Anatomical characteristics of thalamus cortical sensory tract in the human brain using diffusion tensor tractography at 3.0 tesla scanner

Journal of military pharmaco-medicine n06-2018

ANATOMICAL CHARACTERISTICS OF THALAMUS-CORTICAL
SENSORY TRACT IN THE HUMAN BRAIN USING DIFFUSION
TENSOR TRACTOGRAPHY AT 3.0 TESLA SCANNER
Pham Thanh Nguyen*; Lam Khanh**; Nguyen Duy Bac***
SUMMARY
Objectives: To study characteristics of thalamocortical tract according to the cerebral origin.
Using diffusion tensor tractography at 3.0 Tesla scanner, we attempted to characterize the
morphology of thalamocortical tract in the human brain. Subjects and methods: 50 healthy
subjects were enrolled in this study. Reconstructed images of thalamocortical tract in the human
brain using diffusion tensor tractography at 3.0 Tesla scanner. Results: The median length of
the right thalamocortical tract was 130.64 mm and the left was 123.14 mm, the average of two
sides was 126.34 mm. The difference between two sides was statistically significance. The
median fiber number of the right thalamuscortical tract was 401.50 and the left was 315.00 fibers,
and the average of two sides was 365.50 fibers. There was a diverse branch of thalamuscortical
tract: two branches (5%); three branches (25%); four branches (42%); five branches (16%); six
branches (12%); in which contralateral branch for the right was 50%, equal to the left (50%).
Conclusion: Using the diffusion tensor images and 3D image reconstruction technique allows to
build the intuitive and accurate image of sensory thalamocortical tract, which helps to identify the
morphological characteristics of the thalamus-cortical tract of healthy people without invasion.
* Keywords: Sensory thalamocortical tract, Diffusion tensor tractography.

INTRODUCTION
Understanding the connection in a
region and between regions within the
brain helps us to know the functional
activities and coordinate activity role of
those regions (Passingham, Stephan et al,
2002). The nervous tract within the human
brain can be determined by injecting

fluorescent pigments after autopsy;
however, the distance for observing only
about 10 mm (Mufson, Brady et al, 1990).

For further distance can be determined by
dissection of the large conduction bundle,
or by degradation after a local injury (Van
Buren, 1972). However, they are invasive
methods and impossible to identify and
visualize the neural tract in the live human
brain. Studying about the conduction bundle
by non-invasive methods was almost
handled on animals (Barbas and Pandya,
1987; Scannell, Burns et al, 1999) [2],
the researchers on human brain did not
use this method much.

* Haiphong University of Medicine and Pharmacy
** 108 Military Central Hospital
*** Vietnam Military Medical University
Corresponding author: Nguyen Duy Bac ()
Date received: 11/04/2018
Date accepted: 20/06/2018

129


Journal of military pharmaco-medicine n06-2018
The diffusion tensor imaging (DTI) based on the diffusion anisotropy of the water
molecules in the axons (Basser, Mattiello et al, 1994 [3, 4]). DTI is a new technique,

which helps to determine the neural tracts, mostly in the living human brain.
The anatomical images of sensory tract connected from the thalamus to other regions
throughout brain are important for clinical practice. However, it has not been studied much,
especially in Vietnam.
We carried out the research: To investigate the characteristics of thalamus-cortical
sensory tract according to the cerebral origin in the living human brain by using DTI
and tractography.
SUBJECTS AND METHODS
1. Subjects.
50 healthy subjects ≥ 18 years old with no previous history of neurological, psychiatric,
or physical illness were enrolled into this study. All subjects understood the purpose of
the study. The study protocol was approved by 108 Military Central Hospital.
2. Methods.
* Diffusion tensor image:
DTI data were obtained by using Phillips Achieva 3.0 T, SENSE NV 16 coil
channels. Make the sections from background to top of the skull with the basic pulse
chain T1W, T2W, FLAIR. Imaging parameters were as follows: acquisition matrix 128 x 128,
FOV 230 x 230 mm2, TR: 10,172 ms, 93 ms, EPI factor b0 and b 1,000 s/mm2, section
thickness of 2 mm (acquired isotropic voxel size, 1.8 x 1.8 x 2 mm3).
* Fiber tracking:
Diffusion-weighted image and DTI data were analyzed using software Philips Extended
MR Workspace 2.6.3.1.
A

B

C

Figure 1: The seed regions of interests (ROI).
Construction 2D color map of fractional anisotropy (FA) was used to seed ROI.

130


Journal of military pharmaco-medicine n06-2018
Construction 2D color map of fractional
anisotropy (FA) has used to seed regions
of interest (ROI) according to know anatomy
(Akter, Hirai et al, 2011) [1]. The first ROI
placed in the Commissuracerebelli, dark
blue region on the FA 2D map (fig.1A);
the second ROI placed in the thalamus
(fig.1B); the third ROI placed in the posterior
of capsulainterna, dark blue area on the
the FA 2D map (fig.1C).
The software to reconstruct 3D image of
sensory thalamocortical tract was used to
analyze the length, number of tract, and
morphology.

