Page 65 - NNS 2014 Program & Abstract Book

structure when occasionally undersegmented, and (3) ensure proper
delineation of the hippocampal head/body, wherein the head was
considered to be any coronal slice in which the uncus was even par-
tially visible. The CA2 and CA3 subfields and the parahippocampal
gyrus (PHG) and entorhinal cortex were subsequently combined into
CA23 and PHG respectively. These volumes at baseline were assessed
in a multiple regression, using supratentorial volume and age as
covariates of non-interest. The volume of both hippocampal heads
was found to be lower in football players compared to volleyball
players (P = 0.0021 left, 0.0254 right, uncorrected). Preliminary results
suggest that MTL structures may be affected in contact-sport athletes,
though it is unknown if this anatomic difference is secondary to the
presumed long history of prior contact-sport exposure, or other fac-
tors. Future studies will include assessing hippocampal subfield vol-
ume changes in these athletes longitudinally.
Key words
hippocampus, traumatic brain injury
A2-24
QUANTIFYING WHITE MATTER INJURY IN TRAUMATIC
BRAIN INJURY WITH HIGH DEFINITION FIBER
TRACKING
Okonkwo, D.O., Schneider, W., Presson, N., Beers, S., Morrow, L.,
Borrasso, A.J., Puccio, A.M.
University of Pittsburgh, Departments of Neurosurgery, Psychiatry
and Psychology, Pittsburgh, PA
There is an urgent, unmet demand to pinpoint the location and
quantify extent of damage in traumatic brain injury (TBI) with ad-
vanced neuroimaging. We have developed High Definition Fiber
Tracking (HDFT), a 3T MRI-based diffusion spectrum imaging (DSI)
and tractography analysis pipeline, to quantify axonal injury in TBI
patients. The goal is to visualize white matter injury and correlate with
neurologic outcomes.
Subjects in the chronic phase of TBI were recruited along with
healthy volunteer control subjects. A novel homologue correlation
methodology quantified tractography to estimate white matter integrity
in patients and healthy controls. After reconstruction, bilateral hemi-
sphere homologues of eight major tracts were segmented. Integrity of
segmented tracts was estimated by calculating homologue correlation
and tract spread, with subsequent quantification of left-right symmetry.
Forty-one subjects (23 TBI, 18 controls) were scanned with the
HDFT DSI protocol. Both groups showed high correlations for all
tracts. TBI patients showed reduced homologue correlation and tract
spread and increased outlier count (correlations > 2.32 SD below con-
trol mean). On average, 6.5% of tracts in the TBI group were outliers,
with substantial variability among patients. Number and summed de-
viation of outlying tracts correlated with initial Glasgow Coma Scale
(GCS) score and 6-month Glasgow Outcome Scale – Extended (GOS-
E) score, suggesting that correlation metrics can detect heterogeneous
damage affecting a low proportion of tracts, presenting a potential
mechanism for advancing TBI diagnosis.
Using HDFT imaging with quantitative analysis, we demonstrated
high correlation of volume of white matter pathways in normal sub-
jects, and select sites of loss of symmetry in TBI subjects. These
results show TBI can be detected through quantifying loss of axonal
symmetry, that the damage is heterogeneous, and that an outlier ap-
proach can capture such heterogeneous damage.
Key words
high definition fiber tracking, traumatic brain injury
A2-25
DIFFUSED TENSOR IMAGING METRICS IN ACUTE MILD
TRAUMATIC BRAIN INJURY AND ITS CORRELATION
WITH EARLY NEUROPSYCHOLOGICAL IMPAIRMENT
Veeramuthu, V.1, Tan, L.K.1 , Narayanan, V.1, Waran, V.1, Ramli, N.2,
Ganesan, D.1
1Division of Neurosurgery, Department of Surgery, Faculty of Med-
icine, University of Malaya, Kuala Lumpur, Malaysia
2University Malaya Research Imaging Centre, University of Malaya,
Kuala Lumpur, Malaysia
Mild traumatic brain injury (mTBI) remains a contentious diagnosis
as the outcome is not always homogenous, even in the absence of any
visible intracranial lesions or injury through conventional magnetic
resonance imaging (MRI). Various neuropsychological impairments
are commonly reported in a subset of these patients.The availability of
new techniques such as diffuse tensor imaging (DTI) enables better
characterization of the extent of immediate microstructural changes
post-mTBI.
We aimed to establish the correlation between the changes in
fractional anisotropy (FA), mean diffusivity (MD) and early neu-
ropsychological impairment in the immediate aftermath of mTBI.
Forty-seven patients with mTBI were prospectively recruited, along
with 15 healthy controls. Anatomical MRI and structural DTI were
performed on all patients with mTBI using a 3T MRI (within 24 hours
from the time of trauma). The DTI volumes were registered to the
ICBM DTI-81 white matter atlas. FA and MD values were automat-
ically calculated for 16 white matter tracts. Comprehensive neu-
ropsychological evaluation was done using the Neuropsychological
Assessment Battery within the same admission.
Neuropsychological deficits including attention, language, execu-
tive function and memory were commonly seen in the patients’ group.
The changes in FA values of the anterior corpus collosum and left
anterior internal capsule negatively correlated with memory-related
impairments. The FA changes in uncinate fasciculus negatively cor-
related with the deficits of executive function. The decrease in FA and
increase of MD in the medial lemniscus, corona radiata and superior
longitudinal fasciculus negatively correlated with the attention and
language deficits.
White matter abnormalities in the immediate aftermath of mTBI
and its influence on higher cognitive functions needs to be further
investigated for long term effects.
Key words
cognition, DTI, MTBI, neuropsychology
A2-26
MRI TARGETED PATHOLOGY OF ACUTE TBI
Dempsey, A.I.1, Moses, A.D.1, Armstrong, R.C.1,3, Butman, J.A.2,
Cota, M.R.1 , Nair, G.2 , Perl, D.P.1,3, Chaudhury, A.R.2, Reich, D.S.2,
Parikh, G.2, Latour, L.L.2
1Center for Neuroscience & Regenerative Medicine, Bethesda, US
2National Institutes of Health, Bethesda, US
3Uniformed Services University of the Health Sciences, Bethesda, US
Acute and longitudinal imaging after TBI reveals evolving injury to
the brain. Interpretation of imaging findings is limited by availability
of corresponding pathological study. A brain donated through the
CNRM THINC study provided the opportunity to connect acute and
follow-up MRI to pathology.
A-33