Voxel sensitivity function description of flow-induced signal loss in MR imaging: Implications for black-blood MR angiography with turbo spin-echo sequences
✍ Scribed by H. Jara; B.C. Yu; S.D. Caruthers; E.R. Melhem; E.K. Yucel
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 259 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
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 spinecho (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 twodimensional (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