Rationale: MagTrace® will be implemented as standard of care for sentinel lymph node biopsy, since it has several advantages compared to a radioactive technique. However, MagTrace® is known to interfere with MRI during follow-up imaging when using 2 mL. No data is available for patients who received 1 mL of MagTrace®, as is described in our current protocol. A contrast enhanced mammography (CEM) could be an alternative for MRI if it still shows artefacts.

Objective: The primary objective in this trial is to evaluate the use of MRI and contrast enhanced mammography after using MagTrace® to perform a sentinel node biopsy.

Study design: Prospective trial in an outpatient clinic setting.

Study population: Patients who were included in the previous MagTrace study will be asked to participate in this subsequent trial.

Study procedure: Participants will undergo MRI and CEM as standard 1-year follow-up. Since the MagTrace study started in August 2021 and finished in February 2022, this trial will start August 2022 to February 2023.

Main study parameters/endpoints: To evaluate the use of MRI and CEM, the following primary endpoints will be assessed: Visibility and size of artefacts undergoing MRI and CEM and its consequences of the quality for image assessment.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Since MagTrace® will be implemented as standard localisation technique for breast conserving surgery and sentinel lymph node biopsy in Zuyderland MC, the information obtained from this trial is essential for the follow-up planning of all breast cancer patients. Therefore, the burden for the patients (undergoing extra imaging) will be in proportion to the added value of this trial.

Inclusion Criteria:

• Female patients of 18 years and older.
• Previously underwent sentinel lymph node biopsy using MagTrace®.
• Undergoing standard follow-up for previous breast cancer

Exclusion Criteria:

• Unable to comprehend the extend and implications of the study and sign for informed consent.

• Standard MRI exclusion criteria:

  • Implantable (electrical) devices (e.g., pacemaker, cochlear implants, neurostimulator);
  • Any other metal implants;
  • Claustrophobia;
  • MR-incompatible prosthetic heart valves.

• Standard CEM exclusion criteria:

  • Breast implants.

Patients who participated in the previous MagTrace study will be included. All patients will be approached before their 1-year follow-up appointment at the radiology department. Patients will be informed by telephone by the coordinating investigator. If they are interested in this study, the patients will receive the patient information folder. Forty patients were included in the MagTrace study, so depending on the participants' willingness to participate in this subsequent trial, up to 40 patients will participate.