1
|
Foss KD, Billhymer AC. Magnetic resonance imaging in canine idiopathic epilepsy: a mini-review. Front Vet Sci 2024; 11:1427403. [PMID: 39021411 PMCID: PMC11251927 DOI: 10.3389/fvets.2024.1427403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Accepted: 06/19/2024] [Indexed: 07/20/2024] Open
Abstract
Magnetic resonance imaging (MRI) in an integral part of the diagnostic workup in canines with idiopathic epilepsy (IE). While highly sensitive and specific in identifying structural lesions, conventional MRI is unable to detect changes at the microscopic level. Utilizing more advanced neuroimaging techniques may provide further information on changes at the neuronal level in the brain of canines with IE, thus providing crucial information on the pathogenesis of canine epilepsy. Additionally, earlier detection of these changes may aid clinicians in the development of improved and targeted therapies. Advances in MRI techniques are being developed which can assess metabolic, cellular, architectural, and functional alterations; as well alterations in neuronal tissue mechanical properties, some of which are currently being applied in research on canine IE. This mini-review focuses on novel MRI techniques being utilized to better understand canine epilepsy, which include magnetic resonance spectroscopy, diffusion-weighted imaging, diffusion tensor imaging, perfusion-weighted imaging, voxel based morphometry, and functional MRI; as well as techniques applied in human medicine and their potential use in veterinary species.
Collapse
Affiliation(s)
- Kari D. Foss
- Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL, United States
| | | |
Collapse
|
2
|
Behroozi M, Graïc JM, Gerussi T. Beyond the surface: how ex-vivo diffusion-weighted imaging reveals large animal brain microstructure and connectivity. Front Neurosci 2024; 18:1411982. [PMID: 38988768 PMCID: PMC11233460 DOI: 10.3389/fnins.2024.1411982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/12/2024] [Indexed: 07/12/2024] Open
Abstract
Diffusion-weighted Imaging (DWI) is an effective and state-of-the-art neuroimaging method that non-invasively reveals the microstructure and connectivity of tissues. Recently, novel applications of the DWI technique in studying large brains through ex-vivo imaging enabled researchers to gain insights into the complex neural architecture in different species such as those of Perissodactyla (e.g., horses and rhinos), Artiodactyla (e.g., bovids, swines, and cetaceans), and Carnivora (e.g., felids, canids, and pinnipeds). Classical in-vivo tract-tracing methods are usually considered unsuitable for ethical and practical reasons, in large animals or protected species. Ex-vivo DWI-based tractography offers the chance to examine the microstructure and connectivity of formalin-fixed tissues with scan times and precision that is not feasible in-vivo. This paper explores DWI's application to ex-vivo brains of large animals, highlighting the unique insights it offers into the structure of sometimes phylogenetically different neural networks, the connectivity of white matter tracts, and comparative evolutionary adaptations. Here, we also summarize the challenges, concerns, and perspectives of ex-vivo DWI that will shape the future of the field in large brains.
Collapse
Affiliation(s)
- Mehdi Behroozi
- Department of Biopsychology, Faculty of Psychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Jean-Marie Graïc
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, Italy
| | - Tommaso Gerussi
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, Italy
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| |
Collapse
|
3
|
Jacqmot O, Van Thielen B, Hespel AM, Luijten PR, de Mey J, Van Binst A, Provyn S, Tresignie J. T2-weighted turbo spin-echo magnetic resonance imaging of canine brain anatomy at 1.5T, 3T, and 7T field strengths. Anat Rec (Hoboken) 2021; 305:222-233. [PMID: 34357697 DOI: 10.1002/ar.24724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 06/10/2021] [Accepted: 06/20/2021] [Indexed: 01/07/2023]
Abstract
Post-mortem T2 weighted images of canine heads were acquired at 1.5T, 3T, and 7T. This study aimed to (1) identify anatomical structures of the canine brain using an ultra-high-field magnetic resonance imaging (MRI) (7T) to help to facilitate their localization on high field MRI images (3T and 1.5T), where these structures may appear less well defined and delineated and (2) evaluate the visibility of canine brain anatomical structures on 1.5T, 3T, and 7T MRI images for optimizing clinical utility. Our hypothesis was that the provided subjective image quality comparison at different field strengths may offer a general baseline for canine brain anatomy and may help clinicians evaluate MRI options better. Six canine heads were examined with 1.5T, 3T, and 7T MRI scanners. T2-weighted images were acquired in three orthogonal planes at each field strength using a turbo spin-echo sequence. Fifty neuroanatomic structures were identified and evaluated on the 7T MR images; subsequently, those were found on the 3T and 45 out of the 50 structures were detected on the 1.5T imaging. The structures that were not able to be identified on the 1.5T imaging included the septum pellucidum, oculomotor nucleus, substantia nigra, claustrum, and thalamic nucleus griseus. Images acquired at 7T were subjective of higher spatial and contrast resolution. However, the ultra-high-field images were prone to artifacts at the interface between tissues of different magnetic properties. In conclusion, 3T MR imaging appears to be the best comprise for evaluating canine brain anatomy on MRI with fewer imaging artifacts.
