Ultrasound Research Interface

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.

A normal clinical ultrasound user only has access to the ultrasound data in its final processed form, typically a B-Mode image, in DICOM format. For reasons of device usability they also have limited access to the processing parameters that can be modified.Dickie K, Leung C, Zahiri R, Pelissier L. A flexible research interface for collecting clinical ultrasound images. SPIE Multispectral Image Acquisition. 2009 Oct;7494(02)Rohling R, Fung W, Lajevardi P. PUPIL: Programmable Ultrasound Platform and Interface Library. MICCAI. 2003 Nov;(2879);424-431Shamdasani V, Bae U, Sikdar S, Yoo YM, Karadayi K, Managuli R, Kim Y. Research interface on a programmable ultrasound scanner. Ultrasonics. 2008 Jul;48(03);159-168.

A URI allows a researcher to achieve different results by either acquiring the image at various intervals through the processing chain, or changing the 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 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 amplifier (VCA)
*Multiple analog-to-digital converters convert the analog radio frequency (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)
*Beamforming 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 detector and is log compressed into a grayscale format

Multiple signals processed in this way are lined up together and interpolated and rasterized into a 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 MATLAB programs for reading and processing signal and image data
* Software Development Kits (SDKs) for communicating with the URI, signal processing and other specialized modes of operation available on the URI

References

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Ultrasound
Medical ultrasonography
Medical physics