Hiroyasu Morikawa1, Shin Toyota2, Kenji Wada2, Sawako Uchida-Kobayashi3, Norifumi Kawada3, Hiromichi Horinaka2. 1. Department of Premier Preventive Medicine, Graduate School of Medicine, Osaka City University, Abeno Harukas 21F, 1-1-43 Abenosuji, Abeno, Osaka, 545-6090, Japan. morikawa-h@med.osaka-cu.ac.jp. 2. Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Japan. 3. Department of Hepatology, Graduate School of Medicine, Osaka City University, Osaka, Japan.
Abstract
PURPOSE: Indocyanine green (ICG) accumulation in hepatocellular carcinoma means tumors can be located by fluorescence. However, because of light scattering, it is difficult to detect ICG fluorescence from outside the body. We propose a new fluorescence imaging method that detects changes in the intensity of ICG fluorescence by ultrasound-induced temperature changes. METHODS: ICG fluorescence intensity decreases as the temperature rises. Therefore, it should theoretically be possible to detect tissue distribution of ICG using ultrasound to heat tissue, moving the point of ultrasound transmission, and monitoring changes in fluorescence intensity. A new probe was adapted for clinical application. It consisted of excitation light from a laser, fluorescence sensing through a light pipe, and heating by ultrasound. We applied the probe to bovine liver to image the accumulation of ICG. RESULTS: ICG emits fluorescence (820 nm) upon light irradiation (783 nm). With a rise in temperature, the fluorescence intensity of ICG decreased by 0.85 %/°C. The distribution of fluorescent ICG was detected using an ultrasonic warming method in a new integrated probe. CONCLUSION: Modulating fluorescence by changing the temperature using ultrasound can determine where ICG accumulates at a depth, highlighting its potential as a means to locate hepatocellular carcinoma.
PURPOSE:Indocyanine green (ICG) accumulation in hepatocellular carcinoma means tumors can be located by fluorescence. However, because of light scattering, it is difficult to detect ICG fluorescence from outside the body. We propose a new fluorescence imaging method that detects changes in the intensity of ICG fluorescence by ultrasound-induced temperature changes. METHODS:ICG fluorescence intensity decreases as the temperature rises. Therefore, it should theoretically be possible to detect tissue distribution of ICG using ultrasound to heat tissue, moving the point of ultrasound transmission, and monitoring changes in fluorescence intensity. A new probe was adapted for clinical application. It consisted of excitation light from a laser, fluorescence sensing through a light pipe, and heating by ultrasound. We applied the probe to bovine liver to image the accumulation of ICG. RESULTS:ICG emits fluorescence (820 nm) upon light irradiation (783 nm). With a rise in temperature, the fluorescence intensity of ICG decreased by 0.85 %/°C. The distribution of fluorescent ICG was detected using an ultrasonic warming method in a new integrated probe. CONCLUSION: Modulating fluorescence by changing the temperature using ultrasound can determine where ICG accumulates at a depth, highlighting its potential as a means to locate hepatocellular carcinoma.
Entities:
Keywords:
Fluorescence imaging; Indocyanine green; Temperature change; Ultrasound