Comparison of 7.0-T T₂*-magnetic resonance imaging of cerebral bleeds in post-mortem brain sections of Alzheimer patients with their neuropathological correlates

Prevalence of cerebral microbleeds in Alzheimer's disease, dementia with Lewy bodies and Parkinson's disease dementia: A systematic review and meta-analysis

Cerebral microbleeds (CMB) are often associated with vascular risk factors and/or cerebral amyloid angiopathy and are frequently identified in people with dementia. The present study therefore aimed to estimate the pooled prevalence and associations of CMB in Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), using meta-analytic methods. Sixty-five MRI studies were included after a systematic search on major electronic databases. We found that the prevalence of CMB was comparable across the three dementia subtypes (31-36%) and was highly influenced by the MRI techniques used. CMB in AD were associated with a history of hypertension and amyloid-β burden. In contrast, CMB in DLB, despite being predominantly lobar, were associated with hypertension, but not amyloid-β burden. These findings suggest that the underlying pathophysiology of CMB in DLB might differ from that of AD. There was substantially larger number of AD studies identified and more studies evaluating CMB in Lewy body dementias are warranted.

Neuropathology of microbleeds in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Cerebral microbleeds (CMBs) detected on magnetic resonance imaging are common in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The neuropathologic correlates of CMBs are unclear. In this study, we characterized findings relevant to CMBs in autopsy brain tissue of 8 patients with genetically confirmed CADASIL and 10 controls within the age range of the CADASIL patients by assessing the distribution and extent of hemosiderin/iron deposits including perivascular hemosiderin leakage (PVH), capillary hemosiderin deposits, and parenchymal iron deposits (PID) in the frontal cortex and white matter, basal ganglia and cerebellum. We also characterized infarcts, vessel wall thickening, and severity of vascular smooth muscle cell degeneration. CADASIL subjects had a significant increase in hemosiderin/iron deposits compared with controls. This increase was principally seen with PID. Hemosiderin/iron deposits were seen in the majority of CADASIL subjects in all brain areas. PVH was most pronounced in the frontal white matter and basal ganglia around small to medium sized arterioles, with no predilection for the vicinity of vessels with severe vascular changes or infarcts. CADASIL subjects have increased brain hemosiderin/iron deposits but these do not occur in a periarteriolar distribution. Pathogenesis of these lesions remains uncertain.

Neuropathology of Vascular Brain Health: Insights From Ex Vivo Magnetic Resonance Imaging-Histopathology Studies in Cerebral Small Vessel Disease

Sporadic cerebral small vessel disease (SVD) is a major contributor to vascular cognitive impairment and dementia in the aging human brain. On neuropathology, sporadic SVD is characterized by abnormalities to the small vessels of the brain predominantly in the form of cerebral amyloid angiopathy and arteriolosclerosis. These pathologies frequently coexist with Alzheimer disease changes, such as plaques and tangles, in a single brain. Conversely, during life, magnetic resonance imaging (MRI) only captures the larger manifestations of SVD in the form of parenchymal brain abnormalities. There appears to be a major knowledge gap regarding the underlying neuropathology of individual MRI-detectable SVD abnormalities. Ex vivo MRI in postmortem human brain tissue is a powerful tool to bridge this gap. This review summarizes current insights into the histopathologic correlations of MRI manifestations of SVD, their underlying cause, presumed pathophysiology, and associated secondary tissue injury. Moreover, we discuss the advantages and limitations of ex vivo MRI-guided histopathologic investigations and make recommendations for future studies.

Postmortem brain 7T MRI with minimally invasive pathological correlation in deceased COVID-19 subjects

BACKGROUND

Brain abnormalities are a concern in COVID-19, so we used minimally invasive autopsy (MIA) to investigate it, consisting of brain 7T MR and CT images and tissue sampling via transethmoidal route with at least three fragments: the first one for reverse transcription polymerase chain reaction (RT-PCR) analysis and the remaining fixed and stained with hematoxylin and eosin. Two mouse monoclonal anti-coronavirus (SARS-CoV-2) antibodies were employed in immunohistochemical (IHC) reactions.

RESULTS

Seven deceased COVID-19 patients underwent MIA with brain MR and CT images, six of them with tissue sampling. Imaging findings included infarcts, punctate brain hemorrhagic foci, subarachnoid hemorrhage and signal abnormalities in the splenium, basal ganglia, white matter, hippocampi and posterior cortico-subcortical. Punctate brain hemorrhage was the most common finding (three out of seven cases). Brain histological analysis revealed reactive gliosis, congestion, cortical neuron eosinophilic degeneration and axonal disruption in all six cases. Other findings included edema (5 cases), discrete perivascular hemorrhages (5), cerebral small vessel disease (3), perivascular hemosiderin deposits (3), Alzheimer type II glia (3), abundant corpora amylacea (3), ischemic foci (1), periventricular encephalitis foci (1), periventricular vascular ectasia (1) and fibrin thrombi (1). SARS-CoV-2 RNA was detected with RT-PCR in 5 out of 5 and IHC in 6 out 6 patients (100%).

CONCLUSIONS

Despite limited sampling, MIA was an effective tool to evaluate underlying pathological brain changes in deceased COVID-19 patients. Imaging findings were varied, and pathological features corroborated signs of hypoxia, alterations related to systemic critically ill and SARS-CoV-2 brain invasion.

Correlations in post-mortem imaging-histopathology studies of sporadic human cerebral small vessel disease: A systematic review

AIMS

Sporadic human cerebral small vessel disease (SVD) commonly causes stroke and dementia but its pathogenesis is poorly understood. There are recognised neuroimaging and histopathological features. However, relatively few studies have examined the relationship between the radiological and pathological correlates of SVD; better correlation would promote greater insight into the underlying biological changes.

METHODS

We performed a systematic review to collate and appraise the information derived from studies that correlated histological with neuroimaging-defined SVD lesions. We searched for studies describing post-mortem imaging and histological tissue examination in adults, extracted data from published studies, categorised the information and compiled this narrative.

RESULTS

We identified 38 relevant studies, including at least 1146 subjects, 342 of these with SVD: 29 studies focussed on neuroradiological white matter lesions (WML), six on microinfarcts and three on dilated perivascular spaces (PVS) and lacunes. The histopathology terminology was diverse with few robust definitions. Reporting and methodology varied widely between studies, precluding formal meta-analysis. PVS and 'oedema' were frequent findings in WML, being described in at least 94 and 18 radiological WML, respectively, in addition to myelin pallor. Histopathological changes extended beyond the radiological lesion margins in at least 33 radiological WML. At least 43 radiological lesions not seen pathologically and at least 178 histological lesions were not identified on imaging.

CONCLUSIONS

Histopathological assessment of human SVD is hindered by inconsistent methodological approaches and unstandardised definitions. The data from this systematic review will help to develop standardised definitions to promote consistency in human SVD research.

