ULTRASOUND DEVICES AND METHODS FOR NEEDLE PROCEDURES

BACKGROUND

The present disclosure generally relates to ultrasound imaging systems and medical devices and more particularly to the use of such systems and devices for needle procedures such as biopsies, nerve blocks, and vascular access.

Ultrasound is the most common medical imaging modality after X-ray imaging. The benefits of ultrasound are clear: it is safe, relatively affordable, and fast. Given these benefits, it is no surprise that ultrasound usage is increasing.

Doctors commonly use ultrasound to guide needle placement in patients. For example, where there is a suspicion of breast cancer, a practitioner will use ultrasound on a patient to visualize a suspicious lesion and subsequently guide a needle to acquire a tissue sample from that lesion for testing. Such needle procedures are typically difficult for a number of reasons. First, ultrasound image-guided procedures require expert hand-eye coordination. Second, even under optimal imaging conditions, ultrasound can be difficult for a number of reasons. The resulting ultrasound image does not accurately depict the exact location of tools, such as needles or catheters, due to the specular reflector nature of the materials of the tools. Furthermore, ultrasound images can be colorless, speckled, and difficult to interpret. These factors add to time and complexity of ultrasound-guided procedures while decreasing precision and confidence.

Myriad approaches try to address these and other issues. For example, U.S. Pat. No. 5,329,927 describes a vibrating mechanism coupled to a cannula or needle for Doppler enhanced visualization. Such an arrangement unfortunately requires additional workflow steps including having to sterilize and then attach the vibrating mechanism. Furthermore, smaller ultrasound units may not have Doppler capability required for functionality.

Several needle manufacturers have used echogenic or texturing methods to enhance needle visibility such as that described in U.S. Patent Application Publication 2012/0059247. The texture is generally a dimpling or scoring of a typically smooth surface to reduce the specular reflector properties. Results show that these textured needles only provide slight benefit in ideal conditions.

Another approach to try to effect accurate needle guidance is to restrict the motion of the needle within the ultrasound imaging plane. For example, U.S. Pat. No. 6,485,426 describes a frame that clips onto the ultrasound imaging probe and biopsy needle to direct the needle. Such an arrangement unfortunately also adds steps to workflow and sterilization. Furthermore, the arrangement severely limits the important aspect of range of motion for needle manipulation.

Yet another attempt to improve ultrasound guidance is by way of an electromagnetic (“EM”) position sensing system to detect the needle tip in relation to the ultrasound imaging probe and then annotate the ultrasound image accordingly. Such a system is made by Ultrasonix. However, this system is a proprietary one that requires specific compatibility between the needles and the imaging system and therefore limits the range of procedures. Furthermore EM sensing is costly, requires a calibration step, and is prone to registration error with the ultrasound image.

Ultrasonix also released a spatial compounding feature for enhanced needle visualization. This feature relies on enhancing straight line features in the image, and therefore requires the needle to be in the imaging plane to be useful.

A further attempt to improve ultrasound guidance involves a stylet having an ultrasound transducer associated therewith, wherein the stylet is carried within a hollow biopsy needle. Such an arrangement is described in U.S. Pat. Nos. 5,158,088; 4,407,294; and 4,249,539. In particular, the stylet is a wired, non-disposable device that signals acoustically and/or electronically between the tool in question and the ultrasound imaging device for ultrasound image enhancement. Unfortunately, this attempt also introduces a number of additional steps into the clinical workflow. For example, using the stylet requires an additional step of placing the stylet into the hollow needle. Moreover, as the stylet is nondisposable, it must be sterilized before each use. In addition, because the stylet must be used along with other tools, only certain types of tools are compatible with the system.

Accordingly, an ultrasound device for needle procedures that is simple to use, wireless, disposable, accurate, and compatible with pre-existing ultrasonic diagnostic imaging systems and devices is therefore desired.

SUMMARY

One exemplary embodiment of the disclosed subject matter includes techniques of controlling a transducer. In some aspects, the technique includes transmitting signals to the transducer, receiving signals from the transducer, and automatically adjusting the signals transmitted to the transducer based on characteristic of the signals received from the transducer. The transducer may be an ultrasound transducer. The adjustment of the signal may be performed at least in part by dynamically updating a signal threshold, for example via a proportional-integral-derivative or other type of control loop implemented at least in part by a field programmable gate array. One or more visual, audio, and haptic feedback to a user based on the signals received from the transducer. The signal may be also included a coded excitation communication and/or a Doppler signal. Automatically adjusting the signals transmitted to the transducer may achieve synchronization with an external imaging system. Also, systems that perform the techniques.

This brief summary has been provided so that the nature of the invention may be understood quickly. Additional steps and/or different steps than those set forth in this summary may be used. A more complete understanding of the invention may be obtained by reference to the following description in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Some non-limiting exemplary embodiments of the disclosed subject matter are illustrated in the following drawings. Identical or duplicate or equivalent or similar structures, elements, or parts that appear in one or more drawings are generally labeled with the same reference numeral, optionally with an additional letter or letters to distinguish between similar objects or variants of objects, and may not be repeatedly labeled and/or described. Dimensions of components and features shown in the figures are chosen for convenience or clarity of presentation. For convenience or clarity, some elements or structures are not shown or shown only partially and/or with different perspective or from different point of views.

