Diffusion‐weighted Magnetic Resonance Imaging of the Normal Canine Brain

Abstract

Diffusion-weighted imaging (DWI) MRI has been primarily reported as a method for diagnosing cerebrovascular disease in veterinary patients. In humans, clinical applications for diffusion-weighted MRI have also included epilepsy, Alzheimer's, and Creutzfeld-Jakob disease. Before these applications can be developed in veterinary patients, more data on brain diffusion characteristics are needed. Therefore, the aim of this study was to evaluate the distribution of diffusion in the normal canine brain. Magnetic resonance imaging of the brain was performed in ten, clinically normal, purpose-bred beagle dogs. On apparent diffusion coefficient maps, regions of interest were drawn around the caudate nucleus, thalamus, piriform lobe, hippocampus, semioval center, and cerebral cortex. Statistically significant differences in mean apparent diffusion coefficient were found for the internal capsule, hippocampus, and thalamus. The highest apparent diffusion coefficient (1044.29 ± 165.21 μm(2)/s (mean ± SD (standard deviation)) was detected in the hippocampus. The lowest apparent diffusion coefficient was measured in the semioval center (721.39 ± 126.28 μm(2)/s (mean ± SD)). Significant differences in mean apparent diffusion coefficients of the caudate nucleus, thalamus, and piriform lobe were found by comparing right and left sides. Differences between brain regions may occur due to differences in myelination, neural density, or fiber orientation. The reason for the differences between right and left sides remains unclear. Data from the current study provide background for further studies of diffusion changes in dogs with brain disease.

Diffusion-weighted imaging of the brains of dogs with idiopathic epilepsy

“…The MRI protocol was similar to a previous study that was approved by the Committee on the Ethics of Animal Experiments of the Justus-Liebig-University Giessen and local Hessian government (reference number: V54-19c2015(1)GI18/17 Nr. 78/2011) [ 32 ].…”

“…The anesthetic protocol and MRI system were identical to the settings published for normal dogs using a using a 1.0 Tesla 1 superconductive system and a SENSitivity Encoding (SENSE) coil 2 [ 32 ]. The following sequences were acquired: dorsal, sagittal and transverse T2-weighted images (TE: 85 ms; TR: 4000 ms), transverse T2-weighted FLAIR images (TE: 97.5 ms; TR: 3962 ms; TI: 2000 ms), transverse T2*-weighted gradient echo images (TE: 21 ms; TR: 454 ms), transverse T1-weighted images (TE: 15 ms TR: 593 ms) and dorsal 3D T1-weighted gradient echo images (TE: 6.9 ms; TR: 25 ms).…”

“…T1-weighted images were acquired pre- and post-contrast medium administration. Diffusion-weighted images using a single shot echo planar imaging sequence (SSh-EPI) with a b value of b = 0 s/mm 2 and b = 800 s/mm 2 were acquired in a dorsal and transverse plane with diffusion gradients in all three planes (x-, y- and z-plane) before contrast medium administration identical to the published protocol in normal dogs [ 32 ]. The slice orientation was parallel to the base of the skull for dorsal images and perpendicular to it for transverse images.…”

Consensus recommendations on standardized magnetic resonance imaging protocols for multicenter canine brain tumor clinical trials

“…Recommended sequence protocols should include, at a minimum, pre‐ and postcontrast three‐dimensional T1‐weighted images, T2‐weighted turbo spin echo (TSE) in all three planes, T2*‐weighted gradient recalled echo, T2‐weighted fluid attenuated inversion recovery (FLAIR), and diffusion weighted imaging/diffusion tensor imaging in transverse plane (Table ). The rationale for these sequences is described in more detail below, with consideration of relevant veterinary‐specific MRI literature . To maximize scanning efficiency, recommendations as to the order of scanning are presented in Table and described later in the text.…”

Normal diffusivity of the domestic feline brain

“…This study adds to the growing research in grey matter diffusion and provides a healthy range of diffusivity measures for feline populations. As established in human (Lee et al, ; Löbel et al, ) and canine (Hartmann et al, ; MacLellan et al, ) diffusivity research, it is important to have a reference for diffusion parameters for the population in question. Similarly, this study demonstrates a pattern of diffusivity across cortical grey matter regions in the feline population.…”