Contrast-enhanced mammography (CEM) is an emerging breast imaging modality that is based on dual-energy mammography and the injection of iodinated contrast agent. A typical CEM study consists of a low-energy image (equal to a FFDM image) and a recombined image (in which areas of contrast enhancement can be appreciated). However, the situation can occur that lesions are visible only on the recombined (contrast) images (in this protocol defined as 'recombined-only lesions' or ROLs). In these cases, radiologists need to perform 'contrast-enhanced stereotactic biopsy' (CESB), in which CEM is used as a targeting modality.

However, experiences with CESB are still limited and one of the most urgent questions that need to be answered is the amount of tissue sampling that is required to reach a final diagnosis. The investigators aim to study where the cut off will be in terms of tissue sampling volume needed (i.e., number of biopsies) for a reliable diagnosis.

Rationale: Contrast-enhanced mammography (CEM) is an emerging breast imaging modality that is based on dual-energy mammography and the injection of iodinated contrast agent. A typical CEM study consists of a low-energy image (equal to a FFDM image) and a recombined image (in which areas of contrast enhancement can be appreciated). However, the situation can occur that lesions are visible only on the recombined (contrast) images (in this protocol defined as 'recombined-only lesions' or ROLs). In these cases, radiologists need to perform 'contrast-enhanced stereotactic biopsy' (CESB), in which CEM is used as a targeting modality.

However, experiences with CESB are still limited and one of the most urgent questions that need to be answered is the amount of tissue sampling that is required to reach a final diagnosis. The investigators aim to study where the cut off will be in terms of tissue sampling volume needed (i.e., number of biopsies) for a reliable diagnosis.

Objective: To determine the minimum number of CESB-guided tissue samples needed to establish a final histopathological biopsy diagnosis for ROLs.

Study design: Prospective, single center, observational cohort study. Study population: Non-pregnant women (>18 years) able to provide written informed consent and with a ROL recently observed during a regular CEM examination.

Intervention: Included subject will undergo CESB, consisting of an intravenous injection of iodinated contrast agent prior to image acquisition. After administration, a contrast-enhanced stereotactic localization will be performed of the ROL to determine the location and depth of the lesion within the breast. After targeting, 18 samples will be acquired using a 9 Gauge vacuum-assistend biopsy (VAB), collected in six separate and numbered cassettes, to be able to determine the chronological order of the tissue sampling. Each specimen will be histologically analyzed in this chronological order and findings will be compared with the final histopathological result after assessment of all 18 specimens.

Main study parameters/endpoints: The primary study aim will be to calculate the cumulative diagnostic yield per specimen, enabling us to define a minimum number of biopsies required (or tissue volume needed) to establish a reliable diagnosis using CESB. Secondary study outcomes will be general parameters of the biopsy procedure itself, such as patient characteristics, histopathological results, pain experienced during the procedure, and complication rates (hematoma, infection).

Inclusion Criteria:

• Women >18 years of age;
• Recent detection of a ROL on CEM;
• Able to provide written informed consent.

Exclusion Criteria:

• All men (male sex);
• Women (female sex) who are contra indicated for CESB (for example: impaired renal function, known hypersensitivity to iodinated contrast);
• Pregnant women.

All women recently underwent CEM in our hospital, showing a ROL. Common indications to perform a CEM examination in our hospital are: recalls from breast cancer screening, as problem-solving tool after inconclusive FFDM and/or ultrasound, breast MRI alternative, preoperative staging of breast cancer and baseline examination for women treated with neoadjuvant systemic therapy (where CEM will be used as response monitoring tool).

Anonymized data can be made available to other researchers.

2 years

Signed agreement between institutes