Post-Mortem 7.0-Tesla Magnetic Resonance Imaging of the Hippocampus in Progressive Supranuclear Palsy with and without Cerebral Amyloid Angiopathy

Introduction and Purpose: Cerebral amyloid angiopathy (CAA) can be observed in patients with progressive supranuclear palsy (PSP), though to a lesser degree than in Alzheimer’s disease. The present post-mortem 7.0-tesla magnetic resonance imaging (MRI) evaluates whether CAA has an influence on the degree of hippocampal atrophy (HA) and on the incidence of associated micro-infarcts (HMIs) and cortical micro-bleeds (HMBs). Material and Methods: Eight brains with PSP-CAA were compared to 20 PSP brains without CAA. In addition to the neuropathological examination, the hippocampus was evaluated on the most representative coronal section with T2 and T2*-weighted MRI sequences. The average degree of HA was determined in both groups. The incidence of HMIs and HMBs was also compared as well as the frequency of cortical micro-infarcts (CoMIs) and cortical micro-bleeds (CoMBs) in the hemispheric neocortex. Results: The neuropathological examination showed a higher incidence of lacunar infarcts in the PSP-CAA brains compared to the PSP ones. With magnetic resonance imaging (MRI), the severity of HA and the incidence of HMIs and HMBs was similar between both groups. Additionally, the frequency of CoMIs and CoMBs in the neocortex was comparable. Conclusions: The association of CAA in PSP brains has no influence on the degree of HA and on the incidence of the small cerebrovascular lesions in the hippocampus as well as in the neocortex.

A Review of Translational Magnetic Resonance Imaging in Human and Rodent Experimental Models of Small Vessel Disease

Cerebral small vessel disease (SVD) is a major health burden, yet the pathophysiology remains poorly understood with no effective treatment. Since much of SVD develops silently and insidiously, non-invasive neuroimaging such as MRI is fundamental to detecting and understanding SVD in humans. Several relevant SVD rodent models are established for which MRI can monitor in vivo changes over time prior to histological examination. Here, we critically review the MRI methods pertaining to salient rodent models and evaluate synergies with human SVD MRI methods. We found few relevant publications, but argue there is considerable scope for greater use of MRI in rodent models, and opportunities for harmonisation of the rodent-human methods to increase the translational potential of models to understand SVD in humans. We summarise current MR techniques used in SVD research, provide recommendations and examples and highlight practicalities for use of MRI SVD imaging protocols in pre-selected, relevant rodent models.

Magnetic Susceptibility in Normal Brains of Young Adults Based on Quantitative Susceptibility Mapping

OBJECTIVES

To explore the changes of brain susceptibility of different sides and genders in healthy young adults using quantitative susceptibility mapping (QSM).

METHODS

Totally 42 healthy young right-handed adults underwent conventional brain magnetic resonance imaging and QSM scans, and the susceptibility maps were obtained by image post-processing software. Then the regions-of-interest (ROI) of bilateral frontal gray matter (FGM), frontal white matter (FWM), caudate (CA), globus pallidus (GP), putamen (PU), thalamus (TH), substantia nigra (SN), red nucleus (RN), dentate nucleus (DN), pons (PO), and corpus callosum (CC) were manually drawn to obtain magnetic susceptibility on the susceptibility maps. The magnetic susceptibility of each ROI was compared between 2 sides and genders by Wilcoxon rank sum test.

RESULTS

Magnetic susceptibility of bilateral ROI was the highest in GP, followed by SN, and the lowest in FWM. No statistically significant difference was found in susceptibility of bilateral FGM, FWM, CA, GP, PU, TH, SN, RN, DN, PO, or CC. Magnetic susceptibility in CA significantly different genders.

CONCLUSION

Brain magnetic susceptibility measured by QSM can be used to quantitatively assess brain iron concentrations.

Matching ex vivo MRI With Iron Histology: Pearls and Pitfalls

Iron levels in the brain can be estimated using newly developed specific magnetic resonance imaging (MRI) sequences. This technique has several applications, especially in neurodegenerative disorders like Alzheimer's disease or Parkinson's disease. Coupling ex vivo MRI with histology allows neuroscientists to better understand what they see in the images. Iron is one of the most extensively studied elements, both by MRI and using histological or physical techniques. Researchers were initially only able to make visual comparisons between MRI images and different types of iron staining, but the emergence of specific MRI sequences like R2^* or quantitative susceptibility mapping meant that quantification became possible, requiring correlations with physical techniques. Today, with advances in MRI and image post-processing, it is possible to look for MRI/histology correlations by matching the two sorts of images. For the result to be acceptable, the choice of methodology is crucial, as there are hidden pitfalls every step of the way. In order to review the advantages and limitations of ex vivo MRI correlation with iron-based histology, we reviewed all the relevant articles dealing with the topic in humans. We provide separate assessments of qualitative and quantitative studies, and after summarizing the significant results, we emphasize all the pitfalls that may be encountered.

The choice of embedding media affects image quality, tissue R2 * , and susceptibility behaviors in post-mortem brain MR microscopy at 7.0T

PURPOSE

The quality and precision of post-mortem MRI microscopy may vary depending on the embedding medium used. To investigate this, our study evaluated the impact of 5 widely used media on: (1) image quality, (2) contrast of high spatial resolution gradient-echo (T₁ and T₂ ^* -weighted) MR images, (3) effective transverse relaxation rate (R₂ ^* ), and (4) quantitative susceptibility measurements (QSM) of post-mortem brain specimens.

METHODS

Five formaldehyde-fixed brain slices were scanned using 7.0T MRI in: (1) formaldehyde solution (formalin), (2) phosphate-buffered saline (PBS), (3) deuterium oxide (D₂ O), (4) perfluoropolyether (Galden), and (5) agarose gel. SNR and contrast-to-noise ratii (SNR/CNR) were calculated for cortex/white matter (WM) and basal ganglia/WM regions. In addition, median R₂ ^* and QSM values were extracted from caudate nucleus, putamen, globus pallidus, WM, and cortical regions.

RESULTS

PBS, Galden, and agarose returned higher SNR/CNR compared to formalin and D₂ O. Formalin fixation, and its use as embedding medium for scanning, increased tissue R₂ ^* . Imaging with agarose, D₂ O, and Galden returned lower R₂ ^* values than PBS (and formalin). No major QSM offsets were observed, although spatial variance was increased (with respect to R₂ ^* behaviors) for formalin and agarose.

CONCLUSIONS

Embedding media affect gradient-echo image quality, R₂ ^* , and QSM in differing ways. In this study, PBS embedding was identified as the most stable experimental setup, although by a small margin. Agarose and Galden were preferred to formalin or D₂ O embedding. Formalin significantly increased R₂ ^* causing noisier data and increased QSM variance.