Collapse
Affiliation(s)
- Olivier Jacqmot
- Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel, Brussels, Belgium.,MOVE - HIM (Morpho Veterinary & Human Imaging) Brussels, University Hospital Brussels, UZ Brussel, Brussel, Belgium
| | - Bert Van Thielen
- MOVE - HIM (Morpho Veterinary & Human Imaging) Brussels, University Hospital Brussels, UZ Brussel, Brussel, Belgium.,Department of Radiology, University Hospital Brussels, UZ Brussel, Brussels, Belgium.,Anatomical Research, Training and Education (ARTE), Vrije Universiteit Brussel, VUB, Brussels, Belgium
| | | | - Peter R Luijten
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Johan de Mey
- Department of Radiology, University Hospital Brussels, UZ Brussel, Brussels, Belgium
| | - Anne Van Binst
- Department of Radiology, University Hospital Brussels, UZ Brussel, Brussels, Belgium
| | - Steven Provyn
- Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel, Brussels, Belgium.,Anatomical Research, Training and Education (ARTE), Vrije Universiteit Brussel, VUB, Brussels, Belgium
| | - Jonathan Tresignie
- Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel, Brussels, Belgium
| |
Collapse
|
4
|
Graham KL, Johnson PJ, Barry EF, Pérez Orrico M, Soligo DJ, Lawlor M, White A. Diffusion tensor imaging of the visual pathway in dogs with primary angle-closure glaucoma. Vet Ophthalmol 2020; 24 Suppl 1:63-74. [PMID: 32990378 DOI: 10.1111/vop.12824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/09/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To describe measurements of in vivo structures of the visual pathway beyond the retina and optic nerve head associated with canine primary angle-closure glaucoma (PACG). METHODS A prospective pilot study was conducted using magnetic resonance diffusion tensor imaging (DTI) to obtain quantitative measures of the optic nerve, chiasm, tract, and lateral geniculate nucleus (LGN) in dogs with and without PACG. 3-Tesla DTI was performed on six affected dogs and five breed, age- and sex-matched controls. DTI indices of the optic nerve, optic chiasm, optic tracts, and LGN were compared between normal, unilateral PACG, and bilateral PACG groups. Intra-class correlation coefficient (ICC) was calculated to assess intra-observer reliability. RESULTS Quantitative measurements of the optic nerve, optic tract, optic chiasm, and LGN were obtained in all dogs. There was a trend for reduced fractional anisotropy (FA) associated with disease for all structures assessed. Compared to the same structure in normal dogs, FA, and radial diffusivity (RD) of the optic nerve was consistently higher in the unaffected eye in dogs with unilateral PACG. Intra-observer reliability was excellent for measurements of the optic nerve (ICC: 0.92), good for measurements of the optic tract (ICC: 0.89) and acceptable for measures of the optic chiasm (ICC: 0.71) and lateral geniculate nuclei (ICC: 0.76). CONCLUSION Diffusivity and anisotropy measures provide a quantifiable means to evaluate the visual pathway in dogs. DTI has potential to provide in vivo measures of axonal and myelin injury and transsynaptic degeneration in canine PACG.
