Morphometric study of the ventricular indexes in healthy ovine BRAIN using MRI.

BACKGROUND: Sheep (Ovis aries) have been largely used as animal models in a multitude of specialties in biomedical research. The similarity to human brain anatomy in terms of brain size, skull features, and gyrification index, gives to ovine as a large animal model a better translational value than small animal models in neuroscience. Despite this evidence and the availability of advanced imaging techniques, morphometric brain studies are lacking. We herein present the morphometric ovine brain indexes and anatomical measures developed by two observers in a double-blinded study and validated via an intra- and inter-observer analysis. RESULTS: For this retrospective study, T1-weighted Magnetic Resonance Imaging (MRI) scans were performed at 1.5 T on 15 sheep, under general anaesthesia. The animals were female Ovis aries, in the age of 18-24 months. Two observers assessed the scans, twice time each. The statistical analysis of intra-observer and inter-observer agreement was obtained via the Bland-Altman plot and Spearman rank correlation test. The results are as follows (mean ± Standard deviation): Indexes: Bifrontal 0,338 ± 0,032 cm; Bicaudate 0,080 ± 0,012 cm; Evans' 0,218 ± 0,035 cm; Ventricular 0,241 ± 0,039 cm; Huckman 1693 ± 0,174 cm; Cella Media 0,096 ± 0,037 cm; Third ventricle ratio 0,040 ± 0,007 cm. Anatomical measures: Fourth ventricle length 0,295 ± 0,073 cm; Fourth ventricle width 0,344 ± 0,074 cm; Left lateral ventricle 4175 ± 0,275 cm; Right lateral ventricle 4182 ± 0,269 cm; Frontal horn length 1795 ± 0,303 cm; Interventricular foramen left 1794 ± 0,301 cm; Interventricular foramen right 1,78 ± 0,317 cm. CONCLUSIONS: The present study provides baseline values of linear indexes of the ventricles in the ovine models. The acquisition of these data contributes to filling the knowledge void on important anatomical and morphological features of the sheep brain

In vivo Diffusion Tensor Magnetic Resonance Tractography of the Sheep Brain : An Atlas of the Ovine White Matter Fiber Bundles

Diffusion Tensor Magnetic Resonance Imaging (DTI) allows to decode the mobility of water molecules in cerebral tissue, which is highly directional along myelinated fibers. By integrating the direction of highest water diffusion through the tissue, DTI Tractography enables a non-invasive dissection of brain fiber bundles. As such, this technique is a unique probe for in vivo characterization of white matter architecture. Unraveling the principal brain texture features of preclinical models that are advantageously exploited in experimental neuroscience is crucial to correctly evaluate investigational findings and to correlate them with real clinical scenarios. Although structurally similar to the human brain, the gyrencephalic ovine model has not yet been characterized by a systematic DTI study. Here we present the first in vivo sheep (ovis aries) tractography atlas, where the course of the main white matter fiber bundles of the ovine brain has been reconstructed. In the context of the EU's Horizon EDEN2020 project, in vivo brain MRI protocol for ovine animal models was optimized on a 1.5T scanner. High resolution conventional MRI scans and DTI sequences (b-value = 1,000 s/mm2, 15 directions) were acquired on ten anesthetized sheep o. aries, in order to define the diffusion features of normal adult ovine brain tissue. Topography of the ovine cortex was studied and DTI maps were derived, to perform DTI tractography reconstruction of the corticospinal tract, corpus callosum, fornix, visual pathway, and occipitofrontal fascicle, bilaterally for all the animals. Binary masks of the tracts were then coregistered and reported in the space of a standard stereotaxic ovine reference system, to demonstrate the consistency of the fiber bundles and the minimal inter-subject variability in a unique tractography atlas. Our results determine the feasibility of a protocol to perform in vivo DTI tractography of the sheep, providing a reliable reconstruction and 3D rendering of major ovine fiber tracts underlying different neurological functions. Estimation of fiber directions and interactions would lead to a more comprehensive understanding of the sheep's brain anatomy, potentially exploitable in preclinical experiments, thus representing a precious tool for veterinaries and researchers

PARATOPIE DISCALI IN DICIANNOVE CANI: RISONANZA MAGNETICA (RM) E ISTOPATOLOGIA

Le paratopie discali (intervertebral disk disease \u2013 IVDD) rappresentano nel cane una frequente patologia, accompagnata da dolore spinale, deficit motori, sensoriali e viscerali, che si verifica quando il disco degenerato danneggia le strutture neurali. Lo studio \ue8 stato condotto su 19 casi di IVDD non traumatici e mielopatici campionati nel 2007-2008 e casi di controllo privi di patologie discali. In tutti i discopatici \ue8 stato effettuato un esame di RM tramite scansioni secondo i tre piani fondamentali del rachide, T1- T2 dipendenti, dello spessore di 3 mm, cui \ue8 seguito l\u2019intervento chirurgico durante il quale, mediante miniemilaminectomia o peduncolectomia, sono stati asportati dei frammenti discali, poi processati per l\u2019istologia e colorati con EE, Alcian e secondo la metodica di Gruber. La casistica \ue8 composta da 9 femmine e 10 maschi, con et\ue0 media di 8 anni: 6 Bassotti, 2 Pastore Tedesco, 1 Rottweiler, 1 Dalmata, 1 Bassetthound, 1 Beagle, 1 Bracco Italiano e 6 meticci. La RM ha diagnosticato 16 prolassi e 3 protrusioni, con segni di esordio acuto in 11 casi, con simile coinvolgimento dei diversi tratti vertebrali. Tutti i cani hanno mostrato recupero funzionale post-chirurgico. L\u2019esame istologico dei frammenti discali ha evidenziato in 11 casi tessuto riferibile sia ad anello fibroso che a nucleo polposo, in 4 solo anello fibroso, in 2 solo nucleo polposo, in 2 il materiale era insufficiente. La componente cellulare condrocitica ha mostrato segni di degenerazione, di grado moderato-grave, riferibili a ipoplasia, apoptosi e megalocitosi; in 12 casi erano presenti aree di necrosi e in un caso si sono osservati segni di flogosi cronica. In 9 casi il materiale discale era costituito da una componente calcificata. Infine, le fibre dell\u2019anello fibroso presentavano gradi variabili di disorganizzazione. Il test di Fisher non ha evidenziato correlazioni significative tra diagnosi RM (prolasso o protrusione) e componenti erniate (anello fibroso o nucleo polposo) o presenza di necrosi