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Method and apparatus for elastographic measurement and imaging

  • US 5,474,070 A
  • Filed: 03/11/1994
  • Issued: 12/12/1995
  • Est. Priority Date: 11/17/1989
  • Status: Expired due to Term
First Claim
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1. A method for taking elastographic measurements of a heterogeneous target body comprising the steps of:

  • (a) sonically coupling an ultrasonic source to the surface of a target body;

    (b) emitting a first pulse of ultrasonic energy from the source along a radiation axis in the target body;

    (c) recording the arrival time of the first echo sequence having at least one echo segment arriving in response to said first pulse of ultrasonic energy;

    (d) displacing the surface of the target body a known displacement, Δ

    X, along a force axis so as to compress the target body;

    (e) emitting a next pulse of ultrasonic energy from the source along said radiation axis in the target body following said movement;

    (f) recording the arrival time of a next echo sequence arriving in response to said next pulse of ultrasonic energy, said echo sequence having at least one echo segment that is congruent with at least one said echo segment that arrived in response to the preceding pulse;

    (g) measuring the differential displacement from at least one congruent echo segment of the two most recent pulses of ultrasonic energy;

    (h) calculating the strain from the differential displacement data obtained in step (g);

    (i) storing strain data that meets a predetermined quality standard in a retrievable medium;

    (j) normalizing the calculated strain data stored in step (i) using the formula;

    NSn =CSn /n where;

    NSn =normalized strain at displacement interval nCSn =calculated strain at displacement interval n; and

    (k) repeating steps (d)-(j) until enough strain data has been stored to produce an image of the tissue body region under interrogation.

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