Biomedical imaging

People: Pavel Zakharov, Bruno Weber* and Frank Scheffold

Biomedical imaging with infrared light is a promising research field, which has been attracting increasing attention over the last ten years. It has a high potential as complimentary diagnosis for many common techniques such as x-rays, ultra-sound, magnetic resonance imaging (MRI) or positron emission tomography (PET). Some specialized diagnostic imaging techniques may well be replaced by optical techniques in near future. Only recently a first commercial device for optical mammography has become available; a methods for early detection of breast tumors.


The advantages of biomedical imaging with light are:

  • High resolution in space and time.
  • No radiation danger to health (as compared to x-ray or PET).
  • Relative low cost (compared to MRI, PET and x-ray).

The major setback of optical imaging is low penetration depth. Due to scattering and absorption in tissue, optical techniques with high resolution are limited to roughly one centimeter of depth, whereas x-rays penetrate the body in a straight line and sharp images can be taken in transmission. Never the less the research on light diffusion in tissue is ongoing and with growing knowledge deeper regions become accessible to optical methods.

Biomedical research at the Soft Matter Optics group of the University of Fribourg focuses on a technique called Laser Speckle Imaging (LSI). Anyone who owns a laser pointer has probably observed Speckle once. They occur when laser light illuminates a rough surface or a scattering diffusive medium such as biological tissue.

The resulting speckle pattern contains information about the medium with which the laser light has interacted. By computer processing the CCD image of a speckle pattern valuable physiological information can be extracted (e.g. the dynamics of blood flow). The surging interest in speckles for medical imaging has encouraged further research on the fundamental physics involved and the applied aspects. Besides improving the image processing, we aim to learn more about the relation of speckle contrast and light propagation.

Click the link to get more detailed information on the ongoing biomedical research in Fribourg:

  1. Laser speckle contrast analysis
  2. Laser speckle biomedical imaging (pdf)
  3. Active noise reduction in laser speckle contrast images

*University Hospital Zürich, Institute of Pharmacology and Toxicology, University of Zurich, 8091 Zurich, Switzerland