tumors who exhibited CMBs on susceptibility-weighted images due to prior external beam radiation therapy. Our method achieved heightened sensitivity and acceptable amount of false positives compared to prior methods without compromising computation speed. Its superior performance and simple, accelerated processing make it easily adaptable for detecting CMBs in the clinic and expandable to a wide array of neurological disorders.

Cerebral microhemorrhages in a collegiate football player: clinical implications in the management of sports concussion

Most concussions in sports medicine are managed without advanced neurological imaging. However, computed tomography and magnetic resonance imaging are sometimes used in the management of complex sports concussions to identify acute/delayed intracranial bleeding or other associated pathology. Advances in imaging techniques have led to greater resolution and the identification of pathology of uncertain clinical significance. This report describes the presence of persistent cerebral microhemorrhages identified on magnetic resonance imaging in a collegiate football player who suffered a concussion. The associated risks and clinical significance of cerebral microhemorrhages have not been determined in the young athletic population. This case highlights provocative issues in the management of sports concussions as related to findings on modern neurological imaging and their potential implication on to return-to-play considerations.

Postoperative outcome of cerebral amyloid angiopathy-related lobar intracerebral hemorrhage: case series and systematic review

BACKGROUND

Despite its accessible superficial location, the indication for surgical evacuation in cases of lobar intracerebral hemorrhage (LICH) suspected to be related to cerebral amyloid angiopathy (CAA) is controversial because of advanced patient age and concerns about postoperative hemostasis.

OBJECTIVE

To examine factors associated with postoperative outcome in CAA-related LICH.

METHODS

Review of consecutive patients with pathologically proven CAA who underwent LICH evacuation at Saint Marys Hospital, Rochester, Minnesota, between 1987 and 2006. End points were length of stay and postoperative outcome at discharge and last follow-up using the Glasgow Outcome Scale. We also performed a systematic review of all published studies evaluating the outcome of surgically treated CCA-related LICH published between 1984 and 2010.

RESULTS

We identified 23 patients with CAA-related LICH treated surgically. Favorable outcome (Glasgow Outcome Scale >3) at discharge was noted in 5 patients (22%), and at 6- to 12-month follow-up (n = 15) in 7 patients (47%). Three (13%) died in the hospital, including 1 of 4 patients with postoperative hemorrhage. Intraventricular hemorrhage (IVH) was associated with poor outcome at discharge. Older age (≥75 years), history of hypertension, and degree of preoperative midline shift were associated with more prolonged length of stay. In our systematic review, we identified 14 studies including 278 cases. Overall mortality rate was 25%, and poor postoperative outcome was associated with older age, IVH, and preoperative dementia.

CONCLUSION

Neurosurgical evacuation may be performed with acceptable safety in patients with CAA-related LICH. A systematic literature review indicates that older age, preexistent dementia, and presurgical IVH portend poor postoperative outcome.

Cerebral amyloid angiopathy in the elderly

Cerebral amyloid angiopathy (CAA) results from deposition of β-amyloid in the media and adventitia of small arteries and capillaries of the leptomeninges and cerebral cortex and is a major cause of lobar intracerebral hemorrhage and cognitive impairment in the elderly. CAA is associated with a high prevalence of magnetic resonance imaging markers of small vessel disease, including cerebral microbleeds and white matter hyperintensities. Although advanced CAA is present in approximately ¼ of brains with Alzheimer disease (AD), fewer than half of CAA cases meet pathologic criteria for AD. This review will discuss the pathophysiology of CAA and focus on new imaging modalities and laboratory biomarkers that may aid in the clinical diagnosis of individuals with the disease.

Dynamic temporal change of cerebral microbleeds: long-term follow-up MRI study

Background

Cerebral microbleeds (MBs) are understood as an important radiologic marker of intracerebral hemorrhage. We sought to investigate the temporal changes of MBs and clinical factors associated with the changes using long-term follow-up MRI.

