Gain deep access to raw imaging data for offline analysis
Digital RF-Mode allows users to acquire, digitize, and save the RF (radio frequency) data from the ultra-high frequency ultrasound signal. Ultrasound transducers convert electrical signals into pressure waves which are transmitted into the tissue (transmit pulse). Differences in tissue density and speed of sound cause reflection and scattering of the transmit pulses, such that a portion of the sound waves reflect back towards the transducer. When these waves reach the transducer, they are converted into a receive electrical signal. The receive signal is composed of multiple reflections which combine together to form an interference pattern known as speckle. This receive signal is commonly referred to as RF data. On the Vevo Imaging Systems, the analog receive signal is first amplified, then sampled (converted into a digital signal), and then processed by the beamformer.
Available Data Formats
Quadrature sampling is used to convert the processed signal into two digital quadrature signals, the I (in-phase) and the Q (quadrature), referred to collectively as the IQ signal. Beamforming is then performed on the IQ signal, followed by further processing to finally generate the images displayed on the system.
If required, a digital representation of the RF signal can be reconstructed from the IQ data. This is accomplished through interpolation of the I and Q signals, and subsequent multiplication by a complex exponential.
Raw Image Data
IQ data can be envelope-detected, log-compressed, and subsequently exported. This envelope format, referred to on the Vevo Imaging Systems as "RAW", is a useful way of accessing image data that correlates exactly to what is seen on the system display. Image data in this format are readily available for offline image processing applications.