• Title/Summary/Keyword: Diffusion Tensor Imaging

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MEDICAL IMAGE ANALYSIS USING HIGH ANGULAR RESOLUTION DIFFUSION IMAGING OF SIXTH ORDER TENSOR

  • K.S. DEEPAK;S.T. AVEESH
    • Journal of applied mathematics & informatics
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    • v.41 no.3
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    • pp.603-613
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    • 2023
  • In this paper, the concept of geodesic centered tractography is explored for diffusion tensor imaging (DTI). In DTI, where geodesics has been tracked and the inverse of the fourth-order diffusion tensor is inured to determine the diversity. Specifically, we investigated geodesic tractography technique for High Angular Resolution Diffusion Imaging (HARDI). Riemannian geometry can be extended to a direction-dependent metric using Finsler geometry. Euler Lagrange geodesic calculations have been derived by Finsler geometry, which is expressed as HARDI in sixth order tensor.

The Software Development for Diffusion Tensor Imaging

  • Song, In-Chan;Chang, Kee-Hyun;Han, Moon-Hee
    • Proceedings of the KSMRM Conference
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    • 2001.11a
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    • pp.112-112
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    • 2001
  • Purpose: We developed the software for diffusion tensor imaging and evaluated its feasibility in norm brains. Method: Five normal volunteers, aged from 25 to 29 years, were examined on a 1.5 T MR system. the diffusion tensor pulse sequence used a SE-EPI with 6 diffusion gradie directions of (1, 1, 0), (-1, 1,0), (1, 0, 1), (-1, 0, 1), (0, 1, 1), (0, 1, -1) and also with no diffusion gradient. A b-factor of 500 sec/mm2 was used. Measurement parameter were as follows; TR/TE=10000 ms/99 ms, FOV=240 mm, matrix=128$\times$128, slice thickness/gap=6 mm/0 mm, bandwidth=91 kHz and the number of total slices=20. Four repeated axial diffusion images were averaged for diffusion tensor imaging. A total scan 11 of 4 min 30 sec was used. Six full diffusion tensor components of Dxx, Dyy, Dzz, Dxy, Dxz and Dyz were obtained using two-point linear regression model from 7 diffusion-weight images at each pixel and fractional anisotropy and lattice index images was estimated fr their eigenvectors and eigenvalues. Our program was written on a platform of IDL. W evaluated the qualities of fractional anisotropy and lattice index images of normal brains a knew whether our software for diffusion tensor imaging may be feasible.

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The Quantitative Diffusion-Tensor Anisotropy of Human Brain Using Fast STEAM DTI

  • 박현정;황문정;김용선;이상권;장용민
    • Proceedings of the KSMRM Conference
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    • 2001.11a
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    • pp.165-165
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    • 2001
  • Purpose: To obtain quantitative diffusion-tensor anisotropy information of human cerebral structu using turbo STEAM diffusion-tensor imaging. Method: Quantitative diffusion anisotropy MR images were obtained in 7 healthy adults using turbo STEAM sequence and a combination of tetrahedral and orthogonal diffusi gradients. Both relative anisotropy(RA) and fractional anisotropy(FA) values were measured various brain regions. The anisotropy index was then compared with the reported valu resulting from EPI-based diffusion tensor imaging.

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The Quantitative Diffusion-Tensor Anisotropy of Human Brain Using Fast STEAM DTI

  • 박현정;황문정;김용선;이상권;장용민
    • Proceedings of the KSMRM Conference
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    • 2001.11a
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    • pp.138-138
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    • 2001
  • Purpose: To obtain quantitative diffusion-tensor anisotropy information of human cerebral structu using turbo STEAM diffusion-tensor imaging. Method: Quantitative diffusion anisotropy MR images were obtained in 7 healthy adults using turbo STEAM sequence and a combination of tetrahedral and orthogonal diffusi gradients. Both relative anisotropy(RA) and fractional anisotropy(FA) values were measured various brain regions. The anisotropy index was then compared with the reported valu resulting from EPI-based diffusion tensor imaging.

