Patent Publication Number: US-2021169453-A1

Title: Thermoacoustic method and system configured to interface with an ultrasound system

Description:
FIELD 
     This application relates to a method and system configured to interface with a clinical ultrasound system, and more particularly to a method and system configured to process information at a thermoacoustic imaging system that was transmitted by the clinical ultrasound system and intended for a peripheral device of the clinical ultrasound system. 
     BACKGROUND 
     Typically, ultrasound systems that are utilized in health care have an ultrasound monitor and input devices (keyboard, touch screen, roller ball) that are integral to the system. The ultrasound monitor displays available ultrasound images derived from transducers that connect to the acquisition system of the ultrasound scanner. Any peripheral devices that are tied to the ultrasound system may have their own available displays, but these displays show images that are separate from the image on the ultrasound monitor. 
     A conventional approach may integrate the ultrasound image with a peripheral device on a peripheral display. A graphical element can be superimposed upon an ultrasound image and displayed on the peripheral display. The graphical element can be selected by a user in a tactile manner and used to implement a processing operation. 
     This conventional approach, however, assumes separate control of both the ultrasound and peripheral systems. Hence, the ultrasound and peripheral systems run in a parallel control scheme. A potentially more efficient control method would be to control ultrasound functionality from the peripheral device. Hence, there exists a need for a method and system to utilize a peripheral ultrasound device display to both control ultrasound functionality and peripheral device functionality. 
     SUMMARY 
     A thermoacoustic system configured to receive an ultrasound system output from an ultrasound system which includes a communication port comprises: a radio-frequency emitter; at least one thermoacoustic transducer; a processor; and a display that is integrated with the processor and configured to display an image that is a function of the ultrasound system output and data from said at least one thermoacoustic transducer, wherein the thermoacoustic system is configured to perform an action as a result of receiving the ultrasound system output. 
     A method to utilize a thermoacoustic system that is configured to receive an ultrasound system output from an ultrasound system which includes a communication port wherein the thermoacoustic system comprises: a radio-frequency emitter; at least one thermoacoustic transducer; a processor; and a display that is integrated with the processor and configured to display an image that is a function of the ultrasound system output and data from said at least one thermoacoustic transducer, wherein the thermoacoustic system is configured to perform an action as a result of receiving the ultrasound system output comprises: utilizing the ultrasound system to acquire B-mode image data of a subject; utilizing the B-mode image to estimate a distance between a skin surface at a subcutaneous fat boundary and an intercostal muscle surface of the subject; utilizing the B-mode image to estimate a distance between the skin surface at the subcutaneous fat boundary and a liver surface of the subject; utilizing the ultrasound system to send the ultrasound system output via the communication port, wherein the ultrasound system output comprises said B-mode image data, said estimated distance between the skin surface at the subcutaneous fat boundary and a liver surface of the subject, and said estimated distance between the skin surface at the subcutaneous fat boundary and a liver surface of the subject; receiving the ultrasound system output via the communication port with the thermoacoustic system; and performing the action with the thermoacoustic system as a result of receiving the ultrasound system output. 
     In one embodiment, the ultrasound system output is an image file, such as a JPEG or a medical image file. 
     In one embodiment, the communication port is a universal serial bus (USB) port. In a separate embodiment, the communication port is a wired or wireless communication method such as TCPIP over ethernet or wirelessly networked devices over a WiFi network. 
     In one embodiment, the action is a thermoacoustic data acquisition which comprises the steps of: emitting pulsed radio-frequency energy with the radio-frequency emitter into a subject, wherein the subject absorbs part of the pulsed radio-frequency energy and generates thermoacoustic signals; and receiving said thermoacoustic signals with said at least one thermoacoustic transducer to generate said data. 
     In one embodiment, the ultrasound system output comprises a fat-layer thickness and muscle-layer thickness of the subject. 
     In one embodiment, the processor is configured to process said data in conjunction with the ultrasound system output to calculate a parameter. 
