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 excitation 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 acquisitions (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 interpolated from the nonuniformly sampled k(x) - k(y) space to a Cartesian frame with a gridding scheme to take advantage of the Fast Fourier Transform. The technique was successfully applied to phantoms and normal volunteers, giving reasonable real-time measurements of velocity.