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The Diffusion Tensor Imaging of Muscle Preliminary Results

  • 황문정;박현정;장용민;강덕식
    • Proceedings of the KSMRM Conference
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    • 2001.11a
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    • pp.167-167
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    • 2001
  • Purpose: To obtain normative human skeletal muscle data and evaluate quantitative diffusion-ten anisotropy information using diffusion-tensor imaging technique. Method: Quantitative extremity muscle diffusion tensor MR images were obtained in 5 healt adults by using turbo STEAM sequence and a combination of tetrahedral and orthogon diffusion gradients. Relative anisotropy(RA) and fractional anisotropy(FA) values we measured in soleus and gastrocnemius muscle in addition to mean ADC value.

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Significance of Preoperative Nerve Reconstruction Using Diffusion Tensor Imaging Tractography for Facial Nerve Protection in Vestibular Schwannoma

  • Yuanlong Zhang;Hongliang Ge;Mingxia Xu;Wenzhong Mei
    • Journal of Korean Neurosurgical Society
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    • v.66 no.2
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    • pp.183-189
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    • 2023
  • Objective : The facial nerve trace on the ipsilateral side of the vestibular schwannoma was reconstructed by diffusion tensor imaging tractography to identify the adjacent relationship between the facial nerve and the tumor, and to improve the level of intraoperative facial nerve protection. Methods : The clinical data of 30 cases of unilateral vestibular schwannoma who underwent tumor resection via retrosigmoid approach were collected between January 2019 and December 2020. All cases underwent magnetic resonance imaging examination before operation. Diffusion tensor imaging and anatomical images were used to reconstruct the facial nerve track of the affected side, so as to predict the course of the nerve and its adjacent relationship with the tumor, to compare the actual trace of the facial nerve during operation, verify the degree of coincidence, and evaluate the nerve function (House-Brackmann grade) after surgery. Results : The facial nerve of 27 out of 30 cases could be displayed by diffusion tensor imaging tractography, and the tracking rate was 90% (27/30). The intraoperative locations of facial nerve shown in 25 cases were consistent with the preoperative reconstruction results. The coincidence rate was 92.6% (25/27). The facial nerves were located on the anterior middle part of the tumor in 14 cases, anterior upper part in eight cases, anterior lower part in seven cases, and superior polar in one case. Intraoperative facial nerve anatomy was preserved in 30 cases. Among the 30 patients, total resection was performed in 28 cases and subtotal resection in two cases. The facial nerve function was evaluated 2 weeks after operation, and the results showed grade I in 12 cases, grade II in 16 cases and grade III in two cases. Conclusion : Preoperative diffusion tensor imaging tractography can clearly show the trajectory and adjacent position of the facial nerve on the side of vestibular schwannoma, which is beneficial to accurately identify and effectively protect the facial nerve during the operation, and is worthy of clinical application and promotion.

Mini-Review of Studies Reporting the Repeatability and Reproducibility of Diffusion Tensor Imaging

  • Seo, Jeong Pyo;Kwon, Young Hyeon;Jang, Sung Ho
    • Investigative Magnetic Resonance Imaging
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    • v.23 no.1
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    • pp.26-33
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    • 2019
  • Purpose: Diffusion tensor imaging (DTI) data must be analyzed by an analyzer after data processing. Hence, the analyzed data of DTI might depend on the analyzer, making it a major limitation. This paper reviewed previous DTI studies reporting the repeatability and reproducibility of data from the corticospinal tract (CST), one of the most actively researched neural tracts on this topic. Materials and Methods: Relevant studies published between January 1990 and December 2018 were identified by searching PubMed, Google Scholar, and MEDLINE electronic databases using the following keywords: DTI, diffusion tensor tractography, reliability, repeatability, reproducibility, and CST. As a result, 15 studies were selected. Results: Measurements of the CSTs using region of interest methods on 2-dimensional DTI images generally showed excellent repeatability and reproducibility of more than 0.8 but high variability (0.29 to 1.00) between studies. In contrast, measurements of the CST using the 3-dimensional DTT method not only revealed excellent repeatability and reproducibility of more than 0.9 but also low variability (repeatability, 0.88 to 1.00; reproducibility, 0.82 to 0.99) between studies. Conclusion: Both 2-dimensional DTI and 3-dimensional DTT methods appeared to be reliable for measuring the CST but the 3-dimensional DTT method appeared to be more reliable.

