Spectroscopic photoacoustic imaging for cardiovascular interventions

Alongside ultrasound imaging, photoacoustic imaging (PA) augments the imaging system with tissue composition information. Indeed, PA primarily maps tissue optical absorption and thus can reveal tissue composition. Localizing and identifying specific biomolecules can be very useful for both diagnostic imaging and evaluation of the treatment effect in various applications. PA imaging can for instance discern lipid-rich atherosclerotic plaques from fibrotic ones. It can also distinguish highly vascularized or highly oxygenated tissue from hypoxic areas in tumors. However, multiple parameters affect the PA signal received, rendering a direct mapping from signal received to absorption challenging. For instance, at selected wavelengths, multiple chromophores may contribute to the signal observed. In order to separate the different chromophores, judicious spectral tuning of imaging wavelengths can help. We call this technique spectroscopic photoacoustic imaging (sPA). Based on sPA imaging, we were capable to super-localize sources down to 1/20th of the imaging system point spread function (PSF). sPA can also improve the imaging specificity and sensitivity of targeted tissue features. In this talk, we showcase the many benefits of sPA imaging for image enhancement. We also discuss challenges and feasibility to integrate in surgical tools for minimally invasive interventions. In particular, we focus on how sPA studies can take the specific problem of visualization of RF ablation for atrial fibrillation from bench to bedside.