FIG. 1 is a perspective view of an embodiment of the inventions disclosed herein being used by a medical practitioner to help perform a biopsy;

FIG. 2 illustrates aspects of an embodiment of the inventions disclosed herein and particularly the aspect of a drop-in beacon transducer unit;

FIG. 3 illustrates “before and after” ultrasound images wherein the exact location of the needle tip of an embodiment of the inventions disclosed herein may be seen on the “after” ultrasound image once a drop-in beacon transducer unit is activated;

FIG. 4 illustrates a threaded housing aspect of a drop-in beacon transducer unit;

FIG. 5 illustrates another aspect and particularly an integrated circuit disposed between a transducer film and an adhesive layer;

FIG. 6 illustrates a schematic of an exemplary electrical subsystem;

FIG. 7 illustrates another aspect and particularly a needle device with a transducer and an adapter with electrical subsystem;

FIG. 8 illustrates another aspect of the inventions disclosed herein and particularly a needle device with a transducer and a removable adapter with electrical subsystem, wherein the adapter is in turn coupled to a handle;

FIG. 9 illustrates a bayonet-mount aspect of the disclosed inventions;

FIG. 10 illustrates a slide-and-click aspect of the disclosed inventions;

FIG. 11 illustrates a cartridge-mount aspect of the inventions disclosed herein;

FIG. 12 illustrates a mechanically powered vacuum aspect; and

FIG. 13 illustrates a gas-powered vacuum aspect of the disclosed inventions.

FIG. 14 illustrates a needle visualization system aspect of the disclosed inventions.

FIG. 15 illustrates forming a square shaped beacon signal according to aspects of the disclosed inventions.

FIG. 16 illustrates a block diagram of an electronic system that shapes beacon signals according to aspects of the disclosed inventions.

FIG. 17 illustrates a block diagram of a part of an electronic system according to aspects of the disclosed inventions.

FIG. 18 illustrates a process flow according to aspects of the disclosed inventions.

FIG. 19 illustrates data captured from a beacon transducer according to aspects of the disclosed inventions.

FIGS. 20 to 22 illustrate threshold detection according to aspects of the disclosed inventions.

FIG. 23 illustrates pulse waveform characterization according to as aspect of the disclosed inventions.

FIG. 24 illustrates synchronization with an external system according to aspects of the disclosed inventions.

FIG. 25 illustrates external system timing according to aspects of the disclosed inventions.

FIG. 26 illustrates a modular flex circuit transducer and fabrication thereof according to aspects of the disclosed inventions.

FIG. 27 illustrates integration of a modular flex transducer component into a needle introducer according to aspects of the disclosed inventions.

FIG. 28 illustrates use of aspects of the disclosed inventions with a biopsy needle device.

DETAILED DESCRIPTION

A general problem in the field of needle devices using ultrasound to guide the needle during a needle procedure is an inaccurate representation on an ultrasound imaging display of the actual locale of the needle tip within a patient's body. A general solution is an ultrasound needle device comprising a needle shaft and a transducer integrated within a distal end of the needle shaft.

A technical problem in the field of biopsy devices is accurate tissue sampling. A technical solution implementing the spirit of the disclosed inventions is a needle shaft adapted to cut tissue and a transducer disposed about the distal end of the needle shaft. The transducer may be part of a drop-in, self-contained beacon unit that fits within the needle shaft. The transducer may alternatively include electrical leads connectable to an electrical subsystem housed within an adapter that is connectable to a handle. Alternatively, the electrical subsystem may be housed within a handle connectable to the needle shaft by a bayonet mount configuration, a slide-and-click configuration, or a cartridge configuration. The electrical subsystem is preferably configured to control when the transducer emits an ultrasound pulse. The handle may include all or part of a vacuum means for suctioning in tissue disposed at or near a tissue sampling aperture of the needle shaft.

Potential benefits of the general and technical solutions provided by the disclosed subject matter include a “plug and play” disposable transducer beacon unit designed for use with a needle shaft. Other potential benefits include a disposable needle and transducer unit easily mountable to an adapter that is in turn easily attachable to a handle. Further potential benefits include a biopsy device quickly attachable to a handle that may include efficient mechanical or pneumatic structures for pulling tissue into the device.

A general nonlimiting overview of practicing the present disclosure is presented below. The overview outlines exemplary practice of embodiments of the present disclosure, providing a constructive basis for variant and/or alternative and/or divergent embodiments, some of which are subsequently described.

FIG. 1 is a perspective view of an embodiment of the inventions disclosed herein being used by a medical practitioner to help perform a biopsy. The disclosed inventions need not be limited to use for a biopsy but may instead be used in a variety of needle procedures, including but not limited to nerve blocks, vascular access, and ultrasound-guided catheter diagnostic and therapeutic procedures such as ultrasound-guided ablation. As seen in FIG. 1, a practitioner 106 is using an ultrasound imaging system 100 to extract a tissue sample from a patient 116. The system 100 may include a display 102, computer 104, ultrasound imaging probe 108, and novel needle device 110 according to one or more aspects of the inventions disclosed herein.

The display 102 of the ultrasound imaging system 100 displays the real-time sonogram of the tissue. The practitioner uses this display 102 to visualize, for example, a suspected lesion and needle for guidance. It is here where the needle shaft of the needle device 110 is supposed to be visualized going into the suspected lesion. The probe 108 is used to image the suspected lesion located inside the body of the patient 116.

The needle device 110 includes a handle 114 attachable to a needle 112 that is adapted to cut tissue and an ultrasound transducer integrated with the needle 112. The needle 112 is preferably a hollow shaft having a tissue sampling aperture with one or more sharp surfaces for cutting tissue. The transducer is preferably integrated near or about one end of the needle shaft. “Integrated” means affixed permanently or temporarily inside or outside the needle shaft, or alternatively a part of the needle shaft 118.

