Surgery – Truss – Pad
Patent
1992-08-11
1995-01-24
Jaworski, Francis
Surgery
Truss
Pad
A61B 806
Patent
active
053834658
DESCRIPTION:
BRIEF SUMMARY
INTRODUCTION AND BACKGROUND
The present invention relates to an ultrasonic instrument for use in interventional procedures employed in surgical and medical investigations, treatment or diagnosis, in research and in related fields.
In procedures involving the insertion of an instrument into a human or animal body, it is often necessary for the position of the instrument to be known accurately. The use of ultrasonic instruments, in particular imaging scanners, to guide the insertion of surgical instruments such as puncture needles or catheters during invasive medical procedures is known. The imaging system usually relies on detection of passive echos from the instruments, but more recently techniques have been developed in which an ultrasonic transducer is located on the end of the instrument to provide an "active" detection system. The ultrasonic wave emitted by the imaging system is detected by the transducer, and an electrical signal is conveyed back to the imaging system, or the transducer emits an ultrasonic signal for detection by the imaging system. For more general information reference can be made to U.S. Pat. No. 3,556,079 and U.S. Pat. No. 4,249,539. GB-A-2157828 describes an instrument in which the ultrasonic sensor is connected to a detection circuit by a pair of solid conductive paths. This requires quite complicated and accurate fabrication techniques.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ultrasonic invasive instrument where the fabrication can be significantly less complicated and therefore less costly.
It has been found unexpectedly that it is not essential to have a conductive or very low resistance, connection to the transducer, but that satisfactory performance can be made if an ohmic or capacitive coupling is used.
According to the invention there is provided an ultrasonic invasive instrument comprising a device having an ultrasonic sensor secured at or near a first end of the device which is inserted into the body, and two electrically conductive paths extending from the sensor to a second end of the device for connection to the electronic circuitry, the sensor having first and second electrode surfaces, at least one of which surfaces is electrically connected to a respective conductive path by an ohmic or capacitive coupling.
More particularly the invention is applied to a biopsy probe in which an electrically conductive stylet is arranged to be surrounded by an electrically conductive cannula. An electrically insulating barrier, such as an electrically non-conducting polymer film is positioned between the outer surface of the stylet and the inner surface of the cannula, and the ultrasonic sensor is mounted on the remote end of the stylet and, in use, is electrically coupled by body fluids or the like to the cannula so that signals generated by the sensor can be detected by an electronic circuit connected across the near ends of the stylet and the cannula.
The electrical connection between the stylet and sensor may be a capacitive and/or an ohmic coupling.
The coupling between the sensor and the needle may be a capacitive and/or an ohmic coupling, the latter being provided by the medium present in use adjacent the sensor.
Thus the invention provides a construction for an invasive ultrasonic instrument which is easier to manufacture than the instrument of, for example, GB-A-2157828.
The invention is applicable to a wide range of instruments used in surgical and medical investigations, diagnosis, treatment and associated research, for example puncture needles, catheters and endoscopes, used for example for aspiration of liquids, taking histological and cytological biopsy samples, chorionic villus sampling, umbilical cord blood sampling, amniocentesis, in vivo fertilisation, positioning capsules for taking small bowel biopsies, ductography, selective arteriography, phlebography, embolisation, drug administration, radioactive source implantation and cardiac catheterisation.
Other aspects, preferred features and advantages of the in
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Fukutome, T. et al "Puncturing Apparatus", Europ. Pat Applin. Publ. #EP0190719 Publ. Aug. 1986.
Extract found on p. 169 of "Engineering" Journal, Mar. 1983.
Aindow Joseph D.
Lesny Jan
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