The Spectrum of MR Detectable Cortical Microinfarcts: A Classification Study with 7-Tesla Postmortem MRI and Histopathology

Cerebral microinfarcts (CMIs) are common neuropathologic findings in aging and dementia. We explored the spectrum of cortical CMIs that can be visualized with 7T magnetic resonance imaging (MRI). Thirty-three coronal brain slices of 11 individuals with neuropathologically confirmed dementia were subjected to a high-resolution postmortem 7T MRI protocol. First, we identified all visible small (5 mm) intracortical and juxtacortical lesions on postmortem MRI. Lesions were classified as CMI or nonCMI based on histology, and their MR features were recorded. Thirty lesions were identified on the initial MRI evaluation, of which twenty-three could be matched with histology. Histopathology classified 12 lesions as CMIs, all of which were located intracortically. On the basis of their MR features, they could be classified as chronic gliotic CMIs—with or without cavitation or hemorrhagic components—and acute CMIs. Eleven MRI identified lesions were not of ischemic nature and most commonly enlarged or atypically shaped perivascular spaces. Their MRI features were similar to gliotic CMIs with or without cavitation, but these ‘CMI mimics’ were always located juxtacortically. 7T postmortem MRI distinguishes different histopathologic types of cortical CMIs, with distinctive MR characteristics. On the basis of our findings, we propose in vivo rating criteria for the detection of intracortical CMIs.

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Body mass index, time of day, and genetics affect perivascular spaces in the white matter

10.1101/2020.06.20.162404 ◽

2020 ◽

Author(s):

Giuseppe Barisano ◽

Farshid Sepehrband ◽

Nasim Sheikh-Bahaei ◽

Meng Law ◽

Arthur W. Toga

Keyword(s):

Body Mass Index ◽

White Matter ◽

Body Mass ◽

Structural Changes ◽

Large Population ◽

Time Of Day ◽

Perivascular Spaces ◽

Healthy Human ◽

Magnetic Resonance Imaging Mri

AbstractThe analysis of cerebral perivascular spaces (PVS) using magnetic resonance imaging (MRI) allows to explore in vivo their contributions to neurological disorders. To date the normal amount and distribution of PVS in healthy human brains are not known, thus hampering our ability to define with confidence pathogenic alterations. Furthermore, it is unclear which biological factors can influence the presence and size of PVS on MRI. We performed exploratory data analysis of PVS volume and distribution in a large population of healthy individuals (n = 897, age = 28.8 ± 3.7). Here we describe the global and regional amount of PVS in the white matter, which can be used as a reference for clinicians and researchers investigating PVS and may help the interpretation of the structural changes affecting PVS in pathological states. We found a relatively high inter-subject variability in the PVS amount in this population of healthy adults (range: 1.31-14.49 cm3). We then identified body mass index, time of day, and genetics as new elements significantly affecting PVS in vivo under physiological conditions, offering a valuable foundation to future studies aimed at understanding the physiology of perivascular flow.

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Body mass index, time of day, and genetics affect perivascular spaces in the white matter

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x20972856 ◽

2020 ◽

pp. 0271678X2097285

Author(s):

Giuseppe Barisano ◽

Nasim Sheikh-Bahaei ◽

Meng Law ◽

Arthur W Toga ◽

Farshid Sepehrband

Keyword(s):

Body Mass Index ◽

White Matter ◽

Body Mass ◽

Structural Changes ◽

Large Population ◽

Time Of Day ◽

Perivascular Spaces ◽

Healthy Human ◽

Magnetic Resonance Imaging Mri

The analysis of cerebral perivascular spaces (PVS) using magnetic resonance imaging (MRI) allows to explore in vivo their contributions to neurological disorders. To date the normal amount and distribution of PVS in healthy human brains are not known, thus hampering our ability to define with confidence pathogenic alterations. Furthermore, it is unclear which biological factors can influence the presence and size of PVS on MRI. We performed exploratory data analysis of PVS volume and distribution in a large population of healthy individuals (n = 897, age = 28.8 ± 3.7). Here we describe the global and regional amount of PVS in the white matter, which can be used as a reference for clinicians and researchers investigating PVS and may help the interpretation of the structural changes affecting PVS in pathological states. We found a relatively high inter-subject variability in the PVS amount in this population of healthy adults (range: 1.31–14.49 cm3). The PVS volume was higher in older and male individuals. Moreover, we identified body mass index, time of day, and genetics as new elements significantly affecting PVS in vivo under physiological conditions, offering a valuable foundation to future studies aimed at understanding the physiology of perivascular flow.

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The Influence of Inaccuracies in Carotid MRI Segmentation on Atherosclerotic Plaque Stress Computations

Journal of Biomechanical Engineering ◽

10.1115/1.4026178 ◽

2014 ◽

Vol 136 (2) ◽

Cited By ~ 4

Author(s):

Harm A. Nieuwstadt ◽

Lambert Speelman ◽

Marcel Breeuwer ◽

Aad van der Lugt ◽

Anton F. W. van der Steen ◽

...

