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Voxel sensitivity function description of flow‐induced signal loss in MR imaging: Implications for black‐blood MR angiography with turbo spin‐echo sequences
Author(s) -
Jara H.,
Yu B.C.,
Caruthers S.D.,
Melhem E.R.,
Yucel E.K.
Publication year - 1999
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/(sici)1522-2594(199903)41:3<575::aid-mrm22>3.0.co;2-w
Subject(s) - nuclear magnetic resonance , physics , voxel , spin echo , fast spin echo , attenuation , bloch equations , laminar flow , dephasing , fourier transform , image quality , blood flow , pulse sequence , magnetic resonance imaging , optics , computer science , radiology , condensed matter physics , medicine , mechanics , image (mathematics) , artificial intelligence , quantum mechanics
The conditions in which the image intensity of vessels transporting laminar flow is attenuated in black‐blood MR angiography (BB‐MRA) with turbo spin‐echo (TSE) and conventional spin‐echo (CSE) pulse sequences are investigated experimentally with a flow phantom, studied theoretically by means of a Bloch equation‐voxel sensitivity function (VSF) formalism, and computer modeled. The experiments studied the effects of: a) flow velocity, b) imaging axes orientation relative to the flow direction, and c) phase encoding order of the TSE train. The formulated Bloch equation‐VSF theory describes flow effects in two‐dimensional (2D)‐ and 3D‐Fourier transform magnetic resonance imaging. In this theoretical framework, the main attenuation mechanism instrumental to BB‐MRA, i.e., transverse magnetization dephasing caused by flow in the presence of the imaging gradients, is described in terms of flow‐induced distortions of the individual voxel sensitivity functions. The computer simulations predict that the intraluminal homogeneity and extent of flow‐induced image intensity attenuation increase as a function of decreasing vessel diameter, in support of the superior image quality achieved with TSE‐based BB‐MRA in the brain. Magn Reson Med 41:575–590, 1999. © 1999 Wiley‐Liss, Inc.