COMBINED 2D PULSE -ECHO ULTRASOUND AND OPTOACOUSTIC SIGNAL

FIELD OF THE INVENTION

The present invention relates to glaucoma treatment. More particularly, the present invention relates to utilization of combined 2D pulse-echo ultrasound and optoacoustic signal for guiding a laser beam to a specified location and follow up glaucoma treatment at the specified location.

BACKGROUND OF THE INVENTION

Ultrasound imaging of ophthalmic structures, cardiac structures, the vascular systems, the fetus and uterus, abdominal organs such as the liver, kidneys, and gall bladder is a known medical imaging technique. Ultrasound imaging is based on transmission of short ultrasound pulses along a definite direction and receiving the ultrasound echoes from the different tissue interfaces along the propagation direction of the ultrasound pulse. The arrival time of the echoes determine the distance of the echo source from the ultrasound transmitter/receiver. A complete image can be reconstructed by varying the direction of the ultrasound beam and recording the echo intensities as a function of direction and distance. The beam direction can be varied by mechanically moving a single transmit/receive ultrasound transducer, or by electronic means using an array of transducers. Usually the same transducer is used for transmitting and for receiving. This type of image displays tissue interfaces with intensities proportional to the reflection coefficients of these interfaces. Optoacoustic imaging of ophthalmic, vascular and breast structures is also a known method. The optoacoustic imaging is based on transmitting short pulses of light using a laser that can be a narrow beam along a definite

direction, or a spread out beam illuminating a selected volume. The laser beam excites ultrasound in the tissue that now becomes an ultrasound source. The ultrasound is detected by an ultrasound receiver, or array of receivers, to produce a complete image, or a signal distribution along a single laser beam direction. This type of image represents the characteristic of the laser light absorption (function of wave-length), the elasticity, and the thermal properties of the tissue.

Examples of using lasers in optoacoustic imaging are disclosed in several patent disclosures such as: 1. US patent no. 4,385,634 "Radiation induced thermoacoustic imaging" filed in 1981 by Bowen.

2. US patent no. 6,652,459 Ophthalmic uses of lasers" filed in 2001 by Payne et al. This patent teaches a method for analyzing and therapy of the eye utilizing laser-induced ultrasound. 3. US patent no. 5,840,023 "Optoacoustic imaging for medical diagnosis" filed in 1996 by Oraevsky et al. 4. US patent no. 6,309,352 "Real time optoacoustic monitoring of changes in tissue properties" filed in 1998 by Oraevsky et al. Combination of ultrasound echo intensity image with other echo properties such as tissue motion image (Color Flow Imaging), using the Doppler effect to analyze the ultrasound echo, is a known method for imaging of blood flow and tissue motion. The excitation source for both is the same ultrasound source, and the ultrasound echo is analyzed.

In the present invention, the two methods are combined while the optoacousticaly generated ultrasound data is overlaid on the pulse echo ultrasound image, in real time. The method produces a combined image that reflects the pulse echo ultrasound properties together with the optoacoustic properties of the tissue as a function of spatial location.

In most recent years, the need for such combination was expressed by researchers in the industry and examples can be viewed at:

1. Emilianov et al. - "Combined ultrasound, optoacoustic, and elasticity imaging" Proceedings SPIE vol. 5320, (2004).

2. Niederhouser et al. - "Combined ultrasound and optoacoustic system for real time, high contrast, vascular imaging" IEEE transactions on medical imaging vol. 24 no. 4, (2005).

However, to the best of the inventors knowledge, there is no description and no reference in the prior art of how to ^" combine the two methods in order to achieve the results that are needed real time imaging.

Regulation of the intraocular pressure is an accepted treatment for glaucoma. One of the established methods is transscleral laser cyclophotocoagulation of small parts of the ciliary body. The main problem with the available method is the exact localization of the relevant target and the possibility of following up the outcome of the ^v procedure in real time. Localization of an ophthalmic operation is disclosed in DE patent no. 19916653 "Laser cyclo-photocoagulation for treatment of the ciliary body in cases of intractable glaucoma uses opto-acoustic tissue differentiation so that tissue type is more accurately determined and an appropriate dose applied" by Bruder et al., which was published in 2000. However, the procedure that is performed is a pre-operational procedure in which optical characteristics are established so as to plan the operation.

