Role of Diffusion Tensor MR Imaging (DTI) and Fiber Tractography in Predicting Neurological Sequalae in Patients with Head 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 Head Trauma, ESSAM A. EL-SHEIKH, MARWAN M. EL-TOUKHY, OMAR A. EL-SERAFY and AYMAN A. EL-BASSMY
Abstract
Background: Brain imaging by CT and standard MRI is invaluable for defining post-traumatic sequallae that require immediate neurosurgical intervention. However, these tools currently lack the specificity to allow judgment on long-term functional outcome in most cases. This may in part be due to their insensitivity to detect more subtle white matter injuries.
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 head injuries.
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 sub-jected to head trauma. The aim of this study is to study the pattern of involvement of the white matter tracts and their integrity following head trauma and correlate this with the clinical outcome.
A total number of 40 patients (30 male and 10 female) with age range 14-67 (mean 34.7), The time of imaging varied from under one week up to 3 weeks following the traumatic insult.
The MRI sequences obtained were axial T1W, T2W, FLAIR, T2* and 3D T1, Diffusion Tensor. Images were post-processed using the Philips software for tractography. The maps obtained were (1) FA maps. (2) Directionally-encoded color FA maps. (3) 3D fiber tractography. The FA values were measured at the region of abnormality and were compared with the normal values on the unaffected contralateral side. Color-coded DTI maps were analyzed, followed by tractog-raphy of individual tracts. DTI data and MR tractography of the involved white matter tracts were compared with the corresponding tracts of the contralateral normal hemisphere. The tracts were visually inspected for changes in size and orientation, and compared to those in the contralateral hemi-sphere. The tracts were characterized as either displaced or disrupted.
Results: Our study included 40 patients who were subjected to head trauma. We found good association between tractog-raphy findings and Glasgow outcome scale. Most of the patients with disruption of white matter tracts had residual deficits on clinical follow-up, whereas the patients with displaced and preserved tracts had near complete neurological recovery.
We did not find significant association between the FA at the site of the lesion and the clinical score at admission or the clinical outcome after 6 months and we didn’t find signif-icant statistical association between fractional anisotropy (FA) at lesion and fiber tract morphology changes.
Conclusion: DTI can visualize and quantify the changes in the integrity and orientation of the white matter tracts that are transected by focal brain contusions, which are otherwise not shown on conventional MR imaging. MR tractography offers a potential tool for clinical-imaging correlation of the involved white matter tracts and patient’s clinical recovery.