Curved-Array-Based Multispectral Photoacoustic Imaging of Human Finger Joints

Objective: In this study, we present the design, fabrication, and evaluation of a curved-array-based photoacoustic imaging system designed for imaging vasculatures inside human finger joints with multispectral strategy. Methods: The transducers were fabricated with polyvinylidene fluoride (PVDF) film with a size of 30 mm × 2.8 mm and a curvature radius of 82 mm. A detailed comparison between the PVDF transducer and commercial piezoelectric ceramic transducers was performed. In addition, phantom and in vivo mouse experiments were carried out to evaluate the system performance. Furthermore, we recruited healthy volunteers and did multispectral photoacoustic imaging of blood vessels in finger joints. Results: The transducers have an average center frequency of 6.6 MHz and a mean bandwidth of 95%. The lateral and axial resolutions of the system are 110 and 800 μ m, respectively, and the diameter of the active imaging is larger than 50 mm. We successfully captured the drug-induced cerebral bleeding spots in intact mouse brains, and recovered both morphology and oxygen saturation of the blood vessels in human finger joints. Conclusions: The PVDF transducer has a better performance in bandwidth compared with commercial transducers. The curved design of the transducer offers a better sensitivity and a higher axial resolution compared with the flat design. Significance: Based on the phantom, animal, and human experiments, the proposed system has the potential to be used in clinical diagnosis of early-stage arthritis.