There is a need to provide the surgeon with guidance as to the ophthalmic operation during the operation itself in a real-time manner so as to allow him to accurately perform the operational procedure in order to treat the glaucoma.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus and method for combining image that reflects the pulse echo ultrasound properties together with the optoacoustic properties of the tissue as a function of spatial location.

It is another object of the present invention to provide an apparatus that overlays ultrasound signals generated by a laser beam through the optoacoustic effect on top of a standard, 2D real time ultrasound image.

It is yet another object of the present invention to provide a combination of ultrasound imaging with ultrasound signal generation by laser so as to allow localization of the laser beam as well as the follow up of the treatment results, in real time.

It is therefore provided in accordance with a preferred embodiment of the present invention an apparatus for guiding a laser beam to a predetermined position and follow up treatment at the predetermined position, the apparatus comprising: an ultrasound system and ultrasound prooe adapted to provide real-time 2D ultrasound image; attachment means attached to said ultrasound probe allowing a laser beam to be directed to a predetermined position relative to said ultrasound probe, wherein said laser beam generates radiation that is adapted to be directed to the predetermined position; an array of ultrasound receivers including at least three receivers provided in said attachment means, wherein said array of ultrasound receivers is adapted to sense a signal generated from said radiation;

Furthermore, in accordance with another preferred embodiment of the present invention, the position of the laser beam focus and the position/positions of said signal are overlaid over said real-time 2D ultrasound image so as to establish a target for treatment and the relevant properties of the tissue at the predetermined target position.

Furthermore, in accordance with another preferred embodiment of the present invention, the predetermined position is a ciliary body in the eye. Furthermore, in accordance with another preferred embodiment of the present invention, said signal is an opto-acoustic signal.

Furthermore, in accordance with another preferred embodiment of the present invention, said radiation imparts power for treatment.

Furthermore, in accordance with another preferred embodiment of the present invention, a standoff is provided to said ultrasound probe. Furthermore, in accordance with another preferred embodiment of the present invention, said standoff is a water bag.

Furthermore, in accordance with another preferred embodiment of the present invention, said ultrasound system is a standard ultrasound probe for 2D real-time imaging. Furthermore, in accordance with another preferred embodiment of the present invention, said laser beam is directed by a fiber.

Furthermore, in accordance with another preferred embodiment of the present invention, said laser beam is focused by at least one lens.

Furthermore, in accordance with another preferred embodiment of the present invention, data established from said signal is processed and delivered to a controller adapted to control the generator of said laser beam.

Furthermore, in accordance with another preferred embodiment of the present invention, said ultrasound system is integrated with a fiber adapted to direct said laser beam. It is further provided in accordance with yet another preferred embodiment of the present invention, a method for guiding a laser beam to a predetermined position and follow up treatment at the predetermined position, the method comprising: displaying an ultrasound image of a selected anatomical site using an ultrasound probe; directing and focusing a first laser beam onto the predetermined position on the displayed ultrasound image to generate an opto-acoustic signal; sensing said opto-acoustic signal and determine the location of said opto-acoustic signal relative to the displayed ultrasound image;

directing and focusing a second laser beam onto the predetermined position on the displayed ultrasound image for treatment; directing and focusing said first laser beam onto the predetermined position on the displayed ultrasound image to generate an opto-acoustic signal and sense said opto-acoustic signal for the follow up of the treatment.

In addition, it is provided in accordance with another preferred embodiment of the present invention an apparatus for guiding a laser beam to a predetermined position and follow up treatment at the predetermined position, the apparatus comprising: an ultrasound system and a probe for real-time 2D ultrasound imaging adapted to receive the optoacousticaly generated ultrasound signals by said probe; means to allow a laser beam to be directed and focused to a predetermined position relative to said probe, wherein said laser beam generates an opto-acoustic signal, or alternatively generates power for treatment.

Furthermore, in accordance with another preferred embodiment of the present invention, the position of the laser beam focus and the position/positions of the opto-acoustic signals are overlaid over the ultrasound image so as to establish a target for treatment and relevant properties of the tissue at the predetermined target position.

Furthermore, in accordance with another preferred embodiment of the present invention, the predetermined position is a ciliary body in the eye.

Furthermore, in accordance with another preferred embodiment of the present invention, said probe is a standard electronic array probe.

