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The initial clinical experience of using multi-colour fluorescence imaging has shown that the technique has the potential to reveal malignant tumour tissue, including non-invasive early carcinoma and also precancerous tissue. Further investigations are needed to fully develop the method.

Laser Doppler perfusion imaging offers a new modality for in vivo monitoring of the superficial blood perfusion in biological tissue. In this study, the superficial blood perfusion of malignant non-melanoma skin tumours and the surrounding normal skin was measured in conjunction with photodynamic therapy (PDT) using topical delta-aminolaevulinic acid (ALA)-induced protoporphyrin IX as a photosensitizer. The results clearly show that, in contradiction to PDT with the intravenously administered photosensitizer Photofrin, no direct vascular damage can be seen. With the topical sensitization the blood perfusion is increased immediately after the treatment irradiation. The increased blood flow is seen up to a week after treatment, in a similar way as for an inflammatory reaction. Despite this, all basal cell carcinoma and squamous cell carcinoma in situ lesions in this study healed without any sign of residual tumour after the treatment, suggesting an efficient direct tumour cell destruction induced by PDT.

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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.