Image Reconstruction of Eigenvalue of Diffusion Principal Axis Using Diffusion Tensor Imaging (확산텐서영상을 이용한 확산 주축의 고유치 영상 재구성)

  • Kim, In-Seong;Kim, Joo-Hyun;Yeon, Gun;Suh, Kyung-Jin;Yoo, Don-Sik;Kang, Duk-Sik;Bae, Sung-Jin;Chang, Yong-Min
    • Investigative Magnetic Resonance Imaging
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    • v.11 no.2
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    • pp.110-118
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    • 2007
  • Purpose: The objective of this work to construct eigenvalue maps that have information of magnitude of three primary diffusion directions using diffusion tensor images. Materials and Methods: To construct eigenvalue maps, we used a 3.0T MRI scanner. We also compared the Moore-Penrose pseudo-inverse matrix method and the SVD (single value decomposition) method to calculate magnitude of three primary diffusion directions. Eigenvalue maps were constructed by calculating of magnitude of three primary diffusion directions. We did investigate the relationship between eigenvalue maps and fractional anisotropy map. Results: Using Diffusion Tensor Images by diffusion tensor imaging sequence, we did construct eigenvalue maps of three primary diffusion directions. Comparison between eigenvalue maps and Fractional Anisotropy map shows what is difference of Fractional Anisotropy value in brain anatomy. Furthermore, through the simulation of variable eigenvalues, we confirmed changes of Fractional Anisotropy values by variable eigenvalues. And Fractional anisotropy was not determined by magnitude of each primary diffusion direction, but it was determined by combination of each primary diffusion direction. Conclusion: By construction of eigenvalue maps, we can confirm what is the reason of fractional anisotropy variation by measurement the magnitude of three primary diffusion directions on lesion of brain white matter, using eigenvalue maps and fractional anisotropy map.

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Multi-slice Multi-echo Pulsed-gradient Spin-echo (MePGSE) Sequence for Diffusion Tensor Imaging MRI: A Preliminary Result (일회 영상으로 확산텐서 자기공명영상을 얻을 수 있는 다편-다에코 펄스 경사자장 스핀에코(MePGSE) 시퀀스의 초기 결과)

  • Jahng, Geon-Ho;Pickup, Stephen
    • Progress in Medical Physics
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    • v.18 no.2
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    • pp.65-72
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    • 2007
  • An echo planar imaging (EPI)-based spin-echo sequence Is often used to obtain diffusion tensor imaging (DTI) data on most of the clinical MRI systems, However, this sequence is confounded with the susceptibility artifacts, especially on the temporal lobe in the human brain. Therefore, the objective of this study was to design a pulse sequence that relatively immunizes the susceptibility artifacts, but can map diffusion tensor components in a single-shot mode. A multi-slice multi-echo pulsed-gradient spin-echo (MePGSE) sequence with eight echoes wasdeveloped with selective refocusing pulses for all slices to map the full tensor. The first seven echoes in the train were diffusion-weighted allowing for the observation of diffusion in several different directions in a single experiment and the last echo was for crusher of the residual magnetization. All components of diffusion tensor were measured by a single shot experiment. The sequence was applied in diffusive phantoms. The preliminary experimental verification of the sequence was illustrated by measuring the apparent diffusion coefficient (ADC) for tap water and by measuring diffusion tensor components for watermelon. The ADC values in the series of the water phantom were reliable. The MePGSE sequence, therefore, may be useful in human brain studies.

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In vivo Visualization of Human White Matter Tract by Diffusion Tensor Imaging Fiber Tractography (DTI-FT)

  • Lee, Seung-Koo;Kim, Dong-Ik
    • Proceedings of the KSMRM Conference
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    • 2002.11a
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    • pp.85-85
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    • 2002
  • Purpose: To evaluate the white matter fiber connectivity of normal human using diffusion tensor MRI. Method: Normal young healthy volunteers (2 women and 1 man) and 3 brain tumor patients participated in this study. All studies were performed using a 1.5T Philips Gyroscan Intern system. Diffusion weighted imaging was performed using single-shot echo planar imaging, with navigator echo phase correction and SENSE. Diffusion weighting was performed along six independent axes, using diffusion weighting of b=800s/$\textrm{mm}^2$. 128matrix, 23cm FOV, 2.5mm slice thickness were used for Imaging parameters. Data were processed on a Window-2000 PC equipped with IDL and PRIDE (Philips Medical System). Corticospinal tract was traced from mid-pons level via posterior limb of internal capsule. Corpus callosum, cerebellar peduncles and frontal fibers were traced by fiber tractography.

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