Keyword(s):

Ground Truth ◽

Black Blood ◽

Element Analysis ◽

Voxel Size ◽

Carotid Plaques ◽

Fea Model ◽

Carotid Mri ◽

Mri Protocol ◽

Magnetic Resonance Imaging Mri

Biomechanical finite element analysis (FEA) based on in vivo carotid magnetic resonance imaging (MRI) can be used to assess carotid plaque vulnerability noninvasively by computing peak cap stress. However, the accuracy of MRI plaque segmentation and the influence this has on FEA has remained unreported due to the lack of a reliable submillimeter ground truth. In this study, we quantify this influence using novel numerical simulations of carotid MRI. Histological sections from carotid plaques from 12 patients were used to create 33 ground truth plaque models. These models were subjected to numerical computer simulations of a currently used clinically applied 3.0 T T1-weighted black-blood carotid MRI protocol (in-plane acquisition voxel size of 0.62 × 0.62 mm2) to generate simulated in vivo MR images from a known underlying ground truth. The simulated images were manually segmented by three MRI readers. FEA models based on the MRI segmentations were compared with the FEA models based on the ground truth. MRI-based FEA model peak cap stress was consistently underestimated, but still correlated (R) moderately with the ground truth stress: R = 0.71, R = 0.47, and R = 0.76 for the three MRI readers respectively (p < 0.01). Peak plaque stretch was underestimated as well. The peak cap stress in thick-cap, low stress plaques was substantially more accurately and precisely predicted (error of −12 ± 44 kPa) than the peak cap stress in plaques with caps thinner than the acquisition voxel size (error of −177 ± 168 kPa). For reliable MRI-based FEA to compute the peak cap stress of carotid plaques with thin caps, the current clinically used in-plane acquisition voxel size (∼0.6 mm) is inadequate. FEA plaque stress computations would be considerably more reliable if they would be used to identify thick-cap carotid plaques with low stresses instead.

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Microvascular MRI and Unsupervised Clustering Yields Histology-Resembling Images in Two Rat Models of Glioma

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2014.90 ◽

2014 ◽

Vol 34 (8) ◽

pp. 1354-1362 ◽

Cited By ~ 22

Author(s):

Nicolas Coquery ◽

Olivier Francois ◽

Benjamin Lemasson ◽

Clément Debacker ◽

Régine Farion ◽

...

Keyword(s):

Cerebral Blood Volume ◽

Volume Fraction ◽

Region Of Interest ◽

Tissue Type ◽

Rat Models ◽

Glioma C6 ◽

Mri Features ◽

Apparent Diffusion ◽

Magnetic Resonance Imaging Mri

Imaging heterogeneous cancer lesions is a real challenge. For diagnosis, histology often remains the reference, but it is widely acknowledged that biopsies are not reliable. There is thus a strong interest in establishing a link between clinical in vivo imaging and the biologic properties of tissues. In this study, we propose to construct histology-resembling images based on tissue microvascularization, a magnetic resonance imaging (MRI) accessible source of contrast. To integrate the large amount of information collected with microvascular MRI, we combined a manual delineation of a spatial region of interest with an unsupervised, model-based cluster analysis (Mclust). This approach was applied to two rat models of glioma (C6 and F98). Six MRI parameters were mapped: apparent diffusion coefficient, vessel wall permeability, cerebral blood volume fraction, cerebral blood flow, tissular oxygen saturation, and cerebral metabolic rate of oxygen. Five clusters, defined by their MRI features, were found to correspond to specific histologic features, and revealed intratumoral spatial structures. These results suggest that the presence of a cluster within a tumor can be used to assess the presence of a tissue type. In addition, the cluster composition, i.e., a signature of the intratumoral structure, could be used to characterize tumor models as histology does.

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In vivo 3D Reconstruction of the Human Pallidothalamic and Nigrothalamic Pathways With Super-Resolution 7T MR Track Density Imaging and Fiber Tractography

Frontiers in Neuroanatomy ◽

10.3389/fnana.2021.739576 ◽

2021 ◽

Vol 15 ◽

Author(s):

Dae-Hyuk Kwon ◽

Sun Ha Paek ◽

Young-Bo Kim ◽

Haigun Lee ◽

Zang-Hee Cho

Keyword(s):

Basal Ganglia ◽

3D Reconstruction ◽

Human Brain ◽

Super Resolution ◽

Track Density ◽

7 Tesla ◽

Fiber Tractography ◽

Resolution Limit ◽

Magnetic Resonance Imaging Mri

The output network of the basal ganglia plays an important role in motor, associative, and limbic processing and is generally characterized by the pallidothalamic and nigrothalamic pathways. However, these connections in the human brain remain difficult to elucidate because of the resolution limit of current neuroimaging techniques. The present study aimed to investigate the mesoscopic nature of these connections between the thalamus, substantia nigra pars reticulata, and globus pallidus internal segment using 7 Tesla (7T) magnetic resonance imaging (MRI). In this study, track-density imaging (TDI) of the whole human brain was employed to overcome the limitations of observing the pallidothalamic and nigrothalamic tracts. Owing to the super-resolution of the TD images, the substructures of the SN, as well as the associated tracts, were identified. This study demonstrates that 7T MRI and MR tractography can be used to visualize anatomical details, as well as 3D reconstruction, of the output projections of the basal ganglia.