* Statistical analysis:
The statistical package for the social
sciences software (version 15.0; SPSS,
Chicago, Illinois) was used for data analysis.
The independent t-test was used to
determine the difference in values of
length, volume of sensory thalamocortical
tract between sexes and two hemispheres.
The significance level was set as p < 0.05.
The distribution of ages, sexes and
morphology of sensory thalamocortical

tract were shown as the percentages.

RESULTS
1. Characteristics of the subjects.
Table 1: Age and gender of the subjects.
Age groups, n (%)

Total

18 - 39

40 - 59

≥ 60

Male

9 (18%)

14 (28%)

3 (6%)

26 (52%)

Female

12 (24%)

9 (18%)

3 (6%)

24 (48%)

Both genders

21 (42%)

23 (46%)

6 (12%)

50 (100%)

In this study, subjects distributed mostly in young and middle-age (18 - 39 years old)
accounted for 42%; 40 - 49 years old accounted for 46% and ≥ 60 years old accounted
for 15%. The percentage of two genders was similar with male (52%) and female (48%).
2. Characteristics of thalamus-cortical sensory tract.

Figure 2: The 3D reconstructed images of sensory thalamocortical tract.
Green showed the tract on the right hemisphere and the yellow illustrated for tract of
the left hemisphere.
131


Journal of military pharmaco-medicine n06-2018
The 3D reconstructed images of sensory thalamocortical tract were built successfully
based on diffusion tensor image and fiber tracking by using the dedicated software.
Based on the clearly images, we can measure the length, and count the number of

bunch in each hemisphere separately.

Figure 3: Comparison of sensory thalamocortical tract length between right and
left hemisphere. Values represent median (± SD); n = 50 for each side;
*** represent p < 0.001 left side versus right side.
The results showed that the median length of sensory of thalamocortical tract on the
right hemisphere (130.64 mm) was statistically significance longer than the left one
(123.14 mm). This suggested that there were differences in the anatomical characteristics
of sensory thalamocortical tract length between the right and the left.

Figure 4: Length comparison of right (A) and left (B) of the sensory of thalamocortical
tract between sexes; values represent median (± SD); male (n = 26), female (n = 24).
132


Journal of military pharmaco-medicine n06-2018
We also investigated influence of gender on the length of sensory of thalamocortical
tract by comparing the sexes. Results of statistical analysis showed that the length
bunch of male tended to be longer than that of female; however, there were no significant
differences between sexes.

Figure 5: Comparison of number of sensory thalamocortical tract lines between right
and left hemisphere. Values represent median (± SD); n = 50 for each side.
We counted the number of lines of the sensory of thalamocortical tract on both
sides of the hemisphere. The statistical analysis showed that the median number of
right side (401.5) tended to be higher than the left (315.0). However, the difference was
not statistically significant.

Figure 6: Comparison of number of lines in right (A) and left (B) sensory of thalamocortical
tract between two genders; values represent median (± SD); male (n = 26), female (n = 24).

133


Journal of military pharmaco-medicine n06-2018
The results of comparing the number of sensory thalamocortical tract lines between
two genders showed that the lines of right side was equivalent in the two sexes, in the
left side, the lines of male tended to be lower than female. However, the difference had
no statistically significance.

Figure 7: Branch morphology of the sensory thalamocortical tract.
(A - E: The number of branches from 2 - 6; F: Branching into contralateral hemisphere)
Based on the 3D reconstruction images of the sensory of thalamocortical tract and
the number of branches, we classified the branch morphology as following: 2, 3, 4, 5, 6
or contralateral branches.
Table 2: The branch morphological distribution of the sensory thalamocortical tract.
Branch morphology, n (%)

Total

Right hemimsphere

Left hemisphere

2 branches

3 (3%)

2 (2%)

5 (5%)

3 branches

14 (14%)

11 (11%)

25 (25%)

4 branches

22 (22%)

20 (20%)

42 (42%)

5 branches

6 (6%)

10 (10%)

16 (16%)

6 branches

5 (5%)

7 (7%)

12 (12%)

Contralateral branches

6 (50%)

6 (50%)

12 (100%)

The results showed that sensory thalamocortical tract was the polymorphic branch.
The most abundant was 4 branches morphology; the other morphologies, including
3 branches, 5 branches, 6 branches, 2 branches morphology was the lowest. The obtained
images showed the appearance of branch into the contralateral hemispheres, with the
left and right ratio equal on each side.
134


