Currently, for cancer diagnosis, the most commonly used methods are (i) ultrasound imaging, (ii) X-ray imaging, and (iii) magnetic resonance imaging (MRI). While all these technologies are widely used all over the world, each of them suffers from different disadvantages. Ultrasound imaging has a long history of speckle-like artifact and low molecular specificity, which can only outline different layer structures with low resolution and contrast. X-ray imaging is good at imaging hard tissue (e.g., bones), but its specificity towards cancer imaging is skeptical, not to mention its ionizing radiation nature. MRI is one of the most powerful imaging technologies. However, the cost of the imaging machine is high, which is not affordable and not accessible to many patients. Furthermore, the most commonly used contrast agent in MRI, gadolinium, has recently been showed that there is some deposition in the brain. Although there is no clear evidence showing it is harmful to patients, this can potentially cause unexpected neurodegenerative diseases in the future.

To address this need, our proposed photoacoustic imaging system (which combines the advantages of both light and sound) allows non-invasive, high-speed, and deep-tissue imaging in vivo. Together with the development of a safe and specific contrast agent based on proteins, the proposed photoacoustic imaging system allows safe, fast, high resolution, and specific imaging in a cost-effective manner.