Ultrasound Research Interface
Encyclopedia
An ultrasound research interface (URI) is a software tool loaded onto a diagnostic clinical ultrasound
device which provides functionality beyond typical clinical modes of operation. Before an ultrasound image can be displayed to the user, it must undergo a series of transformations, typically referred to as the ultrasound processing chain. As data moves through the processing chain, it may be desirable to acquire it at certain intervals, so it can be processed offline for research purposes. A set of processing parameters sent to the ultrasound device control how the processing chain performs its operations. It may also be desirable to change these processing parameters to achieve different imaging results. A clinical ultrasound user only has access to the ultrasound data in its final processed form, referred to as a B-Mode image. The format of the images are typically in the DICOM file format. The clinical user also has limited access to the processing parameters that can be modified; for reasons of device usability, and so the device cannot be put into a state that renders itself inoperable.
The URI provides a means to step beyond the limits of the clinical usage, and allow researchers to acquire data from certain points in the processing chain, as well as change a larger set of processing parameters.
Multiple signals processed in this way are lined up together and interpolated and rasterized into readable image.
Where many diagnostic ultrasound devices have Doppler imaging modes for measuring blood flow, the URI may also provide access to Doppler related signal data, which can include:
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
device which provides functionality beyond typical clinical modes of operation. Before an ultrasound image can be displayed to the user, it must undergo a series of transformations, typically referred to as the ultrasound processing chain. As data moves through the processing chain, it may be desirable to acquire it at certain intervals, so it can be processed offline for research purposes. A set of processing parameters sent to the ultrasound device control how the processing chain performs its operations. It may also be desirable to change these processing parameters to achieve different imaging results. A clinical ultrasound user only has access to the ultrasound data in its final processed form, referred to as a B-Mode image. The format of the images are typically in the DICOM file format. The clinical user also has limited access to the processing parameters that can be modified; for reasons of device usability, and so the device cannot be put into a state that renders itself inoperable.
The URI provides a means to step beyond the limits of the clinical usage, and allow researchers to acquire data from certain points in the processing chain, as well as change a larger set of processing parameters.
Typical B-mode receive processing chain
A typical digital ultrasound processing chain for B-Mode imaging may look as follows:- Multiple analog signals are acquired data from the ultrasound transducer (the transmitter/receiver applied to the patient)
- Analog signals may pass through one or more analog notch filters and a variable-gain amplifierVariable-gain amplifierA variable-gain or voltage-controlled amplifier is an electronic amplifier that varies its gain depending on a control voltage .VCAs have many applications, including audio level compression, synthesizers and amplitude modulation....
(VCA) - Multiple analog-to-digital converterAnalog-to-digital converterAn analog-to-digital converter is a device that converts a continuous quantity to a discrete time digital representation. An ADC may also provide an isolated measurement...
s convert the analog radio frequencyRadio frequencyRadio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
(RF) signal to a digital RF signal sampled at a predetermined rate (typical ranges are from 20MHz to 160MHz) and at a predetermined number of bits (typical ranges are from 10 bits to 16 bits) - BeamformingBeamformingBeamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in the array in a way where signals at particular angles experience constructive interference and while others experience destructive...
is applied to individual RF signals by applying time delays and summations as a function of time and transformed into a single RF signal - The RF signal is run through one or more digital FIR or IIR filters to extract the most interesting parts of the signal given the clinical operation
- The filtered RF signal runs through an envelope detectorEnvelope detectorAn envelope detector is an electronic circuit that takes a high-frequency signal as input and provides an output which is the "envelope" of the original signal. The capacitor in the circuit stores up charge on the rising edge, and releases it slowly through the resistor when the signal falls...
and is log compressed into a grayscale format
Multiple signals processed in this way are lined up together and interpolated and rasterized into readable image.
Data access
A URI may provide data access at many different stages of the processing chain, these include:- Pre-beamformed digital RF data from individual channels
- Beamformed RF data
- Envelope detected data
- Interpolated image data
Where many diagnostic ultrasound devices have Doppler imaging modes for measuring blood flow, the URI may also provide access to Doppler related signal data, which can include:
- Demodulated (I/Q) data
- FFT spectral data
- Autocorrelated velocity color Doppler data
Tools
A URI may include many different tools for enabling the researcher to make better use of the device and the data captured, some of these tools include:- Custom MATLABMATLABMATLAB is a numerical computing environment and fourth-generation programming language. Developed by MathWorks, MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages,...
programs for reading and processing signal and image data - Software Development KitSoftware development kitA software development kit is typically a set of software development tools that allows for the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar platform.It may be something as simple...
s (SDKs) for communicating with the URI, signal processing and other specialized modes of operation available on the URI