Comparison of chlorin-e6 detection efficiency by video systems with excitation wavelengths of 405nm and 635nm

BACKGROUND

Fluorescence diagnostics with two different wide field-of-view imaging systems with fluorescence excitation at 405 nm and 635 nm, respectively, were compared. Both systems include fluorescence quantification and experimental geometry normalization algorithms.

METHODS

A newly developed system with an excitation wavelength of 405 nm was tested on intralipid fluorescent tumor phantoms with chlorin-e6. Both, this new system and a second existing system with an excitation wavelength of 635 nm, were used for fluorescent diagnosis in six patients with basal cell carcinoma and cancer of the oral mucosa. For PDT, a red diode laser with a wavelength of 660 nm was used for all 6 patients. One patient received an additional irradiation using the red LED source of the new system RESULTS: The boundaries of the lesions and the fluorescence intensity were successfully determined by both video systems.

CONCLUSIONS

Both fluorescence imaging approaches showed comparable contrast between diseased and healthy tissues. For oral mucosal cancer, a system with violet fluorescence excitation, bispectral frame analysis, and time-resolved background suppression showed better contrast between the tumor and normal tissue and effective elimination of autofluorescence. Moreover, both systems provided efficient quantification of fluorescence and gave fluorescence indices that were weakly dependent on the distance between the device and the tissue.

New approaches to diagnostics and treatment of cholangiocellular cancer based on photonics methods

Cholangiocellular cancer (CCC) is an oncological disease of the bile ducts characterized by a high mortality rate. To date, the use of standard methods for the diagnosis and treatment of CCC has not been able to reduce mortality from this disease. This work presents the results of fluorescence diagnostics (FD), which consists in using a modified optical fiber and photodynamic therapy (PDT) using a therapeutic laser instead of a low-intensity laser. This technique was tested on 43 patients in a clinical setting. The results obtained indicate a direct correlation between spectroscopic and video FD methods. Furthermore, a direct correlation was found between the photobleaching of a chlorin e6-based photosensitizer, with the commercial names of Photolon Radachlorin and Photoran and stricture regression. Our findings demonstrate the possibility of using a therapeutic laser with a wavelength of 660 nm for both diagnosis and treatment of bile ducts cancer, which results in a significant reduction of the operation time without decreasing its effectiveness.

[Intraoperative fluorescence diagnostics in surgery of intracranial meningiomas: analysis of 101 cases]

Fluorescence diagnostics has been extensively applied in surgery of malignant brain gliomas. However, the use of this technique in surgery of intracranial meningiomas has remained controversial.

OBJECTIVE

The study objective was to assess the sensitivity of 5-aminolevulinic acid-based (5-ALA) fluorescence diagnostics in surgery of brain meningiomas and to clarify the clinical and biological factors that may influence the fluorescent effect.

MATERIAL AND METHODS

The study consistently included 101 patients with intracranial meningiomas of various locations who were operated on using 5-ALA. There were 28 (27.72%) males and 73 (72.27%) females (median age, 54 years). In all patients, surgery was performed using an operating microscope equipped with a fluorescent module; in 24 of these, laser spectroscopy was used. For comparison of chances to observe the fluorescent effect of 5-ALA in patients having meningiomas with different WHO histological grades (Grade I vs Grade II-III), we performed a meta-analysis that included 10 studies (the largest series) on outcomes of surgical treatment of meningiomas using intraoperative fluorescence diagnostics.

RESULTS

Of 101 patients included in this series, observable fluorescence was detected in 95 (94.1%) patients: weak fluorescence in 12 (11.9%), moderate fluorescence in 23 (22.8%) cases, and strong fluorescence in 60 (59.4%) patients. There was no statistically significant relationship (p>0.05) between the rate and intensity of observable fluorescence and the tumor growth pattern (primary/continued), location, WHO grade of malignancy, and histological subtype. In the absence of intraoperative bleeding, tumor fluorescence was statistically significantly brighter (p=0.02). Of 26 patients with hyperostosis, bone fluorescence was observed in 11 (42.3%) cases. There was no statistically significant relationship between administration of dexamethasone, its dose, administration of anticonvulsants, gastrointestinal tract diseases, as well as diabetes mellitus and the fluorescence intensity. There was also no significant relationship between the extent of tumor resection (Simpson scale) and the presence of fluorescence as well as its intensity. Comparison of the observable fluorescence intensity and the laser spectroscopy indicators revealed a significant correlation (r=0.75; p=0.005).

CONCLUSION

Meningioma is a well fluorescent tumor, with the technique sensitivity being 94.1%. In some cases, the use of fluorescence diagnostics in surgery of meningiomas improves identification of residual tumor fragments and enables correction of a surgical approach. To assess the effect of fluorescence diagnostics on the recurrence rate and disease-free duration, further research is required.

Photodynamic therapy with chlorin-based photosensitizer at 405 nm: numerical, morphological, and clinical study

Employment of chlorin-based photosensitizers (PSs) provides additional advantages to photodynamic therapy (PDT) due to absorption peak around 405 nm allowing for superficial impact and efficient antimicrobial therapy. We report on the morphological and clinical study of the efficiency of PDT at 405 nm employing chlorin-based PS. Numerical studies demonstrated difference in the distribution of absorbed dose at 405 nm in comparison with traditionally employed wavelength of 660 nm and difference in the in-depth absorbed dose distribution for skin and mucous tissues. Morphological study was performed at the inner surface of rabbit ear with histological examinations at different periods after PDT procedure. Animal study revealed tissue reaction to PDT consisting in edema manifested most in 3 days after the procedure and neoangiogenesis. OCT diagnostics was confirmed by histological examination. Clinical study included antimicrobial PDT of pharynx chronic inflammatory diseases. It revealed no side effects or complications of the PDT procedure. Pharyngoscopy indicated reduction of inflammatory manifestations, and, in particular cases, hypervascularization was observed. Morphological changes were also detected in the course of monitoring, which are in agreement with pharyngoscopy results. Microbiologic study after PDT revealed no pathogenic bacteria; however, in particular cases, saprophytic flora was detected.

[Clinical guidelines for the use of intraoperative fluorescence diagnosis in brain tumor surgery]

In this paper, we present a review of current literature on the application of intraoperative fluorescence diagnosis and fluorescence spectroscopy using 5-aminolevulinic acid in surgery for various types of brain tumors, both alone and in combination with other neuroimaging methods. Authors' extensive experience with these methods allowed them to develop a set of clinical guidelines for the use of intraoperative fluorescence diagnosis and fluorescence spectroscopy in surgery of brain tumors.