Fluorescence imaging and spectroscopy of 5-aminolevulinic acid induced protoporphyrin IX for the detection of neoplastic lesions in the oral cavity.

BACKGROUND: Semiquantitative fluorescence measurements following topical application of 5-aminolevulinic acid (5-ALA) in 16 patients with neoplastic lesions of the oral cavity were performed.

METHODS: Time course and type of porphyrin accumulation were analyzed in neoplastic and surrounding healthy tissue by measuring emission spectra of 5-ALA-induced protoporphyrin IX fluorescence. Fluorescence images in the red and green spectral range from the tumor tissue were recorded with a charge-coupled device camera.

RESULTS: Protoporphyrin IX fluorescence was detected in the oral mucosa of all patients after local application of 5-ALA. Protoporphyrin IX in neoplastic tissue accumulated earlier in comparison with the surrounding normal tissue. The maximum fluorescence contrast of 10:1 between tumor and host tissue was generally seen 1-2 hours after application, allowing a demarcation of tumor tissue even with the naked eye.

CONCLUSION: Labeling of mucosal lesions of the oral cavity with Protoporphyrin IX fluorescence induced by the local application of 5-ALA seems to be a promising diagnostic procedure for neoplastic lesions that are difficult to visualize under white light examination. It is the aim of further investigations to evaluate the relevance of this new diagnostic procedure as a noninvasive and sensitive method for patients with oral cancer.