Diffusion tensor imaging of cerebral white matters in children younger than 16 years of age
Date Issued
2005-07-31
Date
2005-07-31
Author(s)
黃國茂
DOI
932314B002189
Abstract
Background:
Before the age of 18 months, myelination process is active in various regions of the brain and
the degree of myelination varies in different regions of the brain from decades to decades of ages.
A recent cerebral histologic study of rats suggest the potential of applying diffusion tenosor (DT)
imaging in evaluating the cerebral whit matter diseases arising from disordered myelination.
However, the normal developmental data of first, second and third eigenvalues (EV 1-3) as well as
fractional anisotropy (FA) of children before the age of three years were hardly found in literature.
Purpose:
The study is designed to obtain the developmental changes of Ev1, EV2, EV3, and FA of white
matter tracts in children under 16 years of age. The result of the study will become the basis of
applying DT indices to the diagnosis of white matter diseases.
Method:
About 100 children before the age of sixteen years who are free of focal neurologic deficits,
metabolic disturbances, tumors or infectious signs will be recruited if their cerebral
fluid-attenuated inversion recovery (FLAIR), T1-weighted, T2-weighted images show no
significant signal changes. After obtaining informed consent from their family, these children will
receive MR DT imaging in addition to the routine MR examinations and chloral hydrate
(0.5-1cc/kg body weight) will be given to the uncooperative children.
All patients in the study received MR examinations using a 1.5-T MR scanner (Sonata; Siemens,
Erlangen, Germany). Fast spin-echo (FSE) T2-weighted images in the axial plane were first
obtained with TR/TE = 4330/100 msec, echo train length = 11, matrix size = 256 x 256, field of
view = 14 x 14 to 20 x 20 according to the patient’s head size, slice thickness = 4–5 mm with gap
of 1–1.5 mm, and one acquisition. DT images were then acquired with diffusion encoding
gradients in six directions (i.e., [1, ±1, 0], [0, ±1, 1], and [±1, 0, 1]) and diffusion sensitivity b =
1500 s/mm2. The parameters for DTI sequence were TR/TE = 240/124 ms, slice thickness = 4 to 5
mm without gap, and five acquisitions. Maps of the first, second and third eigenvalues of the
diffusion tensor, trace of apparent diffusion coefficient (Trace ADC), and fractional anisotropy
were generated off-line. ROIs were also deposited on the bilateral parietal-occipital central white
maters, frontal central white maters, anterior and posterior corpus callosum and corona radiata at
the level of above the lateral ventricular bodies. ROIs were also deposited on bilateral inferior
longitudinal fasciculus and sagittal stratum near the level of the occipital horn. In all ROIs, EV1-3,
trace ADC and FA will obtained. Patients before the ages of 18 months will be divided into 6
groups every three months of age. The other patients will be divided into 8 groups every two years.
We will use Mann-Whitney rank-sum test to find out the areas and DT indices of significant
difference. In addition, Spearman’s rank-order correlation test will be used to correlate the age and
gender with DT indices at various ROIs. P values smaller than 0.05 will be considered significant.
We will perform the axial FSE T2-weighted images, axial fast IR T1-weighted images and DT
imaging examinations. DT indices including EV1, EV2, EV3, trace ADC and FA will be obtained
and analyzed in various ROIs of all patients from all age groups. The results of the study will be
the basis of applying DT indices to evaluate myelination milestones of children. It will become
the important reference when diagnosing white matter diseases using DT images.
Subjects
diffusion tensor imaging
brain
children
magnetic resonance imaging
Publisher
臺北市：國立臺灣大學醫學院放射線科
Type
journal article
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