The employment of contrast agents in photoacoustic imaging has gained significant attention within the past few years
for their biomedical applications. In this study, the use of silica-coated superparamagnetic iron oxide (Fe<sub>3</sub>O<sub>4</sub>)
nanoparticles (SPION) was investigated as a contrast agent in biomedical photoacoustic imaging. SPIONs have been
widely used as Food-and-Drug-Administration (FDA)-approved contrast agents for magnetic resonance imaging (MRI)
and are known to have an excellent safety profile. Using our frequency-domain photoacoustic correlation technique
(“the photoacoustic radar") with modulated laser excitation, we examined the effects of nanoparticle size, concentration
and biological medium (e.g. serum, sheep blood) on its photoacoustic response in turbid media (intralipid solution).
Maximum detection depth and minimum measurable SPION concentration were determined experimentally. The
detection was performed using a single element transducer. The nanoparticle-induced optical contrast ex vivo in dense
muscular tissues (avian pectus) was evaluated using a phased array photoacoustic probe and the strong potential of silicacoated
SPION as a possible photoacoustic contrast agent was demonstrated. This study opens the way for future clinical
applications of nanoparticle-enhanced photoacoustic imaging in cancer therapy.
The Sonix RP is an easy to use ultrasound imaging device that is capable of acquiring high quality images. In addition to supporting the acquisition of multiple data types such as RF, elastography, and color doppler data, the machine is an open ended system providing users with full control over imaging parameters through
an investigational research interface. Since the Sonix RP is PC based and it supports open-source software development toolkits, programs can be developed and executed directly onto the device, thus eliminating the need for extra hardware that is often required for data collection and processing. Due to these advantages, many
universities and research institutes have successfully used the Sonix RP to test and implement their customized solutions for different applications.
Three dimensional heat-induced echo-strain imaging is a potentially useful tool for monitoring the formation of thermal
lesions during ablative therapy. Heat-induced echo-strain, known as thermal strain, is due to the changes in the speed of
propagating ultrasound signals and to tissue expansion during heat deposition. This paper presents a complete system for
targeting and intraoperative monitoring of thermal ablation by high intensity focused acoustic applicators. A special
software interface has been developed to enable motor motion control of 3D mechanical probes and rapid acquisition of
3D-RF data (ultrasound raw data after the beam-forming unit). Ex-vivo phantom and tissue studies were performed in a
controlled laboratory environment. While B-mode ultrasound does not clearly identify the development of either necrotic
lesions or the deposited thermal dose, the proposed 3D echo-strain imaging can visualize these changes, demonstrating
agreement with temperature sensor readings and gross-pathology. Current results also demonstrate feasibility for realtime
computation through a parallelized implementation for the algorithm used. Typically, 125 frames per volume can
be processed in less than a second. We also demonstrate motion compensation that can account for shift within frames
due to either tissue movement or positional error in the US 3D imaging probe.