Fluorescence spectroscopy in selective percutaneous nucleotomy using the excimer laser--experimental studies

Abstract

Our intention was to test fluorescence spectroscopy as a possibility for selective laser ablation. In an experimental setup a XeCl excimer laser (308 nm) with pulse energies between 5 and 50 mJ was used for fluorescence excitation in 20 human and 100 pig vertebral segments. Tissue fluorescence was detected via a quartz fiber bundle and analyzed by a polychromator and optical multichannel analyzer. Both low and high energy levels led to a broad band fluorescence of nucleus pulposus, intervertebral muscle, spinal cord and vertebral end plate and a typical fluorescence of anulus fibrosus with peak maxima at 385 and 435 nm. Tissue fluorescence was independent of surrounding medium (with air and normal saline used) and excitation energy. Borderlines between different tissues could be clearly indicated in all cases. Using intensity rations at 350, 385 and 435 nm (I1 = I350/I385, I2 = I385/I435) tissue discrimination was possible in all cases. This results demonstrate, that discrimination between intervertebral disc and surrounding tissue is possible and could be used for selective percutaneous laser nucleotomy in the near future.