Methods/Principal Findings

From October 2002 to July 2006, we prospectively enrolled patients with stroke or transient ischemic attack, and followed-up their brain MRIs with an interval >12 mo. We compared demographic factors, vascular risk factors, laboratory findings, and radiologic factors according to the presence or changes of MBs. A total of 224 patients successfully completed the follow-up examinations (mean, 27 months). Newly developed MBs were noted in 10 patients (6.8%) among those without MBs at baseline (n = 148), and in those with MBs at baseline (n = 76), the MB count had decreased in 11 patients (14.5%), and increased in 41 patients (53.9%). The estimated annual rate of change of MB numbers was 0.80 lesions per year in all patients, a value which became greater in those patients who exhibited MBs at baseline (MBs≥5, 5.43 lesions per year). Strokes due to small vessel occlusion and intracerebral hemorrhage, as well as white matter lesions were independently associated with an increased MB count, whereas the highest quartile of low-density lipoprotein (LDL) cholesterol was associated with a decreased MB count.

Conclusion

During the follow-up period, most of MBs showed dynamic temporal change. Symptomatic or asymptomatic small vessel diseases appear to act as risk factors while in contrast, a high level of LDL cholesterol may act as a protective factor against MB increase.

"Brush Sign" on susceptibility-weighted MR imaging indicates the severity of moyamoya disease

BACKGROUND AND PURPOSE

SWI is a high spatial resolution MR imaging technique showing magnetic inhomogeneity that could demonstrate increased oxygen extraction in focal cerebral ischemia. The aim of this study was to investigate the characteristics in the signal intensity of DMVs by using SWI and to determine whether this method could indicate the severity of the hemodynamics in MMD by evaluating the correlation between SWI stage and hemodynamics on SPECT.

MATERIALS AND METHODS

Consecutive MMD patients were prospectively analyzed before treatment. Routine MR imaging including SWI was performed, and the number of the conspicuous DMVs draining into the subependymal veins was classified: stage 1, mild (< 5); stage 2, moderate (5-10); and stage 3, severe (> 10). The SWI stage was evaluated in correlation with clinical presentations, and CBF and CVR were quantified by using a SPECT iodine 123 N-isopropyl-p-iodoamphetamine split-dose method.

RESULTS

Patients were 12 males and 21 females (range, 8-66 years), consisting of 4 asymptomatic patients, 13 patients with TIA, 9 patients with infarct, and 7 patients with hemorrhage. There was a significant difference in CVR among clinical presentations, though there was no difference in age, Suzuki stage, or CBF. Conversely, SWI stage was significantly higher in patients with TIA and infarct than asymptomatic patients (P < .01). Higher SWI stage significantly had lower CBF and CVR in the middle cerebral artery area (P < .05).

CONCLUSIONS

SWI stage strongly correlates with ischemic presentations in MMD and also correlates with hemodynamics on SPECT, especially CVR. Increased conspicuity of DMVs, known as "brush sign", could predict the severity of MMD.

Clinical relevance of improved microbleed detection by susceptibility-weighted magnetic resonance imaging

BACKGROUND AND PURPOSE

Susceptibility-weighted imaging (SWI) has been shown to be more sensitive in detecting cerebral microbleeds (MBs) than is conventional T2*-weighted gradient-recalled echo imaging (GRE). However, the clinical relevance of this improved detection in terms of associations with clinical measures and risk factors is unclear. We sought to determine whether associations of MBs with clinical characteristics, risk factors, white-matter hyperintensities, and lacunes were different on GRE versus SWI in memory clinic patients.

METHODS

One hundred forty-one patients presenting at our memory clinic were included and underwent clinical evaluation and a magnetic resonance imaging protocol including both GRE and SWI. Images were analyzed for numbers and locations of MBs and white-matter hyperintensities. In a subset of patients, apolipoprotein E status was determined. Negative binomial regression was used to assess clinical and radiologic associations with MB number.

RESULTS

MB prevalence was 23% on GRE and 40% on SWI. A total of 219 and 284 MBs were detected on GRE and SWI, respectively. Within groups with MBs, the median MB count was 1 (range, 1 to 144) on GRE and 2 (range, 1 to 129) on SWI (P<0.001). The increase in the number of MBs on SWI was equally distributed among brain regions. Strengths of the associations with age, sex, white-matter hyperintensities, and presence of lacunes with higher MB numbers were comparable for GRE and SWI (all P<0.05); no differential independent associations were detected.

