Of the two kinds of ultrasound pulses, "tracking" beams are used to monitor motion created by the second kind -- high-energy "pushing" beams. The pushing beams actually displace tissue by transferring their momentum to tissues via either absorption or reflection.
Development of the ARFI technique was built on a related and earlier studied phenomenon called Streaming Detection, in which the two kinds of ultrasound waves detect the presence of fluid such as that in benign breast cysts by causing the fluid to move.
"With the Streaming Detection method, we can differentiate between a fluid-filled cystic lesion and a solid lesion simply by applying these high-energy pulses and interspersing them with normal pulses," she said.
"If a lesion in the breast is filled with fluid, it is benign and doctors typically leave it alone," said Nightingale. "If the lesion is solid, it can be either benign or malignant, and they generally have to follow it up either with a biopsy or increased visits to monitor the progress of the lesion."
After initially testing the streaming detection idea on "phantom" materials that respond like those in breast tissue, Nightingale's team collaborated with Duke Medical Center radiology researchers to compare results from Streaming Detection with those obtained through normal clinical evaluations. Results were that 14 of 15 patients previously diagnosed as having simple breast cysts were also identified as having fluid-filled cysts by using acoustic streaming.
Streaming Detection was also tried on 14 other patients with les
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Contact: Monte Basgall
monte.basgall@duke.edu
919-681-8057
Duke University Medical Center
8-Apr-2002