In use, the practitioner uses the imaging probe 108 (in one hand) to guide the needle device 110 (in the other hand) by viewing the ultrasound display 102. The needle device 110 may be vacuum assisted to draw tissue into the tissue sampling aperture. Exemplary vacuum assist mechanisms are illustrated in FIGS. 12 and 13. The needle device 110 may be a 20 completely disposable or modular device with disposable needle and transducer.

FIG. 2 illustrates aspects of an embodiment of needle device 110 and particularly a needle 112 having a needle shaft 118 with a distal end 120 and a proximate end 122. The shaft 118 is preferably a hollow cylinder formed by walls having a cut-out to create a tissue sampling aperture 124 disposed between the distal and proximate ends 120, 122. The walls of the tissue sampling aperture 124 are preferably sharp for cutting tissue during a biopsy procedure. A drop-in beacon transducer unit 126 is integrated with the needle shaft 118 at or about the distal end 120 near the tip of the shaft 118. The beacon unit 126 contains an ultrasound transducer 128 and optionally the supporting electronic subsystem 130 and/or power supply 132. In this manner, the beacon unit 126 may advantageously be a “plug and play” disposable component meant for integration with existing needle devices.

FIG. 3 illustrates “before and after” ultrasound images wherein the exact location of the tip of a needle of an embodiment of the inventions disclosed herein may be seen on the “after” ultrasound image once a drop-in beacon transducer unit 126 is activated. Such an invention is clearly highly valuable to those skilled in the art.

The beacon unit 126 may be bonded, threaded, or otherwise attached or fitted to or within some component of the needle shaft 118 being used during the needle procedure. FIG. 4 illustrates a threaded housing aspect of a drop-in unit 126. In particular, FIG. 4 shows that the beacon unit 126 may comprise a housing 134 with external threading 136 and the needle shaft 118 may have internal threading 138 wherein the beacon unit may be screw-fit within the needle shaft 118 or similar arrangement. The housing 134 of the beacon unit 126 may have a hex slot 140 or the like for screwing the unit 126 into the walls of the shaft 118. Alternatively, the housing 134 may also be the needle shaft 118 itself or a sub-component of the needle assembly, as in the case of biopsy needles that have multiple components.

A drop-in beacon unit such as that illustrated in FIGS. 2 through 4 may be fabricated by way of one or more of the following steps. Start with a hollow tube with outer diameter of approximately 3 millimeters and length of approximately 5 to 10 millimeters. Add an integrated circuit for the electrical subsystem, such as system 130 illustrated in FIG. 2. Drill a hole in the side of the tube to accommodate wiring (not shown) and transducer (such as that shown in FIG. 2). Run a wire from the integrated circuit to an electrical interconnect and to the hole and also to an optional power supply. The power supply may be a small, high voltage battery 132 that may fit within the self-contained beacon unit 126 or in the handle 114. Alternatively, the beacon unit 126 may be wirelessly powered by the use of wireless power technology disclosed by one or more of the following United States patents, each of which is incorporated by reference as if fully disclosed herein: U.S. Pat. Nos. 6,289,237; 6,615,074; 6,856,291; 7,027,311; 7,057,514; 7,084,605; 7,373,133; 7,383,064; 7,403,803; 7,440,780; 7,567,824; 7,639,994; and 7,643,312. Next, fill the hollow tube with non-conductive acoustic backing material (not shown) and cure. If a battery is to be used, add the battery 132. Then place piezoelectric material in the hole, completing electrical connection with wiring. Finally, create the acoustic bond and coat the unit 126 with parylene.

Instead of a drop-in beacon unit arrangement such as that illustrated in FIGS. 2 through 4, the beacon transponder unit 126 may comprise a film or flex circuit that is wrapped or bonded onto the needle shaft 118 or needle sub-component. FIG. 5 depicts an integrated film embodiment of a self-contained beacon unit 126. Turning in detail to FIG. 5, transducer 128 may comprise a piezoelectric ultrasound transducer film or material. This film material 142 may either be rigid or flexible with electrodes (not shown) on both the top and bottom surfaces to receive and apply a voltage potential across the transducer 128. An integrated circuit 144 may be fabricated on either a substrate such as a silicon wafer or printed circuit board and be connected to both electrodes of the piezoelectric transducer film 142. The integrated circuit 144 may be coupled with a logic and/or power source to comprise in whole or in part the electrical subsystem 130 for the beacon unit 126. An adhesive layer or patch 146 may serve as a coupling interface between the needle shaft 118 and beacon unit 126. If the beacon unit 126 is not a self-contained or self-powered unit, electrical leads (not shown) may be in communication with the film 142. In such case, when the transducer 128 receives and sends acoustic pulses from and to the imaging probe 108, the leads will be used to conduct the electrical signals to and from the transducer 128 to the electrical subsystem 130.

FIG. 6 illustrates a schematic of an exemplary electrical subsystem of the disclosed inventions, such as electrical subsystem 130 depicted in FIG. 2. The electrical subsystem 130 may particularly be designed such that it is built to receive and send ultrasound pulses automatically through the transducer 128. The electrical subsystem 130 preferably and advantageously is configured to control when an ultrasound pulse from the transducer 128 is to be emitted.

Turning in detail to FIG. 6, a signal from transducer 128 is amplified by amplifier 150 and then sent to a high threshold detector 154 and a low threshold detector 152. If the signal is above the low threshold, the field effect transistor 148 is closed and the amplified signal is sent back to the transducer 128. However, once the amplified signal reaches above the high threshold, the field effect transistor 156 closes and connects the transmitting line to ground 158 to stop the transmission of the signal. In this manner, the system 100 sends back ultrasound pulses to achieve the desired end result, such as the bright beacon-like image on the ultrasound imaging monitor depicted in the “after” version of FIG. 3. Further details of an exemplary electrical subsystem of the disclosed inventions are discussed below with respect to FIGS. 14 to 24.

