The highly malignant brain tumor, glioblastoma multiforme, is difficult to totally resect without aid due to its infiltrative
way of growing and its morphological similarities to surrounding functioning brain under direct vision in the operating
field. The need for an inexpensive and robust real-time visualizing system for resection guiding in neurosurgery has been
formulated by research groups all over the world. The main goal is to develop a system that helps the neurosurgeon to
make decisions during the surgical procedure.
A compact fiber optic system using fluorescence spectroscopy has been developed for guiding neurosurgical resections.
The system is based on a high power light emitting diode at 395 nm and a spectrometer. A fiber bundle arrangement is
used to guide the excitation light and fluorescence light between the instrument and the tissue target. The system is
controlled through a computer interface and software package especially developed for the application. This robust and
simple instrument has been evaluated in vivo both on healthy skin but also during a neurosurgical resection procedure.
Before surgery the patient received orally a low dose of 5-aminolevulinic acid, converted to the fluorescence tumor
marker protoporphyrin IX in the malignant cells. Preliminary results indicate that PpIX fluorescence and brain tissue
autofluorescence can be recorded with the help of the developed system intraoperatively during resection of glioblastoma
multiforme.
In vivo diagnostics of skin diseases as well as understanding of the skin biology constitute a field demanding
characterization of physiological and anatomical parameters. Biomedical optics has been successfully used, to
qualitatively and quantitatively estimate the microcirculatory conditions of superficial skin. Capillaroscopy, laser
Doppler techniques and spectroscopy, all elucidate different aspects of microcirculation, e.g. capillary anatomy and
distribution, tissue perfusion and hemoglobin oxygenation. We demonstrate the use of a diffuse reflectance hyperspectral
imaging system for spatial and temporal characterization of tissue oxygenation, important to skin viability. The system
comprises: light source, liquid crystal tunable filter, camera objective, CCD camera, and the decomposition of the
spectral signature into relative amounts of oxy- and deoxygenized hemoglobin as well as melanin in every pixel resulting
in tissue chromophore images. To validate the system, we used a phototesting model, creating a graded inflammatory
response of a known geometry, in order to evaluate the ability to register spatially resolved reflectance spectra. The
obtained results demonstrate the possibility to describe the UV inflammatory response by calculating the change in tissue
oxygen level, intimately connected to a tissue's metabolism. Preliminary results on the estimation of melanin content are
also presented.
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