Ultrasound-guided optical coherence tomography (OCT) appears to be an effective means for differentiating early-stage breast cancers from benign lesions, according to researchers at the University of Connecticut in Storrs.1 As such, it has the potential to reduce the number of breast biopsies women undergo for suspicious lesions.
Diffuse optical tomography measures light absorption within the tissue at two optical wavelengths to quantify blood content (hemoglobin levels). Since cancerous lesions tend to have many more blood vessels than normal tissue, hemoglobin levels can help distinguish malignant from benign lesions. Working to determine the effectiveness of the approach, Quing Zhu and colleagues examined data on 178 women undergoing biopsy on solid lesions via ultrasound with a near-infrared (NIR) imager. The device uses a traditional handheld ultrasound probe to pinpoint suspicious masses in the breast and near-infrared lighting projected through a series of optical fibers around the probe's periphery to penetrate and characterize the mass once it is found. The infrared light can penetrate tissue up to four centimeters.
The researchers measured light absorption at two wavelengths to compute total hemoglobin concentrations (tHb), and correlated those measurements with results from biopsy. Their efforts revealed 114 benign lesions and 61 carcinomas. Maximum and average tHb were significantly higher in the malignant group, and the technique produced the best results (sensitivity at 92% and specificity at 93%) for cancers less than 2 cm.
The approach "holds promise as an adjunct to mammography and ultrasound for distinguishing early-stage invasive breast cancers from benign lesions," Zhu says. "We expect this technology will be used to help radiologists evaluate small to intermediate size lesions that are harder to diagnose with conventional imaging technologies."
1. Q. Zhu et al., Radiology 256: 367-378 (2010)