US-20260123945-A1 - Histotripsy Apparatus With Acoustically Registered Auxiliary Probe

US20260123945A1US 20260123945 A1US20260123945 A1US 20260123945A1US-20260123945-A1

Abstract

A histotripsy device treating tissue with cavitating microbubbles produced by a high power therapy ultrasonic transducer provides an independently positionable ultrasound probe located and registered to the therapy ultrasonic transducer using ultrasonic ranging signals communicating through the patient. In one embodiment the independently positionable ultrasound probe is an intra-cavity probe.

Inventors

Martin Gerd Wagner

Assignees

WISCONSIN ALUMNI RESEARCH FOUNDATION

Dates

Publication Date: 20260507
Application Date: 20241101

Claims (20)

1 . An ultrasound therapy system, comprising; an ultrasound therapy transducer array adapted to deliver histotripsy pulses into a subject to generate cavitation in the subject at a focal region; an ultrasound probe independently positionable with respect to the ultrasound therapy transducer array and adapted to receive acoustic signals from the subject for producing an ultrasonic image of the subject; a first set of ultrasonic transducer elements at predetermined separated locations fixed with respect to the ultrasonic therapy transducer array and adapted to couple acoustic signals between the first set of ultrasonic transducer elements and the subject; a second set of ultrasonic transducer elements at predetermined separated locations fixed with respect to the ultrasound probe and adapted to couple acoustic signals between the second set of ultrasonic transducer elements and the subject; and a localizing circuit operating to activate transducers of one of the first or second set of ultrasonic transducers to couple independently distinguishable locating acoustic signals into the subject and to monitor a receipt of the independently distinguishable locating acoustic signals at transducers of a different of the first and second set of ultrasonic transducers to deduce a relative location of the ultrasonic probe with respect to the ultrasound therapy transducer.
2 . The ultrasound therapy system of claim 1 wherein the second set of ultrasonic transducers is separated in two dimensions and the localizing circuit uniquely localizes the ultrasonic probe with respect to relative translation and rotation of the ultrasonic probe with respect to the ultrasonic therapy transducer.
3 . The ultrasound therapy system of claim 1 further including at least one image processing circuit communicating with the ultrasound probe to produce an ultrasonic image of the subject from ultrasonic signals received by the ultrasound probe; a compositor communicating with the localizing circuit to register a fiducial mark representing the focal region with respect to the ultrasonic image; and a display communicating with the compositor to display an image of the subject registered to the fiducial mark.
4 . The ultrasound therapy system of claim 1 wherein the therapy transducer array further includes at least one image processing circuit communicating with the ultrasound probe to produce an ultrasonic image of the subject from ultrasonic signals received by the ultrasound probe; a cursor control device communicating with the localizing circuit to place a targeting mark representing a desired treatment area on the ultrasonic image; and a motorized actuator communicating with the therapy transducer array and operating to steer the focal region into alignment with the targeting mark with respect to the subject.
5 . The ultrasound therapy system of claim 1 wherein the ultrasound probe transmits and receives ultrasonic signals for a production of the ultrasonic image of the subject.
6 . The ultrasound therapy system of claim 1 further including a second ultrasound probe fixed with respect to the ultrasound therapy transducer and communicating with the at least one image processing circuit to develop a second ultrasound image of the subject from ultrasound signals received by the second ultrasound probe.
7 . The ultrasound therapy system of claim 1 further including a computer memory holding non-ultrasound image data of the subject obtained from a non-ultrasonic imaging modality and wherein the compositor registers the non-ultrasound image data to the ultrasonic image to display on the display a composite of the ultrasound image and the non-ultrasound image data.
8 . The ultrasound therapy system of claim 1 wherein the first set of ultrasonic transducer elements provides at least three ultrasonic transducer elements.
9 . The ultrasound therapy system of claim 1 wherein first set of ultrasonic transducer elements operates alternatively to provide the independently distinguishable locating acoustic signals and histotripsy pulses.
10 . The ultrasound therapy system of claim 1 wherein the localizing circuit deduces the relative location of the different of the first and second ultrasonic transducer elements based on a speed of sound through the subject between the first and second set of ultrasonic transducers, and further including a sound speed corrector iteratively correcting an assumed sound speed using the deduced relative location of the ultrasonic probe with respect to the ultrasonic therapy transducer.
11 . The ultrasound therapy system of claim 9 wherein the sound speed corrector iteratively corrects an assumed sound speed using at least one of image data obtained from the ultrasound probe and image data obtained from a non-ultrasound imaging modality.
12 . A method of an ultrasound therapy system using: an ultrasound therapy transducer array adapted to deliver histotripsy pulses into a subject to generate cavitation in the subject at a focal region; an ultrasound probe independently positionable with respect to the ultrasound therapy transducer array and adapted to receive acoustic signals from the subject for producing an ultrasonic image of the subject; a first set of ultrasonic transducer elements at predetermined separated locations fixed with respect to the ultrasonic therapy transducer array and adapted to couple acoustic signals between the first set of ultrasonic transducer elements and the subject; a second set of ultrasonic transducer elements at predetermined separated locations fixed with respect to the ultrasound probe and adapted to couple acoustic signals between the second set of ultrasonic transducer elements and the subject; and a localizing circuit operating to activate transducers of one of the first or second set of ultrasonic transducers to couple independently distinguishable locating acoustic signals into the subject and to monitor a receipt of the independently distinguishable locating acoustic signals at transducers of a different of the first and second set of ultrasonic transducers to deduce a relative location of the ultrasonic probe with respect to the ultrasound therapy transducer, the method comprising: (a) activating transducers of one of the first or second set of ultrasonic transducers to send independently distinguishable locating acoustic signals into the subject; (b) monitor a receipt of the independently distinguishable locating acoustic signals at transducers of a different of the first and second set of ultrasonic transducers to deduce a relative location of the ultrasonic probe with respect to the ultrasound therapy transducer.
