Diffusion Tensor Imaging of Myelopathy

Overview

Myelopathy describes any neurologic deficit related to the spinal cord. Myelopathy is caused by various pathological states of the human spinal cord, including tumors, inflammatory lesions, spinal cord compression and degenerative myelopathy. Clinically, the diagnosis of myelopathy depends on localization of the neurologic finding to the spinal cord, rather than the brain or peripheral nervous system and then to a particular segment of the spinal cord. Magnetic resonance imaging (MRI) plays an essential role in the diagnosis and follow-up of the lesions of the spinal cord using conventional MRI T1- and T2-weighted sequences. Sometimes a studied spinal cord may appear normal on conventional MRI even though patients have symptoms of myelopathy causing a discrepancy between MRI findings and clinical findings. Diffusion tensor imaging (DTI) is an advanced non-invasive MR imaging technique which assesses the microstructural integrity of nerve fiber tracts.

A number of 70 patient with myelopathy included within the study. DTI is used primarily for assessing white matter of the brain and spinal cord. DTI can depict alterations to the white matter tract and quantify these changes. Disturbances of diffusion (restriction or increase) may be assessed quantitatively by measurements of apparent diffusion coefficient (ADC). The apparent diffusion coefficient (ADC), is used to measure diffusive strength. Diffusion anisotropy can be assessed quantitatively by using the fractional anisotropy (FA) parameter, which may be also visualized on fractional anisotropy maps. FA is considered as a marker of white matter integrity. Image acquisition will be conducted on a 1.5-Tesla MR scanner. The imaging will be done throughout the following sequences: 1. Conventional MRI sequences: sagittal T1W, sagittal and axial T2W sequences. 2. DTI sequence: Single-shot spin-echo echo-planar imaging (EPI) and parallel imaging techniques to achieve motion-free and higher signal-to-noise ratio (SNR) DTI. Post processing: The diffusion-tensor imaging data is transferred to an offline workstation utilizing software used for reconstruction of the Diffusion Tensor imaging (DTI) with regions of interest were defined and measured on the ADC and fractional anisotropy (FA) maps. diffusion tensor tractogram will be constructed on the acquired data source.