Laser-induced fluorescence diagnostics of basal cell carcinomas of the skin following topical ALA application

Abstract

Fourteen patients with superficial basal cell carcinomas (BCCs) and fifteen patients with nodular BCCs were investigated by means oflaser-induced fluorescence (LIE) in connection with photodynainic therapy (PDT). Topical application of E'-amino levulinic acid (ALA) was performed six hours prior to the treatment session. Fluorescence spectra were recorded, using a point-monitoring system with an excitation wavelength of 405nm. The measurements were performed in scans over the lesion and the surrounding normal skin before application of ALA, and immediately before and after the laser treatment The selective uptake of the photosensitiser resulted in a fluorescence intensity ratio of 2.4: 1 for superficial BCCs and 2.5:1 for nodular BCCs. If the fluorescence intensity was divided by the autofluorescence, this resulted in a contrast enhancement of about a factor 6 for tumour tissue.In seven patients (five with nodular BCC and two with superficial BCC), additional fluorescence measurements were performed two and four hours following the ALA application, and two hours after the PDT procedure. Thus, the kinetics of the transformation of ALA to protoporphyrin IX (PpIX) could be followed, which indicated that the synthesis of PpIX was more rapid in the tumour than in the normal tissue. After four hours, the PpJX level inside the tumour was saturated, while there still was an accumulation in the surrounding skin. The highest contrast between tumour and normal skin was reached within two hours after the ALA application.

Photodynamic therapy utilising topical δ‐aminolevulinic acid in non‐melanoma skin malignancies of the eyelid and the periocular skin

“…Only in one spot outside the tumour there is some PpIX left due to the fact that this was located outside the border of the laser illumination. Detailed studies of the PpIX production and photodegradation during illumination of noneyeclose BCCs have shown the same pattern (af Klinteberg et al 1996).…”

Laser-induced fluorescence made simple: implications for the diagnosis and follow-up monitoring of basal cell carcinoma

“…Evaluated methods include principle peak ratio, differential normalized fluorescence (DNF), bivariate DNF (2-D-DNF), principal component analysis, and correlation coefficient mapping. [56][57][58][59][60][61][62][63][64] Among these methods, DNF is a simple, straightforward method and provides excellent classification. 56 In the DNF analysis, the diagnostic features are extracted from the difference between the averaged cancerous and averaged normal tissue spectra.…”

In vivo fluorescence spectroscopic monitoring of radiotherapy in cancer treatment

“…Laser-induced fluorescence (LIF) is a real-time spectroscopic technique that can be used to characterize biomedical and morphological changes of different kinds of tissue both in vitro 6 and non-invasively in vivo. In vitro fluorescence measurements are usually recorded from an area of the tissue surface that is larger than the size of the excitation beam.…”