Van der Waals-Zeeman Colloquium
Thursday, 26 May 2009, 16:00h
Optical Coherence Tomography: from plain towards molecular imaging
Prof. Ton van Leeuwen
Biomedical Engineering & Physics, Academic Medical Center, University of Amsterdam
Optical Coherence Tomography (OCT), also described as the optical analogue of US imaging, facilitates in vivo high resolution (1-15 micrometer) cross-sectional imaging of superficial tissues (down to ~2 mm in scattering tissue. In contrast to US imaging, which uses time of flight measurements for depth ranging, OCT depth information is obtained by low coherence interferometry, in which the depth resolution is determined by the coherence length of the broadband light source. The lateral resolution is determined by the focal spot size of the OCT light. In fact, OCT is an extension of confocal microscopy, in which the lateral resolution is determined by the confocal properties (numerical aperture) of the sample arm optics. The combination of confocal and coherence gating allows the detection of back reflected light that has been scattered once or a few times. Consequently, compared to (confocal) microscopy, OCT provides morphological details at significantly greater depths in dense tissue, allowing in vivo video rate imaging on a routine basis for certain clinical applications and as an ‘optical biopsy’ tool in other fields of medicine e.g. gastro-enterology and cardiology. Currently, research in OCT is focusing on the ability to obtain functional information from living tissue, e.g. blood flow, oxygenation, tissue viability with as ultimate goal to obtain molecular information, e.g. via the use of nanoparticles.