Differentiation of tumor sensitivity to photodynamic therapy and early evaluation of treatment effect by nuclear medicine techniques

• Published in: Annals of nuclear medicine Vol. 27; no. 7; pp. 669 - 675
• Main Authors: Liu, Jie, Ogawa, Mikako, Sakai, Toshihiro, Takashima, Misato, Okazaki, Shigetoshi, Magata, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.08.2013; Springer Nature B.V
• Subjects: Biological Transport; Cell Line, Tumor; Dihematoporphyrin Ether - metabolism; Dihematoporphyrin Ether - therapeutic use; Fluorodeoxyglucose F18; Humans; Imaging; Medicine; Medicine & Public Health; Nuclear Medicine; Original Article; Photochemotherapy; Radiology; Technetium Tc 99m Sestamibi; Time Factors; Treatment Outcome; Tc-MIBI; Photodynamic therapy (PDT); F-FDG
• ISSN: 0914-7187; 1864-6433
• DOI: 10.1007/s12149-013-0734-4

Objective Our final goal is to develop an appropriate method using nuclear medicine technique for monitoring the effect and prediction of Photodynamic Therapy (PDT) on tumors. The aim of this study is to evaluate the effect of PDT on tumor cells in vitro using 18 F-FDG and 99m Tc-MIBI as tracers. Methods Five tumor cell lines (A431, DU145, H1650, LS180, SHIN3) with varied characteristics were irradiated after incubating for 24 h with several doses of Photofrin (PF). Singlet oxygen was monitored by the near-IR emission detection system during irradiation and generated 1 O 2 was calculated. PDT effects were rapidly evaluated by nuclear medicine techniques (uptake of 18 F-FDG and 99m Tc-MIBI) and traditional methods for cell viability (MTT and trypan blue assays) at 3 h after PDT. Intracellular PF concentration was measured by absorption spectrometer and cell protein content was measured by the Lowry method. 18 F-FDG uptake, 99m Tc-MIBI uptake, singlet oxygen, and intracellular PF concentration were standardized by protein content. Decrease % of 18 F-FDG and 99m Tc-MIBI, MTT, and trypan blue was normalized to the control group. Results Decrease % of 18 F-FDG was exponentially related to decrease % of MTT ( R 2  = 0.650, P  < 0.01) while decrease % of 99m Tc-MIBI was linearly related to that of MTT ( R 2  = 0.719, P  < 0.01). The decrease % of MTT was more sensitive than that of trypan blue. However, neither 1 O 2 nor PF uptake was correlated with sensitivity to PDT. In addition, 18 F-FDG uptake before PDT was linearly related to decrease % of MTT ( R 2  = 0.800, P  < 0.05). Conclusions Our findings in in vitro studies suggest that 99m Tc-MIBI is better than 18 F-FDG for early evaluation of PDT effect, but 18 F-FDG uptake may be used to predict PDT sensitivity before therapy.