Intra-tumoural PpIX concentrations exhibited pronounced inter- and intra-tumoural variations in glioblastoma, which are directly linked to variable degrees of fluorescence intensity. High intra-tumoural PpIX concentrations with strong fluorescence intensity and complete photobleaching after iPDT seem to be associated with favourable outcome. Real-time monitoring of PpIX fluorescence intensity and photobleaching turned out to be feasible and safe and might be employed for early treatment prognosis of iPDT.

Proper treatment of deep seated brain tumors requires correct histological diagnosis which unambiguously necessitates biopsy sampling. Stereotactically guided sampling of biopsies is widely used but bears the danger of incorrect sampling locations and damage to intracerebral blood vessels. Here, we present a minimally invasive contact endoscopic probe that can be inserted into the tissue inside a standard biopsy needle and allows for fluorescence detection of both tumorous tissue and intracerebral blood vessels. Outer diameter of our contact probe is smaller than 1.5 mm, field-of-view in the range of several hundred microns; the optical design allows for simultaneous detection and visualization of tissue autofluorescence and selective fluorescence signals from deep seated brain tumors and vasculature as shown on in vivo animal models. We demonstrate the tumor detection capability during stereotactic needle insertion in a clinical pilot trial. Using our probe, we expect stereotactic interventions to become safer and more precise and the technology might ultimately be used also for various other kinds of applications.

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An optical filter unit is demonstrated, which uses two successively arranged tunable thin-film optical band-pass filters and allows for simultaneous adjustment of the central wavelength in the spectral range 522-555 nm and of the spectral bandwidth in the range 3-16 nm with a wavelength switching time of 8 ms/nm. Different spectral filter combinations can cover the complete visible spectral range. The transmitted intensity was found to decrease only linearly with the spectral bandwidth for bandwidths >6 nm, allowing a high maximum transmission efficiency of >75%. The image of a fiber bundle was spectrally filtered and analyzed in terms of position-dependency of the transmitted bandwidth and central wavelength.

Objective: Demonstration of whether a low dose of mTHPC (temoporfin , Foscan) is sufficient to induce an efficient clinical response in palliative PDT of non-resectable cholangiocarcinoma (CC), while showing a low side effect profile as compared to the standard Photofrin PDT. Materials and Methods: 13 patients (14 treatment sessions) with non-resectable CC were treated with stenting and PDT (3 mg Foscan per treatment, 0.032-0.063 mg/kg body weight, 652 nm, 50 J/cm). Fluorescence measurements were performed with a single bare fiber for 5/13 patients prior to PDT at the tumor site to determine the fluorescence contrast. For another 7/13 patients, long-term fluorescence-kinetics were measured on the oral mucosa to determine the time of maximal relative fluorescence intensity.Results: Foscan fluorescence could clearly be identified spectroscopically as early as 20 hours after administration. It was not significantly different between lesion and normal tissue within the bile duct. Fluorescence kinetics assessed at the oral mucosa were highest at 72-96 hours after administration. The DLI was therefore extended from 20 hours to approx. 70 hours for the last 5 patients treated. The treatment effect was promising with a median survival of 11 months for the higher grade tumors (Bismuth types III and IV). Local side effects occurred in one patient (pancreatitis), systemic side effects were much reduced compared to prior experience with Photofrin. Conclusion:Combined stenting and photodynamic therapy (PDT) performed with a low dose of Foscan results in comparable survival times relative to standard Photofrin PDT, while lowering the risk of side effects significantly.