Leland Stanford Junior University

Palo Alto Medical Research Foundation

Roger A Stern

Bruce C Hill

F Graham Sommer

Diseased tissue such as cirrhotic liver is differentiated from normal tissue by applying an ultrasound wave to the tissue, receiving backscattered ultrasound waves therefrom and bandpass filtering electrical signals generated from the backscattered wave. Assuming that the ultrasound wave has a spectrum and a center frequency, the bandpass is narrow relative to the spectrum and centered within the bounds of the spectrum of the ultrasound wave. The filtered signal will have an amplitude distribution for diseased tissue which is different from the amplitude distribution of normal tissue.

Filtered ultrasonic wave method and apparatus for detecting diseased

For non-invasive diagnosis of conditions subsequent to a medical operative procedure, at the time of operation a 'target' is sutured to tissue. Later, by use of an ultrasonic imaging system or other diagnostic instrument, the location of the target can be accurately determined. Thereupon, non-invasive techniques may be used in the target area to determine changes in physiology subsequent to implanting the target. For example, a target consisting of a fused array of small stainless steel balls is sutured to a coronary artery bypass graft. Later, to determine if the bypass graft is patent, by ultrasonic methods the location of the target and hence the bypass graft is determined. Then, using a Doppler-effect flowmeter, flow through the bypass graft may be measured and compared with prior measurements. The marking technique is also believed to be useful in postoperative determination of tumor growth at the locus of said marker.

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Palo Alto, CA, United States of America

Roger A Stern