Point-of-care functional and molecular imaging using LED-based photoacoustics

Abstract

Photoacoustic (PA) or optoacoustic imaging can visualize tissue-optical absorbers, especially hemoglobin, with optical contrast and ultrasound (US)-like resolution and imaging depth. Since both PA and US imaging involves US detection, it is straightforward to develop dual-mode imaging systems with unprecedented functional and structural imaging capabilities. Researchers have already demonstrated the potential of utilizing this complementary contrast for several animal imaging experiments and early clinical pilot studies. PA imaging conventionally uses slow, bulky and high-priced lasers as excitation sources. Use of these high-power pulsed lasers is hindering the clinical translation process of this imaging modality with tremendous potential. Advances in solid-state device technology have recently resulted in the development of a new class of high-power light emitting diodes (LEDs) that can be used as fast, robust and affordable pulsed excitation sources for PA imaging. In this paper, we review multiple LED-based PA/US imaging implementations (commercial and lab-made systems) and demonstrate its functional, molecular and structural imaging capabilities using several clinical/preclinical imaging examples. Specific focus will be given to 2D and 3D superficial vasculature and oxygen saturation imaging in multiple in vivo clinical and preclinical studies.