Radiation Force Based Imaging: Clinical Promise Shown

The American Roentgen Ray Society (ARRS) is reporting that a new study out of Duke Medical Center has demonstrated potential for a novel imaging modality to distinguish between solid breast masses and fluid-filled cysts. The technique called “streaming detection” ultrasound is based on a broader modality called the acoustic radiation force impulse (ARFI) imaging.
This is how the group at Duke describes the working principles of ARFI:

Acoustic radiation force is a phenomenon associated with the propagation of acoustic waves through a dissipative medium. It is caused by a transfer of momentum from the wave to the medium, arising either from absorption or reflection of the wave. This momentum transfer results in the application of a force in the direction of wave propagation. The magnitude of this force is dependent upon both the tissue properties and the acoustic beam parameters. The duration of the force application is determined by the temporal profile of the acoustic wave. We are studying the potential for imaging the response of tissue to acoustic radiation force for the purpose of characterizing the mechanical properties of the tissue. When the duration of the radiation force is short (less than 1 millisecond), the tissue mechanical impulse response can be observed. Thus, this imaging method is called Acoustic Radiation Force Impulse (ARFI) imaging. ARFI imaging has many potential clinical applications, including: detecting and characterizing a wide variety of soft tissue lesions, and identifying and characterizing atherosclerosis, plaque, and thromboses.
When acoustic radiation force is applied to a fluid, the fluid begins to flow, a phenomenon called ‘acoustic streaming’. We have demonstrated that this fluid motion can be generated in vivo in human cysts and it can be detected using Doppler processing. The detection of acoustic streaming is then used to differentiate fluid-filled (or cystic) from solid lesions. This imaging modality is termed ‘Streaming Detection’…
We have shown that in breast cysts (i.e. fluid-filled breast lesions), acoustic radiation force ‘stirs’ the fluid, and this fluid motion can be detected using Doppler methods. If acoustic streaming is detected, the lesion can be diagnosed as a cyst, because streaming cannot be generated in a solid lesion.

Image Caption: Clip of Streaming Detection in a cyst phantom, where high intensity pulses are focused along the Pulsed Doppler cursor line (the vertical white line in the center of the lesion). The resulting fluid motion is being detected both with color Doppler (as shown in the blue and green motion away from the transducer, which is located at the top of thie image) and spectral Doppler (the horizontal white spectral display on the bottom half of the image, with motion away from the transducer apparent in that the spectrum is below the 0 baseline). (Duke U.)
More at Radiation Force Based Imaging Group at Duke University Medical Center (see also here)…