PHILADELPHIA -- November 18, 2009 -- Intraoperative optical coherence tomography (OCT) rapidly images larger breast tumour margin areas, dramatically improving the microscopic sampling rate or analysis of the margin, according to research published in the November 15 issue of Cancer Research.
"Intraoperative OCT has the potential to provide diagnostically useful information about margin status in real time, at the point of care, rather than relying on postoperative histopathology," said Stephen Boppart, MD, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana, Champaign, Illinois.
Dr. Boppart and colleagues demonstrated the feasibility of using this technology for evaluating surgical margins during breast-conserving lumpectomy procedures. The aim was to first establish image-based features that could be used to determine negative or positive margins, and then demonstrate how well intraoperative OCT compares with histopathological findings of the tissue.
Thirty-seven patients were divided into 2 groups -- 17 in a training set and 20 in a study set. Of the lumpectomy specimens in the study set, 11 had a positive or close surgical margin; 9 had a negative margin under OCT.
In the study set, intraoperative OCT had 100% sensitivity and 82% specificity for determining margin status using postoperative histopathology as the gold standard, according to Dr. Boppart. OCT, with imaging resolution around 10 microns and depth-of-imaging up to 2 mm into the tissue, identified cell and tissue features to differentiate negative margins from positive margins.
"The imaging depth was equivalent to the tissue depth that pathologists typically examine postoperatively to determine if the margin is negative, close or positive," he said. "Image features could also be used to identify structures such as surface blood or cauterised tissue and distinguish these image artifacts from normal and tumour tissue."
Follow-up studies are ongoing in an effort to develop computer-aided detection algorithms that would automatically identify suspicious areas within images, according to Dr. Boppart. New computed imaging techniques are also being developed to improve the imaging resolution over larger volumes of tissue, which should further improve the ability to distinguish tumor cells.
"OCT is a very promising technology with many advantages for real-time optical biopsies of tissue. We hope that this technology and methodology will shift the microscopic assessment of tissue from postoperative assessment in the pathology lab, which offers limited sampling of the margin, to real-time, point-of-care assessment in the operating room, with improved comprehensive sampling of the surgical margin," Dr. Boppart said.
He believes this will ultimately result in fewer repeat surgeries and long-term, potentially lower local recurrence rates.
SOURCE: American Association for Cancer Research
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