Collapse
Affiliation(s)
- Kathleen L Graham
- Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, NSW, Australia
| | | | - Erica F Barry
- Cornell College of Veterinary Medicine, Ithaca, NY, USA
| | | | | | - Mitchell Lawlor
- Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, NSW, Australia
| | - Andrew White
- Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, NSW, Australia.,Westmead Institute for Medical Research, Westmead, NSW, Australia
| |
Collapse
|
5
|
Boucher S, Arribarat G, Cartiaux B, Lallemand EA, Péran P, Deviers A, Mogicato G. Diffusion Tensor Imaging Tractography of White Matter Tracts in the Equine Brain. Front Vet Sci 2020; 7:382. [PMID: 32850994 PMCID: PMC7406683 DOI: 10.3389/fvets.2020.00382] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/29/2020] [Indexed: 11/29/2022] Open
Abstract
Tractography, a noninvasive technique tracing brain pathways from diffusion tensor magnetic resonance imaging (DTI) data, is increasingly being used for brain investigation of domestic mammals. In the equine species, such a technique could be useful to improve our knowledge about structural connectivity or to assess structural changes of white matter tracts potentially associated with neurodegenerative diseases. The goals of the present study were to establish the feasibility of DTI tractography in the equine brain and to provide a morphologic description of the most representative tracts in this species. Postmortem DTI and susceptibility-weighted imaging (SWI) of an equine brain were acquired with a 3-T system using a head coil. Association, commissural, and projection fibers, the three fiber groups typically investigated in tractography studies, were successfully reconstructed and overlaid on SWI or fractional anisotropy maps. The fibers derived from DTI correlate well with their description in anatomical textbooks. Our results demonstrate the feasibility of using postmortem DTI data to reconstruct the main white matter tracts of the equine brain. Further DTI acquisitions and corresponding dissections of equine brains will be necessary to validate these findings and create an equine stereotaxic white matter atlas that could be used in future neuroimaging research.
Collapse
Affiliation(s)
- Samuel Boucher
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, INSERM, UPS, Toulouse, France
| | - Germain Arribarat
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, INSERM, UPS, Toulouse, France
| | - Benjamin Cartiaux
- INSERM UMR1037, Cancer Research Center of Toulouse, Oncopole, Toulouse, France
| | | | - Patrice Péran
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, INSERM, UPS, Toulouse, France
| | - Alexandra Deviers
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, INSERM, UPS, ENVT, Toulouse, France
| | - Giovanni Mogicato
- ToNIC, Toulouse NeuroImaging Center, Université de Toulouse, INSERM, UPS, ENVT, Toulouse, France
| |
Collapse
|
6
|
Jacqmot O, Van Thielen B, Michotte A, de Mey J, Provyn S, Tresignie J. Neuroanatomical Reconstruction of the Canine Visual Pathway Using Diffusion Tensor Imaging. Front Neuroanat 2020; 14:54. [PMID: 32973464 PMCID: PMC7461977 DOI: 10.3389/fnana.2020.00054] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/28/2020] [Indexed: 11/13/2022] Open
Abstract
The first anatomical atlas of diffusion tensor imaging (DTI) of white matter pathways in the canine brain was published in 2013; however, the anatomical orientation of the entire visual pathway in the canine brain, from the retina to the cortex, has not yet been studied using DTI. In the present study, 3T DTI magnetic resonance (MR) images of three dogs euthanized for reasons other than neurological disorders were obtained. The process of obtaining combined fractional anisotropy and directional maps was initiated within 1 h of death. The heads were amputated immediately after MR imaging and stored in 10% formalin until dissection and histological sampling was performed. The trajectory of the visual pathway is dissimilar to the horizontal representation in other literature. To our knowledge, ours is the first study to visualize the entire canine visual pathway in its full antero-posterior extension. Fibers from the retina to the cortex passed through the optic nerve, optic chiasm, optic tracts, lateral geniculate nucleus, Meyer’s and Baum’s loops, and pretectal fibers. Their projections to the cortex were similar to those in the human visual pathway. The crossing of fibers at the optic chiasm occurred in 75% of fibers. In addition to advancing our knowledge in this field of study, these results could help plan neurosurgical and radiotherapeutic procedures to avoid unnecessary damage to the visual fiber system.
