Role of Diffusion Tensor MR Imaging (DTI) and Fiber Tractography in Predicting Neurological Sequalae in Patients with Spinal Trauma
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- Category: Vol. 85, June 2017
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Role of Diffusion Tensor MR Imaging (DTI) and Fiber Tractography in Predicting Neurological Sequalae in Patients with Spinal Trauma, ESSAM A. EL-SHEIKH, MARWAN M. EL-TOUKHY, OMAR A. EL-SERAFY and AYMAN A. EL-BASSMY
Abstract
Background: Spinal cord injuries result in damage to the myelinated fibers of the spinal cord and/or nerve roots, causing myelopathy. These injuries can cause damage to the central gray matter, involving interneurons and motor neurons. The shearing forces exerted during trauma may cause frank cord laceration or hemorrhage, such changes can be detected by conventional MRI as increased signal intensity on T2W (T2 weighted) images. However, some spinal cord insults can cause Wallerian degeneration either above or below the level of injury at the time where MRI is totally normal.
Diffusion tensor imaging (DTI) is a new modality of MRI scanning that can reconstruct the white matter tracts and can assess the structural connectivity in-vivo that could potentially serve as a tool for prognostic assessment and for studying microstructural changes during recovery from spinal cord injuries.
Material and Methods: This is a prospective study carried out in Radio-diagnosis department, Faculty of Medicine, Cairo University between August 2014 and February 2016 for patients who were subjected to spinal trauma. The aim of this study is to study the pattern of involvement of the white matter tracts and their integrity following spinal cord trauma and correlate this with the clinical outcome. A total number of 40 patients (30 male and 10 female) with age range 5 to 45 years (Mean: 25.20), The time of imaging varied from under one week up to 3 weeks following the traumatic insult.
The MRI sequences obtained were axial FFEW, sagittal T1W, T2W, Diffusion Tensor. Then DTI images were processed to obtain the color coded images in axial and sagittal planes. MR tractography was performed, and the software algorithm tracked the white matter tracts passing through these ROIs. FA values were measured at regions of cord signal alteration and were compared with FA values two vertebral levels above and below, within the same patient. Color-coded DTI maps were analyzed, followed by tractography.
Results: Our study included 40 patients who were subjected to spinal trauma. We found good association between fractional anisotropy (FA) at lesion on admission and ASIA scale at 6 months follow-up. Most of the patients with severe FA reduc-tion had residual deficits on clinical follow-up, whereas the patients with mild and moderate FA reduction reached much better levels of neurological recovery.
We also found good association between fractional anisot-ropy above and below lesion and MRI findings on admission. Almost all of the patients with moderate FA reduction and majority of patients with mild FA reduction, away from lesion site, did not show any signal changes on conventional MRI above or below lesion site.
Conclusion: DTI in the spinal cord is a feasible technique as it can detect cord affection away from lesion site, which is not detected on routine imaging. Also, it correlates well with motor deficits and is a predictor of long-term motor recovery.