Fig. 2
18F–FDG-PET/CTs in a patient with metastatic breast cancer before and after systemic therapy illustrating mixed treatment response. While an osseous cervical spine metastasis (green arrows) responded to treatment, several axillary lymph node metastases (red arrows) showed growth and increased FDG uptake. Mixed response to treatment is more commonly encountered in advanced, previously treated malignancies and hybrid imaging may help to prospectively identify patients in need for alternative treatment regimens