The Evolution of LED-based Photoacoustic Imaging: From Labs to Clinics

Photoacoustic (PA) imaging, with its unique capability to provide simultaneous structural, functional, and molecular information, has emerged as one of the most rapidly advancing biomedical imaging modalities in recent years. As a hybrid technique, it offers superior penetration depth compared to purely optical imaging methods and grants optical contrast for molecular constituents within living tissues. Traditionally, photoacoustic imaging systems have relied on bulky and expensive Class IV lasers, presenting a significant hurdle to the clinical adoption of this promising modality. The integration of light-emitting diodes (LEDs), characterized by their portability and affordability, presents a transformative opportunity to expedite the clinical translation of photoacoustic imaging. In this chapter, we embark on a comprehensive exploration of the historical development of LEDs as an illumination source in biomedical photoacoustic imaging. We delve into key milestones, tracing the evolution from point-source measurements to the realization of high-power LED arrays. These innovations underscore the pivotal role of LEDs in shaping the future of photoacoustic imaging. Furthermore, this chapter encompasses a meticulous analysis of numerous studies, spanning phantom experiments, ex vivo investigations, in vivo animal studies, human in vivo applications, and clinical pilot studies. These examples collectively illuminate the exceptional preclinical and clinical potential harnessed by LED-based photoacoustic imaging, reaffirming its status as a groundbreaking modality with vast promise.