Bidirectional Changes in Anisotropy Are Associated with Outcomes in Mild Traumatic Brain Injury.
OBJECTIVE
Mild traumatic brain injury results in a heterogeneous constellation of deficits and symptoms that persist in a subset of patients. This prospective longitudinal study identifies early diffusion tensor imaging biomarkers of mild traumatic brain injury that significantly relate to outcomes at 1 year following injury.


METHODS
DTI was performed on 39 subjects with mild traumatic brain injury within 16 days of injury and 40 controls; 26 subjects with mild traumatic brain injury returned for follow-up at 1 year. We identified subject-specific regions of abnormally high and low fractional anisotropy and calculated mean fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity across all white matter voxels brain-wide and each of several white matter regions. Assessment of cognitive performance and symptom burden was performed at 1 year.


RESULTS
Significant associations of brain-wide DTI measures and outcomes included the following: mean radial diffusivity and mean diffusivity with memory; and mean fractional anisotropy, radial diffusivity, and mean diffusivity with health-related quality of life. Significant differences in outcomes were found between subjects with and without abnormally high fractional anisotropy for the following white matter regions and outcome measures: left frontal lobe and left temporal lobe with attention at 1 year, left and right cerebelli with somatic postconcussion symptoms at 1 year, and right thalamus with emotional postconcussion symptoms at 1 year.


CONCLUSIONS
Individualized assessment of DTI abnormalities significantly relates to long-term outcomes in mild traumatic brain injury. Abnormally high fractional anisotropy is significantly associated with better outcomes and might represent an imaging correlate of postinjury compensatory processes.
From the Department of Radiology (S.B.S., M.L.L.), Montefiore Medical Center, Bronx, New York.
S B
http://orcid.org/0000-0001-7766-2721
SB
Strauss
Departments of Radiology (N.K., M.L.L.).|The Gruss Magnetic Resonance Research Center (N.K., C.A.B., M.E.K., H.F.S., M.L.L.).
N
http://orcid.org/0000-0003-1618-1363
N
Kim
Physiology and Biophysics (C.A.B.).|The Gruss Magnetic Resonance Research Center (N.K., C.A.B., M.E.K., H.F.S., M.L.L.).
C A
http://orcid.org/0000-0001-5015-7864
CA
Branch
The Gruss Magnetic Resonance Research Center (N.K., C.A.B., M.E.K., H.F.S., M.L.L.).
M E
http://orcid.org/0000-0002-2116-2397
ME
Kahn
Epidemiology and Population Health (M.K., R.B.L.).
M
http://orcid.org/0000-0001-9651-7124
M
Kim
Epidemiology and Population Health (M.K., R.B.L.).|The Saul R. Korey Department of Neurology (R.B.L., M.E.Z.).
R B
http://orcid.org/0000-0003-2652-2897
RB
Lipton
Department of Emergency Medicine (J.M.P.), Jacobi Medical Center, Bronx, New York.
J M
http://orcid.org/0000-0002-9892-4679
JM
Provataris
The Gruss Magnetic Resonance Research Center (N.K., C.A.B., M.E.K., H.F.S., M.L.L.).
H F
http://orcid.org/0000-0003-2236-8087
HF
Scholl
The Saul R. Korey Department of Neurology (R.B.L., M.E.Z.).
M E
http://orcid.org/0000-0002-8071-5369
ME
Zimmerman
From the Department of Radiology (S.B.S., M.L.L.), Montefiore Medical Center, Bronx, New York michael.lipton@einstein.yu.edu.|Departments of Radiology (N.K., M.L.L.).|Psychiatry and Behavioral Sciences (M.L.L.).|The Gruss Magnetic Resonance Research Center (N.K., C.A.B., M.E.K., H.F.S., M.L.L.).|The Dominick P. Purpura Department of Neuroscience (M.L.L.), Albert Einstein College of Medicine, Bronx, New York.
M L
http://orcid.org/0000-0001-5421-8441
ML
Lipton