Compiled by EuroPhotonics staff
JENA, Germany – A new technique takes
the sting out of skin biopsies – in fact, it allows doctors to look for disease
with no skin contact at all.
The label-free, in vivo 3-D optical biopsy uses a hybrid multiphoton
tomography and coherent anti-Stokes Raman scattering (MPT-CARS) technique to glean
information on skin morphology at a subcellular level; it also determines lipid
and water content.
CARS images of psoriasis at the skin surface. Courtesy of JenLab
The MPT-CARS instrument combines the clinical multiphoton tomograph
DermaInspect from JenLab GmbH and an add-on CARS module based on APE GmbH’s
optical parametric oscillator (OPO). The OPO provides the required second laser
beam for CARS imaging. The CARS signal relies on the wavelength difference between
DermaInspect’s tunable femtosecond pump laser beam and the OPO’s Stokes
laser beam, which must be tuned to match vibrational modes of the molecule of interest.
To image the intratissue lipid distribution in patients who suffer
from psoriasis, cancer and other skin diseases, the tomography MPT-CARS wavelengths
were tuned to 811 and 1053 nm, respectively. The combined mean power of both beams
did not exceed 50 mW. Standard acquisition time for an optical section was 7 s.
Using a piezo-driven, high-numerical-aperture objective, the scientists obtained
up to 20 sections per region of interest at various tissue depths.
They also investigated, in time-lapse studies, the distribution
of topically applied lipid-water emulsions that are of interest to companies in
the cosmetics and pharmaceutical industries.
Clinical studies are being conducted at the Charité hospital
in Berlin as part of the German BMBF project ChemoPraevent to evaluate the potential
of the device for early diagnosis of skin diseases, optimization of treatment procedures,
evaluation of the efficacy of cosmetics and investigation of the side effects of
drugs such as chemotherapy agents.
The findings were published online March 1, 2011, by Laser Physics
Letters (doi: 10.1002/lapl.201110014).