Adding 3D automated breast ultrasound (ABUS) to routine mammography of dense-breasted women identified additional cancers that mammography alone did not detect, according to an article published in the European Journal of Radiology. In the study, 2.4 additional cancers were detected per 1,000 women at a high volume breast cancer screening center in Stockholm, Sweden.
3D ABUS streamlines the performance of a handheld ultrasound exam in conjunction with a mammogram. The system uses a standardized, automated acquisition protocol, acquiring large 3D volumes that overlap and can be evaluated in coronal, transverse, and sagittal planes. It is reproducible and is not operator-dependent. The capabilities of 3D ABUS technology enable temporal comparison and can depict cancers in the coronal plane.
The Department of Breast Imaging at Capio S:t Göran Hospital enrolled 1,668 women between November 2010 and February 2012. All had breast density categorized as ACR3 or ACR4, were asymptomatic, and were over age 40. After having a two-view full-field digital mammogram (FFDM), each woman had a 3D ABUS examination. At least three views of each breast (lateral, anterioposterior, and medial) were performed with the patient lying in a supine position with fibroglandular tissue being flattened by compression. A radiographer/radiologic technologist held the transducer during the 15-minute examination.
Lead author and radiologist Brigitte Wilczek, MD, PhD, reported that a dedicated breast radiologist initially interpreted the mammogram, followed by a review of 3D coronal and transverse views of the 3D ABUS. Interpretation times averaged 1-2 minutes for the mammogram and 5-7 minutes for the ABUS. A second radiologist blinded to the initial findings also interpreted the mammogram. When interpretations differed, the second reader also reviewed the 3D ABUS exam. A total of 169 (10.1%) required discussion by the radiologists to reach consensus (78 FFDM and 91 3D ABUS).
Thirty-eight women were recalled for additional examinations, 15 as a result of suspicious findings on mammography images alone and 23 on 3D ABUS images alone. Eleven of the women with suspicious mammograms underwent biopsies, and seven were diagnosed with cancer. Cancer was detected in four of the 12 women who had biopsies based on findings seen only on 3D ABUS. Two of these four women also had axillary metastases. Although 3D ABUS detected four cases of cancer that could not be seen on mammography, two ductal carcinoma in situ (DCIS) were only visible on mammography images.
The authors pointed out that if 3D ABUS had not been performed, 23 women would have been recalled instead of 15 based on suspicious findings on mammography. The addition of 3D ABUS eliminated the need to recall eight patients. But recall rates overall with the combined use of mammography and 3D ABUS nearly doubled, from 13.8 recalls per 1,000 women having only mammograms, to 22.8 with women having both exams.
The authors emphasized that the objective of their study was to determine if it was both diagnostically valuable and feasible to implement a dual exam breast cancer screening protocol for women with dense breasts in a busy, high volume imaging center. The study confirmed both.
The authors did express concern about the additional length of time required both to perform and interpret 3D ABUS exams. While they did not have access during the study to a computer-assisted detection system for 3D ABUS, they do recommend its use as a way to possibly help reduce reading time.
FFDM and 3D ABUS detect more cancers than mammography alone. Appl Radiol.