Characterization of Chronic Axonal Degeneration Using Diffusion Tensor Imaging in Canine Spinal Cord Injury: A Quantitative Analysis of Diffusion Tensor Imaging Parameters According to Histopathological Differences

• Published in: Journal of neurotrauma Vol. 34; no. 21; pp. 3041 - 3050
• Main Authors: Yoon, Hakyoung, Kim, Jaehwan, Moon, Won-Jin, Nahm, Sang-Soep, Zhao, Jun, Kim, Hyoung-Moon, Eom, Kidong
• Format: Journal Article
• Language: English
• Published: United States Mary Ann Liebert, Inc 01.11.2017
• Subjects: Animals; Compression; Data processing; Diffusion Tensor Imaging - methods; Dogs; Female; Histopathology; Image Processing, Computer-Assisted; Magnetic resonance imaging; Male; Medical imaging; Nerve Degeneration - diagnostic imaging; Nerve Degeneration - pathology; Neurodegeneration; NMR; Nuclear magnetic resonance; Quantitative analysis; Rehabilitation; Spinal cord injuries; Spinal Cord Injuries - diagnostic imaging; Spinal Cord Injuries - pathology; Statistical analysis; Studies; Substantia alba; spinal cord injury; histopathology; diffusion tensor imaging; axonal degeneration; canine
• ISSN: 0897-7151; 1557-9042
• DOI: 10.1089/neu.2016.4886

Diffusion tensor imaging (DTI) is more sensitive than conventional magnetic resonance imaging (MRI) for the identification of axonal degeneration. However, no study to date has used DTI to evaluate the severity of axonal degeneration in canine spinal cord injury (SCI). Therefore, the aim of this study was to characterize multi-grade axonal degeneration (mild, moderate, and severe) in a canine model of spinal cord compression injury using DTI. MRI data were obtained from 6 normal dogs and 5 dogs with lumbar SCI 78 days after SCI (L1-L3) using a 3 Tesla MRI scanner. For DTI, transverse multi-shot echo planar imaging sequences (b-value = 0; 800 s/mm ; 12 directions) were used. Regions of interest on DTI maps were selected based on areas of normal white matter (NWM) and mild, moderate, and severe axonal degeneration (AxD) on histopathological images. Statistically significant differences were observed between NWM and AxD, and among different severities of AxD. The severity of AxD demonstrated a negative linear correlation with fractional anisotropy and positive linear correlations with spherical index and radial diffusivity; additionally, positive U-shaped correlations were identified between the severity of AxD and mean diffusivity and axial diffusity (AD). These results demonstrate a potential clinical application for DTI in the noninvasive monitoring of histological changes post-SCI. DTI could be utilized for the early diagnosis and assessment of SCI and, ultimately, used to optimize the treatment and rehabilitation of SCI patients.