확산텐서 MR 영상을 이용한 백질의 비등방성 측정 및 백질섬유 트래킹: 확산경사자장의 방향수가 미치는 영향
Anisotropy Measurement and Fiber Tracking of the White Matter by Using Diffusion Tensor MR Imaging: Influence of the Number of Diffusion-Sensitizing Gradient Direction
2
조회
0
다운로드
3
인용
0
참고문헌
키워드
초록
목적 : 최근 확산텐서영상(diffusion tensor imaging)의 발전으로 뇌백질의 미세 구조적 특성을 평가할 수 있게 되었다. 그러나 확산텐서영상을 얻기 위한 적절한 영상촬영조건 중 확산 강조 경사자장의 적정한 방향 수에 대하여 충분히 연구되지 않은 실정이다. 이에 본 연구에서는 뇌백질의 트래킹(tracking)을 수행하는 데에 있어 확산강조 경사자장의 방향 수가 미치는 영향을 알아보고자 하였다. 대상 및 방법 : 건강한 남녀 13명 (남: 10, 여: 3, 평균나이: 30세, 연령분포: 23-37) 을 대상으로 하였다. 확산텐서영상은 모든 영상촬영조건을 동일하게 유지하면서 확산강조 경사자장의 방향 수를 6-방향, 15-방향, 32-방향으로 변화시키면서 시행하였다. 영상 범위는 뇌교 하방 1 cm부터 측뇌실 상방 2-3 cm까지 포함하였으며 전교련-후교련 연결선에 평행하게 하였다. 영상후처리를 통해 FA (fractional anisotropy, 분할 비등방성) map을 만든 후, 뇌량의 무릎과 팽대에서 FA의 평균값과 표준편차를 각 FA map에서 구하였다. 그리고 뇌의 피질척수로에서 트래킹을 시행하여 트래킹된 백질 섬유의 수를 측정하였다. 얻어진 FA, FA의 표준편차, 트래킹된 피질척수로의 섬유 수를 통계적 방법으로 6-방향, 15-방향, 32-방향사이에서 비교하였다. 결과 : FA는 확산강조 경사자장의 방향 수에 따라 통계적으로 유의한 차이가 없었다. 경사자장의 방향 수가 증가함에 따라 FA의 표준편차는 유의하게 감소하였고, 트래킹된 피질척수로의 섬유 수는 유의하게 증가하였다. 결론 : 확산텐서영상에서 확산강조 경사자장의 방향 수를 증가시킬수록 더 우수한 백질의 트래킹이 가능하였다.
Abstract
Purpose : Recent development of diffusion tensor imaging enables the evaluation of the microstructural characteristics of the brain white matter. However, optimal imaging parameters for diffusion tensor imaging, particularly concerning the number of diffusion gradient direction, have not been studied thoroughly yet. The purpose of this study was to evaluate the influence of the number of diffusion gradient direction on the fiber tracking of the white matter. Materials and methods : 13 healthy volunteers (ten men and three women, mean age 30 years, age range 23-37 years) were included in this study. Diffusion tensor imaging was performed with different numbers of diffusion gradient direction as 6, 15, and 32, keeping the other imaging parameters constant. The imaging field ranged from 1 cm below the pons to 2-3 cm above the lateral ventricle, parallel to the anterior commissure-posterior commissure line. FA (fractional anisotropy) maps were created via image postprocessing, and then FA and its standard deviation were calculated in the genu and the splenium of the corpus callosum on each of FA maps. Fiber tracking of the corticospinal tract in the brain was performed and the number of the reconstructed fibers of the tract was measured. FA, standard deviation of FA and the number of the reconstructed fibers were compared statistically between the different diffusion gradient directions. Results : FA is not statistically significantly different between the different diffusion gradient directions. By increasing the number of diffusion gradient direction, standard deviation of FA decreased significantly, and the number of the reconstructed fibers increased significantly. Conclusion : The higher number of diffusion gradient direction provided better quality of fiber tracking.
참고문헌 (22)
- "M-RI-based topographic parcellation of human cerebral whitematter", 9, pp.1~17 (1999)
- "The role of diffusion tensor imaging in the evalua-tion of ischemic brain injury:a review", 15, pp.561~569 (2002)
- "Clinicotopographical correlation of corticospinal tract stroke:acolor-coded diffusion tensor imaging study", 35, pp.86~92 (2004)
- "Diffusion tensorimaging and axonal tracking in the human brainstem", 14, pp.723~735 (2001)
- "Diffusion tensor MR imaging of the brain andwhite matter tractography", 178, pp.3~16 (2002)
- "Diffusion tensor imaging of cerebral white mat-ter:a pictorial review of physics,fiber tract anatomy,and tu-mor imaging patterns", 25, pp.356~369 (2004)
- "Three-dimensionaltracking of axonal projections in the brain by magnetic reso-nance imaging", 45, pp.265~269 (1999)
- "Diffusion tensor imag-ing of the brain:effect of diffusion weighting on trace andanisotropy measurement", 21, pp.1813~1820 (2000)
- "Toward a quantitative assessment of d-iffusion anisotropy", 36, pp.893~906 (1996)
- "Minimal gradient encoding for robust estimationof diffusion anisotropy", 18, pp.671~679 (2000)
- "확산 경사자장의 방향수에 따른 분할 비등방성 뇌자기공명영상의 잡음에 대한 히스토그램 분석", 52, pp.87~92 (2005)
- "Optimization of dif-fusion-tensor MR imaging data acquisition parameters forbrain fiber tracking using parallel imaging at 3 T", 4, pp.234~238 (2004)
- "Comparison of gradientencoding schemes for diffusion-tensor MRI", 13, pp.769~780 (2001)
- "Diffusion tensor imaging in cerebraltumor diagnosis and therapy", 15, pp.315~324 (2004)
- "DTI tractography based parcel-lation of white matter:application to the mid-sagittal morphol-ogy of corpus callosum", 26, pp.195~205 (2005)
- "Combined magnetic resonancetractography and functional magnetic resonace imaging in e-valuation of brain tumors involving the motor system", 28, pp.551~556 (2004)
- "Brain fiber tracking with clin-ically feasible diffusion-tensor MR imaging:initial experience", 227, pp.295~301 (2003)
- "Fiber-tracking methodreveals sensorimotor pathway involvement in stroke patients", 34, pp.159~162 (2003)
- "Fiber trackingby diffusion tensor imaging in corticospinal track stroke:Topographical correlation with clinical symptoms", 26, pp.771~776 (2005)
- "Three-dimensional white matter tractography by diffusion ten-sor imaging in ischemic stroke involving the corticospinaltract", 45, pp.532~535 (2003)
- "MR tractography for the e-valuation of functional recovery from lenticulostriate infarcts", 64, pp.108~113 (2005)
- "Classification and quantifica-tion of neuronal fiber pathways using diffusion-tensor MRI", 49, pp.716~721 (2003)