Application of photoacuoustic imaging for evaluating tumor vascular maturity

Research Project

Project/Area Number	16K19812
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Radiation science
Research Institution	Kanazawa University
Principal Investigator	Yoshida Kotaro 金沢大学, 医学系, 助教 (30645130)
Project Period (FY)	2016-04-01 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000) Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords	光音響イメージング / インドシアニングリーン / 光音響 / 血管透過性 / 腫瘍血管
Outline of Final Research Achievements	We demonstrated the applicability of photoacoustic (PA) imaging with indocyanine green (ICG) in a mouse tumor model. It allows safe and real-time imaging acquisition, and unlike common conventional contrast agents such as iodinated and gadolinium based contrast agents, ICG-enhanced PA imaging can less depict the IVC and hypervascular organs such as kidney and liver. The PA signal of ICG was rather enhanced in the interstitial extravascular space of tumors and salivary gland at the early phase after ICG injection. PA imaging with ICG allows for assessment of the early treatment response at a time when there is still no difference in tumor size after anti-VEGF therapy in this tumor model in mice and can directly reflect vascular permeability, which is not feasible at all with other imaging systems. Thus, PA imaging has a potential for the broader application for diagnosis of other pathologies characterized by changes in vascular permeability.
Academic Significance and Societal Importance of the Research Achievements	インドシアニングリーンの血管内投与を用いた光音響イメージングは、実験レベルではあるが、生体内の臓器の血管透過性の状態をリアルタイムに非侵襲的に描出することができると考えられる。血管透過性の制御は生体内の様々な状態、特に腫瘍の活動性の状態を把握するために非常に重要であり、これを評価する事ができる新たなイメージング手法であると考えられた。