title: Predicting efficacy of photodynamic therapy by real-time FDG-PET in a mouse tumour model.
abstract: Dynamic positron emission tomography (PET) combined with the constant infusion of 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) as a tracer permits real-time monitoring of systemic transient metabolic changes resulting from photodynamic therapy (PDT) in tumour bearing animals. The effect of PDT on tumour FDG uptake rates was evaluated using four different sulfonated phthalocyanine analogs as photosensitizers (PS) in combination with either continuous or fractionated illumination protocols. Mice bearing two EMT-6 tumours were infused with FDG to start PDT 30 min later. Dynamic images were acquired to produce FDG uptake over time for the treated and reference tumours. Practically all PDT protocols induced a reduction in the FDG uptake rates in the treated tumour during PDT, except for the zinc tetrasulfophthalocyanine, when using fractionated light, reflecting the low photodynamic efficacy of this PS. In general, the response to PDT was characterized by a rebound in the FDG uptake rate after illumination. A strong drop in FDG tumour uptake rates during PDT, followed by a strong rebound, together with short delay-to-response times, corresponded to optimal long-term tumour response outcomes. This dynamic FDG-PET protocol provides real-time observations to predict long-term PDT efficacy, while using fewer animals than conventional methods, thus making possible the rapid optimization of treatment parameters.
authors.affiliation: Sherbrooke Molecular Imaging Centre, CHUS, and Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
authors.forename: Nicole
authors.initials: N
authors.lastname: Cauchon
authors.forename: Eric
authors.initials: E
authors.lastname: Turcotte
authors.forename: Roger
authors.initials: R
authors.lastname: Lecomte
authors.forename: Haroutioun M
authors.initials: HM
authors.lastname: Hasséssian
authors.forename: Johan E van
authors.initials: JE
authors.lastname: Lier
mesh_terms: D000818:Animals; D001692:Biological Transport; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010778:Photochemotherapy; D049268:Positron-Emission Tomography; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D019788:Fluorodeoxyglucose F18