Furthermore, in accordance with another preferred embodiment of the present invention, said means is a fiber delivering the laser beam is an attachment to said ultrasound system and a probe.

Furthermore, in accordance with another preferred embodiment of the present invention, said fiber delivering ..the laser beam is an integral part of said ultrasound system and a probe.

Furthermore, in accordance with another preferred embodiment of the present invention, said laser beam is directed by a fiber.

In addition, in accordance with another preferred embodiment of the present invention, said laser beam is focused by at least one lens.

BRIEF DESCRIPTION OF THE FIGURES

In order to better understand the present invention and appreciate its practical applications, the following Figures are attached and referenced herein. Like components are denoted by like reference numerals. It should be noted that the figures are given as examples and preferred embodiments only and in no way limit the scope of the present invention as defined in the appending Description and Claims.

Figure 1A illustrates a side view of an ophthalmic ultrasound probe provided with an attachment in accordance with a preferred embodiment of the present invention, adjacent to the treated area.

Figure 1 B illustrates a bottom view of the attachment shown in Figure 1A.

Figure 2 illustrates a block diagram of the apparatus in accordance with a preferred embodiment of the present invention.

Figures 3A-C illustrate different views of an integral apparatus in accordance with a preferred embodiment of the present invention.

Figure 4 illustrates a block diagram of the integral apparatus in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION AND THE FIGURES

The present invention provides a novel and unique apparatus and method to be used especially in ophthalmic operation and more particularly, in operations to regulate intraocular pressure. The apparatus and method are used while combining ultrasound imaging with ultras.ound signal generation by laser so as to allow localization of the laser beam as well as the follow up of the treatment results, in real time.

Generally, the localization and follow up laser pulses are applied through the same optical fiber as the treatment laser beam. This ensures that the treatment is performed at the selected location.

According to one aspect of the present invention, it is provided an attachment that can be fitted to a multitude of standard real time ultrasound imaging probes (transducers). The attachment can include: 1. A fiber that delivers the laser beam; the fiber is fixed at a predetermined position and direction relative to the ultrasound probe. The optical fiber is terminated with a lens adapted to focus the laser beam to a predetermined distance.

2. An ultrasound sensor array consisting of at least three, but not limited to, sensors for receiving the optoacoustic signals. The sensors are located at fixed positions relative to the ultrasound probe.

Reference is now made to Figure 1A illustrating a side view of an ophthalmic ultrasound probe provided with an attachment in accordance with a preferred embodiment of the present invention, adjacent to the treated area. An attachment 27 is attached to an ultrasound (ULS) probe 10 that can be a standard high frequency ultrasound probe adapted for ophthalmic use.

Attachment 27 comprises a fiber 12 adapted to guides a laser beam. A lens

14 or optionally a lens assembly is provided on an expected path of the laser beam that is propagating of fiber 12 wherein lens 14 focuses the laser beam to a predetermined position; the focused laser beam path is shown by numerous 16. Lens 14 is adapted to be variable, or replaceable in accordance with the specific application.

Attachment 27, which is adapted to be adjacent to an eye 18, is further provided with opto-acoustic signal receivers 20 that optionally may be ultrasound sensor array consisting of wide band omni directional (for example 5 to 30 MHz) ultrasound receivers. Reference is now made to Figure 1 B illustrating a bottom view of the attachment shown in Figure 1A. Opto-acoustic signaf receivers 20 are shown to be provided on the bottom portion of attachment 27, on a surface that will be facing the treated area. Lens 14 is provided substantially on the same surface of attachment 27. Returning to Figure 1A, the treated area in the ciliary body 22 of eye 18 is treated with laser beam 16 and produces optoacoustic signal represented by number 24 that is backwardly directed towards attachment 27 of the present invention and is received by opto-acoustic signal receivers 20. Laser beam 16 is generating opto-acoustic signal 24, or alternatively can generate power for treatment (the localization laser source and the treatment laser source can be different lasers coupled into the same fiber, in this case fiber 12).

Optionally, a standoff, for example a water bag 26, is provided on the portion of ULS probe 10 and attachment 27. Water bag 26 is adapted to transfer the ultrasound signal to treated area 22 so as to image the anterior portion of eye 18. A water path of about 1 to 2 cm may be required. Any other means that facilitates transmitting the signals can be used without limiting the scope of the present invention.

