title: Mapping blood flow directionality in the human brain.
abstract: Diffusion properties of tissue are often expressed on the basis of directional variance, i.e., diffusion tensor imaging. In comparison, common perfusion-weighted imaging such as arterial spin labeling yields perfusion in a scalar quantity. The purpose of this study was to test the feasibility of mapping cerebral blood flow directionality using alternate ascending/descending directional navigation (ALADDIN), a recently-developed arterial spin labeling technique with sensitivity to blood flow directions. ALADDIN was applied along 3 orthogonal directions to assess directional blood flow in a vector form and also along 6 equally-spaced directions to extract blood flow tensor matrix (P) based on a blood flow ellipsoid model. Tensor elements (eigenvalues, eigenvectors, etc) were calculated to investigate characteristics of the blood flow tensor, in comparison with time-of-flight MR angiogram. While the directions of the main eigenvectors were heterogeneous throughout the brain, regional clusters of blood flow directionality were reproducible across subjects. The technique could show heterogeneous blood flow directionality within and around brain tumor, which was different from that of the contralateral normal side. The proposed method is deemed to provide information of blood flow directionality, which has not been demonstrated before. The results warrant further studies to assess changes in the directionality map as a function of scan parameters, to understand the signal sources, to investigate the possibility of mapping local blood perfusion directionality, and to evaluate its usefulness for clinical diagnosis.
authors.affiliation: Magnetic Resonance Imaging Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea; Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address: sunghongpark@kaist.ac.kr.
authors.forename: Sung-Hong
authors.initials: SH
authors.lastname: Park
authors.affiliation: Magnetic Resonance Imaging Laboratory, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
authors.forename: Won-Joon
authors.initials: WJ
authors.lastname: Do
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.affiliation: MR Research Support, Siemens Healthcare, Pittsburgh, PA, United States.
authors.forename: Tiejun
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States.
authors.forename: Kyongtae Ty
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005240:Feasibility Studies; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013113:Spin Labels
chemical_list: D013113:Spin Labels
keywords: Alternate ascending/descending directional navigation; Arterial spin labeling; Blood flow directionality; Blood flow tensor imaging; Perfusion directionality; Perfusion tensor imaging