Quantification of volumetric morphometry and optical property in the cortex of human cerebellum at micrometer resolution

Liu, Chao J.; Ammon, William; Siless, Viviana; Fogarty, Morgan; Wang, Ruopeng; Atzeni, Alessia; Aganj, Iman; Iglesias, Juan Eugenio; Zöllei, Lilla; Fischl, Bruce; Schmahmann, Jeremy D.; Wang, Hui

doi:10.1101/2021.04.27.441546

Cited by 3 publications

(2 citation statements)

References 41 publications

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“…The median cerebellar cortical surface area was estimated at 949 cm 2 (IQR, 825-1021 cm 2 ), 84% (21) and 60% (1) of the only two previous high-fidelity surface area estimates (both ex vivo and requiring several hours of MRI S7). The median cerebellar cortical thickness was estimated at 0.88 mm (IQR, 0.81-0.93 mm) in agreement with ex vivo reports (0.7-0.8 mm) (22) and four to five times smaller than the current typical imaging-based in vivo estimates. Our median WM volume estimate (64 cm 3 [IQR, 62-69 cm 3 ]) agreed with the reference ex vivo study (63 cm 3 [1]).…”

Section: Cerebellar Cortical Surfacesupporting

confidence: 86%

High-Resolution Motion-corrected 7.0-T MRI to Derive Morphologic Measures from the Human Cerebellum in Vivo

Priovoulos¹,

Andersen²,

Dumoulin³

et al. 2023

Radiology

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NEURORADIOLOGYT he human cerebellum has approximately one-eighth the volume of the neocortex but a cortical sheet with a similar surface area (1). The cerebellar cortex is a prevalent lesion site for various disease processes, including multiple sclerosis (2,3), spinocerebellar ataxias (4), and alcoholism (5).The cerebellar cortex has a regular circuit characterized by the granular cells (granular layer: 250-350 μm wide) that output to the Purkinje cells (Purkinje layer: 12 μm) through the parallel fibers (molecular layer: 250-350 μm). Beams of parallel fibers underlie the characteristic cerebellar mediolateral folds (500-1000 μm) (6). Despite its importance, this mesoscopic scale of the cerebellar architecture is underexamined in humans: Current in vivo techniques are limited to gross anatomic features, such as the main cortical branches, due to inadequate resolution (1). As a result, clinical measures successfully used in the cerebral cortex, such as cortical thickness, volume, and myeloarchitecture/function correlates, have not been applied with high fidelity in the cerebellum (1). This hinders examination of the cerebellum in disease.Herein, we combined methodologic advances in image acquisition and analysis to image the cerebellar cortex, including its foliations and lamination, with use of in vivo 7.0-T MRI to improve the signal-to-noise ratio and signal-to-noise efficiency. We modified two MRI pulse sequences targeted at imaging the cortical surface and intracortical lamination, respectively, to translate this higher signal-to-noise ratio to spatial resolution Background: The human cerebellum has a large, highly folded cortical sheet. Its visualization is important for various disorders, including multiple sclerosis and spinocerebellar ataxias. The derivation of the cerebellar cortical surface in vivo is impeded by its high foliation.Purpose: To image the cerebellar cortex, including its foliations and lamination, in less than 20 minutes, reconstruct the cerebellocortical surface, and extract cortical measures with use of motion-corrected, high-spatial-resolution 7.0-T MRI. Materials and Methods:In this prospective study, conducted between February 2021 and July 2022, healthy participants underwent an examination with either a 0.19 × 0.19 × 0.5-mm 3 , motion-corrected fast low-angle shot (FLASH) sequence (14.5 minutes) or a whole-cerebellum 0.4 × 0.4 × 0.4-mm 3 , motion-corrected magnetization-prepared 2 rapid gradient-echo (MP2RAGE) sequence (18.5 minutes) at 7.0 T. Four participants underwent an additional FLASH sequence without motion correction. FLASH and MP2RAGE sequences were used to visualize the cerebellar cortical layers, derive cerebellar gray and white matter segmentations, and examine their fidelity. Quantitative measures were compared using repeated-measures analyses of variance or paired t tests.Results: Nine participants (median age, 36 years [IQR, 25-42 years; range, 21-62 years]; five women) underwent examination with the FLASH sequence. Nine participants (median age, 37 years [IQR,[34][35...