The combined apparatus is provided with a hardware and software having the following main features:

1. Determination and display of the spatial position and other physical characteristics of the optoacoustic signals received by the sensor array.

2. Import the real time ultrasound image from a standard ultrasound system and following a geometrical calibration, display it together with the optoacoustic data.

3. Control the integrated system operation, such as the timing of the activation of the localizing laser and the treatment laser, if two separate lasers used, or the activation of the different operation modes of a single laser.

Following is an example of a method of treatment in accordance with a preferred embodiment of the present invention: 1. The target of interest, for example the eye, is scanned with a standard ultrasound system and probe that comprise^ the attachment shown herein in Figure 1 and the expected position of the laser focus is overlaid on top of the real-time ultrasound image.

2. The laser focus is brought to the anatomical site of interest by manipulating the ultrasound probe and attachment assembly.

3. During the scan, a pulsed laser is periodically activated to produce the optoacoustic signal from the anatomical site of interest; the spatial location of the optoacoustic signal is determined by the ultrasound sensors and displayed as an overlay on top of the real time ultrasound image. The displayed optoacoustic signal should coincide with the laser focus position. Slight misalignments are corrected by further manipulating the ultrasound probe and attachment assembly.

4. At that time, a treatment laser signal is activated for preset time duration. 5. At the end of that preset time duration, the pulsed laser is activated to observe changes in the optoacoustic signal as a result of the treatment. It is assumed that the variations reflect the effect of the treatment thus they enable the operator to decide regarding the termination, or repetition of the treatment of the selected anatomical site.

Optionally, the laser producing the optoacoustic signal and the treatment laser can be two separate lasers connected to the same fiber, or it can be a single laser activated at two different modes of operation.

Reference is now made to Figure 2 illustrating a block diagram of the apparatus in accordance with a preferred embodiment of the ■ present invention. The innovation of the present invention is exhibited in the control and data processing unit having main functions as follows:

• Control and data processing hardware 100 that receives ultrasound image data from an ultrasound system 102 that is provided in the apparatus as well as opto-acoustic data that is received from the attachment assembly 104 that is provided adjacent and on ultrasound system 102. Laser or lasers 106 transmit the laser beam through attachment assembly 104 by fiber 108, as shown herein before. The hardware controls also laser or lasers 106. Both data information is overlaid so as to provide the position of the laser beam focus over the ultrasound image.

• Supply triggering for the laser sources.

• Acquire and process the Opto-Acoustic signals to localize their origin and overlay them on the ultrasound image. • Display the amplitude and other relevant properties of the relevant

Opto-Acoustic signal on a PC or laptop 110 having a display monitor 112.

In accordance with another aspect of the present invention, the combined apparatus can be integrally built. Reference is now made to Figures 3A-C illustrating different views of an integral apparatus in accordance with a preferred embodiment of the present invention. ^' An integral assembly of an ultrasound imaging probe 200 and a focusing fiber 202 is provided. The assembly is shown in a cross sectional side view in Figure 3A and 3B wherein in Figure 3B, the apparatus is shown adjacent to a treated eye. Figure 3C illustrates a bottom view of the assembly. A lens 204 is provided at the bottom portion of fiber 202 so as to focus the laser beam to a predetermined position as explained herein before.

Ultrasound probe 200 is used for the standard, pulse echo, ultrasound imaging and for the acquisition of the ultrasound signals generated by the optoacoustic effect. An ultrasound array 200, which can be clearly seen in Figure 3C, can be a phased linear array, or a phased linear convex array, or sector phased array, consisting of a multitude of elements, usually 32, ^" or 64, or 128 elements but not limited to these figures.

Reference is now made to Figure 4 illustrating a block diagram of the integral apparatus in accordance with a preferred embodiment of the present invention. The procedure is basically similar to the procedure shown herein before, however, signal splitting 302 is performed. In signal splitting 302, the signal is received by the common transducer array and is directed to ultrasound system 102 and to the optoacoustic signal processing unit 300.

The signal splitting enables to use the same ultrasound probe for the pulse echo ultrasound and for the optoacousticly generated ultrasound. It should be clear that the description of the embodiments and attached

Figures set forth in this specification serves only for a better understanding of the invention, without limiting its scope as covered by the following Claims.

It should also be clear that a person skilled in the art, after reading the present specification can make adjustments or amendments to the attached Figures and above described embodiments that would still be covered by the following Claims.