Spontaneous acute and chronic spinal cord injuries in paraplegic dogs: a comparative study of in vivo diffusion tensor imaging

Abstract

Using DTI, differences between acute and chronic stages of spontaneous canine SCI were detected and correlations between T2W and DTI sequences were found in chronic SCI, supporting canine SCI as a useful large animal model.

The role of diffusion tensor imaging as an objective tool for the assessment of motor function recovery after paraplegia in a naturally-occurring large animal model of spinal cord injury

“…Such laceration is more commonly observed in humans than in dogs and could be responsible for primary transection of axonal membranes with associated intramedullary influx of CSF and haemorrhage fluids, subsequently leading to alterations in the intra- to extracellular water content and therewith decreasing anisotropy [ 9 , 55 – 57 ]. Conversely, an increase in anisotropy at the epicentre of the lesions occurred, which suggests presence of cytotoxic oedema and reduced space between axonal tracts caused by a reduction of the diameter of the vertebral canal due to the presence of herniated disc material during the acute phase [ 39 , 58 , 59 ]. Furthermore, increases of FA values have been proposed to be more dependent on changes of cellular membranes than on myelin sheaths and have been therefore proposed as a biomarker for cytotoxic oedema during the acute phase of axonal injury after traumatic brain lesions [ 28 , 59 – 61 ].…”

“…As controls, six dogs, 5 males and 1 female, with either orthopaedic disease or neurological signs localized outside the T3-L3 segment of the SC were included and already used in another study [ 35 , 39 ]. Their mean age was 6.4 years (median 6.4 years; range 1.7–12.1 years) and their mean body weight 15.6 kg (median = 11.8 kg; range 6–30 kg).…”

“…These voxels were afterwards fused to form a single ROI as previously described; all ROIs were placed on signal deriving from the SC tissue directly dorsal to intervertebral disc spaces. Lesion epicentres were defined as localizations of spinal cord compression caused by herniated disc material in T2W sequences [ 39 ]. ROIs were placed directly at the epicentre and one spinal cord segment adjacent to any compression (cranially and caudally).…”

“…DTI metrics measured during the pre-operative time point were previously reported [ 34 , 39 ]. DTI values from the follow up examination, statistical analysis, and results described in this study have been independently calculated and have not been previously reported.…”

“…As patient management may represent a restraining factor limiting the time for MRI scans in acute traumatic SCI, the interest for using DTI in the spinal cord of dogs as a large animal model for traumatic SCI has been increasingly growing [ 34 – 38 ]. We recently characterized acute and chronic stages of severe SCI and evaluated the prognostic value of DTI for predicting early MFR [ 34 , 39 ]. However, description of DTI metrics during MFR may represent a useful tool for objective in vivo evaluation of the spinal cord parenchyma during clinical trials.…”