Article Figures & Data
Figures
- Fig 1.
A, Selection of the ROIs overlaid on representative color-coded FA images. ROIs were selected in the following regions: 1, genu of the CC; 2, splenium of the CC; 3, body of the CC; 4, ALIC; and 5, PLIC. B–C, Best-fit exponential functions (solid lines) and the respective 95% prediction intervals (dashed lines) overlaid on the scatterplots derived from the raw data of FA and MD values, respectively, detected in the gCC from individual participants. D, The large number of participants throughout the entire study, including the period of maximal changes, is representative of normative data. Abbreviations: n = number of participants.
- Fig 2.
Regression analysis of FA and MD values at approximately the neonatal period and early in development. A, Graphic comparison of the y-intercepts reveals a trend toward the anterior regions of the internal capsule having lower anisotropy and higher mean diffusivity at approximately the neonatal period. B, Comparison of the b-parameter values of the FA and MD best-fit functions suggests that the rostral regions undergo more rapid, age-dependent changes compared with the caudal regions in each respective region of interest.
- Fig 3.
Interregional comparison of fitted exponential curves of FA and MD values. These data are fitted to a monoexponential model with 3 fitted parameter values, shown in Table 1; AIM indicates age in months.
Tables
- Table 1:
Age-dependent changes in FA and MD in cerebral WM of the developing brain with an exponential regression model
Region Regression Coefficients Exponential Fit Model a b c y-intercept r2 RMSE FA gCC −0.307 0.138 0.722 0.416 0.629 0.039 bCC −0.327 0.109 0.740 0.414 0.562 0.046 sCC −0.365 0.117 0.785 0.420 0.729 0.039 ALIC −0.286 0.125 0.565 0.279 0.745 0.029 PLIC −0.206 0.073 0.655 0.449 0.772 0.023 MD gCC 0.616 0.088 0.902 1.518 0.659 0.088 bCC 0.617 0.096 0.818 1.435 0.686 0.070 sCC 0.857 0.069 0.831 1.688 0.671 0.129 ALIC 0.429 0.134 0.771 1.200 0.683 0.049 PLIC 0.319 0.089 0.732 1.051 0.692 0.042 Note:—Given are the values for the regression coefficients describing the best-fit function of the FA and MD values for each region of interest.
bCC indicates body of the corpus callosum; gCC, genu of the CC; r2, square of the correlation coefficient, describing the goodness of fit; RMSE, root mean square error; sCC, splenium of the CC.
DTI Parameter Comparison β3 SE (β3) t P Value FA gCC vs bCC 0.0114 0.0100 1.16 .251 gCC vs sCC 0.0121 0.0082 1.48 .142 bCC vs sCC 0.0007 0.0010 0.07 .941 ALIC vs PLIC 0.0163 0.0042 3.89 <.001 MD gCC vs bCC −0.0042 0.0171 −0.25 .805 gCC vs sCC −0.0423 0.0173 −2.45 .015 bCC vs sCC −0.0381 0.0212 −1.79 .076 ALIC vs PLIC −0.0238 0.0084 −2.85 .005 Note:—The gCC and sCC are statistically different for MD. The age-dependent changes in FA and MD are statistically different between the ALIC and PLIC.
β3 indicates an interaction term; SE, standard error; t, t value; (β3/SE(β3); gCC, genu of the CC; bCC, body of the cc; sCC, splenium of the cc.
DTI Parameter Region Mean ± SD Comparison Mean Difference P Value FA gCC 0.723 ± 0.038 gCC vs bCC −0.015 .0015 bCC 0.738 ± 0.043 gCCvs sCC −0.063 .0001 sCC 0.786 ± 0.038 bCCvs sCC −0.048 .0001 ALIC 0.565 ± 0.026 ALIC vs PLIC −0.092 .0001 PLIC 0.657 ± 0.023 MD gCC 0.897 ± 0.068 gCC vs bCC 0.082 .0001 bCC 0.815 ± 0.056 gCC vs sCC 0.083 .0001 sCC 0.814 ± 0.090 bCC vs sCC 0.001 .9163 ALIC 0.770 ± 0.041 ALIC vs PLIC 0.043 .0001 PLIC 0.727 ± 0.034 Note:—gCC indicates genu of the CC; bCC, body of the CC; sCC, splenium of the sCC.
