Multimodal Imaging With FAPI-PET/MRI in Breast Carcinoma-In-Situ for Detection of Occult Invasive Cancer

Inclusion Criteria: * Newly diagnosed DCIS with extent in mammography, MRI or ultrasound suspected to range \> 4 cm * Planned DCIS resection (breast conserving or mastectomy) as per guideline recommendation * Written informed consent * For women of child bearing potential: confirmed menstrual period (if applicable) and a negative highly sensitive urine or serum pregnancy test * Women of childbearing potential (WOCBP) and male patients with partners of childbearing/reproductive potential must agree to use highly effective contraception (Pearl index \< 1) when sexually active. This applies for the time period between signing of the informed consent form up to the final trial visit. Exclusion Criteria: * Contraindications for MRI (specific metallic implants, severe claustrophobia, history of anaphylaxis following MRI contrast agent application) * GFR \< 30 mL/(min∙1.73 m²) * Current pregnancy or within last 8 weeks before begin of study participation * Current nursing or within last 8 weeks before begin of study participation * Inability to understand the nature, risks, and benefits of the study * History of diagnosis of ipsilateral invasive breast cancer * Concurrent diagnosis of contralateral invasive cancer, if not curatively treated by surgery \> 1 year ago * Known hypersensitivity to the active substance or to any of the excipients of the Investigational Medicinal Product