13 . The method of claim 12 wherein the second set of ultrasonic transducers is separated in two dimensions and the localizing circuit uniquely localizes the ultrasonic probe with respect to relative translation and rotation of the ultrasonic probe with respect to the ultrasonic therapy transducer.
14 . The method of claim 12 further including at least one image processing circuit communicating with the ultrasound probe to produce an ultrasonic image of the subject from ultrasonic signals received by the ultrasound probe and including: (c) registering a fiducial mark representing the focal region with respect to the ultrasonic image; and (d) displaying an image of the subject registered to the fiducial mark.
15 . The method of claim 12 further including at least one image processing circuit communicating with the ultrasound probe to produce an ultrasonic image of the subject from ultrasonic signals received by the ultrasound probe and including; communicating with the localizing circuit to place a targeting mark representing a desired treatment area on the ultrasonic image; and operating a motorized actuator communicating with the therapy transducer array and operating to steer the focal region into alignment with the targeting mark with respect to the subject.
16 . The method of claim 12 further including registering non-ultrasound image data to the ultrasonic image to display on the display a composite of the ultrasound image and the non-ultrasound image data.
17 . The method of claim 12 wherein first set of ultrasonic transducer elements operates alternatively to provide the independently distinguishable locating acoustic signals and histotripsy pulses.
18 . The method of claim 12 wherein a deduction of the relative location of the different of the first and second ultrasonic transducer elements is based on a speed of sound through the subject between the first and second set of ultrasonic transducers, and further including an iteratively correcting and assumed sound speed using the deduced relative location of the ultrasonic probe with respect to the ultrasonic therapy transducer.
19 . The method of claim 18 wherein the assumed sound speed is corrected using at least one of image data obtained from the ultrasound probe and image data obtained from a non-ultrasound imaging modality.
20 . The method of claim 12 wherein the ultrasound probe is placed within a cavity within the subject.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under EB031007 awarded by the National Institutes of Health. The government has certain rights in the invention. BACKGROUND OF THE INVENTION The present invention relates generally to histotripsy devices using high intensity ultrasound to destroy targeted tissue and in particular to an auxiliary ultrasound imaging probe for a histotripsy device. Histotripsy employs short, intense bursts of ultrasonic acoustic energy from a therapy transducer outside of a patient to generate microbubbles at a focal point within tissue. The rapid expansion and collapse of the microbubbles disrupts tissue cell walls destroying those cells while avoiding the side effects of more invasive treatments such as cryo-or thermal ablation. The energy of a histotripsy device may be targeted using an imaging probe fixed with respect to the therapy transducer. While such a fixed imaging probe desirably maintains registration with the therapy transducer focal spot, it precludes repositioning the imaging probe for better coupling to patient tissue or to avoid obstructions such as bone or air cavities, or the use of intra-cavity probes whose position is not readily fixed. SUMMARY OF THE INVENTION The present invention provides an independently positionable ultrasound probe for a histotripsy system whose image may be registered to the therapy transducer using acoustic signals transmitted through the patient. In some embodiments, these acoustic signals may be produced and detected using the existing therapy transducer and transducer elements of the ultrasound probe and thus may be implemented with minimal hardware modifications to existing histotripsy machines. In one embodiment, the invention provides an ultrasound therapy system including an ultrasound therapy transducer array adapted to deliver histotripsy pulses into a subject to generate cavitation in the subject at a focal region. The invention further provides an ultrasound probe independently positionable with respect to the ultrasound therapy transducer array and adapted to receive acoustic signals from the subject for the production of an ultrasonic image of the subject. A first set of ultrasonic transducer elements is positioned at predetermined separated locations fixed with respect to the ultrasonic therapy transducer array and adapted to couple acoustic signals between the first set of ultrasonic transducer elements and the subject. A second set of ultrasonic transducer elements is positioned at predetermined separated locations fixed with respect to the ultrasound probe and adapted to couple acoustic signals between the second set of ultrasonic transducer elements and the subject. A localizing circuit operates to activate transducers of one of the first or second set of ultrasonic transducers to couple independently distinguishable locating acoustic signals into the subject and to monitor a receipt of the independently distinguishable locating acoustic signals at transducers of a different of the first and second set of ultrasonic transducers to deduce a relative location of the ultrasonic probe with respect to the ultrasound therapy transducer. It is thus a feature of at least one embodiment of the invention to greatly improve the imaging of the treatment site in histotripsy by using an independently positionable ultrasonic probe that is nevertheless registered to the therapy transducer. The second set of ultrasonic transducers may be separated in two dimensions and the localizing circuit may uniquely localize the ultrasonic probe with respect to relative translation and rotation of the ultrasonic probe with respect to the ultrasonic therapy transducer. It is thus a feature of at least one embodiment of the invention to fully characterize the field-of-view of the independent ultrasonic probe to assist the user in orienting the obtained image with respect to the therapy transducer and/or previously obtained reference images of the patient. The system may include at least one image processing circuit communicating with the ultrasound probe to produce an ultrasonic image of the subject from ultrasonic signals received by the ultrasound probe and a compositor communicating with the localizing circuit to register a fiducial mark representing the focal region with respect to the ultrasonic image. A display may communicate with the compositor to display an image of the subject registered to the fiducial mark. Alternatively or in addition, a targeting mark may be placed on the ultrasonic image and used to control the therapy transducer to move its focus into alignment with that targeting mark according to the registration. It is thus a feature of at least one embodiment of the invention to use the registration of the ultrasonic probe to provide the user with an indication of the location of the therapy transducer focal spot in the ultrasonic image or to guide movement of the