     In one embodiment, the parameter is a fat concentration of tissue of the subject. 
     In one embodiment, said tissue is liver tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will now be described more fully with reference to the accompanying drawings in which: 
         FIG. 1  shows a block diagram of a system with a peripheral system interfaced to an ultrasound system, according to an embodiment. 
         FIG. 2  shows a flow chart of a process, according to an embodiment. 
         FIG. 3  shows a thermoacoustic imaging system, according to an embodiment. 
         FIGS. 4A-4C  show an ultrasound scan, according to an embodiment. 
         FIG. 5  shows a graphical user interface, according to an embodiment. 
         FIG. 6  shows a graphical user interface, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present disclosure discusses a thermoacoustic system and method of use. The thermoacoustic system is configured to work with a pre-existing ultrasound system, without requiring any changes to the ultrasound system. 
     Thermoacoustic imaging describes the use of a pulsed energy source (e.g., light or radio frequency waves) to generate ultrasonic waves in tissue. The waves may be detected with conventional ultrasound equipment and used to create a high-contrast image of the tissue composition. 
     Photo-stimulated thermoacoustics (also referred to as photoacoustic imaging) uses visible or near-infrared light as an energy source and is well-suited for shallow-depth (e.g., 2 cm) applications, such as small-animal imaging for preclinical research, and certain shallow-depth human applications, such as breast imaging. Photoacoustic imaging does not penetrate deeply enough to render images of the human liver, kidneys, and other abdominal organs. 
     Radio-frequency stimulated thermoacoustics (also referred to as thermoacoustic imaging) uses radio frequency energy to penetrate deep into tissue (similar to MRI), allowing for imaging of human anatomy at depths up to about 20 cm with capabilities unavailable to traditional ultrasound and without the radiation or contrast allergy risks of CT. 
     A thermoacoustic system described herein transmits very short radio pulses, using a small fraction of the energy used in MRI scans, which are differentially absorbed in tissue according to water and ion (salt) content. For example, blood and organ tissues, like the liver, have a high water and ion concentration resulting in a greater signal than that from fatty tissue, with a low water and ion concentration, which result in a low signal. The radio pulses are converted by absorption in the tissue into thermoacoustic ultrasound signals, which are detected by a thermoacoustic transducer that is calibrated with a center frequency and bandwidth to maximize thermoacoustic ultrasound reception while minimizing interference. The detected thermoacoustic ultrasound is processed into measurements. 
     The thermoacoustic system enables the generation, display, and review of preset thermoacoustic enhanced ultrasound measurements when used with an ultrasound system for identifying gross regions of interest. The ultrasound system provides positioning (location) data, typically presented as a B-mode image on a display. The ultrasound system combines a pulsed RF source, e.g., operating at a center frequency of about 434 MHz in Europe and 915 MHz in the United States, and an RF applicator that directs the RF energy into the tissue along a desired trajectory. The emitted acoustic intensity (“response”) is detectable with a thermoacoustic transducer. The transducer and pulsed RF source (emitter) can be integrated within an imaging probe. 
     The imaging probe estimates the permittivity (an electrical material property) of an object (e.g., the liver, where the permittivity is strongly dependent on liver fat content). Permittivity is the measure of a material&#39;s ability to store an electric field in the polarization of the medium, expressed in Farads per meter (F/m). As lean tissue is replaced with increasing amounts of fat, its permittivity decreases. 
     The ultrasound system allows for output of data, including images, from a conventional ultrasound imaging system to a peripheral device, such as a printer, storage device (e.g., USB stick), or monitor. As described herein, the thermoacoustic imaging system can receive this data intended for a peripheral device of a conventional ultrasound imaging system and utilize the data for thermoacoustic imaging analysis, view, and storage. 
     In one embodiment, the thermoacoustic system communicates with the pre-existing ultrasound system via a pre-existing universal serial bus (USB) port on the pre-existing ultrasound system. 
