Usefulness of visual evaluation of the anterior thalamic radiation by diffusion tensor tractography for differentiating between Alzheimer’s disease and elderly major depressive disorder patients

Figures & data

Table 1 Clinical characteristics of all samples (n = 54)

Characteristic	AD	MDD	HC	H	χ^2	df	P-value
Samples	13	19	22
Sex
Male	6	3	8		3.71	2	0.156
Female	7	16	14
Age, years	59–77	58–74	59–77
Mean ± SD	69.5 ± 5.1	65.8 ± 5.7	67.4 ± 4.8	3.9		2	0.141
MMSE	19.6 ± 4.2
≤8	0
9–16	3
17–24	8
≥25	2

Abbreviations: AD, Alzheimer’s disease; df, degrees of freedom; H, Kruskal–Wallis nonparametric multiple sample test; HC, healthy control; MDD, major depressive disorder; MMSE, Mini Mental State Examination; SD, standard deviation; χ², Chi-square for independence test.

Figure 1 Superimposition of a DTT image of the left ATR on a sagittal T₁-weighted image in HC. (A) INCLUDE-ROI I was set in the coronal plane passing the anterior commissure, and INCLUDE-ROI 2 was set in the coronal section passing the center of the genu of the corpus callosum. The ATR passing both ROIs is depicted with the corticospinal and corticopontine tracts. (B) The corticospinal and corticopontine tracts in this region were excluded by setting EXCLUDE-ROI 3 in the cross sectional plane passing the midbrain, resulting in the depiction of pure ATR.

Abbreviations: ATR, anterior thalamic radiation; DTT, diffusion tensor tractography; HC, healthy control; ROI, region of interest.

Figure 2 Nerve fascicles superimposed on T₁-weighted sagittal images in HCs. (A) Anterior thalamic radiation; (B) cingulate fasciculus; (C) superior longitudinal fasciculus; (D) inferior longitudinal fasciculus; (E) uncinate fasciculus; (F) inferior fronto-occipital fasciculus; (G) fornix.

Abbreviation: HC, healthy control.

Figure 3 An example of poor depiction of the nerve fascicles superimposed on T₁-weighted sagittal images. (A) Anterior thalamic radiation. Only a few nerve fascicles were depicted in the region beyond the genu of the corpus callosum (arrow). (B) Cingulate fasciculus. No nerve fascicle was depicted in the anterior upper region of the corpus callosum (arrow). (C) Superior longitudinal fasciculus. The region from the parietal to temporal lobe was not depicted (arrow). (D) Inferior longitudinal fasciculus. Only a few nerve fascicles were depicted (arrow). (E) Uncinate fasciculus. The nerve fascicle extending to the orbitofrontal cortex was not depicted (arrow). (F) Inferior fronto-occipital fasciculus. Very few nerve fascicles were noted, and no nerve fiber extending to the prefrontal area was depicted (arrow). (G) Fornix. The crus was not depicted (arrow).

Table 2 Number of samples with poor depiction of nerve fascicles

	ATR	CF	SLF	ILF	UF	IFOF	FX
AD (n = 13)
R	2	2	1	1	0	2
L	0	0	0	0	2	1
R and L	7	2	1	0	0	2
Total	9	4	2	1	2	5	11
MDD (n = 19)
R	0	2	4	0	0	1
L	0	0	1	0	1	0
R and L	0	0	1	0	0	0
Total	0*	2	6	0	1	1	9
HC (n = 22)
R	0	1	0	0	0	2
L	0	0	0	0	0	2
R and L	0	0	2	0	0	1
Total	0*	1	2	0	0	5	11

Note: *P < 0.001 vs. AD ATR.

Abbreviations: AD, Alzheimer’s disease; ATR, anterior thalamic radiation; CF, cingulate fasciculus; FX, fornix; HC, healthy control; IFOF, inferior frontooccipital fasciculus; ILF, inferior longitudinal fasciculus; L, left; MDD, major depressive disorder; R, right; SLF, superior longitudinal fasciculus; UF, uncinate fasciculus.

Table 3 FA values of the nerve fascicles (means ± SD)

	AD	MDD	HC
R ATR	0.422 ± 0.025	0.415 ± 0.013	0.424 ± 0.023
L ATR	0.417 ± 0.032	0.414 ± 0.014^d	0.429 ± 0.025
R CF	0.435 ± 0.025	0.439 ± 0.019	0.447 ± 0.023
L CF	0.436 ± 0.037	0.446 ± 0.012	0.447 ± 0.020
R SLF	0.412 ± 0.017	0.417 ± 0.013*	0.416 ± 0.026
L SLF	0.410 ± 0.017^a″,c	0.430 ± 0.020	0.429 ± 0.022
R ILF	0.415 ± 0.021^b,d	0.431 ± 0.018	0.434 ± 0.027
L ILF	0.409 ± 0.024^c	0.422 ± 0.017	0.430 ± 0.020
R UF	0.383 ± 0.025^d	0.386 ± 0.017^d	0.397 ± 0.016^†
L UF	0.388 ± 0.038^d	0.393 ± 0.014^c	0.413 ± 0.016
R IFOF	0.447 ± 0.019	0.445 ± 0.015**	0.454 ± 0.023
L IFOF	0.444 ± 0.018^b	0.458 ± 0.019	0.458 ± 0.021
FX	0.300 ± 0.023^a,c	0.336 ± 0.024	0.338 ± 0.025

Notes: ^aVs. MDD P < 0.01; ^bvs. MDD P < 0.05; ^cvs. HC P < 0.01; ^dvs. HC P < 0.05 (Student’s t-test); ^d′vs. HC P < 0.05 (Welch’s t-test); ^a″ vs. MDD P < 0.01; (Mann-Whitney’s U test) *P < 0.05 vs. MDD L SLF (Mann-Whitney’s U test); **P = 0.023 vs. MDD L IFOF (Student’s t-test); ^†P=0.003 vs. HC L UF (Student’s t-test).

