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microglial activation in the rTBI model. Conversely, cortical regions
had reduced axial diffusivity (AD) in the rTBI mice but not in sTBI
mice. Respective DTI changes, in the corpus callosum after sTBI and
in the cortex after rTBI, persisted through 42 days. These findings
demonstrate that evaluation of mild rTBI should include region-of-
interest analysis in the cerebral cortex and could be missed with
widely used approaches for DTI analysis that are confined to white
matter tracts. Funded by the DoD in the Center for Neuroscience and
Regenerative Medicine.
Keywords: diffusion mri, mouse TBI model, repeat injury, cortical
changes
B6-16
QUANTITATIVE WHITE MATTER ANALYSIS WITH HIGH
DEFINITION FIBER TRACKING PREDICTS NEUROPSYCHO-
LOGICAL TEST PERFORMANCE IN CHRONIC TBI
Walter Schneider
1,2,4
, Nora Presson
4
, Sue Beers
3
, Lisa Morrow
3
,
Lauren Wagner
4
, Will Bird
4
, Gina Droeder
4
, Joshua Penderville
2
,
Steven Benso
2
, Ava Puccio
2
, David Okonkwo
2
1
University of Pittsburgh, Psychology, Pittsburgh, USA
2
University of Pittsburgh Medical Center, Neurosurgery, Pittsburgh,
USA
3
University of Pittsburgh, Psychiatry, Pittsburgh, USA
4
University of Pittsburgh, Learning Research & Development Center,
Pittsburgh, USA
Objective:
White matter injury is hypothesized to underlie the cog-
nitive consequences of TBI. The current study correlated neu-
ropsychological test performance with spatial properties of MR-based
advanced diffusion tractography in chronic TBI and healthy control
subjects.
Methods:
Diffusion spectrum imaging data were acquired and
processed for white matter tractography in a High Definition Fiber
Tracking (HDFT) pipeline. All participants in both chronic TBI
(N
=
22 injured
>
3 mo. before enrollment, 18 male, mean age
=
38)
and healthy control (N
=
15, 8 male, mean age
=
31) groups completed
a neuropsychological test battery including TrailsAB, CVLT, WAIS-
IV PSI, ANAM, and COWAT.
Results:
In the chronic TBI group, HDFT metrics of symmetry
(left-right homologue correlation, in X/Y/Z dimensions) and spread
(proportion of voxels contacted in left and right hemispheres) were
significantly correlated with neuropsychological tests across a
range of cognitive functions. Correcting all tests for False Dis-
covery Rate, within the TBI sample, verbal recall (CVLT) was
positively correlated with Arcuate asymmetry, (Y dimension
r
=
0.53,
p
=
0.01) and Genu spread, (right hemisphere
r
=
0.64,
p
<
0.01), among others. PSI was correlated with Corona Radiata
asymmetry (Y dimension
r
=
0.61,
p
<
0.01) and Genu spread (left
hemisphere
r
=
0.51,
p
=
0.04). Trails A was positively correlated
with Cingulum asymmetry (Y dimension
r
=
0.48,
p
=
0.03) and
FOF spread (right hemisphere
r
=
0.57,
p
=
0.01. Trails B was
positively correlated with Corona Radiata asymmetry (Y dimension
r
=
0
.65,
p
<
0.01) and Uncinate spread (left hemisphere
r
=
0.52,
p
=
0.01). In contrast, almost all correlations in the control sample
were zero or negative.
Conclusions:
These results provide preliminary evidence that
spatial white matter properties on MR-based diffusion spectrum
imaging may be more informative in capturing impairment in be-
havioral performance following TBI than in capturing normal vari-
ability.
Keywords: DTI, TBI, neuropsychology, Fiber Tracking
B6-17
THE TYPE AND LOCATION OF INTRACRANIAL AB-
NORMALITIES FOLLOWING MILD TRAUMATIC BRAIN
INJURY
Harri Isokuortti
1
, Grant L. Iverson
2
, Anneli Kataja
3
, Antti Brander
3
,
Juha O¨ hman
4
, Teemu M. Luoto
5
1
University of Tampere, Medicine, Tampere, Finland
2
Harvard Medical School, Physical Medicine and Rehabilitation,
Boston, USA
3
Tampere University Hospital, Radiology, Tampere, Finland
4
Tampere University Hospital, Neurosciences and Rehabilitation,
Tampere, Finland
5
Tampere University Hospital, Neurosurgery, Tampere, Finland
Background:
Following mild traumatic brain injury (MTBI), head
CT is used to identify gross structural brain damage and aid decision
making on emergency treatment. Our objective was to describe the
type and location of both acute and pre-existing intracranial abnor-
malities of patients who sustained head trauma and underwent com-
puted tomography. Additionally, we investigated whether chronic
cerebral lesions detectable with CT predispose to acute traumatic
intracranial lesions.
Methods:
The study population included all consecutive patients
who underwent head CT due to acute head injury (n
=
3,023; average
age
=
55.0 years, SD
=
24.0; male
=
56.4%) at the emergency depart-
ment of Tampere University Hospital between August 2010 and July
2012. A neuroradiologist interpreted all the CT scans. The cohort was
divided into two groups according the TBI severity: (i) mild TBI
(n
=
1,970) and (ii) moderate-severe TBI (n
=
370).
Results:
Pre-existing chronic lesions were present in 35.5% of
MTBI and 30.3% of moderate-severe patients. In the MTBI group and
the moderate-severe TBI group, the most common pre-existing
chronic lesions were microangiopathy and generalized atrophy. Acute
traumatic lesions were found in 19.9% of MTBI and 64.6% of mod-
erate-severe TBI patients. In the MTBI group and the moderate-severe
TBI group, the most common traumatic lesions were subdural he-
matomas (11.8% and 43.8%), subarachnoid hemorrhages (7.1% and
38.6), and contusions (5.6% and 30.2%). Pre-existing traumatic le-
sions (previous contusions and hemorrhages) were associated with
contusions (risk ratio 1.21, p
<
0.001), subdural hematomas (RR 1.14,
p
=
0.011), any traumatic lesion (RR 1.17, p
=
0.02) and multiple
traumatic lesions (RR 1.15, p
=
0.003).
Conclusions:
A significant number of TBI patients have chronic
lesions found in CT imaging. One in five MTBI patients have an
acute traumatic CT finding. Patients, who have chronic trauma-
related lesions seem to be more likely to sustain acute traumatic
lesions.
Keywords: Head injury, CT imaging, Comorbidity, Patient re-
cruitment, Mild traumatic brain injury
B6-18
PET IMAGING WITH PITTSBURGH COMPOUND B OF
AMYLOID DEPOSITION IN WHITE MATTER IN CHRONIC
TBI
David Okonkwo
1
, Nora Presson
3,2
, Davneet Minhas
3
, James Mountz
2
,
Catherine Fissell
3
, Rebecca Hachey
3
, Charles Laymon
2
, Julie Price
2
,
Ava Puccio
1
, Walter Schneider
3
1
UPMC Presbyterian, Dept of Neurosurgery, Pittsburgh, USA
2
UPMC Presbyterian, Dept of Radiology, Pittsburgh, USA
3
University of Pittsburgh, Dept of Psychology, Pittsburgh, USA
A-64