TY - JOUR
T1 - Quantitative analysis along the pyramidal tract by length-normalized parameterization based on diffusion tensor tractography
T2 - Application to patients with relapsing neuromyelitis optica
AU - Lin, Fuchun
AU - Yu, Chunshui
AU - Jiang, Tianzi
AU - Li, Kuncheng
AU - Li, Xiaobo
AU - Qin, Wen
AU - Sun, Hong
AU - Chan, Piu
N1 - Funding Information:
The authors are highly grateful to the anonymous reviewers for their significant and constructive remarks and suggestions, which are greatly helpful in improving the paper. The authors also thank Drs. Edmund F. and Rhoda E. Perozzi of Beijing University of Technology for extensive English language assistance. This work was partially supported by the Natural Science Foundation of China, Grant Nos.30570509, 30425004, 60121302 and 30470519, and the National Key Basic Research and Development Program (973) Grant No. 2003CB716100 and Beijing Natural Science Foundation, Grant No. 7042026.
PY - 2006/10/15
Y1 - 2006/10/15
N2 - In this study, we introduced a length-normalized parameterization method to establish anatomical correspondence of white matter fiber tracts across subjects and applied this method to investigate the presence of abnormal diffusion along the pyramidal tract (PYT) of relapsing neuromyelitis optica (RNMO) patients without visible brain lesions. In this approach, the part of the PYT between the lowest slice of the cerebral peduncle and the uppermost slice of the lateral ventricle was reconstructed to establish the anatomical correspondence across subjects using diffusion tensor tractography. Then it was parameterized by normalizing its length and dividing equally the normalized length into a certain number of segments, so that the comparability of each segment across subjects along the PYT was established. Tract-specific diffusion indices, including directionally averaged diffusivity (Dav), fractional anisotropy (FA), primary diffusivity (λ1) and transverse diffusivity (λ23), were obtained from each segment. Thus, the distribution maps of these indices along the PYT were obtained. The distribution maps of Dav, FA, and λ23 of RNMO patients were significantly different from those of healthy controls, especially in the lower part of the PYT. The differences may be caused by secondary degeneration to lesions in the spinal cord. In conclusion, a length-normalized parameterization method is proposed to establish anatomical correspondence for the PYT. Compared with existed methods, a major merit of our method is to provide comparability across subjects along the PYT on the basis of diffusion tensor tractography and to make it possible for the quantitative analysis along the fiber tract. This method can also be used to quantitatively analyze other white matter fiber tracts between two definite anatomic landmarks in many neurological or psychiatric diseases.
AB - In this study, we introduced a length-normalized parameterization method to establish anatomical correspondence of white matter fiber tracts across subjects and applied this method to investigate the presence of abnormal diffusion along the pyramidal tract (PYT) of relapsing neuromyelitis optica (RNMO) patients without visible brain lesions. In this approach, the part of the PYT between the lowest slice of the cerebral peduncle and the uppermost slice of the lateral ventricle was reconstructed to establish the anatomical correspondence across subjects using diffusion tensor tractography. Then it was parameterized by normalizing its length and dividing equally the normalized length into a certain number of segments, so that the comparability of each segment across subjects along the PYT was established. Tract-specific diffusion indices, including directionally averaged diffusivity (Dav), fractional anisotropy (FA), primary diffusivity (λ1) and transverse diffusivity (λ23), were obtained from each segment. Thus, the distribution maps of these indices along the PYT were obtained. The distribution maps of Dav, FA, and λ23 of RNMO patients were significantly different from those of healthy controls, especially in the lower part of the PYT. The differences may be caused by secondary degeneration to lesions in the spinal cord. In conclusion, a length-normalized parameterization method is proposed to establish anatomical correspondence for the PYT. Compared with existed methods, a major merit of our method is to provide comparability across subjects along the PYT on the basis of diffusion tensor tractography and to make it possible for the quantitative analysis along the fiber tract. This method can also be used to quantitatively analyze other white matter fiber tracts between two definite anatomic landmarks in many neurological or psychiatric diseases.
KW - Diffusion indices
KW - Length-normalized parameterization
KW - Pyramidal tract
KW - Relapsing neuromyelitis optica
KW - Tractography
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U2 - 10.1016/j.neuroimage.2006.03.055
DO - 10.1016/j.neuroimage.2006.03.055
M3 - Article
C2 - 16919971
AN - SCOPUS:33748705721
SN - 1053-8119
VL - 33
SP - 154
EP - 160
JO - NeuroImage
JF - NeuroImage
IS - 1
ER -