FIG. 7 illustrates another aspect of an embodiment of the inventions disclosed herein and particularly a needle 112 with a transducer 128 integrated at a distal end of a needle shaft 118. At the opposite end thereof is an adapter 160 with electrical subsystem 130. The adapter 160 has electrical/mechanical connection means 162 for connection to a handle such as that shown in FIG. 1. The integrated unit illustrated in FIG. 7 is advantageously disposable.

FIG. 8 illustrates another aspect of an embodiment of the inventions disclosed herein and particularly a needle device 110 with a transducer 128 integrated at a distal end of a needle shaft 118. At the opposite end thereof is a connector 164 that is attachable to a removable adapter 160 with electrical subsystem 130. The adapter 160 is attachable to a handle 114.

FIG. 9 illustrates a bayonet-mount aspect of the disclosed inventions. As shown in FIG. 9, needle device 110 comprises a needle 112 with needle shaft 118 including a tissue sampling aperture 124, transducer (not shown) disposed at or about aperture 124, adapter 160 with electrical/mechanical connection means 162 and particularly a bayonet configuration thereof, and handle 114 with button 174 for actuating the device 110. In association with adapter 160, the connection means 162 may comprise one or more of the following: a male mechanical interconnect locking mechanism 166, a vacuum channel 168, an electrical (+) lead connect 170, and an electrical (−) lead connect 172. In association with handle 114, the connection means 162 may comprise one or more of the following: a female mechanical interconnect locking mechanism 166a, a vacuum channel 168a, an electrical (+) lead connect 170a, and an electrical (−) lead connect 172a.

FIG. 10 illustrates a slide-and-click aspect of the disclosed inventions. As shown in FIG. 10, needle device 110 comprises a needle 112, adapter 160 with electrical/mechanical connection means 162, and handle 114. Connection means 162 may comprise complementary mechanical and electrical interconnects 178, 178a that slide and click into one another. A vacuum port 176, 176a enables negative pressure to be applied to tissue at or about the distal end of needle 112.

FIG. 11 illustrates a cartridge-mount aspect of the inventions disclosed herein. As shown in FIG. 11, needle device 110 comprises a needle 112, adapter 160 with electrical/mechanical connection means 162, and handle 114. Connection means 162 may comprise a male cartridge insert 180 at the end of needle 112 opposite tissue sampling aperture 124 and a female component 180a in handle 114. The cartridge insert 180 may contain the electrical contacts so the electrical subsystem 130 (not shown) in the handle 114 may be connected to the transducer 128 (not shown) at the distal tip of the needle shaft 118. FIG. 12 illustrates a cross-sectional view of another aspect of an embodiment of the inventions disclosed herein and particularly a mechanically powered vacuum aspect. The integrated tissue-cutting needle device 110 includes a vacuum means in the form of a needle syringe arrangement. In particular, as seen in FIG. 12, a plunger barrel or handle 114 contains a spring 182 so when plunger 184 is depressed (barrel is in “empty” position), the spring 182 resists and applies force to push the plunger 184 back into the “full” position. The tendency of the plunger 184 to return to the “full” position creates negative air pressure in the barrel chamber. The spring 182 need not be within the barrel chamber, as the same force may be achieved from a spring 186 between the plunger shaft and the outside of the chamber.

The needle device 110 illustrated in FIG. 12 may comprise a cutting mechanism that may include two nested, concentric thin-walled tubes 188, 190. The outer tube 188 ends in a sharp cone-tip 192. A spring 198 inside the tip of the outer tube 188 pushes against the inner tube 190. Both tubes 188, 190 may include sampling notches 124, 124a in the tube walls 188, 190, positioned so when the inner tube 190 fully compresses the tip-spring 198, both sampling notches 124, 124a line up and the cutter is considered in the “open” position. The edges of the sampling notches 124, 124a are sharp so when the inner tube 190 slides and the sampling notches 124, 124a becomes “shut,” the action is like a guillotine, cutting whatever tissue is within the notches 124, 124a.

To initiate the vacuum and cutting mechanisms, the user must first depress the plunger 184 to the “empty position.” The air-tight plunger 184, in addition to displacing air from the barrel and compressing the plunger spring 182 or 186, also pushes against the inner needle tube 190, which compresses the needle spring 192. With the plunger 184 in the fully depressed position, cams 194, 196 activate to cock each spring 182, 186 in their compressed position. One cam 196 engages the plunger shaft to hold the plunger 184 in the “empty” position. The other cam 194 engages the inner needle tube 190 to hold the cutter window 124 in the “open” position.

With the needle vacuum and cutter cocked, the user then inserts and guides the needle 112 to the appropriate location within the body of the patient 116. Upon identifying the suspicious lesion, the user engages the vacuum by disrupting the plunger-cam 196. This disruption allows the spring 182 to decompress until the next cam-engagement point on the plunger shaft to create negative pressure in the barrel chamber. This negative pressure is continuous to the sampling notch 124 in the needle 112, which pulls tissue into the notch 124. If the vacuum pressure is not sufficient, the user can disrupt the plunger-cam several more times until the spring is fully decompressed.

Once sufficient tissue is pulled into the sampling notch 124, the user then disrupts the cutter-cam 194. This releases the spring action on the inner cutting tube 190, closing the “guillotine.” With the tissue sample cut, the user removes the needle 112 from the patient 116 and then removes the sample from the needle 112.

