Characterizing the canine and feline optic pathways in vivo with diffusion MRI

Andrews, Erica F; Jacqmot, Olivier; Gomes, Filipe N C M Espinheira; Sha, Megan F; Niogi, Sumit N.; Johnson, Philippa J.

doi:10.1111/vop.12940

Cited by 5 publications

(4 citation statements)

References 58 publications

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“…Another unique aspect of canid sulcal anatomy was the ectomarginal sulcus in the occipital lobe. Histological research on the African wild dog (Chengetanai et al, 2020b) and neuroimaging and diffusion MRI in domestic dogs (Andrews et al, 2022; Boch et al, 2021) shows that the ectomarginal gyrus and adjacent sulcal region is part of the extrastriate visual cortex with the territory between the neighbouring marginal sulcus and dorsal convexity housing the primary visual cortex (V1; see Figure 6 ). The emergence of an ectomarginal sulcus may, therefore, indicate an expansion of the visual cortex in Canidae.…”

Section: Resultsmentioning

confidence: 99%

Comparative neuroimaging of the carnivoran brain: Neocortical sulcal anatomy

Boch,

Karadachka,

Loh

et al. 2024

Preprint

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Carnivorans are an important study object for comparative neuroscience, as they exhibit a wide range of behaviours, ecological adaptations, and social structures. Previous studies have mainly examined relative brain size, but a comprehensive understanding of brain diversity requires the investigation of other aspects of their neuroanatomy. Here, we obtained primarily post-mortem brain scans from eighteen species of the order Carnivora, reconstructed their cortical surfaces, and examined neocortical sulcal anatomy to establish a framework for systematic inter-species comparisons. We observed distinct regional variations in sulcal anatomy, potentially related to the species' behaviour and ecology. Arctoidea species with pronounced forepaw dexterity exhibited complex sulcal configurations in the presumed somatosensory cortex but low sulcal complexity in the presumed visual and auditory occipitotemporal cortex. Canidae had the largest number of unique major sulci with a unique sulcus in the occipital cortex and highly social canids featuring an additional frontal cortex sulcus. We also observed differentially complex occipito-temporal sulcal patterns in Felidae and Canidae, indicative of changes in auditory and visual areas that may be related to foraging strategies and social behaviour. In conclusion, this study presents an inventory of the sulcal anatomy of a number of rarely studied carnivoran brains and establishes a framework and novel avenues for further investigations employing a variety of neuroimaging modalities to reveal more about carnivoran brain diversity.

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Section: Resultsmentioning

confidence: 99%

Comparative neuroimaging of the carnivoran brain: Neocortical sulcal anatomy

Boch,

Karadachka,

Loh

et al. 2024

Preprint

Self Cite

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“…Therefore, imaging evaluation of the eye and its environment in the management of periocular and oral surgical tumors in dogs and cats is being considered [17][18][19]. The optic pathway has also been studied under in vivo conditions in dogs and cats [20,21]. However, there is a notable absence of metrological studies of orbital landmarks and the location of the optic chiasm within the skull.…”

Section: Introductionmentioning

confidence: 99%

Breed-Specific Skull Morphology Reveals Insights into Canine Optic Chiasm Positioning and Orbital Structure through 3D CT Scan Analysis

Ichikawa,

Kanemaki,

Kanai

2024

Animals

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This study’s CT scan-based morphometric analysis of 50 adult dogs explored the relationship between skull shape variations (determined by the skull index, SI), optic chiasm, optic canals, and orbital shape. Dogs were classified as brachycephalic (SI ≥ 59), mesocephalic (SI ≥ 51 but <59), and dolichocephalic (SI < 51). No significant age or weight differences were observed. Skull lengths (brachycephalic: 11.39 ± 1.76 cm, mesocephalic: 15.00 ± 2.96 cm, dolichocephalic: 17.96 ± 3.44 cm) and facial lengths (brachycephalic: 3.63 ± 1.00 cm, mesocephalic: 6.46 ± 1.55 cm, dolichocephalic: 8.23 ± 1.03 cm) varied significantly, with shorter orbital depths (brachycephalic: 2.58 ± 0.42 cm, mesocephalic: 3.19 ± 0.65 cm, dolichocephalic: 3.61 ± 0.77 cm) in brachycephalic dogs. The optic chiasm-to-inion horizontal length ratio to cranial horizontal length positively correlated with the SI (r = 0.883, p < 0.001), while the ratio to neurocranial length showed no SI correlation (range: 55.5–75.0). Brachycephalic breeds had a significantly wider optic canal angle (93.74 ± 16.00°), along with broader lacrimal-zygomatic and zygomatic frontal process angles. These findings highlight the zygomatic bone’s role in influencing breed-specific orbital variations by connecting the face to the neurocranium, projecting the orbital rim outward and forward with facial shortening.

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“…10 Several studies have focused on the identification of the optic pathway using advanced imaging in the dog. [11][12][13] However, to the best of the authors' knowledge, there have been no studies that describe a method for contouring the canine optic pathway.…”

Section: Introductionmentioning

confidence: 99%

“…There is one published guideline for contouring the feline optic pathway from the transverse view utilizing both CT and MRI 10 . Several studies have focused on the identification of the optic pathway using advanced imaging in the dog 11–13 . However, to the best of the authors’ knowledge, there have been no studies that describe a method for contouring the canine optic pathway.…”

Section: Introductionmentioning

confidence: 99%

Contouring in the optic plane improves the accuracy of computed tomography‐based segmentation of the optic pathway

Walther

Griffin

Randall

et al. 2023

Vet Radiology Ultrasound

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Canine optic pathway structures are often contoured on CT images, despite the difficulty of visualizing the optic pathway with CT using standard planes. The purpose of this prospective, analytical, diagnostic accuracy study was to examine the accuracy of optic pathway contouring by veterinary radiation oncologists (ROs) before and after training on optic plane contouring. Optic pathway contours used as the gold standard for comparison were created based on expert consensus from registered CT and MRI for eight dogs. Twenty-one ROs contoured the optic pathway on CT using their preferred method, and again following atlas and video training demonstrating contouring on the optic plane. The Dice similarity coefficient (DSC) was used to assess contour accuracy. A multilevel mixed model with random effects to account for repeated measures was used to examine DSC differences. The median DSC (5th and 95th percentile) before and after training was 0.31 (0.06, 0.48) and 0.41 (0.18, 0.53), respectively. The mean DSC was significantly higher after training compared with before training (mean difference = 0.10; 95% CI, 0.08-0.12; P < 0.001) across all observers and patients. DSC values were comparable to those reported (0.4-0.5) for segmentation of the optic chiasm and nerves in human patients. Contour accuracy improved after training but remained low, potentially due to the small optic pathway volumes. When registered CT-MRI images are not available, our study supports routine addition of an optic plane with specific window settings to improve segmentation accuracy in mesaticephalic dogs ≥11 kg.

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Characterizing the canine and feline optic pathways in vivo with diffusion MRI

Cited by 5 publications

References 58 publications

Comparative neuroimaging of the carnivoran brain: Neocortical sulcal anatomy

Comparative neuroimaging of the carnivoran brain: Neocortical sulcal anatomy

Breed-Specific Skull Morphology Reveals Insights into Canine Optic Chiasm Positioning and Orbital Structure through 3D CT Scan Analysis

Contouring in the optic plane improves the accuracy of computed tomography‐based segmentation of the optic pathway

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