Photoacoustic imaging of small organic molecule-based photoacoustic probe in subcutaneous tumor using P(VDF-TrFE) acoustic sensor

摘要

The P(VDF-TrFE) sensor which had uniform sensitivity in a frequency range of 2.9 - 19.6 MHz was developed for multispectral photoacoustic imaging (MS-PAI). A small organic molecule-based PA probe synthesized by our group had the absorption maximum at 530 ran and was used as a contrast agent. The PA probe was designed to have low quantum yield. Therefore, the PA probe efficiently converted absorbed optical energies to PA signals. The probe was injected in subcutaneous tumor of mice. Then, the subcutaneous tumor was imaged in vivo by using P(VDF-TrFE) sensor. MS-PAI successfully discriminated the probe signals from background signals produced from endogenous optical absorbers such as hemoglobin. The probe detectability of the P(VDF-TrFE) sensor was evaluated and then compared with that of lead zirconium titanate (PZT) sensors. The P(VDF-TrFE) sensor imaged the tumor more clearly than the PZT sensor with central frequency of 20 MHz, especially when the probe was accumulated in the tumor with low concentration. That was because the low-concentrated probe generated PA signals with low frequency. MS-PAI using P(VDF-TrFE) sensor which can detect PA signals with wide range of frequency is able to image various distribution of the probe and is superior to that using PZT sensor which detects PA signals with narrow frequency range.