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Contrast enhancement of optoacoustic imaging techniques

English title Contrast enhancement of optoacoustic imaging techniques
Applicant Frenz Martin
Number 103872
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.04.2004 - 31.03.2007
Approved amount 183'191.00
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All Disciplines (2)

Other disciplines of Physics
Clinical Pharmacology

Keywords (5)


Lay Summary (English)

Lay summary
Optical techniques for tissue imaging and diagnostics keep attractingstrong interest because of their non-invasive and non-ionizing nature.Purely optical techniques, however, must cope with strong scattering oflight in the tissue. Their resolution is limited, despite sophisticateddetection schemes and reconstruction algorithms. Increasingly importantalternative to purely optical techniques is the hybrid method ofoptoacoustic imaging. The idea behind optoacoustic imaging is to harnessboth, the good contrast attainable with optical imaging and the highimaging resolution of ultrasonic techniques: specific interaction of lightwith localized absorption centers generates pressure waves, whichpropagate with little disturbance through the tissue to be detected andanalyzed with techniques similar to conventional ultrasonic imaging. Thepresent project tackels the following two goals: The first goal is thedevelopment of a highly sensitive and transparent transducer array.Ultrasonic waves can be detected with piezo-electrical detectors, whichuse a piezoelectric crystal or foil to convert an acoustic wave into anelectronic signal, or by optical pressure transducers, which measure thepressure-induced changes of index of refraction. Optical transducers havethe advantage of being optically transparent, which makes illumination anddetection at exactly the same location possible. However, theirsensitivity is still much lower, when compared to piezo-electricaldetection. We will therefore develop an optically transparent pressuretransducer based on PVDF covered with a transparent conductive oxide suchas indium-tin-oxide (ITO). The second goal is to exploit consequently thestrength of the optoacoustic technique, namely the selectivity of theoptical excitation of the ultrasound. Up to now, the main source ofcontrast in optoacoustic tissue imaging was given by hemoglobin of blood.Here, we propose to enhance the optical contrast by using an exogeneouscontrast agent which binds selectively to specific target cells.Eventually, we would like to combine the selective imaging with selectivetherapeutic treatment of cells by use of the photothermal effect. The ideais to combine the superb selectivity of immunogold labeling with thepeculiar optical properties of gold nanoparticles. We will study thepossibility of using the strong absorption of bioconjugated goldnanoparticles specially bound to human breast cancer cells to firstselectively image the tumor structure and secondly damage the cells. Abenefit of this approach over photodynamic therapy would be that goldnanoparticles are nontoxic and tissue damage only occurs when thetemperature is locally raised above approximately 60oC. Thus, unlikephotodynamic therapy, concerns regarding unwanted side-effects uponexposure to normal daylight should be minimal.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants


Associated projects

Number Title Start Funding scheme
116343 Selective cell diagnosis and killing by nanoparticle absorption of pulsed laser radiation 01.04.2007 Project funding (Div. I-III)
66622 Optoacoustic monitoring for biomedical diagnostics 01.04.2002 Project funding (Div. I-III)