SWE could help assess suspicious findings detected on mammograms

Shear wave elastography (SWE) may be an effective tool for characterizing suspicious microcalcifications of the breast first detected on mammograms, according to a new study published in the American Journal of Roentgenology.

When breast microcalcifications are detected on a patient’s mammogram, they are often benign, but there is also always the chance they are malignant. B-mode ultrasound (US) is one supplemental screening option for seeking other signs of invasive cancer or additional lesions, but it does not necessarily provide enough additional information on its own. This, the authors noted, is where SWE could potentially make an impact.  

“SWE, which is able to measure tissue stiffness quantitatively, is a relatively recent US technique and has been shown to improve characterization of breast lesions, especially masses,” wrote Foucauld Chamming’s, MD, PhD, department of radiology at McGill University Health Center in Montreal, Quebec, Canada, and colleagues. “SWE has also been shown to improve performance of B-mode US for the characterization of more subtle findings, such as hypoechoic areas with ill-defined margins described as nonmass-like lesions.”

The authors examined data from patients who underwent US after being referred for image-guided biopsy based on microcalcifications detected on a mammogram. All examinations occurred at the same institution between Feb. 9 and June 23, 2016. If the suspicious findings were detected on US, the patient was eligible for this study.

The final study cohort included 29 patients with 29 groups of microcalcifications identified during the US examination. The median patient age was 60 years old. Fifteen patients had no personal or family history of breast cancer, and two patients had a personal history of breast cancer. The biopsies were successful, with no complications, for all 29 patients.

Pathology revealed that 16 groups of microcalcifications were benign and 13 were malignant. SWE revealed that the stiffness of the malignant calcifications was “significantly higher” than the benign calcifications. The area under the ROC curve of SWE for diagnosing a finding’s malignancy was 0.89. It also had a sensitivity of 69%, specificity of 100%, negative predictive value (NPV) of 80%, positive predictive value (PPV) of 100% and accuracy of 86%.

“Our results showed that in situations in which calcifications were visible on US, SWE had good performance for the diagnosis of malignancy,” the authors wrote. “NPV was relatively low, indicating that negative (soft) characteristics on SWE cannot be used to exclude malignancy. However, SWE showed high specificity and PPV. In the clinical setting, these results are of particular interest for assessment of concordance between radiologic and pathologic findings.”

SWE also showed potential for detecting microcalcifications US had issues properly identifying “by showing stiffness within the area of concern.”

“Although our population was too small for this result to be statistically significant, it nevertheless suggests that SWE may be a useful tool for the targeting of microcalcifications on US,” the authors wrote.  

The team added that larger studies including more patients are still needed to confirm these findings.