FIG. 13 illustrates a cross-sectional view of a gas-powered vacuum aspect of an embodiment of the disclosed inventions. In particular, FIG. 13 depicts a gas-powered vacuum assisted device sub-component of ultrasound device 110 that may be integrated within the handle 114. As seen in FIG. 13, handle 114 may contain a high-pressure gas canister 200 that may contain liquid carbon dioxide, compressed air, or the like. The pressure from the gas in this canister 200 is released when a sharp pin 202 pierces the canister 202, releasing the gas to press up against the positive pressure piston 204 coupled to the negative pressure piston 206 via the physical connection 210. When the negative pressure piston 206 is forced to the right side of FIG. 13, a vacuum is created in the vacuum cylinder 208. This vacuum cylinder 208 extends into the needle 112 via a needle vacuum cylinder attachment on the needle 112 where it terminates at the sampling aperture 124. Thus, when the gas canister 200 is forced into the pin 202 via the canister button cam 214 upon actuation of button 212, a vacuum is applied to the vacuum cylinder 208 in the needle 112. Tissue is then pulled into the sampling aperture 124 where a cutting mechanism, such as sharp walls forming the sample aperture 124, may excise the tissue.

Transducer and Electronic Subsystem

Conventional 2D ultrasound images (B-mode) can be considered a linear or swept raster ensemble of 1D scan lines (A-mode). Basically each scan line is created when the ultrasound imaging probe transmits a focused pulse of ultrasound energy into the patient and then captures the echoed energy. The timing and amplitude of the echoes form a single column of an image of the patient's anatomy. Multiple sequential scan lines cover the field-of-view to form, column by column, a 2D image. Ultrasound works well to image soft tissue. However, needles and other surgical tools are difficult to image reliably because they behave as specular reflectors. This makes the ultrasound-guided procedure more difficult.

Aspects of the disclosed inventions attempt to enhance ultrasound needle visualization by selectively triggering return ultrasound pulses directed towards the imaging probe upon receiving incident transmit energy from the appropriate scan lines. The external imaging system's receiving beamformer treats these generated pulses as it does all return echo energy and the end result is a bright, clear “beacon” signal appearing on the imaging system's display. Since the process of beamforming in the external imaging system is understood, an electronic subsystem according to aspects of the disclosed inventions generates a transmit waveform and precisely controlled time points so that the pulses are received by an external imaging system at the appropriate time and converted into a useful signal that shows the position of the ultrasound transducer. For example, the signal may be used to generate a position “beacon” signal on an external ultrasound or other system's imaging display.

FIG. 14 illustrates a needle visualization system design in an effort to achieve the foregoing. The system includes biopsy needle 300 with beacon transducer 301 and electronic subsystem 302. Transducer 301 and electronic subsystem 302 preferably form a disposable “plug-and-play” package that can be integrated with existing disposable interventional tools.

Beacon transducer 301 is mounted in or on needle 300. The transducer (e.g., an acoustic stack and electrical connectors) should be compact in order to fit into the form factor of the needle. For example, if the transducer is to fit into a 14 AWG core biopsy needle, all components including the transducer and connecting cable must be housed inside the inner trocar shaft so as not to interfere with the biopsy needle's tissue sampling mechanism.

More generally, any type of transducer may be used, for example a transducer incorporated into, part of, or otherwise attached to an instrument used to perform a procedure. For example, the transducer may be mounted in or on a needle shaft, introducer, dilator, catheter or any other tool that can be inserted inside the body and guided with ultrasound imaging. Aspects of the disclosed inventions may also be used with multiple transducers, for example to show two separate locations on a needle (i.e. biopsy needle tip and biopsy needle cutting sheath) or other tool.

An exemplary design and fabrication method for transducer 301 is discussed below with respect to FIGS. 25 to 27.

Electronic subsystem 302 receives incoming electrical signals from the transducer when ultrasonic pulses transmitted by the imaging probe array through the tissue are received. This imaging probe array may be any type of linear, phase, curved-linear, 2D array, mechanically swept imaging probe, or other imaging probe device. Using this technique, a bright marker may be introduced into the B-mode ultrasound image to indicate the tip or other positions of the needle or interventional tool.

This image enhancement preferably is achieved through purely acoustic energy transmission techniques without the need to modify the software or hardware of the external ultrasound imaging system. As one possible result, aspects of the disclosed inventions preferably can work with nearly all ultrasound imaging systems universally. Possible benefits of such broad-ranging applicability include but are not limited to the ability to use this beacon visualization system with any external ultrasound imaging system, the ability to use this beacon visualization system with existing devices such as biopsy needles, having more freedom to update external systems without having to update other components, flexibility in choice of imaging systems, and simplified stock control (e.g., of transducers and other equipment). The system furthermore preferably results in real-time or near real-time imaging, allowing the user to perform procedures such biopsies and other procedures without interruption to the clinical workflow. In addition, less experienced technicians may be able to use the system because they may not have to learn how to compensate for “lag” in generated images.

User outputs from or driven by the electronic subsystem may include imaging information, characteristics about signals sent to and/or received from one or more transducers, information derived from some or all of those characteristics, visual display data, audio feedback, haptic feedback, and/or some combination thereof. In some aspects, data for the outputs may be provided via one or more data output ports such as GPIB and/or USB ports. Output data may be formatted or otherwise applicable to generating a heads-up and/or virtual reality display (e.g., via smartglasses or some other headset) that corresponds with transducer position relative to an external imaging probe. For example, an indicator light or signal appearing in the user's field of view may instruct the user when the transducer(s) and therefore associated needle or other tool is within the imaging plane, thus helping the user guide the tool throughout a procedure.