       FIG. 1  shows a block diagram of a system with a peripheral system interfaced to an ultrasound system. Shown are an ultrasound input/output (I/O) port  102 , ultrasound imaging system  104 , thermoacoustic imaging system  106 , ultrasound transducer arrays  108 , B-mode image limits  118 , thermoacoustic transducer  110 , radiofrequency (RF) emitter  112 , subject (person)  116 , skin and subcutaneous fat layer  152  (both skin and subcutaneous fat shown as one layer), ultrasound waves  120 , RF energy pulses  122 , intercostal muscle  142 , boundary  126 , liver  128 , boundary locations  134  and  136 , and thermoacoustic multipolar signals  124  and  138 . 
     In one embodiment, the ultrasound imaging system  104  sends a signal to ultrasound transducer arrays  108 , which sends ultrasound waves  120  into subject  116 . The ultrasound waves travel through the subject  116  and are reflected to give locations of skin and subcutaneous fat layer  152 , intercostal muscle  142 , liver  128 , boundary  126  between the liver  128  and intercostal muscle  142 , and boundary locations  134  and  136 . The reflected sound waves are used to generate a B-mode image via the ultrasound imaging system  104  (B-mode image limits  118  shown as dashed line). 
     The ultrasound imaging system  104  includes an I/O port for a peripheral device. The peripheral device may be a printer, storage device (e.g., USB stick), monitor, or the like. The ultrasound imaging system  104  transmits imaging data to the peripheral device for storage, display, printing, or other function of the peripheral device. The I/O port of the ultrasound imaging system  104  may be configured as a universal serial bus (USB) port. When the peripheral device is coupled (e.g., plugged into) the I/O port, a user of the ultrasound imaging system  104  can input an instruction that causes the data to be transmitted to the peripheral device. For example, upon selecting a particular key (e.g., pressing P1 key or activating a foot pedal), data can be saved to a storage device plugged into the I/O port. 
     A user optionally stops imaging with the ultrasound imaging system  104 , since position coordinates are now known. The thermoacoustic imaging system  106  mimics a peripheral device that is configured to communicate with the thermoacoustic imaging system  106 . For example, the ultrasound imaging system  104  interacts with the thermoacoustic imaging system  106  via the I/O port as though the thermoacoustic imaging system  106  is a USB memory storage device. The ultrasound imaging system  104  and thermoacoustic imaging system  106  may use a master-slave network configuration with the ultrasound imaging system  104  functioning as master and the thermoacoustic imaging system  106  functioning as slave. The thermoacoustic imaging system  106  receives the data, which may be used for storage, display, analysis, or other function in the thermoacoustic imaging system  106 . 
     In a separate embodiment, the thermoacoustic imaging system  106  signal mimics a USB storage device with I/O event capability and requests image file data from the ultrasound imaging system  104 , then storing or otherwise utilizing the image file data as discussed in this disclosure. 
     The thermoacoustic imaging system  106  I/O event is configured to initiate the ultrasound imaging system  104  to (a) transfer an ultrasound image file from the ultrasound imaging system  104  to the thermoacoustic imaging system  106 , (b) trigger an event on the thermoacoustic imaging system  106  (e.g., the act of saving and transferring an image from the ultrasound imaging system  104  actually causes the thermoacoustic imaging system  106  to acquire data), or (c) an I/O event on the ultrasound imaging system  104  triggers at least one processing step on the thermoacoustic imaging system  106 . Examples of processing steps on the thermoacoustic imaging system  106  are emitting radio-frequency energy into a subject (person), receiving a thermoacoustic signal with a thermoacoustic transducer, calculating a subject&#39;s fat layer thickness with ultrasound data, calculating a subject&#39;s muscle layer thickness with ultrasound data, and calculating a subject&#39;s liver fat concentration with a combination of thermoacoustic data and ultrasound data. 
     The thermoacoustic imaging system  106  has a visual display  107  that is integrated with a processor  109  and configured to display an image that is a function of a received ultrasound signal and a received thermoacoustic transducer signal, wherein the thermoacoustic imaging system  106  is configured to receive signals from the ultrasound system  104  and receive signals from the at least one thermoacoustic transducer  110 , further wherein the thermoacoustic imaging system  106  is configured to mimic one or more of the specified ultrasound system peripheral devices. 
