FIG 2.
A 62-year-old woman with metastatic breast cancer (HER2+) status post lumpectomy, adjuvant chemotherapy, radiation treatment, and immunotherapy. She had a history of intracranial metastases since 2016, treated by multiple stereotactic radiosurgeries and resections in 2021 and 2022. 18F-FES brain PET/MRI demonstrates avid FES uptake (SUVmax, 2.29) associated with a heterogeneously enhancing lesion involving the cerebellar vermis and left mesial superior cerebellar hemisphere, findings consistent with active metastatic disease (red arrow). Notably, there is no evidence of tracer uptake associated with the heterogeneously enhancing lesion in the left anterior inferior temporal lobe (yellow arrow), which was biopsy-proved radiation necrosis. Conventional MRI findings demonstrate an increase in size and degree of enhancement of the 1.4 × 1.9 × 1.3 cm vermian and left mesial superior cerebellar hemisphere lesion (previously, 1.0 × 1.1 × 1.1 cm) with increased surrounding vasogenic edema, concerning for disease progression. There is no interval change in the heterogeneously enhancing left anterior temporal lesion.