In an attempt to achieve the foregoing, the electronic subsystem uses received ultrasound pulses to “learn” what type of scanner it is being used with and then to “pair” with that system by synchronizing a pulse pattern and transmitting a pulse waveform that matches that of the imaging system. Part of the learning process according to aspects of the disclosed inventions include dynamic threshold detection. Threshold detection according to aspects of the disclosed inventions includes detecting depth and position in the azimuth and elevation direction relative to an imaging probe:

Depth Position:

The needle transducer should have sufficient sensitivity to detect imaging pulse trains up to a depth of 20 centimeters from the probe, the generally accepted maximum realistic depth for most applications of the subject technology. Different maximum depths may be used.

Azimuthal Plane Position:

Aspects of the disclosed invention capture a signal from each scan line pulse within the pulse train of each imaging frame. Within only 1 frame, the pulse repetition frequency (PRF) of the external imaging system preferably may be calculated by measuring the time between adjacent pulse trains. With each imaging plane, a threshold may be applied to determine how many scan line pulses are above a threshold. This number may be used as an error value for a proportional-integral-derivative (PID) controller. A set point may be establish for the number of scan lines that should be above the fixed threshold, and the error value may be used to modulate the gain applied to the incoming signal. This feedback control mechanisms preferably ensures that system only transmits an excitation pulse to the transducer when the imaging probes scan lines are most directly lined up with the needle transducer. The intended result is that the imaging probe receives pulses from the transducer beacon system only when the scan lines are generated when the imaging aperture is centered directly above the needle transducer. Thus, the imaging screen should display a bright beacon signal in the azimuthal plane precisely at the transducer's location.

Elevation Direction:

From a user perspective it is preferably not to see a beacon signal on the imaging screen when the needle tip itself is not within the imaging plane of the transducer array. Not transmitting a pulse from the needle transducer when the transducer is outside the imaging plane is therefore preferable. One technique for doing so according to aspects of the disclosed inventions is to use a fixed amplitude threshold and variable gain modulated by the error of the PID controller.

Some aspects of the disclosed inventions attempt to precisely control the critical characteristics of the beacon signal in order to maintain a uniform signal at the prices location of the needle tip. These characteristics and their control mechanisms illustrated in FIG. 15. In the figure, block 304 represents an imaging array probe and area 305 represents an imaging field for the probe. Beacon signal 306 in the imaging field is characterized by horizontal position 308, vertical position (depth) 310, signal height 312, and signal width 314. The signal also may be characterized by signal brightness and “blinking” frequency. Audio feedback may also be used to provide real-time information to a user about the beacon signal. Control mechanisms associated with these factors according to aspects of the disclosed inventions include the following:

Beacon Signal

Characteristic
Control Mechanism

Horizontal Position
Select pulses from within a pulse train set of a

single imaging frame to center a signal on the

actual position of the needle transducer.

Vertical Position (Depth)
Send transmit pulses so external imaging array

pulse(s) reach a needle transducer at precisely

the same time.

Signal Width
Select a discrete number of scan lines within

an imaging frame to which the system

responds.

Signal Height
Select a number of transmit waveform cycles.

The transmit signal pulse length and number of

cycles determines the total signal height.

Signal Brightness
Vary a transmit signal amplitude. In some

aspects, signal brightness may be pure white

on B-mode imaging if the transmit signal is at

the top most of the dynamic range of the

receive beamformer of the external imaging

system.

Blinking Frequency
Transmit the pulses at calculated intervals,

which may cause the signal to appear to

“blink.” A blinking signal may be more

conspicuous and therefore more useful for

identifying a position of a needle tip that

includes a transducer. These intervals can be

determined based on the frame rate of the

external imaging system. For example, by

transmitting for 10 consecutive frames and

then not transmitting for 10 consecutive frames

with a frame rate of 20 Hz the beacon signal

will appear to blink at frequency of 1 Hz.

Audio Feedback
Emit an audio signal, for example from the

electronics subsystem, when the transducer

(and therefore needle) is within the imaging

plane, thereby helping the user to keep the

needle within the plain throughout a

procedure.

The foregoing control mechanisms were successfully tested in conjunction with commercial ultrasound scanners. The Appendix to the Specification shows the results of one such test using a Phillips iu22 scanner with linear array probe. The various image tiles in the Appendix show that these mechanisms have the ability to manipulate a beacon signal in the depth position as well as the height and width of the signal. The Appendix forms a part of this disclosure and is hereby incorporated as if fully set forth herein.

Doppler signals may be sent by the electrical subsystem in some aspects of the disclosed inventions. These signals may be interpreted by the external imaging system as echo signals from tissue. The signals may be coded to a certain frequency shift, which may be translated by the external imaging system to a velocity and be displayed in an imaging mode such as color Doppler as a red or blue signal, providing enhanced beacon signal contrast to the user. This doppler signal waveform may be interpreted by the electric subsystem, which in turn may trigger a visual, auditory, or other cue. Examples of such cues include but are not limited to particular colors, sounds, haptic outputs, and the like. The cue(s) may provide an enhanced indication of transducer position during a procedure.

In some aspects, the electrical subsystem may also transmit coded excitation pulses in order to send communication signals other than the ones used to form a beacon signal. These coded excitation pulses could communicate information such as commands, position and orientation information, and/or Doppler signal information.