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Neuroimaging in dementia

Wiener Medizinische Wochenschrift ◽

10.1007/s10354-021-00825-x ◽

2021 ◽

Author(s):

Julia Furtner ◽

Daniela Prayer

Keyword(s):

Imaging Techniques ◽

Resonance Imaging ◽

Clinical Criteria ◽

Mri Features ◽

Reporting Systems ◽

Diagnosis Of Dementia ◽

Subdural Hemorrhages ◽

Mri Protocol ◽

Magnetic Resonance Imaging Mri

SummaryDespite the fact that the diagnosis of dementia is mainly based on clinical criteria, the role of neuroimaging is still expanding. Among other imaging techniques, magnetic resonance imaging (MRI) plays a core role in assisting with the differentiation between various dementia syndromes and excluding other underlying pathologies that cause dementia, such as brain tumors and subdural hemorrhages. This article gives an overview of the standard MRI protocol and of structural radiological reporting systems in patients who suffer from dementia. Moreover, it presents characteristic MRI features of the most common dementia subtypes.

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Large anterior temporal Virchow–Robin spaces: Evaluating MRI features over the years—Our experience and literature review

Clinical and Translational Neuroscience ◽

10.1177/2514183x20905252 ◽

2020 ◽

Vol 4 (1) ◽

pp. 2514183X2090525

Author(s):

Raffaella Capasso ◽

Alberto Negro ◽

Sossio Cirillo ◽

Silvia Iovine ◽

Gianfranco Puoti ◽

...

Keyword(s):

Brain Mri ◽

Perivascular Spaces ◽

Mri Features ◽

Signal Change ◽

Long Term Follow Up ◽

Magnetic Resonance Imaging Mri ◽

Preferential Location ◽

The Stability

Dilated Virchow–Robin spaces (VRSs) are expansions of the normal perivascular spaces with a short axis greater than 2 mm or, according to some authors, greater than 3 mm. They are usually documented at the basal ganglia, at the convexity white matter (WM) and centrum semiovale, and at the mesencephalon. The anterior temporal WM is a recently described preferential location for large (≥5 mm) VRSs. The aim of our study was to evaluate the magnetic resonance imaging (MRI) features and their modifications during a long-term follow-up period (≥24 months) of the anterior temporal VRSs with a retrospective analysis among all brain MRI studies performed at our institution between January 2010 and January 2017. In our study, the presence and the stability of characteristic MRI features certainly increased our diagnostic confidence allowing us to continue conservative approach while the surrounding signal change, as reported in the literature, should not in itself prompt alternative diagnoses to be entertained.

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Mapping the human subcortical auditory system using histology, postmortem MRI and in vivo MRI at 7T

eLife ◽

10.7554/elife.48932 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 7

Author(s):

Kevin R Sitek ◽

Omer Faruk Gulban ◽

Evan Calabrese ◽

G Allan Johnson ◽

Agustin Lage-Castellanos ◽

...

Keyword(s):

Auditory System ◽

Structural Connectivity ◽

Three Dimensional ◽

Auditory Pathway ◽

7 Tesla ◽

Post Mortem ◽

Subcortical Structures ◽

Isotropic Resolution ◽

Postmortem Mri

Studying the human subcortical auditory system non-invasively is challenging due to its small, densely packed structures deep within the brain. Additionally, the elaborate three-dimensional (3-D) structure of the system can be difficult to understand based on currently available 2-D schematics and animal models. Wfe addressed these issues using a combination of histological data, post mortem magnetic resonance imaging (MRI), and in vivo MRI at 7 Tesla. We created anatomical atlases based on state-of-the-art human histology (BigBrain) and postmortem MRI (50 µm). We measured functional MRI (fMRI) responses to natural sounds and demonstrate that the functional localization of subcortical structures is reliable within individual participants who were scanned in two different experiments. Further, a group functional atlas derived from the functional data locates these structures with a median distance below 2 mm. Using diffusion MRI tractography, we revealed structural connectivity maps of the human subcortical auditory pathway both in vivo (1050 µm isotropic resolution) and post mortem (200 µm isotropic resolution). This work captures current MRI capabilities for investigating the human subcortical auditory system, describes challenges that remain, and contributes novel, openly available data, atlases, and tools for researching the human auditory system.

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