Sharon K. Schreiber BS, Presenter: Nothing to Disclose

Katharine Teal Bluestein BS, MS, Abstract Co-Author: Nothing to Disclose

Seongjin Choi PhD, Abstract Co-Author: Nothing to Disclose

Amir Abduljalil, Abstract Co-Author: Nothing to Disclose

Michael Vinzenz Knopp MD, PhD, Abstract Co-Author: Nothing to Disclose

Petra Schmalbrock PhD, Abstract Co-Author: Nothing to Disclose

Mild Traumatic Brain Injury (mTBI) often occurs without anatomical findings in conventional MRI. Diffusion Tensor Imaging (DTI) has been used successfully as a biomarker to assess mTBI; however, many open questions exist regarding the relation between DTI parameters, most notable FA and ADC, and microstructural changes observed in pathology. Here we explored the potential of Susceptibility Weighted Imaging (SWI) at ultra-high field for providing additional microstructural information in the assessment of mTBI.

Seven mTBI patients with long-term persistent symptoms and six approximately age-matched healthy controls were recruited and underwent SWI and DTI acquisition at 7T and with IRB approval. Phase images were reconstructed using high pass filtering of the complex SWI data (TR/TE – 25/12 ms, flip angle - 5⁰, voxel size 0.40×0.68×1.60mm3), and FA and ADC maps were computed for DTI (TR/TE - 6526/75 ms, voxel size 1.6×1.6×3.2mm3, 6 directions, SENSE-factor 5, and b-values 0, 1000 s/mm2). Small ROIs were manually drawn on the genu and splenium in SWI phase and magnitude and DTI FA and ADC data. Quartile analysis and independent samples t-tests were carried out to evaluate the statistical significance of the difference in the measurements.

DTI showed statistically significant (p<0.05) lower FA and higher ADC in the mTBI patients. SWI magnitude and phase images also showed statistically significant (p<0.05) differences between TBI and control patient groups, specifically in the Corpus Callosum (CC) for both the genu and splenium regions (see figures below).

7T DTI results were comparable to previously published findings in chronic mTBI. SWI phase and magnitude also showed differences. This indicates that SWI, which has recently been shown to detect tissue microstructure, can also differentiate between mTBI and control groups.Thus, a combination of the MRI techniques DTI and SWI could improve clinical diagnosis of chronic mTBI as well as provide additional knowledge regarding the underlying tissue microstructure.

A combined DTI and SWI imaging strategy at ultra-high field may improve the assessment of subtle white matter abnormalities in mTBI patients.

Schreiber, S, Bluestein, K, Choi, S, Abduljalil, A, Knopp, M, Schmalbrock, P, Does Susceptibility-weighted Imaging at 7 T Show Microstructural Changes in Mild Traumatic Brain Injury?.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11009739.html