An affordable, portable fluorescence imaging device for skin lesion detection using a dual wavelength approach for image contrast enhancement and aminolaevulinic acid-induced protoporphyrin IX. Part II. In vivo testing.

A fluorescence imaging prototype for skin lesion detection and diagnosis using aminolaevulinic acid (ALA) induced protoporphyrin IX (PpIX) was tested in vivo and in the clinic. The prototype was designed as an affordable, portable device to allow contrast enhanced imaging of skin lesions using either the dual excitation wavelength method or the dual emission wavelength method or both. In this study the prototype was tested first on an animal model. Topical application of ALA on defined spots on mouse skin gave PpIX fluorescence after about 3 hours of application. After successful in vivo testing the instrument was tested on basal cell carcinoma patients before ALA-PpIX photodynamic therapy. The patients were topically applied with ALA. After three hours the device was tested (immediately before treatment). The prototype showed good results in terms of contrast enhancement (elimination of unwanted background signals, e.g. autofluorescence) using either contrast enhancement method, both methods achieving similar results. The results achieved in this study, combined with the affordable design of the device, seem to allow cost-effective, contrast-enhanced imaging of skin lesions before or during photodynamic therapy using ALA induced PpIX.