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Section: Cerebellar Cortical Surfacesupporting

confidence: 86%

High-Resolution Motion-corrected 7.0-T MRI to Derive Morphologic Measures from the Human Cerebellum in Vivo

Priovoulos¹,

Andersen²,

Dumoulin³

et al. 2023

Radiology

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“…One advantage of OCT/OCM is the block-face imaging that allows physical slicing to be conducted after imaging the surface of the sample block and hence removes the distortion during volumetric reconstruction. By integrating a vibratome into the OCT/OCM system and adopting a serial sectioning strategy, cubic centimeters of postmortem human tissues have been reconstructed and analyzed across various brain structures by OCT (Wang et al, 2014(Wang et al, , 2018Jones et al, 2020;Liu et al, 2021). In addition, the same slices can be used for further validation and assessment by standard histology.…”

Section: Introductionmentioning

confidence: 99%

Quantitative optical coherence microscopy of neuron morphology in human entorhinal cortex

et al. 2023

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IntroductionThe size and shape of neurons are important features indicating aging and the pathology of neurodegenerative diseases. Despite the significant advances of optical microscopy, quantitative analysis of the neuronal features in the human brain remains largely incomplete. Traditional histology on thin slices bears tremendous distortions in three-dimensional reconstruction, the magnitude of which are often greater than the structure of interest. Recently development of tissue clearing techniques enable the whole brain to be analyzed in small animals; however, the application in the human remains challenging.MethodsIn this study, we present a label-free quantitative optical coherence microscopy (OCM) technique to obtain the morphological parameters of neurons in human entorhinal cortex (EC). OCM uses the intrinsic back-scattering property of tissue to identify individual neurons in 3D. The area, length, width, and orientation of individual neurons are quantified and compared between layer II and III in EC.ResultsThe high-resolution mapping of neuron size, shape, and orientation shows significant differences between layer II and III neurons in EC. The results are validated by standard Nissl staining of the same samples.DiscussionThe quantitative OCM technique in our study offers a new solution to analyze variety of neurons and their organizations in the human brain, which opens new insights in advancing our understanding of neurodegenerative diseases.

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Refractive-index matching enhanced polarization sensitive optical coherence tomography quantification in human brain tissue

Liu

Ammon

Jones

et al. 2021

Preprint

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The importance of polarization-sensitive optical coherence tomography (PS-OCT) has been increasingly recognized in human brain imaging. Despite the recent progress of PS-OCT in revealing white matter architecture and orientation, quantification of fine-scale fiber tracts in the human brain cortex has been a challenging problem, due to a low birefringence in the gray matter. In this study, we investigated the effect of refractive index matching by 2,2'-thiodiethanol (TDE) immersion on the improvement of PS-OCT measurements in ex vivo human brain tissue. We obtain the cortical fiber orientation maps in the gray matter, which reveals the radial fibers in the gyrus, the U-fibers along the sulcus, as well as distinct layers of fiber axes exhibiting laminar organization. Further analysis shows that index matching reduces the noise in axis orientation measurements by 56% and 39%, in white and gray matter, respectively. Index matching also enables precise measurements of apparent birefringence, which was underestimated in the white matter by 82% but overestimated in the gray matter by 16% prior to TDE immersion. Mathematical simulations show that the improvements are primarily attributed to the reduction in the tissue scattering coefficient, leading to an enhanced signal-to-noise ratio in deeper tissue regions, which could not be achieved by conventional noise reduction methods.

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Quantification of volumetric morphometry and optical property in the cortex of human cerebellum at micrometer resolution

Cited by 3 publications

References 41 publications

High-Resolution Motion-corrected 7.0-T MRI to Derive Morphologic Measures from the Human Cerebellum in Vivo

High-Resolution Motion-corrected 7.0-T MRI to Derive Morphologic Measures from the Human Cerebellum in Vivo

Quantitative optical coherence microscopy of neuron morphology in human entorhinal cortex

Refractive-index matching enhanced polarization sensitive optical coherence tomography quantification in human brain tissue

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