Real-Time Fluorescence Imaging Using Indocyanine Green to Assess Therapeutic Effects of Near-Infrared Photoimmunotherapy in Tumor Model Mice.
BACKGROUND
Near-infrared photoimmunotherapy (NIR-PIT) is a cancer therapy that causes an increase in tumor perfusion, a phenomenon termed the super-enhanced permeability and retention effect. Currently, in vivo treatment efficacy of NIR-PIT is observable days after treatment, but monitoring would be improved by more acute detection of intratumor change. Fluorescence imaging may detect increased tumor perfusion immediately after treatment.


METHODS
In the first experiment, athymic nude mouse models bearing unilateral subcutaneous flank tumors were treated with either NIR-PIT or laser therapy only. In the second experiment, mice bearing bilateral flank tumors were treated with NIR-PIT only on the left-sided tumor. In both groups, immediately after treatment, indocyanine green was injected at different doses intravenously, and mice were monitored with the Shimadzu LIGHTVISION fluorescence imaging system for 1 hour.


RESULTS
Tumor-to-background ratio of fluorescence intensity increased over the 60 minutes of monitoring in treated mice but did not vary significantly in control mice. Tumor-to-background ratio was highest in the 1 mg kg-1 and 0.3 mg kg-1 doses. In mice with bilateral tumors, tumor-to-untreated tumor ratio increased similarly.


CONCLUSIONS
Acute changes in tumor perfusion after NIR-PIT can be detected by real-time fluorescence imaging.
['Rosenberg|Adrian|A|', 'Fujimura|Daiki|D|', 'Okada|Ryuhei|R|0000-0003-3589-5054', 'Furusawa|Aki|A|', 'Inagaki|Fuyuki|F|', 'Wakiyama|Hiroaki|H|0000-0001-6388-9888', 'Kato|Takuya|T|', 'Choyke|Peter L|PL|', 'Kobayashi|Hisataka|H|0000-0003-1019-4112']
D000818:Animals D045744:Cell Line, Tumor D003199:Computer Systems D004195:Disease Models, Animal D006470:Hemorrhage D006801:Humans D007167:Immunotherapy D007208:Indocyanine Green D007259:Infrared Rays D008819:Mice, Nude D009336:Necrosis D009369:Neoplasms D061848:Optical Imaging D010789:Phototherapy
cancer therapy NIR fluorescence imaging cancer imaging cancer treatment efficacy new optical instrumentation