ABVS acquisition details

The ABVS integrated system (ACUSON S2000, ABVS Ultrasound System, Siemens) is equipped with a flat rectangular transducer (5-14 MHz bandwidth), that is situated on a flexible arm with touch screen monitor. The acquisition is done in axial plane. In one sweep it acquires 15,4 cm x 16,8 cm x 6 cm (maximum) volume data sets and slice thickness is 1 mm. For better image optimization the selection of breast cup (A-D) is needed before the acquisition in order to let ABVS to adjust automatically various settings (gain, frequency, depth, e. c.). The patient lies in a supine position and the transducer is applied with a tender compression on the breast in three main views: anterior-posterior, lateral and medial. If needed, for example in case of large breasts, an additional views can be acquired: superior and inferior view or as well special views targeted on the single quadrant with a suspicious finding. All views have to contain nipple as a reference point. Technically well executed exam provides consistent, reproducible, operator-independent ultrasound imaging of the entire breast [13]. The images are evaluated on a 3D working station connected to ABVS where multiplanar reconstructions are available: coronal and sagittal views. Whole exam of both breasts (standard 3 projection per breast) lasts about 15 minutes and the evaluation of a negative bilateral exam takes about 3-4 minutes by experienced reader.

Breast MRI protocol

MR imaging was performed using a 1.5 T MR scanner (Magnetom, Avanto Siemens Medical System, Erlagen, Germany) with a dedicated, bilateral, 7-channels surface breast coil and the patient in the prone position. In case of pre-menopausal patients MR was performed regardless of the phase of menstrual cycle in order not to delay surgery. T1-weighted (T1w) images were acquired on the axial plane using a 3D fast low-angle shot pulse sequence (FLASH); T2-weighted (T2w) images were acquired on the axial plane using a fast spin-echo short-time inversion recovery sequence (STIR). Imaging acquisition parameters are reported in Table 1.

Gadobenate Dimeglumine (Gd-BOPTA – Multihance, Bracco, Milan, Italy) was administered IV as an automated bolus injection at a dose of 0,2 mL/kg body weight at a flow rate of 2 mL/s, followed by flushing of 20 mL of saline. Serial dynamic images were acquired once before injection of contrast agent and five times after the start of injection. After the examination, images underwent post-processing: subtraction of the pre-contrast images from the post-contrast images, multi-planar reconstruction (MPR) and maximum intensity projection (MIP). Curves of the variations time/signal intensity were constructed placing a region of interest (ROI) on detected foci.

Findings - diagnostic approach

Malignant breast lesions seen on pre-operative MR imaging were evaluated through BI-RADS®RM criteria [14] (Table 2). The same lesions were identified also on the following ABVS examination and evaluated through BI-RADS®US criteria [14] (Table 3).

Findings - clinical cases

First case presents an invasive ductal carcinoma in a 44 years old woman between inferior quadrants in periareolar zone of the left breast. MRI (Figure 1) shows mass-like oval lesion with intense and inhomogeneous enhancement, followed by rapid wash-out (RM4) that correlates on ABVS (Figure 2) to a hypoechoic nodule with vertical growth and irregular margins (U5).

Second case shows an invasive lobular carcinoma in a 48 years old woman localized between outer quadrants of the right breast. MRI (Figure 3) presents mass-like irregular ill-defined inhomogeneous and intense lesion (RM4) that is compatible on ABVS (Figure 4) with a large hypoechoic area with indistinct margins and multiple posterior shadowing artifacts (U5).

Case three is a 70 years old woman with palpable nodule characterized as invasive mucinous carcinoma between outer left quadrants. MRI (Figure 5) shows a mass-like lobulated lesion with intense "rim" enhancement and rapid wash-out (RM5) associated with hyperintensity in STIR T2w sequences that confirms mucinous intralesion content. ABVS images (Figure 6) demonstrate an iso-hypoechoic lobulated suspicious lesion (U4) that is not perfectly distinguished from surrounded breast tissue.

Fourth case is an example of invasive papillary carcinoma in 58 years old woman situated in outer-upper quadrant of right breast. Breast MRI shows (Figure 7) small irregular mass-like intense and inhomogeneous lesion (RM4) that is compatible with a tiny hypoechoic irregular lesion (U4) showed by ABVS (Figure 8).