×

Multiple-echo, multiple-view NMR angiography

  • US 4,796,635 A
  • Filed: 02/11/1987
  • Issued: 01/10/1989
  • Est. Priority Date: 02/11/1987
  • Status: Expired due to Fees
First Claim
Patent Images

1. A method for acquiring a plurality of nuclear magnetic resonance (NMR) angiographic images of flowing material in at least a selected portion of a sample, comprising the steps of:

  • (a) immersing the sample in a main static magnetic field;

    (b) nutating, in an initial part of each of a first sequence and a second sequence of a sequential pair of imaging sequences for each of a multiplicity S of regions of said selected sample portion, the spins of all nuclei of a selected species;

    (c) applying a pair of alternating-polarity flow-encoding signal pulses in a first magnetic field gradient impressed upon the sample in a first direction selected to establish one axis of each of the NMR angiographic projection images, to cause a resulting NMR response echo signal from the spin of a moving nucleus to differ from the NMR response echo signal resulting from the spin of a substantially stationary nucleus;

    each of the flow-encoding pulses in the first sequence of each pair having a polarity flow-encoding pulse in the second sequence of each pair;

    (d) acquiring, responsive to a readout magnetic field gradient impressed upon the sample in a second direction, substantially orthogonal to the first direction, and varied to be different in each j-th one, where 1≦

    j≦

    N, of a plurality N of response data acquisition time intervals of a sequence, with the second direction being the same in each like-numbered j-th acquisition interval of both sequences of all sequence pairs, a set of data from the NMR response echo signal evoked, from the same sample portion, in each different one of the plurality N of acquisition time intervals of each of the first and sequences;

    generating a dephasing pulse in the readout gradient prior to each of the N acquisition time intervals in each sequence;

    generating a rephasing pulse in the readout gradient after each of the first (N-1) acquisition time intervals in each sequence; and

    providing each rephasing pulse with substantially the same amplitude as the associated dephasing pulse;

    (e) subtracting, for each different j-th one of the N different acquisition time intervals, the data acquired in the j-th acquisition interval of one sequence from the data acquired in the like-numbered j-th acquisition interval of the other sequence of each sequence pair, to generate a j-th one of N different-pair difference sets from which response data obtained from stationary nuclei has been substantially removed; and

    (f) generating N different angiographic images, with the j-th image being generated from all of the j-th pair difference sets and with each j-th image lying in a plane having a preselected relationship with respect to the first direction and the different second direction for that j-th image.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×