Quantification of phthalocyanine concentration in rat tissue using laser-induced fluorescence spectroscopy

Quantification of photosensitizer concentration in tissue should improve planning and outcome of photodynamic therapy. Laser-induced fluorescence (LIF) can be used to measure in vivo fluorescence of photosensitizers in tissue. This study was designed to determine if in vivo fluorescence intensity of chloroaluminum phthalocyanine tetrasulfonate correlates with its concentration in different rat tissues. Following LIF measurements, the animals were humanely euthanized and the concentration of phthalocyanine in different tissues was determined using chemical extraction technique. The correlation of phthalocyanine fluorescence intensity and its concentration was determined for each tissue using Pearson product-moment correlation analysis. A strong correlation between in vivo phthalocyanine fluorescence intensity and its concentration was found for spleen, kidney, liver, and chemically induced mammary adenocarcinoma. Low correlation was found for thigh skin and planum of nose. No correlation was found for thigh muscle and tongue.