Comparative Analysis of Cortical Microinfarcts and Microbleeds using 3.0-Tesla Postmortem Magnetic Resonance Images and Histopathology

Microvascular lesions including cortical microinfarctions (CMIs) and cerebral lobar microbleeds (CMBs) are usually caused by cerebral amyloid angiopathy (CAA) in the elderly and are correlated with cognitive decline. However, their radiological-histopathological coincidence has not been revealed systematically with widely used 3-Tesla (3T) magnetic resonance imaging (MRI). The purpose of the present study is to delineate the histopathological background corresponding to MR images of these lesions. We examined formalin-fixed 10-mm thick coronal brain blocks from 10 CAA patients (five were also diagnosed with Alzheimer's disease, three with dementia with Lewy bodies, and two with CAA only) with dementia and six non CAA patients with neurodegenerative disease. Using 3T MRI, both 3D-fluid attenuated inversion recovery (FLAIR) and 3D-double inversion recovery (DIR) were examined to identify CMIs, and T2* and susceptibility-weighted images (SWI) were examined to identify CMBs. These blocks were subsequently examined histologically and immunohistochemically. In CAA patients, 48 CMIs and 6 lobar CMBs were invariably observed in close proximity to degenerated Aβ-positive blood vessels. Moreover, 16 CMIs (33%) of 48 were detected with postmortem MRI, but none were seen when the lesion size was smaller than 1 mm. In contrast, only 1 undeniable CMI was founded with MRI and histopathology in 6 non CAA patients. Small, cortical high-intensity lesions seen on 3D-FLAIR and 3D-DIR images likely represent CMIs, and low-intensity lesions in T2* and SWI correspond to CMBs with in vivo MRI. Furthermore, a close association between amyloid-laden vessels and these microvascular lesions indicated the contribution of CAA to their pathogenesis.

Amyloid Angiopathy in Brain Hemorrhage: A Postmortem Neuropathological-Magnetic Resonance Imaging Study

Background: Risk factors for intracerebral hemorrhage (ICH) include hypertension and cerebral amyloid angiopathy (CAA). The objective of this study was to determine the autopsy prevalence of CAA and the potential overlap with other risk factors among patients who died from ICH and also the correlation of CAA with cerebral microbleeds. Methods: We analyzed 81 consecutive autopsy brains from patients with ICH. Staining for CAA detection was performed. We used an age- and sex-matched control group of routine brain autopsies of nonneurological patients to determine the frequencies of CAA and hypertension. Postmortem 3D T2-weighted gradient-echo magnetic resonance imaging (MRI) with a 1.5-T magnet was performed in 11 brains with ICH (5 with CAA and 6 without) and histological correlation was performed when microbleeds were detected. Results: Hypertension and CAA were found in 69.1 and 24.7% of cases respectively. Among patients with CAA, 65.0% also had hypertension. The prevalence of CAA was similar among non-hypertensive cases and controls (33.3 and 23.1%; p = 0.54), whereas a significant difference was found between hypertensive cases vs. controls (28.9% vs. 0; p = 0.01). MRI documented 48 microbleeds and all 5 brains with CAA had ≥1 microbleed, compared to 3/6 brains without CAA. Among 48 microbleeds on MRI, 45 corresponded histologically to microbleeds surrounding microvessels (23 <200 µm in diameter, 19 between 200 µm and 2 mm, 3 were hemosiderin granules). Conclusions: Both hypertension and CAA frequently coexist in patients with ICH. MRI-detected microbleeds, proven by histological analysis, were twice as common in patients with CAA as in those with hypertensive ICH.

Topographic distribution of brain iron deposition and small cerebrovascular lesions in amyotrophic lateral sclerosis and in frontotemporal lobar degeneration: a post-mortem 7.0-tesla magnetic resonance imaging study with neuropathological correlates

Amyotrophic lateral sclerosis (ALS) is associated with frontotemporal lobar degeneration (FTLD) in 15% of the cases. A neuropathological continuity between ALS and FTLD-TDP is suspected. The present post-mortem 7.0-tesla magnetic resonance imaging (MRI) study compares the topographic distribution of iron (Fe) deposition and the incidence of small cerebrovascular lesions in ALS and in FTLD brains. Seventy-eight post-mortem brains underwent 7.0-tesla MRI. The patients consisted of 12 with ALS, 38 with FTLD, and 28 controls. Three ALS brains had minor FTLD features. Three coronal sections of a cerebral hemisphere were submitted to T2 and T2* MRI sequences. The amount of Fe deposition in the deep brain structures and the number of small cerebrovascular lesions was determined in ALS and the subtypes of FTLD compared to control brains, with neuropathological correlates. A significant increase of Fe deposition was observed in the claustrum, caudate nucleus, globus pallidus, thalamus, and subthalamic nucleus of the FTLD-FUS and FTLD-TDP groups, while in the ALS one, the Fe increase was only observed in the caudate and the subthalamic nuclei. White matter changes were only significantly more severe in the FTLD compared to those in ALS and in controls brains. Cortical micro-bleeds were increased in the frontal and temporal lobes of FTLD as well as of ALS brains compared to controls. Cortical micro-infarcts were, on the other hand, more frequent in the control compared to the ALS and FTLD groups. The present study supports the assumption of a neuropathological continuity between ALS and FTLD and illustrates the favourable vascular risk profile in these diseases.

Cerebrovascular Lesions in Mixed Neurodegenerative Dementia: A Neuropathological and Magnetic Resonance Study

BACKGROUND

In elderly brains of demented patients, Alzheimer and Lewy body pathology (LBP) are frequently associated. Cortical microinfarcts (CoMIs) are more observed in Lewy body disease, even in the absence of cerebral amyloid angiopathy (CAA). The present neuropathological and 7.0-tesla MRI studies investigate whether CoMIs are also more frequent in mixed neurodegenerative dementia syndromes.

SUMMARY

Both examinations revealed that CoMIs are increased to different degrees in mixed dementia syndromes according to the severity of the LBP. They were mainly associated with a trend of older age and arterial hypertension in the patients with the most severe LBP. Messages: The increased number of CoMIs in mixed dementia syndromes with LBP is mainly due to the associated cerebrovascular pathology, even in the absence of CAA.

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.

Neuropsychological state of the population living in the Aral Sea region (zone of ecological crisis)

Background The Aral Sea crisis has led to harmful effects on human habitat. In recent years, mild cognitive impairment is a growing problem. Objectives This article provides the results of studying the neuropsychological state of residents living in the crisis zone of the Aral Sea region in the case of Shalkar city. We have provided an assessment of the neuropsychological state of examined population and determined the leading pathology in this region. Methods The survey sample included 344 persons of reproductive age from 21 to 45 years. We have obtained results in biochemical studies, indicating perturbations of proteometabolism and lipid metabolism. Results A correlation analysis showed dependence between a decrease of albumin and high-density lipoproteins, an increase of low-density lipoproteins and parameters of cognitive function. Conclusions The research suggests a high prevalence of cerebrovascular pathology among the population, changes in cognitive function parameters, long-term and short-term memory problems and high levels of depression.

