LASER‐INDUCED FLUORESCENCE IN MALIGNANT and NORMAL TISSUE OF RATS INJECTED WITH BENZOPORPHYRIN DERIVATIVE

Abstract— Laser‐induced fluorescence was used to characterize the localization of intravenously administered ben‐zoporphyrin derivative‐monoacid (BPD‐MA) 3 h postinjection in different rat tissue types, including an induced experimental malignant tumor. A comparison of the fluorescence properties and the demarcation potential between the newer sensitizer BPD‐MA and four other substances, hematoporphyrin (HP), polyhematoporphyrin ester (PHE), tetrasulfonated phthalocyanine (TSPc) and the commercially available Photofrin earlier investigated, is included. The fluorescence light was induced with a nitrogen laser, emitting at 337 nm. The fluorescence spectrum in the region380–750 nm was analyzed by a polychromator equipped with a diode array detector. The demarcation potential between tumor and surrounding tissue in terms of fluorescence signal for the tumor model used was 2:1 for BPD‐MA. In comparison with the other drugs, HP shows about the same demarcation potential, whereas Photofrin and PHE exhibit about 3 times better and TSPc about 1.5 times better demarcation. By also employing the endogenous tissue fluorescence signature the contrast was enhanced by a factor of about 2 for each of the five drugs.