Journal of military pharmaco-medicine n06-2018
DISCUSSION
Our results showed that the length of
sensory of thalamocortical tract on the right
hemisphere (130.64 mm) was statistically
significance longer than on the left
hemisphere (123.14 mm). The study by
Kamali et al (2009) [7] about the sensations
in the brain stem did not show any differences
in length between the right and left side.
The differences between our results and

the Kamali’s can be explained, the different
anatomical locations could also lead to
differences in the structure. Moreover,
there are always differences in general
function and sensory conduction, in particular,
between the right and left side of brain
(Kobayashi, Takeda et al, 2005 [8]), which
may lead to differences in the length of
sensory of thalamocortical tract between
two sides. When we compared the length
of sensory of thalamocortical tract between
two sexes, the results showed that the
one in male tended to be longer than in
female, this may be due to the brain of
male larger than female (Luders, Gaser
et al, 2009 [9]). However, the differences
were not statistically significant due to the
amount of analysis may be not large enough.
The number of the sensory thalamocortical
tract lines showed in the right hemisphere
(401.5) higher than that in the left hemisphere
(315.0), although the difference was not
statistically significant. This may be due
to the majority of research subjects are
right-handlers, which can make the sensory
transduction differences between the right
and left side of the body (Tan 1993; Patel
and Mehta, 2012 [10,11]). To clarify this
requires, it need to have an extensive

research with the big enough number of
research subjects. In the relationship
between gender and number of the sensory
thalamocortical tract lines, notably the
numbers on the left side in male (295.5)
were much lower than in female (347.0),
although the difference was not statistically
significant, while the number on the right
side is almost equivalent between male
(401.5) and female (398.5). These differences
were quite interesting, though to assert
that require larger studies to clarify these
phenomena.
Our results showed that the sensory
thalamocortical tract was the polymorphic
branch. The diversity of morphology may
be related to the function and distribution
of nerve conduction bundles, and also
related to the diversity of subjects studied
(gender, age).
The DTI in studying the anatomical
characteristics of the sensory thalamocortical
tract was the new advanced techniques
not only in Vietnam but also in the world,
since it was established (1994), so far this
was the ideal method for the study of
white matter, designated the nerves and
neurotransmitters on the non-invasive
living body (Han, Ahn et al, 2008; Hong,
Son et al, 2010 [5, 6]).

CONCLUSIONS
Our results were important to anatomical
reference parameters for understanding
normal function through the brain in
sensory transduction from the thalamus to
the cortex. It was also the basis for the
assessment, detection of functional area
of brain and understanding the mechanics
135


Journal of military pharmaco-medicine n06-2018
of some diseases related to brain injury
and nerve conduction clinically such as:
stroke, degenerative myelin, diffuse axonal
injury, Wallerian degeneration. The study
also opened up a new direction in DTI
applications to study neurotransmitter
activity about physiological conditions and
diseases and understand the function of
neural activity in clinical applications.
REFERENCES
1. Akter M et al. Multi-tensor tractography
of the motor pathway at 3T: A volunteer study.
Magn Reson Med Sci. 2011, 10 (1), pp.59-63.
2. Barbas H. D.N Pandya. Architecture and
frontal cortical connections of the premotor
cortex (area 6) in the rhesus monkey. J Comp
Neurol. 1987, 256 (2), pp.211-228.
3. Basser P.J et al. Estimation of the

effective self-diffusion tensor from the NMR
spin echo. J Magn Reson B. 1994, 103 (3),
pp.247-254.
4. Basser P.J et al. MR diffusion tensor
spectroscopy and imaging. Biophys J. 1994,
66 (1), pp.259-267.
5. Han B.S et al. Cortical reorganization
demonstrated by diffusion tensor tractography

136

analyzed using functional MRI activation.
Neuro Rehabilitation. 2008, 23 (2), pp.171-174.
6. Hong J.H et al. Identification of spinothalamic
tract and its related thalamocortical fibers in
human brain. Neurosci Lett. 2010, 468 (2),
pp.102-105.
7. Kamali A et al. Diffusion tensor
tractography of the somatosensory system in
the human brainstem: Initial findings using
high isotropic spatial resolution at 3.0 T.
Eur Radiol. 2009, 19 (6), pp.1480-1488.
8. Kobayashi M et al. Neural consequences
of somatosensory extinction: An fMRI study.
J Neurol. 2005, 252 (11), pp.1353-1358.
9. Luders E et al. Why sex matters: Brain
size independent differences in gray matter
distributions between men and women.
J Neurosci. 2009, 29 (45), pp.14265-14270.
10. Patel A, A.Mehta. A comparative study

of nerve conduction velocity between left and
right handed subjects. Int J Basic Appl Physiol.
2012, 1 (1), pp.19-21.
11. Tan U. Sensory nerve conduction
velocities are higher on the left than the right
hand and motor conduction is faster on the right
hand than left in right-handed normal subjects.
Int J Neurosci. 1993, 73 (1-2), pp.85-91.