A portable photoacoustic imager for diagnosing vascular diseases

Project Summary/Abstract Vascular diseases are the leading cause of death worldwide. Some common vascular diseases include: cardio vascular disease, stroke, and peripheral artery disease (PAD). Many of these vascular diseases need point-of- care (POC) diagnosis and monitoring using non-ionizing, non-invasive and cost-effective approaches. Although Doppler ultrasound meets all these requirements, it only maps blood flow, which is operator dependent and influenced by motion artifacts, resulting in limited sensitivity and specificity to detect the disease in its early stage. A POC technique that provides direct label-free molecular and functional information of vasculature is needed to reliably detect and monitor vascular diseases. A mobile photoacoustic imager (mPAI) is proposed for diagnosing various vascular diseases in resource poor settings of the world. Leveraging on strong multispectral optical absorption of oxy- and de-oxy hemoglobins, the mPAI is capable of providing multi-parametric information of deep vasculature, such as blood oxygen saturation, plaque lipids, blood flow and blood clot. The mPAI is non-invasive, real time and uses non-ionizing optical and ultrasound radiation. This will be the first and perhaps the only portable technology capable of deriving such multiparametric functional information of deep vasculature without the use of contrast agents. Competing technologies cannot provide such a direct information of vascular health, and certainly not in a compact portable device form. Health care providers can use the mPAI to instantly diagnose several vascular diseases affecting humans of all ages, including infants. In the R21 phase, Aim1 will design and develop the mPAI, integrating the low-cost optical illumination and piezoelectric micromachined ultrasound transducer (PMUT) arrays. Dr. Rundra Pratap team from the Indian Institute of Science (IISc), Bangalore, will design and fabricate the PMUT arrays. Dr. Kothapalli team will develop the mPAI and validate its performance on tissue mimicking vascular phantoms in Aim 1, and rat models of PAD in Aim 2. The ultimate goal of the two-year R21 phase is to achieve a clinical grade mPAI device with reliable vascular imaging metrics. In the R33 phase, to test the clinical performance of the mPAI, the following multicenter pilot clinical studies on PAD patients will be conducted in 1) Penn State Hershey medical center, 2) Vikram Hospital in India through collaborations with the IISc team, and 3) in Ghana in Year 5 with the help of Dr. Colette Pameijer of Penn State who conducts medical camps in Ghana every year through Penn State Global Health Program. Clinical studies in R33 phase will be undertaken only if well-defined milestones are achieved in the R21 phase. The overall goal of these studies is to carefully validate the clinical potential of emerging label-free photoacoustic imaging technology to screen for vascular diseases, in a portable form, in resource poor settings of the world.