Regionally Specific Atrophy Regionally Specific Atrophy Following Traumatic Brain InjuryFollowing Traumatic Brain Injury

DG MCLAREN, BB BENDLIN, and SC JOHNSON

University of Wisconsin—Madison &GRECC, Madison VA Hospital

Background

• Identifying longitudinal changes are essential in understanding plasticity and predicting future outcomes

• Surface-based approaches have been used in functional and structural analyses

Using the Cortical Surface

McLaren et al. 2007, Van Essen et al. 2005 & 2006

Background

• Identifying longitudinal changes are essential in understanding plasticity and predicting future outcomes

• Surface-based approaches have been used in functional and structural analyses

• Can Surface-based approaches be Can Surface-based approaches be used in longitudinal analyses?used in longitudinal analyses?

Study Parameters

• T1-weighted SPGRs were collected at ~79 days and ~409 days post injury

• Standard Axial SPGR sequence with .9375x.9375x1.2mm voxel dimensions

Processing Steps

2 x Original T1

Align Brains via Skull;Compute Flow

SIENA

Global Results Using SIENA

N=30 N=36

P<.0001

Trivedi et al. 2006

Processing Steps

2 x Original T1

Align Brains via Skull;Compute Flow

Bias Corrected T1(Brain Only)

Normalize & Surface AnalysisSIENA

Surface Creation and Registration

Van Essen 2005

Within Subject Surface Co-registration

• Registration to PALS of the same surface produces identical results

• Registration of an image to itself doesn’t produce the same results

Within Subject Surface Co-registration

• T-statistic of time 2 minus time 1 scans

Percent Brain Volume Change: -.048

P<.0001 corrected

Within Subject Surface Co-registration

TBI Patient Cross-section (time 1)

1028

P<.0001 corrected

TBI Patient Cross-section (time 2)

P<.0001 corrected

TBI Patient Longitudinal

Percent Brain Volume Change: -.8276

P<.0001 corrected

Conclusions

• Surface registration is stable• Normal Controls show little or no

changes consistent with SIENA • Method is sensitive to changes over

time (and errors in segmentation)

• One of the first illustrations of longitudinal changes using the cortical surface

Future Directions

• Improve segmentation to increase accuracy

• More automated and stable procedure• Create study specific averages• Compare against SIENAr• Other patient populations

Acknowledgements

• UW Institute of Aging• Collaborators on the project

Trivedi MA, Ward MA, Hess TM, Gale SD, Dempsey RJ, Rowley HA

• Funding Support:– NIH: T32 AG20013– NIH: RO1 MH65723– NIH: T32 GM007507 – Merit Review Grant from the Department of Veterans Affairs