Radiation pneumonitis (RP) can be an adverse complication of radiotherapy and usually occurs as an acute reaction from 6 to 12 weeks after radiotherapy. FDG PET is described as an early and adequate barometer for RP diagnosis. Only 1 case of fluoroestradiol uptake contemporary of metabolic FDG changes attributed to RP is reported. We report a case of a breast cancer patient with asymptomatic RP, who at 1 year later, at sequelar stage on CT, showed long-term memory of RP by 18 F-fluoroestradiol PET imaging with nonmetabolic FDG PET. (Clin Nucl Med 2020;45: e403-e405) REFERENCES 1. Demirev AK, Kostadinova ID, Gabrovski IR. 18 F-FDG PET/CT in patients with parenchymal changes attributed to radiation pneumonitis. Mol Imaging Radionucl Ther. 2018;27:107-112. 2. Liao GJ, Clark AS, Schubert EK, et al. 18 F-fluoroestradiol PET: current status and potential future clinical applications.