| dc.description.abstract | Ultrasound mediated drug delivery is an important tool in the fight against
cancer. A new concept called Acoustic Cluster Therapy (ACT ) is under
development, and two pilot imaging studies have been performed on prostate
cancer xenografts in mice. A large amount of raw ultrasound data has been
recorded, but existing software can not perform the required image processing.
The ACT concept is based on clusters of microbubbles and microdroplets.
When exposed to diagnostic ultrasound, the microdroplets become microbubbles.
This phase-shift from liquid to gas is followed by a microbubble growth to
30μm. These phase-shift bubbles get stuck in the small capillaries of the
tumor vasculature.
A complete program has been developed in MATLAB® to process the
raw ultrasound data. The program is tailored to the unique properties of
the phase-shift bubbles, and is able to reduce noise and motion artefacts, to
visualize the contrast agent, and to count the number of ultrasound activated
phase-shift bubbles. The program produces high quality videos, displaying
both free flowing contrast agent and identified, stuck phase-shift bubbles.
The program was validated against a synthesized data set, and we found
that the program counted accurately up to 2 bubbles/mm2. A saturation
was experienced above this threshold, and too few bubbles were counted.
The program was applied to a data set of 16 tumors, divided into four
groups based on different ACT cluster dose and activation ultrasound
settings. A significant difference (p = 0.023) was found between the different
doses, while no significant difference (p = 0.146) was found between the
different activation ultrasound settings. There was neither a correlation between
the tumor size and the number of stuck phase-shift bubbles. The results show
very good correlation with the resultss obtained from manual counting. | |
