For many patients diagnosed with cancer, the primary treatment plan is surgery to remove the tumor, but in the quest to retain as much healthy tissue as possible, it's impossible for surgeons to know if they've removed all traces of the cancerous tissue while in the operating room. A new imaging technique would give doctors this ability, thus avoiding having the patient return to surgery weeks later for a second procedure.

Engineers at Caltech focused on the problem of breast cancer surgery, noting that between 20 and 60 percent of patients have to return to the operating theater after their initial lumpectomy due to tumor tissue still remaining.

Currently, the process patients undergo after an initial procedure involves delivering extracted tissue to a lab for analysis to ascertain whether tumor cells are found on the surface, indicating the surgeon may have cut through, and not around, a tumor. This process generally takes one to two weeks, and the actual microscopy of the tissue takes up to seven hours of lab time.

"What if we could get rid of the waiting?" asks lead engineer at Caltech, Lihong Wang. "With 3D photoacoustic microscopy, we could analyze the tumor right in the operating room, and know immediately whether more tissue needs to be removed."

The 3D photoacoustic microscopy process developed by Wang and his team uses a low-energy laser to vibrate a tissue sample. The ultrasonic waves emitted by the tissue can then be measured, revealing the size of the nuclei and the packing density of the cells. As cancerous tissue contains more densely packed cells that hold larger nuclei, the process can quickly identify the presence of a tumor.

The current proof-of-concept study can analyze a sample in three hours, but Wang says with faster pulse repetition and parallel imaging this could be cut down to under 10 minutes.

Wang is optimistic about how quickly this technology could be moved into clinical use, estimating that within several years it could be available to surgeons. The system also has potential applications for other cancers, including melanoma and pancreatic tumors.

"Because the device never directly touches a patient, there will be fewer regulatory hurdles to overcome before gaining FDA approval for use by surgeons," Wang explains.

The team's study was published in the journal Science Advances.

Source: Caltech