TY - JOUR
T1 - A method to enhance the sensitivity of DTI analyses to group differences
T2 - A validation study with comparison to voxelwise analyses
AU - Cykowski, Matthew D.
AU - Lancaster, Jack L.
AU - Fox, Peter T.
N1 - Funding Information:
Funding was provided by the National Institute on Deafness and other Communication Disorders/NIH ( F32-DC009116 and Loan Repayment Award to M.D.C.), the National Institute of Mental Health ( R01-MH078143 to David Glahn, PI, who generously allowed access to subject DTI data), and the National Center for Research Resources grant for the Frederic C. Bartter General Clinical Research Center ( M01 RR001346 ).
PY - 2011/9/30
Y1 - 2011/9/30
N2 - Studies of white matter (WM) abnormalities in psychiatric and neurological disorders often use the analysis package Tract-Based Spatial Statistics (TBSS). However, with small samples and/or subtle effects, a study using the standard TBSS approach can be underpowered. For such cases, a new method is presented that summarizes global differences between TBSS-derived fractional anisotropy (FA) images with a single paired t-statistic, estimating the degrees of freedom using spatial autocorrelation. The sensitivity of the method is demonstrated by using well-known aging effects on FA as a proxy for disease effects. Sixty healthy subjects were divided equally into younger- (YA), middle- (MA), and older-aged (OA) groups and significant global differences were demonstrated in the YA versus OA (all N≥4, FA difference ≈ 0.023), MA versus OA (all N≥4, FA difference ≈ 0.017), and YA versus MA (FA difference ≈ 0.005 at N = 20) comparisons. In contrast, no significant difference could be detected in the YA versus MA comparison using voxelwise TBSS analysis with the full sample (N=20 per group). This method should facilitate localizing analyses in the direction of a proven group difference while providing clinically relevant information about pathophysiologic processes globally affecting WM.
AB - Studies of white matter (WM) abnormalities in psychiatric and neurological disorders often use the analysis package Tract-Based Spatial Statistics (TBSS). However, with small samples and/or subtle effects, a study using the standard TBSS approach can be underpowered. For such cases, a new method is presented that summarizes global differences between TBSS-derived fractional anisotropy (FA) images with a single paired t-statistic, estimating the degrees of freedom using spatial autocorrelation. The sensitivity of the method is demonstrated by using well-known aging effects on FA as a proxy for disease effects. Sixty healthy subjects were divided equally into younger- (YA), middle- (MA), and older-aged (OA) groups and significant global differences were demonstrated in the YA versus OA (all N≥4, FA difference ≈ 0.023), MA versus OA (all N≥4, FA difference ≈ 0.017), and YA versus MA (FA difference ≈ 0.005 at N = 20) comparisons. In contrast, no significant difference could be detected in the YA versus MA comparison using voxelwise TBSS analysis with the full sample (N=20 per group). This method should facilitate localizing analyses in the direction of a proven group difference while providing clinically relevant information about pathophysiologic processes globally affecting WM.
KW - Diffusion tensor imaging
KW - Fractional anisotropy
KW - Spatial autocorrelation
KW - Tract-based spatial statistics
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U2 - 10.1016/j.pscychresns.2011.03.005
DO - 10.1016/j.pscychresns.2011.03.005
M3 - Article
C2 - 21764564
AN - SCOPUS:80051683606
VL - 193
SP - 191
EP - 198
JO - Psychiatry Research - Neuroimaging
JF - Psychiatry Research - Neuroimaging
SN - 0925-4927
IS - 3
ER -