Radiologic-Histopathologic Correlation of Cerebral Microbleeds Using Pre-Mortem and Post-Mortem MRI

Introduction

Cerebral microbleeds (CMB), also known as cerebral microhemorrhages, are small areas of susceptibility on brain magnetic resonance imaging (MRI), that are increasingly detected due to the higher availability of high-field MRI systems and dedicated pulse sequences. The prevalence of CMBs increases in cases with cognitive decline. The current investigation assessed the poorly investigated radiologic–histopathologic correlation of CMBs on MRI.

Methods

The local ethical committee approved the current investigation. We retrospectively assessed a consecutive series of 1303 autopsy cases hospitalized in Geneva University Hospitals between 2000–2014. Of 112 cases with pre-mortem T2* sequences, we included 25 cases (mean age 77.3 ± 9.6, 9 females) with at least one CMB. We compared pre-mortem CMBs with targeted histopathology and post-mortem MRI.

Results

25 cases had 31 CMB lesions detected by pre-mortem MRI. 25 additional CMB were detected on histopathology. 4 CMBs on pre-mortem MRI were false positives, resulting in a total of 52 CMBs. 27 CMBs on pre-mortem MRI were confirmed on histopathology, corresponding to a sensitivity or true positive rate of 51.9% (95% CI 37.6–66.0%). The false negative rate of pre-mortem MRI was 48.1% (95% CI 34.0–62.4%). Post-mortem MRI showed only 3 cases with additional CMBs. Overall, pre-mortem MRI significantly underestimated CMBs (p = 0.0001).

Conclusions

Routine clinical brain MRI underestimates the prevalence of CMBs by approximately 50%, and 12% of radiologic pre-mortem MRI CMBs were false positives. Post-mortem MRI confirmed that this discordance is not explained by microbleeds occurring after the pre-mortem MRI.

Neuroimaging in vascular cognitive impairment: a state-of-the-art review

Imaging is critical in the diagnosis and treatment of dementia, particularly in vascular cognitive impairment, due to the visualization of ischemic and hemorrhagic injury of gray and white matter. Magnetic resonance imaging (MRI) and positron emission tomography (PET) provide structural and functional information. Clinical MRI is both generally available and versatile - T2-weighted images show infarcts, FLAIR shows white matter changes and lacunar infarcts, and susceptibility-weighted images reveal microbleeds. Diffusion MRI adds another dimension by showing graded damage to white matter, making it more sensitive to white matter injury than FLAIR. Regions of neuroinflammatory disruption of the blood-brain barrier with increased permeability can be quantified and visualized with dynamic contrast-enhanced MRI. PET shows metabolism of glucose and accumulation of amyloid and tau, which is useful in showing abnormal metabolism in Alzheimer's disease. Combining MRI and PET allows identification of patients with mixed dementia, with MRI showing white matter injury and PET demonstrating regional impairment of glucose metabolism and deposition of amyloid. Excellent anatomical detail can be observed with 7.0-Tesla MRI. Imaging is the optimal method to follow the effect of treatments since changes in MRI scans are seen prior to those in cognition. This review describes the role of various imaging modalities in the diagnosis and treatment of vascular cognitive impairment.

The Role of the Iron Stain in Assessing Intracranial Hemorrhage

The timing of the breakdown of red blood cells and organization of hemorrhage has significance in the catabolism of heme and the processing of iron, but also has a practical application in terms of assigning, or attempting to assign, a time course with respect to traumatic events (e.g. contusions and hemorrhages). Attempts to date contusions, however, have generally been unsuccessful by macroscopic observation, whereas the microscopic observations provide broad data but are also anatomically imprecise as a function of time. Intracranial lesions are of particular significance with respect to the timing of organizing hemorrhage given the acute, and often life-threatening nature of the hemorrhages, and the medicolegal investigation into potential crimes. Of concern is that the Prussian Blue reaction for iron, a relatively straightforward histochemical reaction that has been in use for over 150 years, is sometimes suggested as a diagnostic test for chronicity. Therefore, this study examined the utility of the Prussian Blue iron stain in living patients with intracranial hemorrhages and well-defined symptom onset, to test whether the presence of Prussian Blue reactivity could be correlated with chronicity. It was found that out of 12 cases with intracranial hemorrhage, eight cases showed at least focal iron reactivity. The duration from symptom onset to surgery in those eight cases ranged from < 24 hours to more than 3 days. Of those cases with no iron reactivity, the duration from symptom onset to surgery ranged from < 24 hours to six days. In conclusion, the Prussian Blue reaction was unreliable as an indicator of timing in intracranial hemorrhage. The use of the Prussian blue reaction as an independent indicator of chronicity is therefore not valid and can be misleading. Caution is indicated when employing iron staining for timing purposes, as its only use is to highlight, as opposed to identify, pre-existing lesions. With respect to brain lesions, the Prussian blue reaction should not be used in place of the clinical timing of the neurologic decline, or clinical data that is otherwise more accurate and less susceptible to false positive results.

Lobar intracerebral haematomas: Neuropathological and 7.0-tesla magnetic resonance imaging evaluation

BACKGROUND AND PURPOSE

The Boston criteria for cerebral amyloid angiopathy (CAA) need validation by neuropathological examination in patients with lobar cerebral haematomas (LCHs). In "vivo" 1.5-tesla magnetic resonance imaging (MRI) is unreliable to detect the age-related signal changes in LCHs. This post-mortem study investigates the validity of the Boston criteria in brains with LCHs and the signal changes during their time course with 7.0-tesla MRI.

MATERIALS AND METHODS

Seventeen CAA brains including 26 LCHs were compared to 13 non-CAA brains with 14 LCHs. The evolution of the signal changes with time was examined in 25 LCHs with T2 and T2* 7.0-tesla MRI.

RESULTS

In the CAA group LCHs were predominantly located in the parieto-occipital lobes. Also white matter changes were more severe with more cortical microinfarcts and cortical microbleeds. On MRI there was a progressive shift of the intensity of the hyposignal from the haematoma core in the acute stage to the boundaries later on. During the residual stage the hyposignal mildly decreased in the boundaries with an increase of the superficial siderosis and haematoma core collapse.

CONCLUSIONS

Our post-mortem study of LCHs confirms the validity of the Boston criteria for CAA. Also 7.0-tesla MRI allows staging the age of the LCHs.

Post-mortem assessment in vascular dementia: advances and aspirations

BACKGROUND

Cerebrovascular lesions are a frequent finding in the elderly population. However, the impact of these lesions on cognitive performance, the prevalence of vascular dementia, and the pathophysiology behind characteristic in vivo imaging findings are subject to controversy. Moreover, there are no standardised criteria for the neuropathological assessment of cerebrovascular disease or its related lesions in human post-mortem brains, and conventional histological techniques may indeed be insufficient to fully reflect the consequences of cerebrovascular disease.

