Engineers have developed an imaging technology that could help surgeons removing breast cancer lumps confirm that they have cut out the entire tumor — reducing the need for additional surgeries.

A close up of the photoacoustic microscope, which provides label-free multilayered histologic images of human breast cancer.
(Credit: Caltech)

Photoacoustic microscopy, or PAM, excites a tissue sample with a low-energy laser, which causes the tissue to vibrate. The system measures the ultrasonic waves emitted by the vibrating tissue. Because nuclei vibrate more strongly than surrounding material, PAM reveals the size of nuclei and the packing density of cells. Cancerous tissue tends to have larger nuclei and more densely packed cells.

PAM produces images capable of highlighting cancerous features, with no slicing or staining required. Although the researchers focused primarily on breast cancer tumors, the work has potential applications for any analysis of excised tumors — from melanoma to pancreatic cancer.

In a proof-of-concept scan, PAM analyzed a sample in about three hours. Comparable traditional microscopy takes about seven hours to achieve the same results. The researchers say that PAM's analysis time could be cut down to 10 minutes or less with the addition of faster laser pulse repetition and parallel imaging, which would make the technology useful for clinical applications.