Elastography may slash biopsy rate for benign breast lesions

March 6, 2006

Use of ultrasound elastography, which measures the elastic properties of tissues, may help reduce the rate of biopsies in benign lesions by half, according to new results from a British breast cancer screening program.

Use of ultrasound elastography, which measures the elastic properties of tissues, may help reduce the rate of biopsies in benign lesions by half, according to new results from a British breast cancer screening program.

"We can decrease the biopsy rate in benign lesions. This has great importance, given the increased incidence of screening abnormalities picked up on breast ultrasound," said Dr. William Svensson, who showcased results with the emerging technique at the ECR on Saturday.

The study derived from four years of routine experience with elastography, using a Siemens Elegra ultrasound system, standard breast probes, and software developed in Kansas.

Research has shown that benign lesions have smaller elasticity profiles while malignant lesions are larger than the grayscale appearance.

"The hypothesis was that the size of cancer is larger in elasticity imaging than B-mode, and with benign lesions the reverse is the case," said Svensson, an honorary senior clinical lecturer at the division of investigative science at Imperial College London.

The British study included women who were referred for routine breast ultrasound for focal breast abnormalities. In cases where abnormalities were identified on ultrasound, women underwent breast strain imaging.

Of 260 lesions identified, 71 were malignant, nine were intermediate with malignant potential, and the majority, 180 lesions, were benign.

British researchers noted that lesions with an elasticity-to-grayscale ratio of less than .75 were benign. Based on this ratio, all of the malignant lesions would have been identified, aside from a few intermediate lesions. That result equates to a sensitivity of 96%.

Specificity was just 53%, meaning that if the ratio is applied, half of benign lesions don't need to be biopsied, Svensson said. In addition to the obvious clinical value, there are also economic advantages.

"Benign biopsies cost us a lot of money and if we can reduce them, that would bring significant savings for the health service," he said.

During the same ECR session, French researchers presented positive findings for elasticity imaging in a multicenter prospective study of 345 breast lesions in 314 patients.

Patients were imaged on the Hitachi EUB Logos ultrasound unit with a technique similar to the one used in the British study. Detected lesions were broken down by size and BI-RADS category.

For lesions of all sizes, ultrasound elastography achieved sensitivity of 80%, specificity of 93%, positive predictive value of 85.3%, and negative predictive value of 90.3%. Sensitivity was best for lesions less than 5 mm (90%), while specificity was best for lesions over 10 mm (95%).

For lesions in BI-RADS categories 3 and 4, sensitivity was 68% and specificity was 90%.

Researchers also reported 16 false positives with elastography (such as fibrous mastopathy and sclerosis adenosis) and 26 false negative findings (such as DCIS).

Elastography is easy to perform once practitioners are trained, provides good visualization, and is not time-consuming, said Dr. Anne Tardivon of the Institut Curie in Paris.

"Elastography does not replace standard B-mode imaging, but clearly, it is a useful complementary tool and may reduce biopsies of benign lesions," she said.