Ultrasound contrast imaging

Details Ultrasound contrast imaging Ultrasound contrast imaging

1999-09-07

2001-11-27

Lateef, Marvin M. (Department: 3737)

Surgery

Diagnostic testing

Detecting nuclear, electromagnetic, or ultrasonic radiation

C600S438000

Reexamination Certificate

active

06322512

ABSTRACT:

The present invention relates to ultrasound contrast imaging methods and apparatus and more particularly to measurement of pressure and/or temperature in a body.
In particular the invention provides non-invasive real time determination of temperature, pressure, gas concentration etc in the blood. This is extremely difficult to achieve in, for example, internal organs and, for example, real time determination of temperature of an internal organ during treatment can provide the physician with valuable information allowing enhanced treatment.
This enables local determination of organ perfusion and local determination of ambient pressure, temperature or gas concentration.
The inventive technique is substantially better than alternative techniques to achieve the same objective since organ perfusion measurements require x-ray technology and ambient pressure and gas content measurements respectively require a pressure catheter and a blood sample.
U.S. Pat. No. 5,456,257 discloses an ultrasonic diagnostic system which detects the presence of coated microbubble contrast agents in the body of a patient by transmitting ultrasonic energy which causes the destruction of the coated microbubbles and detects the microbubble destruction through phase insensitive detection and differentiation of echoes received from two consecutive ultrasonic transmissions.
According to the present invention there is provided an ultrasound contrast imaging method comprising generating a first, relatively high power, acoustic field for a first predetermined number of cycles, and following a predetermined time delay generating a second relatively lower power acoustic field for a second predetermined number of cycles, said first predetermined acoustic field causing, in use, power enhanced scattering and said second predetermined acoustic field being below the threshold for power enhanced scattering and causing scattering providing information about possible generated free gas bubbles.
Power enhanced scattering is defined as providing an acoustic pulse at an amplitude at least sufficient to cause a change in the acoustic properties of the region of interest to, for example, cause bubbles to be released from the microcapsules.
Preferably the acoustic field has a frequency of 100 kHz to 10 MHz.
The present invention also provides apparatus for ultrasound contrast imaging comprising means for generating a first relatively high power acoustic field for a first predetermined time period, timing means for generating a predetermined delay time, and means for generating a second relatively low power acoustic field for a second predetermined period following said predetermined delay time.
Preferably the apparatus comprises receiver means for receiving a signal in a period following the generation of the second relatively low power acoustic field.
Preferably the means for generating a second relatively low power acoustic field comprises further timing delay means for repeating said low power acoustic field after a further predetermined delay. Preferably the apparatus includes signal receiver means for interrogating a received signal during said further predetermined delay.
In a preferred embodiment the apparatus comprises time sequencing means for repetitively supplying a series of relatively low power acoustic fields with a predetermined time delay interposed between each relatively low power acoustic field and including receiver means for receiving and interrogating a received signal during each predetermined time delay.
Preferably the apparatus includes means for determining from the received signal whether any generated small bubbles are still present and means for terminating said sequence of relatively low acoustic power signals on determination that no small bubbles are present.
The apparatus also preferably includes means for selectively adjusting the insonifying frequency of the acoustic field to adjust the disappearance period of the generated free gas bubbles.


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