The potential of photoacoustic techniques in inflammatory arthritis: what can it do to assist conventional imaging methods?

To make comprehensive assessments of some rheumatoid diseases, a more reliable imaging method for evaluating joint lesions is required. Photoacoustic imaging (PAI) is a state-of-the-art imaging technique, providing new options for diagnosing joint disease. In light of the recent preclinical studies, detailed morphological structures and micro-vessels of small joints, especially the finger joints, could be visualized by PAI with high spatial resolution and optical contrast using different PA implementations. By measuring the signals of oxygenated and deoxygenated hemoglobin through dual-wavelength PAI, oxygenation of local tissues can be identified, thus enabling functional PA imaging. Notably, among various PA systems, the co-registration of PAI into high-end commercial US units with a special-designed handheld PA/US probe can be of great value in further clinical application. Molecular PAI of small joints can also be performed using exogenous PA chromophores. In this article, we aim to inform readers of this new technique in joint imaging and its potential use, to impart a deeper understanding of medical imaging in this field.