     To generate thermoacoustic data, the thermoacoustic imaging system  106  initiates the RF emitter  112  to send RF energy pulses  122  into subject  116 . The RF energy  122  pulses are absorbed at different rates in the skin and subcutaneous fat layer  152 , intercostal muscle  142 , and liver  128 . The difference in RF energy absorbed between the intercostal muscle  142  and liver  128  can be measured at the boundary  126 . Thermoacoustic multipolar signals  124  and  138  are generated at boundary locations  134  and  136 . Thermoacoustic transducer array  110  receives the thermoacoustic multipolar signals  124  and  138  and sends the resulting data to the thermoacoustic imaging system  106 , which can calculate a fat concentration in the liver  128  based upon the amplitude and optionally other characteristics of the thermoacoustic multipolar signals  124  and  138 . 
       FIG. 2  shows a method embodiment. The method embodiment utilizes a thermoacoustic system configured to receive an ultrasound system output from an ultrasound system comprising a communication port, the thermoacoustic system comprising: a radio-frequency emitter; at least one thermoacoustic transducer; a processor; and a display that is integrated with the processor and configured to display an image that is a function of the ultrasound system output and data from said at least one thermoacoustic transducer, wherein the thermoacoustic system is configured to perform an action as a result of receiving the ultrasound system output. 
     The method embodiment in  FIG. 2  shows the steps of: utilizing the ultrasound system to acquire B-mode image data of a subject (step  202 ); utilizing the B-mode image to estimate a distance between a skin surface at a subcutaneous fat boundary and an intercostal muscle surface of the subject (step  204 ); utilizing the B-mode image to estimate a distance between the skin surface at the subcutaneous fat boundary and a liver surface of the subject (step  206 ); utilizing the ultrasound system to send the ultrasound system output via the communication port, wherein the ultrasound system output comprises said B-mode image data, said estimated distance between the skin surface at the subcutaneous fat boundary and a liver surface of the subject, and said estimated distance between the skin surface at the subcutaneous fat boundary and a liver surface of the subject (step  208 ); receiving the ultrasound system output via the communication port with the thermoacoustic system (step  210 ); and performing the action with the thermoacoustic system as a result of receiving the ultrasound system output (step  212 ). 
     In one embodiment, a measurement obtained with the ultrasound imaging system  104  is used as an input to a processing step on the thermoacoustic imaging system  106  to calculate a parameter of interest. In one embodiment, measurements of fat and muscle thickness are used as inputs, along with thermoacoustic data acquired from the thermoacoustic transducer  204 , to calculate a fat concentration in a tissue such as liver tissue. 
     The thermoacoustic imaging system  106  spoofs (resembles or mimics) an I/O communication method that the ultrasound imaging system  104  typically uses to communicate with a peripheral device such as a universal serial bus (USB) storage drive. In one embodiment, the ultrasound imaging system  104  functions as a master while the thermoacoustic imaging system  106  functions as a slave in a master-slave control configuration. For example, the thermoacoustic imaging system  106  will send a USB command to the ultrasound imaging system  104  which the ultrasound imaging system  104  will interpret a command to transfer data, such as a B-mode image, to the thermoacoustic imaging system  106 . Handshaking can occur to verify data transfer. 
     As shown in  FIG. 3 , the thermoacoustic imaging system  300  has three components: a console  310 , a probe  320 , and a monitor  330 . The probe  320  comprises the RF emitter  112  and thermoacoustic transducer array  110 . 
     The console  310  is shown as cart-mounted, but can be fixed or integrated into another component. The console  310  contains an RF source, power source, electronics, and firmware/processing. 
