Photodynamic therapy and diagnostic measurements of basal cell carcinomas using esterified and non-esterified delta-aminolevulinic acid

Various optical techniques were used to investigate relevant parameters inv olved in photodynamic therapy (PDT) of human basal cell carcinomas (BCCs). The aim of the study was to compare the diagnostic and therapeutic outcome when using topically applied methyl-esterified delta -aminolevulinic acid ( ALA-ME) and delta -aminolevulinic acid (ALA). A total of 35 pathologically verified BCCs in 14 patients were investigated. A diode laser. emitting con tinuous light at 633 nm, was used to induce PDT. The diagnostic measurement s were performed before, during, and after PDT. Laser-induced fluorescence (LIF) was used to monitor the build-up of the ALA/ALA-ME-induced protoporph yrin IX (PpIX), The superficial tissue perfusion was measured with laser-Do ppler perfusion imaging (LDPI) and the temperature of the lesion and the su rrounding tissue was imaged with an IR-camera. A clear demarcation between the lesion and the normal skin was detected with LIF before the treatment f or both PpIX precursors. The fluorescence measurements suggest that PpIX bu ilds up to a higher degree and more selectively in the tumour following ALA -ME as compared to ALA. The LDPI measurements indicate a local transient re striction in blood perfusion immediately post-PDT. The measurement with the IR-camera revealed a temperature rise of about 1-2 degreesC during the tre atment. Copyright (C) 2001 John Wiley & Sons, Ltd.