We demonstrate a flexible stand-alone, minimally invasive video-endomicroscope with an outer diameter of
1.6 mm and a length of the rigid tip of 6.7 mm that enables surgeons and biologists to image hardly accessible
regions in-vivo in epifluorescence mode. The 60 mg light device improves state-of-the-art objectives by a
double deflection approach using a side-fire fiber in combination with spherical microlenses, GRIN-lenses
with a specific adapted gradient index profile and an extremely miniaturized chip-on-the-tip camera to
achieve an excellent imaging quality. A high NA of 0.7 enables the observation of subcellular features within
the entire field of view with a diameter of 183 μm, assure a bright and high-contrast image and promise a
good overview during the intervention. Ex-vivo measurements of biological samples confirmed the
functionality of the probe.
Objective: When a stereotactic biopsy is taken to enable histopathological diagnosis of a suspected brain tumor, it is
essential to i) do this safely, that is not injure a major blood vessel and ii) to obtain relevant vital material from the
tumor. We are investigating the suitability of Indocyanine Green (ICG) fluorescence for blood vessel recognition and 5-
Aminolevulinic acid (5-ALA) induced Protoporphyrin IX (PpIX) fluorescence for identification of proliferative brain
tumor tissue.
Methods: A fiber-optic endoscopic approach was studied to generate and detect both fluorescence signals. PpIX
concentrations in brain tumors have been measured by chemical extraction. Preliminary equipment was studied in a
mouse model.
Results: PpIX-concentrations in glioblastoma tissue showed high inner- and inter-patient variability, but each patient
out of 15 with interpretable data showed at least one sample with a PpIX-concentration exceeding 2.4 μmol/l, which is
easily detectable by state-of-the-art fiberoptic fluorescence spectroscopy and imaging. The imaging fluoroscope with
30,000 pixels resolution could be introduced through a position controlled stereotactic needle. ICG-fluorescence from
vessels with diameters ≥ 0.1 mm can be detected with a contrast of 2-2.5 against surrounding tissue.
Conclusion: Fluorescence detection during stereotactic biopsy might increase safety and precision of the procedure
significantly.
Objective: Following tumour surgery in the head and neck region, skin flap transplants are usually required to cover the resection
area. The purpose of the development was to provide a simple and reliable means to assess whether the transplanted flap
is sufficiently perfused.
Methods: Fluorescence of intravenously injected Indocyanine green (ICG) was detected with a slightly modified 3-chip CCD
camera. Appropriately coated optical filters allow for excitation of ICG with NIR light and detection of NIR ICGfluorescence
with the blue channel of the camera. In addition, low intensities of white light can be transmitted to allow
for simultaneous display of a remission image in the green and red channels of the camera. Further processing was
performed with a LabVIEW program.
Results: A satisfactory white light image (red, green and blue display (RGB)) could be calculated from the remission images
recorded with the green and red channels of the camera via a look-up table. The look-up table was programmed to
provide an optimized blue intensity value for each combination of red and green values. This was generated using a
reference image. Implementation of image tracking and intensity measurements in regions of interest (ROIs) in the
images is useful to reliably monitor perfusion kinetics of flap and adjacent normal tissue.
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