Evaluation of 68-GaNOTA-Anti-HER2 VHH1 Uptake in Brain Metastasis of Cancer Patients

Inclusion Criteria: * Patients who have given informed consent * Age 18 years or older * Patients with brain metastasized cancer, with at least 1 brain lesion of at least 8 mm maximal diameter, as measured by CT or MRI. * Patients with potentially HER2-positive cancer. Either a HER2 staining should have been done in standard of care, or sufficient tissue should be available for HER2-staining for study purpose. Exclusion Criteria: * Pregnant patients * Breast feeding patients * Patients with recent (\< 1 week) gastrointestinal disorders 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 test radiopharmaceutical * Patients who cannot communicate reliably with the investigator * Patients at increased risk of death from a pre-existing concurrent illness