Towards in vivo photoacoustic imaging of vulnerable plaques in the carotid artery.

The main indicator for endarterectomy is the grade of stenosis, which results in severe overtreatment. Photoacoustic imaging (PAI) can provide patient-specific assessment of plaque morphology, and thereby vulnerability. A pilot study of PAI on carotid plaques in patients (n=16) was performed intraoperatively with a hand-held PAI system. By compensating for motion, the photoacoustic (PA) signal-to-noise ratio (SNR) could be increased by 5 dB in vivo. PA signals from hemorrhagic plaques had different characteristics compared to the signals from the carotid blood pool. This study is a key step towards a non-invasive application of PAI to detect vulnerable plaques.