DISCUSSION

Here, we review and discuss both the neuropathological and in vivo imaging characteristics of cerebrovascular disease, prevalence rates of vascular dementia, and clinico-pathological correlations. We also discuss the frequent comorbidity of cerebrovascular pathology and Alzheimer's disease pathology, as well as the difficult and controversial issue of clinically differentiating between Alzheimer's disease, vascular dementia and mixed Alzheimer's disease/vascular dementia. Finally, we consider additional novel approaches to complement and enhance current post-mortem assessment of cerebral human tissue.

CONCLUSION

Elucidation of the pathophysiology of cerebrovascular disease, clarification of characteristic findings of in vivo imaging and knowledge about the impact of combined pathologies are needed to improve the diagnostic accuracy of clinical diagnoses.

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

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

Topographic distribution of white matter changes and lacunar infarcts in neurodegenerative and vascular dementia syndromes: A post-mortem 7.0-tesla magnetic resonance imaging study

Background

White matter changes and lacunar infarcts are regarded as linked to the same underlying small-vessel pathology. On magnetic resonance imaging, white matter changes are frequently observed, while the number of lacunar infarcts is probably underestimated. The present study post-mortem 7.0-tesla magnetic resonance imaging study compares the severity and the distribution of white matter changes and lacunar infarcts in different neurodegenerative and vascular dementia syndromes in order to determine their impact on the disease evolution.

Patients and methods

Eighty-four post-mortem brains consisting of 15 patients with pure Alzheimer's disease and 12 with associated cerebral amyloid angiopathy, 14 patients with frontotemporal lobar degeneration, 7 with Lewy body dementia, 10 with progressive supranuclear palsy, 14 with vascular dementia and 12 control brains were examined. Six hemispheric coronal sections of each brain underwent 7.0-tesla magnetic resonance imaging. Location and severity of white matter changes and lacunar infarcts were evaluated semi-quantitatively in each section separately.

Results

White matter changes predominated in the prefrontal and frontal sections of frontotemporal lobar degeneration and in the post-central section of associated cerebral amyloid angiopathy brains, while overall increased in vascular dementia cases. Lacunar infarcts were more frequent in the vascular dementia brains and mainly increased in the centrum semiovale.

Conclusions

White matter changes have a different topographic distribution in neurodegenerative diseases and are most severe and extended in vascular dementia. Lacunar infarcts predominate in the deep white matter of vascular dementia compared to the neurodegenerative diseases. Vascular cognitive impairment is mainly linked to white matter changes due to chronic ischaemia as well as to lacunar infarcts due to small-vessel occlusion.

Effects of formalin fixation and temperature on MR relaxation times in the human brain

Post-mortem MRI of the brain is increasingly applied in neuroscience for a better understanding of the contrast mechanisms of disease induced tissue changes. However, the influence of chemical processes caused by formalin fixation and differences in temperature may hamper the comparability with results from in vivo MRI. In this study we investigated how formalin fixation and temperature affect T1, T2 and T2* relaxation times of brain tissue. Fixation effects were examined with respect to changes in water content and crosslinking. Relaxometry was performed in brain slices from five deceased subjects at different temperatures. All measurements were repeated after 190 days of formaldehyde immersion. The water content of unfixed and fixed tissue was determined using the wet-to-dry ratio following drying. Protein weight was determined with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Fixation caused a strong decrease of all relaxation times, the strongest effect being seen on T1, with a reduction of up to 76%. The temperature coefficient of T1 was lower in the fixed than unfixed tissue, which was in contrast to T2, where an increase of the temperature coefficient was observed following fixation. The reduction of the water content after fixation was in the range of 1-6% and thus not sufficient to explain the changes in relaxation time. Results from SDS-PAGE indicated a strong increase of the protein size above 260 kDa in all brain structures examined. Our results suggest that crosslinking induced changes of the macromolecular matrix are responsible for T1 shortening and a decreased temperature dependency. The relaxation times provided in this work should allow optimization of post-mortem MRI protocols for the brain.

[Discirculatory encephalopathy and small vessel disease]

The report examines the practicability of the term 'discirculatory encephalopathy' used in the Russian Federation to designate the chronic cerebral ischemia of different origin. The authors discuss the state of small vessel disease which manifests itself through slowly progressive cerebral changes. On the basis of their own research results and literature review the authors conclude that a standardized extract of Ginkgo biloba EGb761 (tanakan) can be effectively used in patients with small vessel disease.

Cerebral microbleeds as a biomarker in Alzheimer's disease? A review in the field

Cerebral microbleeds (CMBs) are a marker of small vessel disease, increasingly recognized as being of importance in the Alzheimer's disease (AD) process. CMBs influence in AD, and its longitudinal impact on disease progression is however still unknown. CMBs show several associations with AD across studies, are associated with decreased cerebrospinal fluid amyloid levels and are related with the ApoE ϵ4 allele, as well as other imaging manifestations typical for small vessel disease. CMBs, in addition to other markers of small vessel disease, are important to discover further in order to discern possible AD phenotypes.

Topography of Cortical Microbleeds in Alzheimer's Disease with and without Cerebral Amyloid Angiopathy: A Post-Mortem 7.0-Tesla MRI Study

Cortical microbleeds (CMBs) detected on T2*-weighted gradient-echo (GRE) magnetic resonance imaging (MRI) are considered as a possible hallmark of cerebral amyloid angiopathy (CAA). The present post-mortem 7.0-tesla MRI study investigates whether topographic differences exist in Alzheimer's brains without (AD) and with CAA (AD-CAA). The distribution of CMBs in thirty-two post-mortem brains, consisting of 12 AD, 8 AD-CAA and 12 controls, was mutually compared on T2*-GRE MRI of six coronal sections of a cerebral hemisphere. The mean numbers of CMBs were determined in twenty-two different gyri. As a whole there was a trend of more CMBs on GRE MRI in the prefrontal section of the AD, the AD-CAA as well as of the control brains. Compared to controls AD brains had significantly more CMBs in the superior frontal, the inferior temporal, the rectus and the cinguli gyrus, and in the insular cortex. In AD-CAA brains CMBs were increased in all gyri with exception of the medial parietal gyrus and the hippocampus. AD-CAA brains showed a highly significant increase of CMBs in the inferior parietal gyrus (p value: 0.001) and a significant increase in the precuneus and the cuneus (p value: 0.01) compared to the AD brains. The differences in topographic distribution of CMBs between AD and AD-CAA brains should be further investigated on MRI in clinically suspected patients.

No neuropathological evidence for a direct topographical relation between microbleeds and cerebral amyloid angiopathy

Introduction

Cerebral microbleeds correspond to blood breakdown products, including hemosiderin-containing macrophages around small vessels on histological examination. Superficial lobar cerebral microbleeds are increasingly recognized on MRI as a biomarker of cerebral amyloid angiopathy but the direct association between amyloid-laden vessels burden and cerebral microbleeds has yet to be validated neuropathologically. To address this issue, we examined the frequency of histopathologically-defined cerebral microbleeds in different brain regions and their relationship with cerebral amyloid angiopathy in a large autopsy population.

