new high tech way being developed to tell if tumor margins clear at surgery
 

Terahertz imaging may reduce breast cancer surgeries [Eureka News Service]
OAK BROOK, Ill.—A promising new technique to ensure complete tumor removal at breast cancer excision is introduced in the May issue of Radiology.

Researchers used light waves in a newly explored region of the electromagnetic spectrum—the terahertz region—to examine excised breast tissue and determine if the removed tissue margins were clear of cancer, with good results. This technology has the potential to eliminate the need for multiple surgeries and tissue samples to get clear surgical margins.

"We found that terahertz light could reliably distinguish between normal breast tissue, tumor and even early-stage 'in situ' cancers in excised tissue samples," said Vincent P. Wallace, Ph.D., lead investigator at TeraView, who worked with Addenbrooke's Hospital in Cambridge, England, in conducting the study. "This technology could aid the surgeon in immediately identifying residual cancer after the main tumor has been removed, thus minimizing the need for additional surgical procedures."

Currently, excised tissue samples must be sent for histopathologic examination, which typically takes several days. Thus, surgeons don't know if all the tumor has been removed until well after the surgical procedure has been completed, and often, repeat surgeries have to be scheduled. For the first time, however, terahertz imaging has the potential to eliminate the need for subsequent procedures by allowing the surgeon to analyze tissue samples during the initial excision procedure.

Terahertz light is located between the infrared and microwave portions of the electromagnetic spectrum. The researchers found that by placing a slice of excised breast tissue on a special quartz plate and exposing it to terahertz light, the light waves reflected from the tissue contained unique information about its state. The researchers were able to distinguish both invasive and noninvasive breast carcinomas from healthy tissue.

Twenty-two excised breast tissue samples were obtained from 22 women who underwent either wide local excision or mastectomy to remove breast cancer. All samples were first sliced and imaged with terahertz light, and then submitted for histopathologic analysis. Imaging took less than five minutes.

"There were substantial differences in the optical properties of normal and diseased tissue," Dr. Wallace said. The size and shape of the diseased regions at terahertz imaging were compared with those at histopathologic examination, with good results. All but three samples yielded invasive cancers. In total, there were two invasive lobular carcinomas, 14 invasive ductal carcinomas, three mixed invasive ductal and lobular carcinomas, two cases of pure ductal carcinoma in situ and one dense radial scar.

In breast cancer excision surgery, the aim is to remove the entire tumor with an adequate margin of normal tissue, while minimizing the amount of healthy tissue being removed. If a histopathologist analyzes the tissue and finds tumor at or near the edges, this indicates that there is a higher chance of cancer recurrence. A second operation is required to remove more tissue, involving additional hospital resources and increased risk of patient morbidity. Thus, there is a clinical need to accurately define the margins of the tumor during surgery.


ABSTRACT: Terahertz Pulsed Imaging of Human Breast Tumors [Radiology; Subscribe]
The feasibility of using terahertz pulsed imaging to map margins of exposed breast tumors was investigated by imaging 22 excised human breast tissue specimens with carcinoma excised from 22 women (mean age, 59 years; range, 39-80 years). The study was approved by the local ethics research committee, and informed consent was obtained from all patients. The size and shape of tumor regions on terahertz images were compared with those identified at histopathologic examination of the imaged section. Two image parameters were investigated: the minimum of the terahertz impulse function and the ratio of the minimum to the maximum of the terahertz impulse function. The correlation coefficient for the tumor area on images compared with that on a photomicrograph of all 22 samples was greater than 0.82 for both parameters. The shape of the tumor regions on terahertz images also correlated well with that on a photomicrograph (median Spearman rank correlation coefficient, 0.69). Findings: of this study demonstrate the potential of terahertz pulsed imaging to depict both invasive breast carcinoma and ductal carcinoma in situ under controlled conditions and encourage further studies to determine the sensitivity and specificity of the technique.