Michael Younghyeuk Im MD, Presenter: Nothing to Disclose

Yongxia Zhou PhD, MSc, Abstract Co-Author: Nothing to Disclose

Zhongwei Zhang MD, Abstract Co-Author: Nothing to Disclose

Joseph Reaume BS, Abstract Co-Author: Nothing to Disclose

Robert I. Grossman MD, Abstract Co-Author: Nothing to Disclose

Yulin Ge MD, Abstract Co-Author: Nothing to Disclose

To demonstrate imaging evidence of functional connectivity and structural changes of the thalamus in patients with mild traumatic brain injury (MTBI) using resting state fMRI (RS-fMRI), diffusional kurtosis imaging (DKI), as well as morphological shape analysis. 

25 clinically diagnosed MTBI patients (GCS, 13~15; age, mean/SD: 38.6/11.8 years) and 23 controls (age, 33.5/11.2 years) underwent MRI, with data acquired at 3T with a mean interval time of 22 days (3-53) after trauma.  The following sequences were obtained: standard resting state RS-fMRI (TR/TE=2sec/30msec, flip angle=75º, matrix=128x128), conventional T2- and T1-weighted imaging, 3D high resolution T1-MPRAGE (resolution=1x1x1mm3), and DKI with 3 b-values and 30 standard directions.  Functional RS networks (RSNs) were obtained using thalamic mask and its segment (total 7 segments) as seed to evaluate thalamocortical connectivity.  DKI derived measures including mean kurtosis (MK), fractional anisotropy (FA), and mean diffusivity (MD) calculated based on the whole and segmental ROI analysis of thalamus.   

No lesions were found in the thalamic region on conventional imaging in MTBI patients.  Compared to age-matched normal controls, MTBI patients showed significantly increased thalamocortical RSNs or connectivity primarily with the prefrontal cortical region, likely reflecting reactive upregulation of thalamocortical functions at resting state.  There was significantly decreased MK in thalamic segment 4 (prefrontal projection site) in patients with MTBI (0.86±0.05) compared to controls (0.90±0.05, p=0.020), however, there was no statistical significance of FA or MD measured either in whole or sub-field of thalamus. 3D morphological analysis also demonstrated shape changes at the medial central lateral nuclei corresponding to segment 4 (corrected P<0.05).  

Structural and functional MRI analysis of thalamic injury in MTBI patients demonstrated multiple statistical differences compared to controls, suggesting there is a significant thalamic involvement in MTBI that is not seen on conventional imaging.  

Early MRI functional and structural thalamic changes in MTBI may help better understand the complex post concussive syndrome (PCS) and to identify patients who have a higher risk of developing PCS. 

Im, M, Zhou, Y, Zhang, Z, Reaume, J, Grossman, R, Ge, Y, Assessment of Thalamic Injury Using Structural and Functional MRI 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/2011/11010643.html