Integrated imaging approach with MEG and DTI to detect mild traumatic brain injury in military and civilian patients.
Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild (and some moderate) TBI can be difficult to diagnose due to lack of obvious external injuries and because the injuries are often not visible on conventional acute MRI or CT. Injured brain tissues in TBI patients generate pathological low-frequency neuronal magnetic signal (delta waves 1-4 Hz) that can be measured and localized by magnetoencephalography (MEG). We hypothesize that abnormal MEG delta waves originate from gray matter neurons that experience de-afferentation due to axonal injury to the underlying white matter fiber tracts, which is manifested on diffusion tensor imaging (DTI) as reduced fractional anisotropy. The present study used a neuroimaging approach integrating findings of magnetoencephalography (MEG) and diffusion tensor imaging (DTI), evaluating their utility in diagnosing mild TBI in 10 subjects in whom conventional CT and MRI showed no visible lesions in 9. The results show: (1) the integrated approach with MEG and DTI is more sensitive than conventional CT and MRI in detecting subtle neuronal injury in mild TBI; (2) MEG slow waves in mild TBI patients originate from cortical gray matter areas that experience de-afferentation due to axonal injuries in the white matter fibers with reduced fractional anisotropy; (3) findings from the integrated imaging approach are consistent with post-concussive symptoms; (4) in some cases, abnormal MEG delta waves were observed in subjects without obvious DTI abnormality, indicating that MEG may be more sensitive than DTI in diagnosing mild TBI.
Huang
Ming-Xiong
MX
Research, Radiology, Rehabilitation, and Psychiatry Services, VA San Diego Healthcare System, San Diego, California, USA. mxhuang@ucsd.edu
Theilmann
Rebecca J
RJ
Robb
Ashley
A
Angeles
Annemarie
A
Nichols
Sharon
S
Drake
Angela
A
D'Andrea
John
J
Levy
Michael
M
Holland
Martin
M
Song
Tao
T
Ge
Sheng
S
Hwang
Eric
E
Yoo
Kevin
K
Cui
Li
L
Baker
Dewleen G
DG
Trauner
Doris
D
Coimbra
Raul
R
Lee
Roland R
RR
D000293:Adolescent; D000328:Adult; D016880:Anisotropy; D001753:Blast Injuries / Q000175:diagnosis*; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000175:diagnosis*; D001931:Brain Mapping; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015601:Injury Severity Score; D015225:Magnetoencephalography; D008297:Male; D008889:Military Personnel; D018579:Patient Selection