Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-09-08
2001-09-04
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S467000, C029S025350
Reexamination Certificate
active
06283920
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of ultrasonic imaging, and more particularly to ultrasonic imaging to determine various characteristics of relatively small cavities and surrounding fluids and structures.
BACKGROUND OF THE INVENTION
Diagnosis and treatment of fully or partially blocked arteries of the heart is essential in the medical profession's endeavor to prevent heart attacks. Physicians have successfully prevented heart attacks arising from artery blockage caused by the build-up of plaque upon the walls of the coronary arteries through the use of percutaneous transluminal coronary angioplasty (PTCA, commonly referred to as “balloon angioplasty”). Balloon angioplasty involves carefully threading a catheter into the affected portion of the artery. After the balloon portion is determined to be properly positioned in the artery, the physician inflates the expandable portion of the catheter in order to broaden the blocked or narrowed passage in the blood vessel caused by the deposition of plaque upon the artery wall.
The desirability of using an imaging device to produce treatment and diagnostic quality images of small enclosed areas such as human blood vessels on a diagnostic video display device is unquestioned. It is known to use a very small ultrasonic imaging device mounted at the end of a catheter to produce a real-time image of the internal walls of a coronary artery. This device is referred to herein as an ultrasound catheter.
In the known ultrasound catheters, the sane material is used for the electronics carrier upon which a set of electronic components are mounted and for the backing material for the transducer assembly. A drawback to the known ultrasound catheters is the difficulty in finding a carrier/backing material which provides the physical and acoustic qualities desired for advantageous use as the carrier for the electronics and the backing material for a transducer assembly comprising a highly sensitive transducer material.
The known ultrasonic catheter structure, though providing the advantage of design and construction simplicity, exhibits certain drawbacks attributable to the particular and mutually incompatible requirements for the backing material and the electronics carrier. It is desirable that the electronics carrier for the electronics body be rigid and capable of withstanding the elevated temperatures produced by the electronics. However, the known electronics carrier materials which satisfy the requirements for the electronics body are not suitable backing materials for the presently preferred transducer assemblies comprising highly sensitive lead zirconate titanate (PZT) composites.
When the new, more sensitive PZT composites are used with the known electronic carrier material as the backing material for the transducer, unwanted ringing occurs in the transducer assembly when an acoustic signal is received or transmitted by the catheter. The signal produced by the ringing reduces the quality of the signal transmitted by the transducer assembly and limits the foreseeable advantages of utilizing the more sensitive transducer materials in ultrasonic catheters. The decreased signal quality attributed to the ringing limits the-image quality provided by an ultrasound catheter. The limited image quality restricts the usefulness of the ultrasound catheter for clinical and diagnostic imaging.
In known ultrasound catheters the transducer electrodes are coupled to the transducer layer through a capacitive glue layer. As was previously mentioned, PZT composites having a relatively high degree of sensitivity to acoustic signals are being considered for replacement of the previously used, less sensitive, ferroelectric polymer transducer materials. While the PZT composites exhibit superior sensitivity in comparison to the ferroelectric copolymers, they also have a higher dielectric constant. The reduced impedance (or increased capacitance) associate with the new PZT composites significantly negates the improved signal sensitivity provided by the PZT composites when coupled to the transducer electrodes through the capacitive glue layer.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a superior virtually real-time ultrasonic image of relatively small cavities and their surrounding tissues than previously obtainable in the prior art.
It is a further object to provide enhanced sensitivity to reflected signals from the wall of a cavity in order to provide improved image resolution.
It is a further object of the invention to meet the other objectives and maintain or reduce ringing and other sources of noise in a signal transmitted or received by the transducer assembly and to thereby provide a clearer image of a cavity.
It is yet another object of the present invention to provide a means for more easily fabricating the very small transducer elements of the transducer assembly of an ultrasound catheter.
It is yet another object of the present invention to provide a means for forming the very small transducer elements for the ultrasound catheter to very close tolerances.
It is another object of the present invention to provide desirable carrier/backing materials for the electronics body and transducer assembly of an ultrasound catheter.
It is yet another object of the present invention to provide a means for joining the conductor lines of the electronics body to the conducting electrodes of the transducer assembly in order to provide a signal path between the separately fabricated sections containing the integrated circuits and the transducer assembly of an ultrasound catheter.
The above objects are met by a catheter probe assembly of the present invention comprising a multi-sectioned body for insertion into a cavity. The multi-sectioned body is characterized by separate and distinct carrier/backing materials for an electronics body and a transducer assembly. The present invention comprises a probe assembly for an ultrasound catheter generally of the type described in Proudian deceased et al. U.S. Pat. No. 4,917,097 and Eberle et al. U.S. Pat. No. 5,167,233 for producing substantially real-time images of small cavities and their surrounding tissue.
The transducer assembly, comprising an array of transducers is mounted upon a first section of the multi-sectioned body. The transducer array transmits ultrasonic acoustic waves to the cavity and generates electrical signals in response to reflected ultrasonic acoustic waves received by the transducers.
The backing material for the transducer assembly is specifically selected for its characteristic low acoustic impedance and high absorption. The low acoustic impedance backing material absorbs signals coupled into the backing material and reduces the presence of ringing in the transducer assembly. In addition, a set of transducer electrodes are directly bonded to the transducer material thereby eliminating a capacitive glue layer previously associated with the transducer circuits.
Integrated circuits are mounted upon a second section of the multi-sectioned body. The second section, acoustically isolated from the first section, comprises a carrier material having a low thermal expansion coefficient. The integrated circuits receive a set of first electrical signals from the transducer array by means of electrical conductors interconnecting the transducer assembly electrodes and the pads of the integrated circuits. The electrical conductors are also used to transmit excitation signals from the integrated circuits to the transducer assembly. The integrated circuits convert the received first electrical signals into a second set of electrical signals. Then the integrated circuits transmit the second set of signals to a signal processor located outside the environment of the cavity by means of a cable.
The unique, multi-sectioned, structure of the probe assembly enables the designer of the probe assembly to separately select a material exhibiting the preferred structural and acoustic characteristic for the carrier of the integrated circuit components an
Eberle Michael J.
Kiepen Horst F.
Rizzuti Gary P.
Endosonics Corporation
Imam Ali M.
Lateef Marvin M.
Leydig , Voit & Mayer, Ltd.
LandOfFree
Ultrasound transducer assembly does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ultrasound transducer assembly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultrasound transducer assembly will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2475122