Tierärztliche Hochschule Hannover

Manuskript I
MRS permits, among others, the investigation of N-acetyl-aspartate (NAA), lactate
(Lac), glutamate and glutamine (Glx), creatine and phosphocreatine (Cr), choline
(Cho) and myo-inositol (mI) in a cuboid region. 4-6 MRS has already been used in
several studies of brain disorders, 7, 8 but only a few investigations were published
about the feasibility of spectroscopic examinations in the spinal cord of animals in
vivo. 6, 9-13 Restrictions of measurements in the spinal cord are due to movement
artifacts, the small diameter and anatomical bending of the spinal cord and magnetic
inhomogeneities caused by the surrounding tissue. All of these factors may lead to
inadequate signal to noise ratios (SNR) impeding the analysis. 4-6
Traumatic spinal cord injury (SCI) is a very common neurological disorder in dogs.
The mechanical insult of the spinal cord leads to an initiation of a secondary cascade
including axonal degeneration, neuronal cell death, glutamate excitotoxicity, and
6, 14, 15
inflammatory reactions. These
pathophysiological findings could be further
characterized in vivo by the measurement of different metabolites in MRS. 4
In the current study the hypothesis should be proven that examinations of the canine
spinal cord by MRS are feasible to support the prognosis in patients with SCI in
future investigations. Restrictions of MRS measurements in the spinal cord should be
evaluated. The areal extent of intramedullary damages in T1- and T2-weighted
images in conventional MRI has been shown to correlate with outcome in dogs with
SCI. 16, 17 However, the nature of such lesions is not always well defined and the
pathogenetic background and significance of these changes are often debated. 7
Therefore, in the current study it was hypothesized that the use of MRS will support
the conventional MRI examination to determine the severity of spinal cord lesions.
4.3 Material and methods
4.3.1 Animals
In the current study, 47 animals were examined with the consent of their owners.
Different breeds were included comprising six Doberman, four Labrador retriever,
three Beagle, three German shepherds, two Australian shepherds, two Border
25