Multiwavelength Laser Diode based Portable Photoacoustic and Ultrasound Imaging System for Point of Care Applications

Vascular diseases are a leading cause of death and disability worldwide. Despite having precursor conditions like peripheral arterial disease (PAD), they are often only diagnosed after the onset of strokes or heart attacks. Low-cost, portable, non-invasive, point-of-care (POC) assessment of deep vascular function benefits PAD diagnosis, especially in low-and-middle-income countries. Doppler ultrasound-based blood flow measurements can diagnose PAD, albeit, with limited sensitivity and specificity. To overcome this, here, we propose the first-of-its-kind photoacoustic-and-ultrasound (PAUS) imaging system that integrates a multiwavelength pulsed laser diode (PLD) with a compact ultrasound data acquisition system. The portable PLD-PAUS system was validated for deep tissue imaging using tissue phantoms, and for multispectral photoacoustic imaging using an atherosclerosis mimicking phantom. Further, we demonstrated high-contrast volumetric in-vivo photoacoustic imaging of rodent abdominal vasculature and quantified vessel reactivity due to hypercapnia stimulation. The multiparametric functional and molecular imaging capabilities of the PLD-PAUS system holds promise for POC applications.