Monte Carlo and Tissue-Phantom studies of Photoacoustic Imaging of Carotid Intraplaque Haemorrhage

Strokes are the second leading cause of death worldwide. Vulnerable carotid plaques are a primary cause of stroke, with carotid Intraplaque Haemmorrghages being a key feature of vulnerability. MR imaging, which is sensitive to the presence of endogenous Methemoglobin (MetHb), is used to detect IPH. MRI is however expensive, and not readily available. We propose the use of Photoacoustic Imaging (PAI) for the detection of IPH, with MetHb being the primary PA imaging target. I examine the feasibility of this approach by performing Monte Carlo studies of light propagation, energy deposition and PA generation in tissuemimicking models, as well as experimental PA measurements of MetHb in tissue-mimicking phantoms. I show that is possible to achieve an SNR of ∼50dB at the average carotid artery depth of ∼21mm, with the possibility of imaging up to ≥ 32mm in Type I skin using commonly available hardware.