Aspects of the disclosed inventions adapt to different brands and/or models of external imaging systems and respond with a suitable pulse sequence. FIG. 16 illustrates a block diagram of an electronic system that may be used to perform such operations. System 320 includes microprocessor 322 that communicates with external control/communications/display unit 324. The microprocessor preferably performs the following functions:

- Control interface GUI and buttons.
- Interface with registers in FPGA
- Calculate received pulse frequency spectrum and center frequency
- Control Proportional-integral-derivative (PID) loop
  
  The external control/communications/display unit preferable provides the following functions:
- External Control/Communication/Display
- Receive user input
- Generate Visual, Audio, Data and Haptic Output

The microprocessor sends and receives data to/from FPGA (Field Programmable Gate Array) 326. The FPGA preferably performs the following functions:

- Store control parameters in registers
- Receive echo data from an analog to digital converter for storage in a first-in-first-out (FIFO) data buffer
- Detect pulses based on a threshold
- Dynamically update the threshold based on percentage of highest amplitude of received pulse
- Generate transmit pulse to transducer

The PID control loop includes digital to analog converter 328, time gain compensation unit 330, band pass filter 332, and analog to digital converter 334. The FPGA uses information from the control loop under control of the microprocessor to control pulser 336, which is provided power by supply 338. The pulser feeds transmit/receive switch 340 or another interface for transmission of pulses to a needle or other type of transducer. Received signals from the switch are sent to amplifier 342, which in turn are sent to time gain compensation unit 330 in the PID control loop. Thus, feedback is provided to the FPGA for implementation of the control mechanisms discussed above.

While a PID control loop is illustrated in FIG. 16, aspects of the disclosed inventions are not limited to a PID control loop. Rather, the subject technology encompasses medical imaging systems and/or subsystems that use learning in order to adapt to different external systems and/or to provide more accurate or real-time imaging information.

Likewise, while FIG. 16 shows use of a microprocessor and FPGA, other types of processors may be used. In addition, various of the elements shown in FIG. 16 may be combined, and certain functions may be divided among various elements in different ways from those depicted and described.

Further details of one possible arrangement of FPGA 326 are illustrated in FIG. 17. FPGA 350 includes low pass filter 352, pulse detection unit 354, noise rejection unit 356, registers and interface unit 358, threshold and mean update unit 360, FIFO buffer 362, transmit pulse generation unit 364, and clock 366. In some aspects, these elements interact as depicted in FIG. 17 to perform the functions of FPGA 326 discussed above with respect to FIG. 16. Details of some possible techniques for performing these operations are described below.

FIG. 18 illustrates a process flow according to aspects of the disclosed inventions. Flow 370 includes learning processes 372, system response 374, and system control 376. Learning process 372 attempt to learn the pulsing pattern of an external imaging system. System response 374 attempts to generate pulse formation and synchronization. System control 376 handles user interface controls and user indicators, for example interfaces to audio and visual indicators.

As depicted, learning process 372 includes threshold detection 378, pulse characterization 380, and external system timing 382. Threshold detection includes the following:

- Compare current pulse(s) to previous pulse(s) from memory
- Update learning data
- Control pulse amplitude
- Control pulse count
  
  Pulse characterization includes the following:
- Fast Fourier Transform
  - Calculate center frequency
  - Calculate bandwidth
- Pulse count
  
  External system timing includes the following:
- Pulse repetition frequency
- Frame rate

As depicted, system response 374 includes external system timing 384 and pulser 386. External system timing includes the following:

- Construct pulse frame pattern
- Synchronize transmit with receive pattern
  
  Pulser includes the following:
- Transmit pulse shape (pulse, sine wave, square wave)
- Generate pulse with learned pulse frequency
- Generate pulse with learned pulse count

Transmit/receive switch 388 controls whether pulses are transmitted to or received from transducer 390. In operation, pulses are transmitted and received, information about the received pulses are used during flow 370 to determine how to modify the pulses to adapt a particular external imaging system, pulse characteristics are modified, and pulses are again transmitted/received.

In more detail, the processing algorithm preferably uses several characterization steps to learn about an external imaging system. FIG. 19 shows plots 400, 402, and 404 at three times scales for a signal received at a needle transducer from an ultrasound imaging probe. In plot 400, the signal exhibits a periodicity of ˜27 milliseconds. This demonstrates two successive scan line ensemble frames for an imaging rate of ˜35 frames per second. Plot 402 zooms in on a single frame and the individual scan line transmit events can be resolved. The amplitudes are based on the spatial focusing of each scan line. Energy directly focused at the needle transducer will yield a higher amplitude signal than transmit energy focused elsewhere. These raster scan lines create one 2D image frame. Plot 404 zooms in on a single scan line, thereby showing that the received pulse is approximately 1 microsecond in half-max duration. The pulse yields a strong primary spike at 633 microseconds but reverberations characteristic of “ring-down” are likely caused by narrow bandwidths. This type of analysis may be used to characterize signals to/from a beacon transducer according to aspects of the disclosed inventions.

FIGS. 20 to 22 illustrate threshold detection according to aspects of the disclosed inventions, for example as may be performed by threshold detection 378 in FIG. 18. The input to threshold detection may include pulse waveform data, and the output may include qualifying pulse pattern and timing. In some aspects, the threshold level is variable and is automatically raised and lowered in order to have a fixed number of pulses PASS above the threshold level. By setting a fixed number of pulses to “Qualify”, the width of the beacon signal may be controlled. FIG. 20 illustrates a threshold level that is too low: too many pulses qualify. FIG. 21 illustrates a threshold level that is too high: too few pulses qualify. FIG. 22 illustrates an appropriate threshold level: an appropriate number of pulses qualify.

