title: Development of ultrasound-assisted fluorescence imaging of indocyanine green.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors: 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.
authors: Hiroyasu
authors: H
authors: Morikawa
authors: Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Japan.
authors: Shin
authors: S
authors: Toyota
authors: Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Japan.
authors: Kenji
authors: K
authors: Wada
authors: Department of Hepatology, Graduate School of Medicine, Osaka City University, Osaka, Japan.
authors: Sawako
authors: S
authors: Uchida-Kobayashi
authors: Department of Hepatology, Graduate School of Medicine, Osaka City University, Osaka, Japan.
authors: Norifumi
authors: N
authors: Kawada
authors: Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Japan.
authors: Hiromichi
authors: H
authors: Horinaka
mesh_terms: D000818:Animals; D002417:Cattle; D004396:Coloring Agents; D004867:Equipment Design; D005453:Fluorescence; D007208:Indocyanine Green; D054023:Lasers, Semiconductor; D008099:Liver / Q000000981:diagnostic imaging; D013552:Swine; D013696:Temperature; D000069453:Ultrasonic Waves; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green
keywords: Fluorescence imaging; Indocyanine green; Temperature change; Ultrasound