SPATIALLY-RESOLVED AND LOCALIZED REAL-TIME VELOCITY DISTRIBUTION

A technique is presented for collecting the spin velocity distribution as a function of position and time. It uses a multidimensional excita tion pulse to select a cylinder, giving localization in two dimensions . Resolution in the third spatial dimension is achieved in the readout . During readout, an oscillating gradient encodes the acquired data in both one spatial dimension (x) and one velocity dimension (v). Two ac quisitions (42 ms each) are needed to get a complete coverage of k(x) - k(v) space, which makes this technique real-time. The data is interp olated from the nonuniformly sampled k(x) - k(y) space to a Cartesian frame with a gridding scheme to take advantage of the Fast Fourier Tra nsform. The technique was successfully applied to phantoms and normal volunteers, giving reasonable real-time measurements of velocity.