Diffusion tensor imaging-based quantitative analysis of the spinal cord in Pembroke Welsh Corgis with degenerative myelopathy

Canine degenerative myelopathy (DM) is a progressive neurodegenerative disease of the spinal cord. The diagnosis is based on the observation of clinical signs, genetic testing, and exclusion of other spinal cord diseases, and a definitive diagnosis of DM can only be confirmed by postmortem histopathological findings. The aim of this study was to investigate the diagnostic ability of diffusion tensor imaging (DTI) for DM. Eight DM-affected Pembroke Welsh Corgis, thirteen dogs with thoracolumbar intervertebral disk herniation (IVDH), and six healthy control dogs were included. All dogs were scanned using a 3.0-T MRI system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were calculated for each intervertebral disk level slice between T8-T9 and L2-L3 intervertebral disk levels, and the entire area of the thoracolumbar spinal cord between T8-T9 and L2-L3 intervertebral disk levels (T8-L3 region). The ADC and FA values of the T8-L3 region were significantly lower in the DM group than in the IVDH group. The ADC values for theT8-L3 region had a moderate negative correlation with clinical duration (r(s) = -0.723, P=0.043); however, the FA values of other intervertebral disk levels and T8-L3 region had no correlation with clinical durations. The measurement of DTI indices can be used to quantitatively assess neurodegeneration and may have diagnostic value for DM. In particular, the ADC value of the T8-L3 region may aid in making a non-invasive premortem diagnosis of DM.