Case collection

Paired studies from women undergoing both bilateral digital mammography (DM) and automated 3D breast ultrasound (ABUS) examination were consecutively collected from a single institution in China between 2016 and 2018. Women attended this hospital for breast imaging after developing symptoms or, without symptoms, for a self-motivated screening breast examination. Cases were excluded from the final cohort when: the main suspicious finding in DM was calcifications, women were pregnant, breastfeeding or planning to become pregnant, women had a prior diagnosis of/or were treated for breast cancer, women had breast implants or another history of breast augmentation. This resulted in an eligible cohort of 430 cases.

The use of patient electronic health records in this study was approved by Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine. Written informed consent was obtained from all patients. Patient and lesion characteristics are listed in Table ​Table1.1. In total 42 malignant, 114 benign, and 274 normal cases were collected. Breast density was classified as heterogeneously or extremely dense in 73% of patients (BI-RADS categories c and d). All malignant and benign cases were confirmed by biopsy. Normal cases were confirmed by at least one year of negative follow-up with ABUS and DM.

Characteristics of the cases collected for the study

A: 10

B: 106

C: 217

D: 97

A: 6

B: 31

C: 69

D: 46

Malignant: 42

Benign: 114

Normal: 274

Malignant: 42

Benign: 30

Normal: 80

Invasive ductal carcinoma: 32

Ductal carcinoma in situ: 3

Mucinous carcinoma: 2

Intraductal papillary carcinoma: 2

Metaplastic carcinoma: 1

Neuroendocrine carcinoma: 1

Apocrine carcinoma: 1

Invasive ductal carcinoma: 32

Ductal carcinoma in situ: 3

Mucinous carcinoma: 2

Intraductal papillary carcinoma: 2

Metaplastic carcinoma: 1

Neuroendocrine carcinoma: 1

Apocrine carcinoma: 1

Fibroadenoma: 79

Cyst: 1

Intraductal papillary: 11

Radial scar: 1

Atypical Ductal Hyperplasia: 6

Lipoma: 1

Phyllodes tumor: 2

Hamartoma: 1

Sclerosing adenosis: 2

Benign hyperplasia: 48

Fibroadenoma: 14

Intraductal papillary: 3

Atypical Ductal Hyperplasia: 2

Lipoma: 1

Phyllodes tumor: 2

Hamartoma: 1

Benign hyperplasia: 12

When available, median and range (within parentheses) are given

BI-RADS Breast imaging reporting and data system, DM Digital mammography

The DM exams were acquired with GE Senographe Essential mammography systems and consisted of two image views per breast (cranio-caudal and medio-lateral oblique). The ABUS scan data were obtained by trained technicians or nurses using a standardized scanning protocol, using a GE Invenia ABUS system. Patients were positioned supine on an examination bed with the ipsilateral arm above the head. Each breast was scanned by an automated 6–14 MHz linear transducer (covering an area of 15.4 × 17.0 × 5.0 cm) in three standard image views: lateral, anteroposterior and medial.