Study to Evaluate the Safety, Biodistribution, Radiation Dosimetry and Tumor Imaging Potential of [131I]-SGMIB Anti-HER2 VHH1 in Healthy Volunteers and Breast Cancer Patients

Inclusion Criteria: Subjects will only be included in the study if they meet all of the following criteria: * Subjects who have given informed consent * Subjects that agree not to drink alcoholic beverages or use any drugs during the study * Subject with blood parameters within normal ranges * Age: at least 18 years old Patients will only be included in the study if they meet all of the following criteria: * Patients who have given informed consent * Patients that agree not to drink alcoholic beverages or use any drugs during the study * Age: at least 18 years old * Patients with local, locally advanced or metastatic HER2+ breast carcinoma as diagnosed on biopsied tissue by immunohistochemistry or fluorescence in situ hybridization (FISH). Exclusion Criteria: Patients will not be included in the study if one of the following criteria applies: * Pregnant patients * Breast feeding patients * Patients with occupational exposure to ionizing irradiation * Patients with previous thyroid disorders * Patients that received radiolabeled compounds with a long half-life (\>7h) for diagnostic or therapeutic purposes within the last 2 days. * Patients with absolute contra-indications for thyroid blockage with potassium iodide. * Patients with abnormal liver: ALT/AST \> 2 times normal values; bilirubin \> 1.5 time normal values. * Patients with abnormal kidney function: \< 50 ml/min/1,73 m2 * Patients with recent (\< 1 week) gastrointestinal disorders (CTCAE v4.0 grade 3 or 4) with diarrhea as major symptom * Patients with any serious active infection * Patients who have any other life-threatening illness or organ system dysfunction, which in the opinion of the investigator would either compromise patient safety or interfere with the evaluation of the safety of the test radiopharmaceutical * Patients who cannot communicate reliably with the investigator * Patients who are unlikely to cooperate with the requirements of the study * Patients at increased risk of death from a pre-existing concurrent illness * Patients who participated already in this study * Patients who participated in a previous trial with Anti-HER2 VHH1 Subjects will not be included in the study if one of the following criteria applies: * Pregnant subjects * Breast feeding subjects * Subjects with occupational exposure to ionizing irradiation * Subjects with clinical significant disease or on concomitant therapy (except contraception) * Subjects with previous thyroid disorders * Subjects that received radiolabeled compounds with a long half-life (\>7h) for diagnostic or therapeutic purposes within the last 2 days. * Subjects with absolute contra-indications for thyroid blockage with potassium iodide. * Subjects with abnormal liver: ALT/AST \> 2 times normal values; bilirubin \> 1.5 time normal values. * Subjects with abnormal kidney function: \< 50 ml/min/1,73 m2 * Subjects with recent (\< 1 week) gastrointestinal disorders (CTCAE v4.0 grade 3 or 4) with diarrhea as major symptom * Subjects with any serious active infection * Subjects who have any other life-threatening illness or organ system dysfunction, which in the opinion of the investigator would either compromise subject safety or interfere with the evaluation of the safety of the test radiopharmaceutical * Subjects who cannot communicate reliably with the investigator * Subjects who are unlikely to cooperate with the requirements of the study * Subjects at increased risk of death from a pre-existing concurrent illness * Subjects who participated already in this study * Subjects who participated in a previous trial with Anti-HER2 VHH1