FIG. 23 illustrates pulse waveform characterization according to aspects of the disclosed inventions, for example as may be performed by pulse characterization 380 in FIG. 18. The input to pulse waveform characterization may include pulse waveform data, and the output may include pulse waveform characteristics. In some aspects, the threshold level is variable and is automatically raised and lowered in order to have a fixed number of pulses PASS above the threshold level. By setting a fixed number of pulses to “Qualify”, the width of the beacon signal may be controlled. Processing and calculations preferably are performed in an FPGA and/or microprocessor (e.g., microcontroller). The output pulse waveform characteristics may include, for example, pulse frequency, pulse amplitude, number of pulse cycles, pulse modulation (frequency or amplitude), and pulse pattern (i.e. multi-cycle duty factor, pulse train pattern for Doppler).

FIG. 24 illustrates synchronization with an external imaging system according to aspects of the disclosed inventions. System 408 in FIG. 24 includes electronic subsystem 410 according to aspects of the disclosed inventions, for example including features described above. According to some aspects, the electronic subsystem creates a communications link with external visualization system 412 by synchronizing with the external system.

For example, by establishing a method of echo data decoding and encoding, the electronics sub-system may be able to encode position data into its transmitted pulses. These transmitted pulses may be sent by the needle transducer, received by the external imaging probe, and then integrated with the received echo data in the imaging system's beamforming process. This technique may be used to transmit data for the purpose of needle (or other instrument) visualization. In some aspects, the data transfer format is essentially analog acoustic energy pulses traveling between the ClariTrac transducer and the external ultrasound probe.

In more detail, the automated nature of the signal processing depicted in FIG. 24, including the decoding and encoding processes, may permit pairing (i.e., synchronization) with many if not all external imaging systems. To achieve this pairing, the electronic subsystem according to some aspects (1) receives and characterize pulses from the external imaging system probe, (2) generates a transmit pulse waveform, for example as described above, and (3) transmits it in a pattern synchronized with that of the external imaging system probe. The synchronization processes attempts to facilitate production of a clear, stable, and precisely located beacon signal on the external ultrasound system's imaging display. Pairing preferably is possible with external systems that use various arrays such as linear and phase arrays operating in various modes such as B-Mode and Doppler-Mode.

FIG. 25 illustrates external system timing according to aspects of the disclosed inventions, for example as may be performed by external timing 382 in FIG. 18. The input to external timing may include pulse waveform data, and the output may include an external system pulse pattern. In some aspects, a new pulser pattern set is created based on the received pulse pattern, and techniques according to the subject technology (e.g., learning and response) continuously adjust the time position of the pulse command signal pattern to synchronize with the external imaging system. Box 414 in FIG. 25 illustrates successful shifting of a pulse pattern to synchronize with an external system.

Modular Flex Circuit Transducer

Aspects of the disclosed inventions include a batch fabrication process that combines flex circuit interconnect technologies with needle fabrication techniques, creating an inexpensive modular solution for ultrasound transducer production that may work with a broad range of existing needle designs including those currently used by medical device companies FIG. 26 illustrates a modular flex circuit transducer and fabrication thereof according to aspects of the disclosed inventions. As shown, piezoelectrical (PZT) elements may be laminated in a single flex circuit panel and subsequently separated to form discrete, modular transducer components. These components may have the electrodes already connected and may be ready for integration with a needle assembly.

FIG. 27 illustrates integration of a modular flex transducer component into a needle introducer according to aspects of the disclosed inventions. In the figure, individual ultrasound transducer (A) is integrated into the polymer needle introducer extrusion to form the (B) finished Introducer. The cross section of an 11 AWG polymer extrusion is shown in (C). The introducer's circular inner lumen may accommodate a large core biopsy needle. This design is intended to allow introducers of various gauges to be made by only changing the polymer extrusion sub-component of the introducer.

FIG. 28 illustrates use of aspects of the disclosed inventions with a biopsy needle device. During a biopsy procedure, the needle and introducer (A) is advanced to a lesion under the guidance of the beacon transducer. Once the lesion is reached as confirmed by the beacon signal on the imaging screen, the needle core may be (B) extended from the introducer. To sample the tissue, the (C) sampling aperture may be shut rapidly under the force of a spring loaded mechanism in the biopsy handle. The needle then may be extracted from the introducer to collect the tissue sample. The introducer may remain at the lesion location throughout the procedure, enabling multiple passes to be performed with the beacon signal confirming the precise location from where the samples are taken.

Generality of Invention

While certain embodiments have been described, the embodiments have been presented by way of example only and are not intended to limit the scope of the inventions. Indeed, the novel devices and methods described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the devices and methods described herein may be made without departing from the spirit of the inventions. For example, the terms “aspect,” “example,” “preferably,” and the like denote features that may be preferable but not essential to include in some embodiments of the invention. In addition, details illustrated or disclosed with respect to any one aspect of the invention may be used with other aspects of the invention. Additional elements and/or steps may be added to various aspects of the invention and/or some disclosed elements and/or steps may be subtracted from various aspects of the invention without departing from the scope of the invention. Singular elements/steps (e.g., “unit,” “element,” and “structure”) imply plural elements/steps and vice versa. Some steps may be performed serially, in parallel, in a pipelined manner, or in different orders than disclosed herein. Many other variations are possible which remain within the content, scope, and spirit of the invention, and these variations would become clear to those skilled in the art after perusal of this application. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

ULTRASOUND DEVICES AND METHODS FOR NEEDLE PROCEDURES

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