This was a retrospective study that included 82 breast masses in 70 female patients detected on mammography and ultrasound. This study was approved by the local Research and Ethical committee; all the included cases gave informed consent.
The study was conducted on 70 patients presented to the breast imaging unit with either palpable breast mass, breast pain, nipple discharge, or for routine check-up. They presented during the period from April 2017 to September 2019. Their ages ranged from 25 to 82 years (mean age, 45 years ± 9). Heterogeneously dense parenchyma (ACR C) or extremely dense breast (ACR D) was included in the study.
Inclusion criteria: Cases with dense breast in mammography (ACR class C and D) who agreed to the study protocol and ABUS study.
Exclusion criteria: Patients who has any contraindication to mammography or cannot lie supine during the ABUS study.
All the cases (n = 70) were subjected to both tomosynthesis and automated breast ultrasound. They were asked to expose the upper part of the body. Pregnancy test was required for those within the childbearing period who might be pregnant.
Tomosynthesis examination protocol design
A craniocaudal (CC) and a medio-lateral oblique (MLO) view DBT were obtained with the patient in a standing position using a DBT unit prototype. Breast compression was applied, like that of mammography. Images were acquired with a GE mammography system “GE Senographe Essential with Seno Bright upgrade.”
Automated breast examination protocol design
A layer of gel was applied to the breast to ensure good contact between the 3D ABUS device and the skin. Then a curved panel (probe) was placed over the breast and gently flattened the tissue against the body. Images were acquired using a GE Invenia ABUS system (GE Healthcare, USA) which is equipped with 14 MHz linear transducer.
The scan was performed with the patient in a supine position, a rolled towel is placed under the back of the patient on the side to be examined; this allows for flattening the breast for improved contact with the probe. After exposure of the breast, application of an adequate amount of ultrasound gel over the entire surface of the breast is done to ensure proper scanning and avoid artifacts. The transducer was applied to the breast using mild compression. Scanning was performed in three standard views (coronal, longitudinal, and transverse views) to allow for adequate coverage of the entire breast. Using the nipple as the center point, the anteroposterior (AP) position is first taken. Lateral position is taken by angling the probe from the axilla toward the sternum, and for medial position the probe is angled from the sternum toward the axilla. The scans are initially reviewed on the machine monitor for quality assurance of the acquired scan. The scan time for each acquisition was 1 min and volumetric data obtained were automatically transferred to the Invenia ABUS workstation for post processing including axial, coronal, and sagittal reformats and analysis. The entire examination time was approximately 15 min for both sides.
Ultrasound studies were reviewed for the presence or absence of lesions, location, size, number, outline, and contour (regular or irregular), margin or borders (micro or macro lobulations), echogenicity compared to the breast fat, and internal echo pattern (homogenous or heterogeneous).
The tomosynthesis and automated ultrasound data were evaluated separately by two experienced radiologists in consensus; both observers were unaware of the pathological data of each patient.
Tomosynthesis (DBT) images
Assessment of breast composition, mass characterization (shape, margin, density, multiplicity, location), asymmetry, calcification, axillary lymphadenopathy, extent of disease (EOD), skin thickening, retraction and architectural distortion, and BIRADS classification were also done.
Automated ultrasound (ABUS) images
The key descriptors that are used with ABUS to differentiate benign from malignant lesions are to evaluate the margin, echogenicity, posterior acoustic features, and parallel orientation of the lesion. Other signs used for ABUS included “white wall sign” which is the presence of an echogenic wall. It corresponds to acoustic enhancement found on US and suggests that the lesion is benign. On the coronal plane, a stellate lesion with desmoplastic retraction may appear as “a retraction phenomenon sign” being highly suspicious for malignancy.
Assessment of breast composition, mass characterization (shape, margin orientation, echo pattern, and posterior feature, multiplicity, location), calcification, axillary lymphadenopathy, extent of disease (EOD), skin thickening, retraction, and BIRADS classification were also done.
All breast masses included in this study were interpreted as above described and then the accuracy in reaching the final diagnosis was calculated for both tomosynthesis and automated ultrasound.
Data were coded and entered using the statistical package SPSS (Statistical Package for the Social Sciences) version 24. Data were summarized using frequency (count) and relative frequency (percentage) for categorical data. Standard diagnostic indices including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. For comparing categorical data, chi-square test was performed. Exact test was used instead when the expected frequency is less than 5, P value less than 0.05 was considered as statistically significant.