CONCLUSIONS

SWI detected more MBs in more patients, irrespective of MB location. However, this enhanced detection had no improved clinical relevance in terms of associations with vascular risk factors or radiologic markers of small-vessel disease.

The difference in location between traumatic cerebral microbleeds and microangiopathic microbleeds associated with stroke

BACKGROUND AND PURPOSE

Microbleeds (MBs) are low-intensity spots on gradient echo T2*-weighted MRI frequently associated with cerebral microangiopathies resulting in stroke. MBs can also be caused by cerebral axonal injuries. We compared the location of MBs associated with cerebral microangiopathies with those associated with trauma.

METHODS

T2*-weighted MRI identified traumatic MBs (t-MBs) in 23 (6 females; 38.7 ± 25.8 years old) of the 312 patients with head trauma consecutively admitted to our hospital between March 2003 and March 2009. We prospectively examined for the presence of microangiopathic MBs (m-MBs) in the 131 patients (59 females; 65.2 ± 9.2 years old) admitted consecutively for stroke (May -December 2004) as controls.

RESULTS

We identified a total of 145 t-MBs and 504 m-MBs. t-MBs were frequently located in the mid portion of the subcortical area of the cerebrum, above the corpus callosum in axial slices, and were absent from the basal ganglia. In contrast, m-MBs were frequently located within the basal ganglia or thalamus.

CONCLUSION

There are substantial differences in locations of MB development in trauma patients in comparison to stroke patients.

Cerebral amyloid angiopathy in East and West

Cerebral amyloid angiopathy, a vasculopathy characterised by the deposition of amyloid fibrils in the arteries and arterioles in the cerebral cortex and meninges, has been reported to be associated with intracerebral haemorrhage and cognitive impairment in the elderly. Advances in neuroimaging and validation of the clinical diagnostic criteria aid in making a correct clinical diagnosis. Associations with Alzheimer's disease, asymptomatic microbleeds and white matter changes on neuroimaging have an influence on the clinical treatment for patients with probable cerebral amyloid angiopathy. Reviewing the reports from Asian countries, we found that patients with cerebral amyloid angiopathy have a strong age-related prevalence and a consistent association with dementia, but a weaker correlation with intracerebral haemorrhage, most likely due to a higher incidence of hypertensive intracerebral haemorrhage. Involvement of the occipital lobe arteries by CAA is common in all races and ethnicities, while frontal lobe arteries may be more frequently involved in the East compared to the West. The clinical impact of cerebral amyloid angiopathy on intracerebral haemorrhage and cognitive impairment could be increasingly obvious in Asian countries with ageing populations, especially with improving control of hypertension, the leading cause of intracerebral haemorrhage.

Cerebral amyloid angiopathy-related microhemorrhages in Alzheimer's disease: a review of investigative animal models

There is a growing understanding of cerebral amyloid angiopathy (CAA), which accounts for the majority of primary lobal intracerebral hemorrhages (ICH) among the elderly [1] and is cited as the cause of 20% of spontaneous ICHs in patients over 70 years of age [2]. The basis for this disease process is the deposition and formation of eventually destructive amyloid plaques in the walls of brain vessels, predominantly arterial but not excluding venules and capillaries [3]. Investigation of the pathophysiology and therapies for CAA-associated hemorrhages have been made possible through animal models utilizing species that develop CAA in a similar fashion to humans, such as the squirrel monkey, rhesus monkey, dog and mutant and transgenic mouse strains, which exhibit the age-related development of amyloid plaques, progressive neurodegeneration and CAA-associated hemorrhages. The disease course in these animal models resembles that seen in the clinical setting for patients with CAA. Rodent studies have been able to demonstrate the strong role of CAA and CAA-associated microhemorrhages in the pathogenesis and progression of CAA with and without AD [4]. This review will present the existing understanding of CAA-associated microhemorrhages frequently observed in AD, different animal models, involved imaging and the role of animal models in the development of therapeutics including immunotherapies such as anti-Aβ antibodies for the treatment of CAA and its associated microhemorrhages.