Voxel sensitivity function description of flow-induced signal loss in MR imaging: implications for black-blood MR angiography with turbo spin-echo sequences

Magn Reson Med. 1999 Mar;41(3):575-90. doi: 10.1002/(sici)1522-2594(199903)41:3<575::aid-mrm22>3.0.co;2-w.

Abstract

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Flow Velocity
  • Cerebrovascular Circulation / physiology*
  • Computer Simulation*
  • Humans
  • Image Processing, Computer-Assisted / methods*
  • Magnetic Resonance Angiography / instrumentation
  • Magnetic Resonance Angiography / methods*
  • Models, Cardiovascular*
  • Phantoms, Imaging*
  • Popliteal Artery / anatomy & histology
  • Popliteal Artery / physiology*
  • Popliteal Vein / anatomy & histology
  • Popliteal Vein / physiology*
  • Reference Values
  • Sensitivity and Specificity