Velocity mapping resonant

FIGURE 55.4 Velocity profiles downstream of the human pulmonary valve obtained with magnetic resonance phase velocity mapping [Sloth, 1994]. Again the timing of the measurements is shown by the market on the flow curve. 

FIGURE 55.8 Magnetic resonance image of a healthy individual during diastole. An outline of the interior left ventricle (LV) is indicated in white as are the mitral valve leaflets (MV) and the aorta (AO). Velocity vectors were obtained from MRI phase velocity mapping and superimposed on the anatomical image. 

Kilner, P.J., Yang, G.Z., Mohiaddin, R.H., Firmin, D.N., and Longmore, D.B. 1993. Helical and retrograde secondary flow patterns in the aortic arch studied by three-directional magnetic resonance velocity mapping. Circulation 88[paitl] 2235-2247. 

Kim, W.Y., Walker, P.G., Pederson, E.M., Poulsen, J.K., Houhnd, K.C., and Oyre, S. 1995. Left ventricular blood flow patterns in normal subjects a quantitative analysis of three-dimensional magnetic resonance velocity mapping. 4 422-438. 

Sloth, E., Houlind, K.C., Oyre, S., Kim, Y.K., Pedersen, E.M., Jorgensen, H.S., and Hasenkam, J.M. 1994. Three-dimensional visualization of velocity profiles in the human main pulmonary artery using magnetic resonance phase velocity mapping. Am. Heart J. 128 1130-1138. 

The two beams intersect at 90° inside the interaction region with t3rpical vacuum pressures of 10 Torr. The beams cross between plates that form a weak uniform electric field of 200V/cm. The crossing of the molecular and atomic beams is further intersected by an ionization laser. The ionization laser(s) ionizes the molecules using resonance enhanced multi-photon ionization, REMPI. Once ionized the molecules are extracted from the interaction region by the uniform electric field into the Velocity Mapped Ion-Imaging system. 

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