Handheld photoacoustic detector and its potential application for sentinel lymph node sensing

We developed a handheld photoacoustic signal detector for sentinel lymph node (SLN) localization. The detector consists of a solid-state dye laser and a transparent ultrasound transducer (TUT). The TUT was designed as a focused-type. The TUT had an 8 MHz center frequency with a 30% bandwidth. Using the detector, we confirmed photoacoustic signals in a tube filled with methylene blue (MB) below 10-mm thick chicken tissues. We successfully performed in vivo photoacoustic detection for MB injected SLN localization and subcutaneously injected melanoma assessments. We believe that our detector will play an effective role in SLN localization and biopsy.