Results

The frontal, parietal and occipital cortex as well as the adjacent white matter and basal ganglia of 113 consecutive autopsies were examined. Cerebral microbleedss were identified on haematoxylin-eosin-stained histological slides, cerebral amyloid angiopathy using anti-amyloid antibody. Cerebral microbleeds were present in 92.9 % of the cases and cerebral amyloid angiopathy in 44.3 % of them. Cerebral microbleeds were more frequent in parietal and frontal lobes followed by the occipital region and basal ganglia. In contrast, cerebral amyloid angiopathy was most frequent in the occipital lobe. There was no significant topographical association between cerebral amyloid angiopathy presence or severity and cerebral microbleeds in any brain region. In lobar areas, cerebral amyloid angiopathy was found in the cortex, predominantly affecting pial arteries and their superficial cortical branches, in contrast to microbleeds which were mainly in the white matter and occurred around deeper arteries and arterioles, including the subcortical segment of long penetrating branches of pial vessels.

Conclusions

Our study does not support a direct relation between cerebral microbleeds and cerebral amyloid angiopathy burden at the neuropathological level, raising intriguing questions on the potential pathophysiological mechanisms of cerebral microbleeds in the context of cerebral amyloid angiopathy or other small vessel disease pathology.

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.

Cerebral microbleeds are associated with the progression of ischemic vascular lesions

BACKGROUND

Despite their different appearance on imaging, hemorrhagic and ischemic vascular lesions frequently co-occur in the brain and are hypothesized to progress concurrently. Although silent hemorrhagic and ischemic vascular brain lesions are highly prevalent in the general population, the concomitant progression of these lesions has only been studied to a limited extent in this population. We therefore aimed to investigate whether pre-existing and incident cerebral microbleeds (CMBs) are related to the progression of ischemic lesions in the general population.

METHODS

In the prospective population-based Rotterdam Scan Study, 803 individuals aged ≥60 years underwent magnetic resonance imaging at baseline and after an average interval of 3.4 years. The presence of microbleeds and lacunes was visually rated by trained research physicians, and white matter lesions (WMLs) were automatically segmented at both time points. Logistic regression was used to investigate the association of microbleeds with incident lacunes, and linear regression was used to investigate the relation between microbleeds and progression of WML volume. All analyses were adjusted for age, sex and the time interval between baseline and follow-up scanning. The analyses were repeated after additional adjustments for cardiovascular risk factors: blood pressures; total and high-density lipoprotein cholesterol; smoking; diabetes mellitus; lipid lowering, antihypertensive and antiplatelet medications, and apolipoprotein E ε4. The analyses involving WMLs were also adjusted for intracranial volume.

RESULTS

We found that pre-existing microbleeds in any location of the brain were related to a higher incidence of lacunes (odds ratio [OR] adjusted for age, sex and scan interval: 4.67; 95% confidence interval [CI]: 1.84-11.85). Pre-existing microbleeds were not related to progression of WML volume (mean difference in WML volume increase: -0.03; 95% CI: -0.15 to 0.09). Additional adjustments for cardiovascular risk factors did not change the results considerably. Incident microbleeds in any location of the brain were associated with a higher incidence of lacunes (OR: 9.18; 95% CI: 3.61-23.35), whereas only incident microbleeds located in cortico-subcortical regions were related to progression of WML volume (mean difference in WML volume increase: 0.41; 95% CI: 0.21-0.62). Again, adjustments for cardiovascular risk factors did not change the results significantly.

CONCLUSIONS

Our findings suggest that in the general population, CMBs serve as a predictor of ischemic brain lesions and may represent an imaging marker of active vasculopathy. These results support the hypothesis of a common underlying pathway in the development of ischemic and hemorrhagic brain lesions.

Iron deposits in post-mortem brains of patients with neurodegenerative and cerebrovascular diseases: a semi-quantitative 7.0 T magnetic resonance imaging study

BACKGROUND AND PURPOSE

Accumulation of iron (Fe) is often detected in brains of people suffering from neurodegenerative diseases. However, no studies have compared the Fe load between these disease entities. The present study investigates by T2*-weighted gradient-echo 7.0 T magnetic resonance imaging (MRI) the Fe content in post-mortem brains with different neurodegenerative and cerebrovascular diseases.

METHODS

One hundred and fifty-two post-mortem brains, composed of 46 with Alzheimer's disease (AD), 37 with frontotemporal lobar degeneration (FTLD), 11 with amyotrophic lateral sclerosis, 13 with Lewy body disease, 14 with progressive supranuclear palsy, 16 with vascular dementia (VaD) and 15 controls without a brain disease, were examined. The Fe load was determined semi-quantitatively on T2*-weighted MRI serial brain sections in the claustrum, caudate nucleus, putamen, globus pallidus, thalamus, subthalamic nucleus, hippocampus, mamillary body, lateral geniculate body, red nucleus, substantia nigra and dentate nucleus. The disease diagnosis was made on subsequent neuropathological examination.

RESULTS

The Fe load was significantly increased in the claustrum, caudate nucleus and putamen of FTLD brains and to a lesser degree in the globus pallidus, thalamus and subthalamic nucleus. In the other neurodegenerative diseases no Fe accumulation was observed, except for a mild increase in the caudate nucleus of AD brains. In VaD brains no Fe increase was detected.

CONCLUSIONS

Only FTLD displays a significant Fe load, suggesting that impaired Fe homeostasis plays an important role in the pathogenesis of this heterogeneous disease entity.

Magnetic resonance imaging of fixed post mortem brains reliably reflects subcortical vascular pathology of frontal, parietal and occipital white matter

AIMS

Subcortical vascular pathology of the white and deep grey matter (WM and DGM) is associated with cognitive impairment. Routine neuropathological assessment of subcortical vascular pathology is based on semiquantitative scoring of characteristic lesions in a limited number of histological slides from selected WM and DGM areas. Clinically, WM and DGM lesions are visualized as hyper-intensities on magnetic resonance imaging (MRI). The aim of this study was to evaluate the feasibility of MRI on fixed post mortem brain hemispheres to complement routine neuropathological assessment of subcortical vascular pathology.

METHODS

We assessed subcortical vascular pathology in 40 post mortem brain hemispheres from demented (n = 26) and nondemented (n = 14) individuals (mean age 83.2 ± 14.8 years; 62.5% female) using (i) routine histological assessment; (ii) extensive histological assessment of the entire hemisphere at 7-mm intervals; and (iii) full T2-weighted MRI performed on fixed post mortem brain hemispheres.

RESULTS

In both WM and DGM routine histological scores for subcortical vascular pathology were significantly lower (P < 0.01) than the corresponding scores obtained by extensive histological assessment. In contrast, no significant differences were seen between scores obtained by MRI and extensive histological assessment in frontal, parietal and occipital lobes while MRI scores were significantly lower in the temporal WM and DGM (P < 0.01).

