A handheld surgical probe that uses optical coherence tomography (OCT) to ensure that surgeons remove all cancerous tissue was found to correlate well with traditional pathologists’ diagnoses in a clinical study, showing that the tool could soon enable reliable, real-time guidance for surgeons.
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The interdisciplinary research team that developed the device, led by Stephen Boppart, a University of Illinois (Champaign, IL) professor of electrical and computer engineering and of bioengineering, performed the study on 35 patients with breast cancers at the Carle Foundation Hospital (Urbana, IL).
“In almost all solid-tumor surgeries, there’s a question of margins,” says Boppart, who also is a medical doctor. “Typically, surgeons will remove the tissue mass that contains the tumor and will send it to the lab. The pathologist will process, section, and stain the tissue, then examine the thin sections on microscope slides. They look at the structure of the cells and other features of the tissue. The diagnosis is made based on subjective interpretation and often other pathologists are consulted. This is what we call the gold standard for diagnosis.”
The new handheld OCT probe uses light to image tissue in real time. Cancer cells and normal tissue scatter light differently because they have different microstructural and molecular features, Boppart says, so OCT gives physicians a way to quantitatively measure the cellular feature of a tumor. Surgeons can pass the OCT wand over a section of tissue and see a video on a screen, with no special chemical stains or lengthy tissue processing required.
In the clinical study, surgeons treated patients according to the standard surgical procedure, but OCT data were collected from the margin of the tumor cavity and the margin of the removed tissue mass during surgery so that the results could be compared later. The study found that the OCT device analysis identified the differences between normal and cancerous tissue with 92 percent sensitivity and 92 percent specificity. They also found that the way that OCT spotted cancer in the removed tissue was closely correlated with the results from the postoperative pathology reports, which often came days later.
The researchers will continue clinical studies with the OCT device, looking at other types of solid-state tumors. Diagnostic Photonics, a start-up company Boppart co-founded that also collaborated on the study, is commercializing the OCT probe technology for broader use.
Full details of the work appear in the journal Cancer Research; for more information, please visit http://dx.doi.org/10.1158/0008-5472.CAN-15-0464.
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