Collapse
Affiliation(s)
- Olivier Jacqmot
- Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel, Brussels, Belgium.,MOVE-HIM (Morpho Veterinary and Human Imaging) Brussels, Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Bert Van Thielen
- MOVE-HIM (Morpho Veterinary and Human Imaging) Brussels, Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium.,Department of Radiology, UZ Brussel, Brussels, Belgium.,Odisee Brussel, Educational Department for Imaging Technologists, Brussels, Belgium.,Anatomical Research, Training and Education (ARTE), Vrije Universiteit Brussel, Brussels, Belgium
| | - Alex Michotte
- Department of Neurology and Neuropathology, Neuroanatomy, UZ Brussel, Brussels, Belgium
| | - Johan de Mey
- Department of Radiology, UZ Brussel, Brussels, Belgium
| | - Steven Provyn
- Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel, Brussels, Belgium
| | - Jonathan Tresignie
- Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel, Brussels, Belgium
| |
Collapse
|
7
|
Johnson PJ, Pascalau R, Luh WM, Raj A, Cerda-Gonzalez S, Barry EF. Stereotaxic Diffusion Tensor Imaging White Matter Atlas for the in vivo Domestic Feline Brain. Front Neuroanat 2020; 14:1. [PMID: 32116572 PMCID: PMC7026623 DOI: 10.3389/fnana.2020.00001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/16/2020] [Indexed: 02/02/2023] Open
Abstract
The cat brain is a useful model for neuroscientific research and with the increasing use of advanced neuroimaging techniques there is a need for an open-source stereotaxic white matter brain atlas to accompany the cortical gray matter atlas, currently available. A stereotaxic white matter atlas would facilitate anatomic registration and segmentation of the white matter to aid in lesion localization or standardized regional analysis of specific regions of the white matter. In this article, we document the creation of a stereotaxic feline white matter atlas from diffusion tensor imaging (DTI) data obtained from a population of eight mesaticephalic felines. Deterministic tractography reconstructions were performed to create tract priors for the major white matter projections of Corpus callosum (CC), fornix, cingulum, uncinate, Corona Radiata (CR), Corticospinal tract (CST), inferior longitudinal fasciculus (ILF), Superior Longitudinal Fasciculus (SLF), and the cerebellar tracts. T1-weighted, fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) population maps were generated. The volume, mean tract length and mean FA, MD, AD and RD values for each tract prior were documented. A structural connectome was then created using previously published cortical priors and the connectivity metrics for all cortical regions documented. The provided white matter atlas, diffusivity maps, tract priors and connectome will be a valuable resource for anatomical, pathological and translational neuroimaging research in the feline model. Multi-atlas population maps and segmentation priors are available at Cornell’s digital repository: https://ecommons.cornell.edu/handle/1813/58775.2.
Collapse
Affiliation(s)
- Philippa J Johnson
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Raluca Pascalau
- Faculty of Medicine, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Wen-Ming Luh
- National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Ashish Raj
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States
| | | | - Erica F Barry
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| |
Collapse
|
8
|
Johnson PJ, Barry EF, Luh WM, Davies E. The use of diffusion tractography to characterize a corpus callosum malformation in a dog. J Vet Intern Med 2018; 33:743-750. [PMID: 30588678 PMCID: PMC6430883 DOI: 10.1111/jvim.15392] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 11/16/2018] [Indexed: 12/24/2022] Open
Abstract
INTRODUCTION The pathogenesis of corpus callosum malformations (CCM) is not well defined in the dog because of inherent limitations of structural magnetic resonance imaging (MRI) to evaluate the white matter. We used the advanced neuroimaging technique of tractography to virtually dissect the white matter projections in a dog with a CCM and in a normal control dog. METHODS A 9-month-old male Coonhound that had a previous structural MRI diagnosis of CCM and a normal control dog underwent anesthesia and 3-Tesla MRI. Diffusion-tensor imaging and 3D T1-weighted and 2D T2-weighted sequences were acquired. Diffusion data were processed before tensor reconstruction and fiber tracking. Virtual dissections were performed to dissect out the major white matter projections in each dog. RESULTS In the dog with CCM, the corpus callosum exhibited interhemispheric crossing fibers at the level of the splenium and formed longitudinal callosal fasciculi (Probst bundles). In addition, the fornix was small and the cingula enlarged and exhibited increased dorsal connectivity relative to the normal control. CONCLUSIONS AND CLINICAL IMPORTANCE We used tractography to describe a white matter malformation in a dog. The results suggest that, embryologically, formed axons fail to cross midline and instead create Probst bundles.
Collapse
Affiliation(s)
- Philippa J Johnson
- Department of Clinical Sciences, College of Veterinary Medicine Cornell University, Ithaca, New York
| | - Erica F Barry
- Department of Clinical Sciences, College of Veterinary Medicine Cornell University, Ithaca, New York
| | - Wen-Ming Luh
- Cornell Magnetic Resonance Imaging Facility, College of Human Ecology, Cornell University, Ithaca, New York
| | - Emma Davies
- Department of Clinical Sciences, College of Veterinary Medicine Cornell University, Ithaca, New York
| |
Collapse
|