Combined X-Ray and Optical Tomography Improve Breast Imaging

November 10, 2010

NEW YORK (Reuters Health) Nov 09 - Benign or malignant breast lesions can be differentiated noninvasively by overlaying 3-D digital mammography images with tissue-physiology images obtained by scanning with near-infrared lasers, researchers report in the January issue of Radiology issued online November 9.

Dr. Qianqian Fang, at Massachusetts General Hospital in Charlestown, and colleagues explain that 3D digital breast tomosynthesis (DBT) provides detailed images resolution but marginal contrast between tumors and dense breast tissue. On the other hand, diffuse optical tomography (DOT) shows the physiologic characteristics of different tissues, but with poor spatial resolution.

The team developed a system to combine 3D optical and x-ray images, hypothesizing that "the resulting functional-structural image overlays may increase screening sensitivity and specificity by allowing the detection of more cancers and the reduction of the number of biopsies of benign lesions, compared with stand-alone conventional mammography."

"We are very excited about adding optical imaging to DBT, because it is low-cost, safe, noninvasive and fast," Dr. Fang said in a statement.

Dr. Fang and colleagues tested the technique in a study of 138 normal breasts and 51 breasts with lesions. Subsequent biopsy showed that 26 of the lesions were malignant and 25 were benign.

Maps of hemoglobin concentration and oxygen saturation, as well as scattering contrasts, obtained by DOT were interpreted using the co-registered DBT images. "In 26 malignant tumors of 0.6-2.5 cm in size, HbT (total hemoglobin) was significantly greater than that in the fibroglandular tissue of the same breast (p=0.0062)," according to the report.

HbT contrast was significantly lower in 17 solid benign and 8 cysts than in the malignant lesions, the researchers found.

"Although cysts are easy to diagnose using ultrasound, distinguishing cysts from malignant or benign lesions during a mammogram would save women the anxiety and costs associated with a second procedure," Dr. Fang pointed out.

Given these results, the authors conclude that the technique "can potentially be exploited to reduce the false-positive rate of conventional mammography and unnecessary biopsies."

They add, "The demonstrated discrimination of malignant and benign lesions motivates further advancement of this technology and a rigorous assessment of its sensitivity and specificity to identify its diagnostic advantages over stand-alone conventional mammography."

Radiology. Posted online November 9, 2011. Abstract


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