Characteristics of Abnormal Diffusivity in Normal-Appearing White Matter Investigated with Diffusion Tensor MR Imaging in Tuberous Sclerosis Complex

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Fig 1.
A–D, T2-weighted image of the diffusion acquisition (A), diffusion-weighted map as an average of the 6 directions (B), ADC map (C), and FA map (D), processed from DTI acquired on a 1.5T scanner in an 8-year-old patient with TSC (6 diffusion directions, 6 averages, b = 1000 [s/mm²]).
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Fig 2.
A–C, Selected ROIs are carefully drawn over the FA color-encoded images (A) and pasted on the corresponding main eigenvalues maps (B) and ADC map (C). The ROIs are indexed as follows: GCC#1, SCC#2, ALIC#3, PLIC#4, and EC#5. Red arrows indicate some of the TSC lesions.
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Fig 3.
A–D, Selected ROIs on the FA color-encoded image (A) are pasted on the eigenvalues maps (eg, main [B], middle [C], and minor [D] eigenvalues). The ROIs are indexed as follows: GCC#1, SCC#2, ALIC#3, PLIC#4, and EC#5. Red arrows indicate some of the TSC lesions.

DTI parameter values for NAWM in patients with TSC and the normal control group (NC)^a

		GCC		SCC		L-EC		R-EC		L-PLIC		R-PLIC		L-ALIC		R-ALIC
		Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
λ₁^b	TSC	1490	96	1437	171	1011	95	1007	80	1221	72	1220	70	1107	58	1007	80
	NC	1344	149	1360	134	963	104	919	81	1153	89	1158	100	963	104	919	81
λ₂	TSC	543	125	526	157	653	118	645	111	455	49	483	60	588	69	582	77
	NC	414	77	375	91	581	121	588	125	408	35	415	44	510	56	503	59
λ₃	TSC	366	98	385	98	452	45	474	59	300	69	306	77	420	90	415	87
	NC	275	78	270	104	373	60	373	60	239	25	245	19	321	54	309	51
ADC	TSC	800	91	783	126	705	69	709	65	659	56	670	66	705	71	709	70
	NC	678	90	668	107	639	67	627	66	600	76	606	72	598	45	577	46
FA^c	TSC	0.643	0.047	0.627	0.101	0.381	0.011	0.366	0.021	0.639	0.028	0.623	0.031	0.469	0.039	0.434	0.035
	NC	0.703	0.051	0.725	0.068	0.437	0.036	0.413	0.035	0.676	0.049	0.670	0.051	0.503	0.035	0.494	0.040

Note:—DTI indicates diffusion tensor imaging; NAWM, normal-appearing white matter; TSC, tuberous sclerosis complex; GCC, genu of corpus callosum; SCC, splenium of corpus callosum; L-EC, left external capsule; R-EC, right external capsule; ADC, apparent diffusion coefficient; FA, fractional anisotropy; L-PLIC, left posterior limb of internal capsule; R-PLIC, right posterior limb of internal capsule; L-ALIC, left anterior limb of internal capsule; R-ALIC, right anterior limb of internal capsule.
a Regions of interest were drawn in the GCC and SCC bilaterally (L and R) over the EC and in both left and right hemispheres over the ALIC and PLIC.
b The 3 eigenvalues, λ₁, λ₂, and λ_3, and ADC are expressed in 10⁻⁶ [mm²/s].
c The FA, the relative anisotropy, and the anisotropy index are dimensionless.