Abbreviations: AD, Alzheimer’s disease; ATR, anterior thalamic radiation; CF, cingulate fasciculus; FA, fractional anisotropy; FX, fornix; HC, healthy control; IFOF, inferior fronto-occipital fasciculus; ILF, inferior longitudinal fasciculus; L, left; MDD, major depressive disorder; R, right; SD, standard deviation; SLF, superior longitudinal fasciculus; UF, uncinate fasciculus.

Table 4 ADC values of the nerve fascicles (means ± SD [× 10⁻³ mm²/s])

	AD	MDD	HC
R ATR	0.905 ± 0.064^a′c′	0.843 ± 0.023	0.848 ± 0.031
L ATR	0.943 ± 0.104^a′c′	0.848 ± 0.035	0.848 ± 0.031
R CF	0.855 ± 0.034^a,d	0.828 ± 0.018	0.828 ± 0.028
L CF	0.863 ± 0.041^b′d	0.830 ± 0.015	0.834 ± 0.024
R SLF	0.860 ± 0.034	0.834 ± 0.037	0.835 ± 0.040
L SLF	0.871 ± 0.037^a,c	0.828 ± 0.028	0.833 ± 0.028
R ILF	0.899 ± 0.046^b,c,*	0.867 ± 0.029**	0.864 ± 0.032
L ILF	0.953 ± 0.063^a,c	0.893 ± 0.033	0.884 ± 0.035
R UF	0.910 ± 0.064^d′	0.884 ± 0.035	0.865 ± 0.027
L UF	0.924 ± 0.087^c′′	0.872 ± 0.031	0.856 ± 0.021
R IFOF	0.903 ± 0.068^d′	0.866 ± 0.032	0.856 ± 0.024
L IFOF	0.928 ± 0.072^a′,c′	0.856 ± 0.033	0.859 ± 0.024
FX	2.040 ± 0.184^a,c	1.807 ± 0.234	1.815 ± 0.211

Notes: ^aVs. MDD P < 0.01; ^bvs. MDD P < 0.05; ^cvs. HC P < 0.01; ^dvs. HC P < 0.05 (Student’s t-test); ^a′vs. MDD P < 0.01; ^b′vs. MDD P < 0.05; ^c′vs. HC P < 0.01; ^d′vs. HC P < 0.05 (Welch’s t-test); ^c′′vs. HC P < 0.01 (M); ^*P < 0.05 vs. AD L ILF (M); ^**P < 0.05 vs. MDD L ILF (M).

Abbreviations: AD, Alzheimer’s disease; ADC, apparent diffusion coefficient; ATR, anterior thalamic radiation; CF, cingulate fasciculus; FX, fornix; HC, healthy control; IFOF, inferior fronto-occipital fasciculus; ILF, inferior longitudinal fasciculus; L, left; M, Mann–Whitney U-test; MDD, major depressive disorder; R, right; SD, standard deviation; SLF, superior longitudinal fasciculus; UF, uncinate fasciculus.

Figure 4 The anterior thalamic radiation superimposed on a T₁-weighted sagittal image in an AD patient. (A) No left radiation passing the genu of the corpus callosum and extending into the prefrontal area was depicted (arrow). (B) Only a few nerve fascicles of the right radiation were observed, and depiction was poor (arrow). (C) The left posterior limb of the fornix was not depicted (arrow). (D) The right posterior limb of the fornix was only partially depicted.

Abbreviation: AD, Alzheimer’s disease.

Table 5 Number of AD cases with poor ATR depiction and their FA and ADC values by MMSE score

MMSE	Right			Left			Right or left
score	Poor depiction	FA	ADC (×10^−3 mm^2/s)	Poor depiction	FA	ADC (×10^−3 mm^2/s)	Poor depiction	FA	ADC (×10^−3 mm^2/s)
≤8 (n = 0)	0	−	−	0	−	−	0	−	−
9−16 (n = 3)	2	0.411 ± 0.011	0.897 ± 0.056	2	0.417 ± 0.006	0.913 ± 0.044	2	0.414 ± 0.008	0.905 ± 0.046
17−24 (n = 8)	6	0.421 ± 0.026	0.916 ± 0.073	4	0.405 ± 0.031	0.973 ± 0.119	6	0.413 ± 0.029	0.945 ± 0.100
≥25 (n = 2)	1	0.447 ± 0.031	0.869 ± 0.039	1	0.465 ± 0.011	0.866 ± 0.076	1	0.456 ± 0.022	0.867 ± 0.050

Abbreviations: AD, Alzheimer’s disease; ADC, apparent diffusion coefficient; ATR, anterior thalamic radiation; FA, fractional anisotropy; MMSE, Mini Mental State Examination.

Figure 5 The anterior thalamic radiation superimposed on a T₁-weighted sagittal image in an AD patient. (A and B) Several radiations passing the bilateral genus of the corpus callosum and extending to the prefrontal area are observed. (C and D) The radiations passing the bilateral genus of the corpus callosum and extending to the prefrontal area were lost by setting the threshold of the FA value at 0.24, and depiction can be readily judged as poor (arrow).

Abbreviations: AD, Alzheimer’s disease; FA, fractional anisotropy.