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Diffusion Tensor MR Imaging of the Brain: Effect of Diffusion Weighting on Trace and Anisotropy MeasurementsGo

Elias R. Melhema,b, Ryuta Itoha, Lisa Jonesa and Peter B. Barkera

a From the Department of Radiology and Radiological Sciences (E.R.M., R.I., P.B.B.), The Johns Hopkins Medical Institutions, and the School of Medicine (L.J.), The Johns Hopkins University, Baltimore, MD.
b Address reprint requests to Elias R. Melhem, the Department of Radiology, The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21287–2182.



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  		FIG 1. Axial ADCi, FA, and eigenvalue maps.

A, ROI used in data analysis are superimposed on axial ADCi map and FA map calculated at the level of the basal ganglia. 1, left putamen; 2, right putamen; 3, genu of corpus callosum; 4, splenium of the corpus callosum. ROI were also placed in the pons and centrum semiovale (not shown). The location and size of the ROI varied across participants and hemispheres but was kept fixed across the different maps.

B, Axial calculated eigenvalue maps ({lambda}1, {lambda}2, {lambda}3) at the level of the basal ganglia.



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  		FIG 2. Signal decay versus b value obtained from diffusion-weighted (six directions) MR images of a water phantom. The monoexponential decay indicates minimal influence of experimental/systemic errors on measurements



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  		FIG 3. Graph of the average ADCi for the different number of b values, obtained from the right centrum semiovale, shows a significant difference between the b0b1 group and the remaining four groups.

FIG 4. Graph of the average ADCi for the different strengths of b values, obtained from the right centrum semiovale, shows a significant difference between all the groups except b0b4 and b0b5.



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  		FIG 5. Graph of the average SD of ADCi for the different strengths of b values, obtained from the splenium of the corpus callosum, shows a significant difference between the b0b1 group and the remaining four groups.

FIG 6. Graph of the average SD of FA for the different strengths of b values, obtained from the splenium of the corpus callosum, shows a significant difference between the b0b1 group and the remaining four groups.





Copyright © 2009 by the American Society of Neuroradiology. Print ISSN: 0195-6108 Online ISSN: 1936-959X