Ultrasound and photoacoustic imaging to guide and monitor photothermal therapy

Photothermal cancer therapy is a potential alternative to surgery and involves selective tissue destruction using thermal energy. Targeted photoabsorbers, used in conjunction with matching a continuous wave laser, make photothermal therapy both noninvasive and tumor-specific. However, to become clinically relevant, there is a need to develop an imaging technique to identify tissue composition and to detect the presence of photoabsorbers in the tumor volume before therapy; to monitor the temperature rise during therapy; and to assess the tumor damage after therapy. In this study, a combined ultrasound and photoacoustic imaging system was designed to assist photothermal therapy. The imaging system was tested on tissue mimicking phantoms, ex-vivo porcine tissue samples, ex-vivo mice and in-vivo mice. First, ultrasound imaging was utilized to differentiate between water-based and lipidbearing tissue. A combined ultrasound and photoacoustic imaging system was then assembled to identify the presence and spatial location of gold nanoparticles. Multiwavelength photoacoustic imaging was used to further confirm the presence of nanoparticles. Temperature monitoring algorithms, using both temperature-dependent time shifts in ultrasound signals and amplitude changes in photoacoustic signals, were developed. Finally, photothermal therapy was carried out on tumor-bearing nude mice using in-vivo ultrasound and photoacoustic imaging to identify the tumor boundary, detect the nanoparticles and monitor the temperature elevation. The results of the studies show that ultrasound and photoacoustic imaging provide complementary and clinically relevant information. Overall, there is potential of using the ultrasound and photoacoustic imaging system to plan, guide and monitor photothermal therapy.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Biomedical Engineering

Grantor

The University of Texas at Austin

Year dc:date.issued

2008

Author dc:creator

• Shah, Jignesh Mukesh, 1979-

Advisor dc:contributor.advisor

• Emelianov, Stanislav Y.

Statement dc:rights

• Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/2152/18123

OAI identifier oai:identifier

oai:repositories.lib.utexas.edu:2152/18123