     The probe  320  is a handheld probe removable from a probe holder on an ultrasound system console  340 . The handheld probe is tethered to the console  310  on a proximal end. The handheld probe has a patient-surface contacting applicator that contains the RF applicator and thermoacoustic transducer at the distal end. A set of LED lights indicate the current system status. 
     The monitor  300  is shown as a touchscreen monitor (may also be referred to as a “display panel”) for entering data by the user and displaying system information. The monitor  300  is integrated with the probe holder. Although the monitor is shown as a touchscreen, the monitor may be configured for use with additional or alternative inputs (e.g., stylus, mouse, keyboard). 
     In one example, the operation of the thermoacoustic imaging system  106  interfacing with the ultrasound imaging system  104  for a subject&#39;s liver as follows. First, the ultrasound imaging system  104  acquires a B-mode image of a subject, as shown in  FIG. 4A . Then, the thermoacoustic imaging system  106  sends a USB command to the ultrasound imaging system  104 , which enables the ultrasound imaging system  104  to transfer B-mode image data to the thermoacoustic imaging system  106 . Alternately, a user can initiate the data transfer at the ultrasound imaging system  104 . 
     Second, the system uses the B-mode image to (a) estimate a distance between a skin surface (e.g., at subcutaneous fat boundary) of the patient and a surface of an intercostal muscle (as shown by measurement  410  from the ultrasound imaging system  104  in  FIG. 4B ) and (b) estimate a distance between the skin surface of the patient and the surface of a liver capsule (i.e., the subject&#39;s liver) (as shown by measurement  420  from the ultrasound imaging system  104  in  FIG. 4C ). Third, the thermoacoustic display (part of the thermoacoustic imaging system  106 ) displays (a) the estimated distance between a skin surface of the patient and a surface of an intercostal muscle and (b) the estimated distance between a skin surface of the patient and a surface of the patient&#39;s liver. 
     The display (which may be displayed on display  107 /monitor  330  of the thermoacoustic imaging system) presents two slider bars, which a user can adjust to correspond to these distance measurements, as shown in  FIG. 5  and  FIG. 6 . 
       FIG. 5  shows a skin surface to intercostal muscle distance of 5.9 mm  501  and a skin surface to liver capsule distance of 13.2 mm  502 . These are initial estimates, prior to utilizing data from the B-mode image ( FIG. 4A ,  FIG. 4B , and  FIG. 4C ). After utilizing B-mode image data, in  FIG. 6  the sliders are set to boundaries of 3.7 mm for the a skin surface to intercostal muscle distance  601  and 7.7 mm for the skin surface to liver capsule distance  602 . 
     Fourth, the thermoacoustic transducer  110  is positioned in a parallel orientation to the intercostal muscle. 
     Fifth, a switch initiates a thermoacoustic measurement with the thermoacoustic imaging system  106 . 
     Sixth, the thermoacoustic imaging system  106  confirms that there is no interfering ultrasound, that there is sufficient contact between the thermoacoustic transducer and the patient, and that sufficient time has elapsed since the last measurement. 
     Seventh, the thermoacoustic imaging system  106  collects thermoacoustic data. 
     Eighth, the thermoacoustic imaging system  106  uses thermoacoustic data to generate calculated data such as a fat concentration in the subject&#39;s liver. As shown in  FIG. 6 , a graphical user interface  600  on a monitor of the thermoacoustic imaging system displays a measured thermoacoustic signal from the skin to a depth of approximately 5 cm. Two dotted lines correspond to the boundaries of the intercostal muscle and liver capsule. The graphical user interface  600  displays numerical data for the current scan and estimated permittivity (or complex relative permittivity), as well as any previous or subsequent scans from the same subject. An average value is displayed in the bottom right corner, which can be correlated to a known equivalent fat concentration of liver tissue or a proton density fat fraction (terminology used for MRI). 
     Ninth, a switch accepts or rejects the data. If the data is accepted, the system saves the data and allows for another scan. 
     Although embodiments have been described above with reference to the accompanying drawings, those of skill in the art will appreciate that variations and modifications may be made without departing from the scope thereof as defined by the appended claims.