CONCLUSIONS

The results of our study indicate that routine histological assessment underrates subcortical vascular pathology and we conclude that MRI could be used in addition to complement neuropathological post mortem assessment of subcortical vascular pathology of the WM.

Differentiation of calcified regions and iron deposits in the ageing brain on conventional structural MR images

PURPOSE

In the human brain, minerals such as iron and calcium accumulate increasingly with age. They typically appear hypointense on T2*-weighted MRI sequences. This study aims to explore the differentiation and association between calcified regions and noncalcified iron deposits on clinical brain MRI in elderly, otherwise healthy subjects.

MATERIALS AND METHODS

Mineral deposits were segmented on co-registered T1- and T2*-weighted sequences from 100 1.5 Tesla MRI datasets of community-dwelling individuals in their 70s. To differentiate calcified regions from noncalcified iron deposits we developed a method based on their appearance on T1-weighted images, which was validated with a purpose-designed phantom. Joint T1- and T2*-weighted intensity histograms were constructed to measure the similarity between the calcified and noncalcified iron deposits using a Euclidean distance based metric.

RESULTS

We found distinct distributions for calcified regions and noncalcified iron deposits in the cumulative joint T1- and T2*-weighted intensity histograms across all subjects (correlations ranging from 0.02 to 0.86; mean = 0.26 ± 0.16; t = 16.93; P < 0.001) consistent with differences in iron and calcium signal in the phantom. The mean volumes of affected tissue per subject for calcified and noncalcified deposits were 236.74 ± 309.70 mm(3) and 283.76 ± 581.51 mm(3); respectively. There was a positive association between the mineral depositions (β = 0.32, P < 0.005), consistent with existing literature reports.

CONCLUSION

Calcified mineral deposits and noncalcified iron deposits can be distinguished from each other by signal intensity changes on conventional 1.5T T1-weighted MRI and are significantly associated in brains of elderly, otherwise healthy subjects.

Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration

Cerebral small vessel disease (SVD) is a common accompaniment of ageing. Features seen on neuroimaging include recent small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, microbleeds, and brain atrophy. SVD can present as a stroke or cognitive decline, or can have few or no symptoms. SVD frequently coexists with neurodegenerative disease, and can exacerbate cognitive deficits, physical disabilities, and other symptoms of neurodegeneration. Terminology and definitions for imaging the features of SVD vary widely, which is also true for protocols for image acquisition and image analysis. This lack of consistency hampers progress in identifying the contribution of SVD to the pathophysiology and clinical features of common neurodegenerative diseases. We are an international working group from the Centres of Excellence in Neurodegeneration. We completed a structured process to develop definitions and imaging standards for markers and consequences of SVD. We aimed to achieve the following: first, to provide a common advisory about terms and definitions for features visible on MRI; second, to suggest minimum standards for image acquisition and analysis; third, to agree on standards for scientific reporting of changes related to SVD on neuroimaging; and fourth, to review emerging imaging methods for detection and quantification of preclinical manifestations of SVD. Our findings and recommendations apply to research studies, and can be used in the clinical setting to standardise image interpretation, acquisition, and reporting. This Position Paper summarises the main outcomes of this international effort to provide the STandards for ReportIng Vascular changes on nEuroimaging (STRIVE).

Characterization of multifocal T2*-weighted MRI hypointensities in the basal ganglia of elderly, community-dwelling subjects

Multifocal T2*-weighted (T2*w) hypointensities in the basal ganglia, which are believed to arise predominantly from mineralized small vessels and perivascular spaces, have been proposed as a biomarker for cerebral small vessel disease. This study provides baseline data on their appearance on conventional structural MRI for improving and automating current manual segmentation methods. Using a published thresholding method, multifocal T2*w hypointensities were manually segmented from whole brain T2*w volumes acquired from 98 community-dwelling subjects in their early 70s. Connected component analysis was used to derive the average T2*w hypointensity count and load per basal ganglia nucleus, as well as the morphology of their connected components, while nonlinear spatial probability mapping yielded their spatial distribution. T1-weighted (T1w), T2-weighted (T2w) and T2*w intensity distributions of basal ganglia T2*w hypointensities and their appearance on T1w and T2w MRI were investigated to gain further insights into the underlying tissue composition. In 75/98 subjects, on average, 3 T2*w hypointensities with a median total volume per intracranial volume of 50.3 ppm were located in and around the globus pallidus. Individual hypointensities appeared smooth and spherical with a median volume of 12 mm³ and median in-plane area of 4 mm². Spatial probability maps suggested an association between T2*w hypointensities and the point of entry of lenticulostriate arterioles into the brain parenchyma. T1w and T2w and especially the T2*w intensity distributions of these hypointensities, which were negatively skewed, were generally not normally distributed indicating an underlying inhomogeneous tissue structure. Globus pallidus T2*w hypointensities tended to appear hypo- and isointense on T1w and T2w MRI, whereas those from other structures appeared iso- and hypointense. This pattern could be explained by an increased mineralization of the globus pallidus. In conclusion, the characteristic spatial distribution and appearance of multifocal basal ganglia T2*w hypointensities in our elderly cohort on structural MRI appear to support the suggested association with mineralized proximal lenticulostriate arterioles and perivascular spaces.

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A rater segmented focal hypointensities on T2*w brain MRI from 98 elderly subjects.

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On average 3 focal hypointensities were found in the basal ganglia of 75 subjects.

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Their spatial distribution suggests an association with lenticulostriate arterioles.

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Signal intensity distributions suggest an underlying inhomogeneous tissue structure.

In vivo detection of cerebral cortical microinfarcts with high-resolution 7T MRI

Cerebrovascular disease has an important role in cognitive decline and dementia. In this context, cerebral microinfarcts are attracting increasing attention, but these lesions could thus far not be detected in vivo. The aim of this study was to try to identify possible cortical microinfarcts on high-resolution 7T in vivo magnetic resonance imaging (MRI) and to perform a histopathologic validation study on similar appearing lesions on 7T ex vivo MRI of postmortem brain tissue. The study population consisted of 22 elderly subjects, who underwent 7T MRI. The fluid attenuated inversion recovery, T(2), and T(1) weighted scans of these subjects were examined for possible cortical microinfarcts. In the ex vivo MRI study, 15 formalin-fixed coronal brain slices of 6 subjects with Alzheimer and vascular pathology were examined and subjected to histopathologic verification. On the in vivo scans, 15 cortical lesions could be identified that were likely to be microinfarcts in 6 subjects. In the postmortem tissue, 6 similar appearing lesions were identified of which 5 were verified as cortical microinfarcts on histopathology. This study provides strong evidence that cortical microinfarcts can be detected in vivo, which will be of great value in further studies into the role of vascular disease in cognitive decline and dementia.

Imaging of iron

Magnetic resonance imaging (MRI) enables a noninvasive in vivo quantification of iron in various organs. Several techniques have been developed that detect signal alterations derived mainly from the magnetic properties of ferritin and hemosiderin, the major iron storage compounds. High magnetic susceptibility of ferritin shortens the transversal relaxation time of nearby water protons and thus induces a focal signal extinction of iron-rich areas in T2-weighted (T2w) MRI. T2w tissue contrast is additionally influenced by other factors such as water content, myelin density, and the presence of other metals. Therefore, more specific methods are needed with higher specificity to iron. These in vivo techniques can be divided into three groups: relaxometry, magnetic field correlation imaging and phase-based contrast covering susceptibility-weighted imaging, and quantitative susceptibility mapping. The differential diagnosis of various neurological disorders is aided by characteristic patterns of iron depositions. Reliable estimates of cerebral tissue iron concentration are equally important in studying physiological age-related as well as pathological conditions in neurodegenerative, neuroinflammatory, and vascular diseases. In the future, monitoring changes in iron storage and content may serve as sensitive biomarker for diagnosis as well as treatment monitoring.

Vascular dementia: different forms of vessel disorders contribute to the development of dementia in the elderly brain

The diagnosis of vascular dementia (VaD) describes a group of various vessel disorders with different types of vascular lesions that finally contribute to the development of dementia. Most common forms of VaD in the elderly brain are subcortical vascular encephalopathy, strategic infarct dementia, and the multi infarct encephalopathy. Hereditary forms of VaD are rare. Most common is the cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Sporadic forms of VaD are caused by degenerative vessel disorders such as atherosclerosis, small vessel disease (SVD) including small vessel arteriosclerosis, arteriolosclerosis, and lipohyalinosis, and cerebral amyloid angiopathy (CAA). Less frequently inflammatory vessel disorders and tumor-associated vessel lesions (e.g. angiocentric T-cell or angiotropic large cell lymphoma) can cause symptoms of dementia. Here, we review and discuss the impact of vessel disorders to distinct vascular brain tissue lesions and to the development of dementia in elderly individuals. The impact of coexisting neurodegenerative pathology in the elderly brain to VaD as well as the correlation between SVD and CAA expansion in the brain parenchyma with that of Alzheimer's disease (AD)-related pathology is highlighted. We conclude that "pure" VaD is rare and most frequently caused by infarctions. However, there is a significant contribution of vascular lesions and vessel pathology to the development of dementia that may go beyond tissue damage due to vascular lesions. Insufficient blood blow and alterations of the perivascular drainage mechanisms of the brain may also lead to a reduced protein clearance from extracellular space and subsequent increase of proteins in the brain parenchyma, such as the amyloid β-protein, and foster, thereby, the development of AD-related neurodegeneration. As such, it seems to be important for clinical practice to consider treatment of potentially coexisting AD pathology in cognitively impaired patients with vascular lesions.

Ultrahigh-field magnetic resonance imaging: the clinical potential for anatomy, pathogenesis, diagnosis, and treatment planning in brain disease

In this review, current (clinical) applications and possible future directions of ultrahigh-field (≥7 T) magnetic resonance (MR) imaging in the brain are discussed. Ultrahigh-field MR imaging can provide contrast-rich images of diverse pathologies and can be used for early diagnosis and treatment monitoring of brain disease. These images may provide increased sensitivity and specificity. Several limitations need to be overcome before worldwide clinical implementation can be commenced. Current literature regarding clinically based ultrahigh-field MR imaging is reviewed, and limitations and promises of this technique are discussed, as well as some practical considerations for the implementation in clinical practice.

Cerebral microhemorrhage in Marchiafava-Bignami disease detected by susceptibility-weighted imaging

Marchiafava-Bignami disease (MBD) is a rare alcohol-associated disorder. Clinical features include not only disturbed consciousness, dysarthria, tetraparesis, astasia-abasia, and symptoms of interhemispheric disconnection as initial symptoms but also cognitive deficits as clinical outcomes. The clinical significance of cerebral microhemorrhage (CMH) has been recognized in patients with cognitive deficits; however, the presence of CMH in patients with MBD has not been emphasized. The aim of the present study was to clarify the relationship between CMH and MBD. For this purpose, we report four patients with MBD, who showed asymmetrical hypointense areas in multiple cortico-subcortical regions on susceptibility-weighted imaging (SWI). All cases had a history of chronic alcohol abuse and symmetrical lesions in the entire corpus callosum. These patients' clinical symptoms included not only coma, dysarthria, and astasia-abasia as initial symptoms but also dementia as a clinical outcome. SWI showed asymmetrical hypointense areas in the multiple cortico-subcortical regions, indicating the presence of CMH. Compared with patients with normal cognitive function, demented patients showed higher severity of CMH. Our report would indicate that CMH is an important factor indicating the severity of dementia in patients with MBD.

Vascular dementia: Current concepts and nomenclature harmonization

Several types of cerebrovascular lesions are associated with cognitive decline, but the role of each type in dementia manifestation has yet to be determined. One of the greatest barriers of conducting clinicopathological studies in vascular dementia concerns the overlapping of nomenclature for these lesions. The aim of the present review was to discuss current nomenclature for cerebrovascular lesions and suggest modifications to allow better diagnostic reproducibility in this field.

Identification of mineral deposits in the brain on radiological images: a systematic review

OBJECTIVES

MRI has allowed the study of mineral deposition in the brain throughout life and in disease. However, studies differ in their reporting of minerals on MRI for reasons that are unclear.

METHODS

We conducted a systematic review from 1985 to July 2011 to determine the appearance of iron, calcium, copper and manganese on MRI and CT and their reliability. We assessed which imaging investigations provided the most consistent results compared with histology.

RESULTS

Of 325 papers on minerals imaging, we included 46 studies that confirmed findings either directly or indirectly using a non-imaging method such as histology. Within this group, there was inconsistency in the identification of iron probably because of changes in its paramagnetic properties during its degradation. Iron appeared consistently hypointense only on T2*-weighted MRI, and along with calcified areas, hyperattenuated on CT. Appearance of copper, calcium and manganese, although consistently reported as hyperintense on T1-weighted MRI, was confirmed histologically in few studies. On T2-weighted imaging, calcified areas were always reported as hypointense, while the appearance of iron depended on the concentration, location and degradation stage.

CONCLUSIONS

More work is required to improve the reliability of imaging methods to detect and differentiate brain mineral deposition accurately.

KEY POINTS

There is inconsistency in reporting the appearance of minerals on radiological images. • Only 46 studies confirmed mineral appearance using a non-imaging method. • Iron is the mineral more widely studied, consistently hypointense on T2*-weighted MRI. • T1-weighted MRI consistently reported copper, calcium and manganese hyperintense. • Calcium is consistently reported hypointense on T2-weighted MRI and hyperattenuating on CT.