Normal Variant 18F-Sodium Fluoride Uptake in the Falx Cerebri Ossification

Falx cerebri ossification is an incidental finding. Mostly it is easy to diagnose, but can be challenging in few cases, and should be distinguished from calcified meningioma, hematoma, and meningeal infiltration. We report a case of a 46-year-old woman with breast cancer complaining of back pain. F-18-NaF PET/CT images show focal increase uptake at facet joints of L5/S1 vertebrae and both knees joints, suggesting degenerative disease. There is normal variant F-18-NaF uptake noted in the ossification at the falx cerebri. Recognition of normal and abnormal extraosseous F-18-NaF uptake is important for correct interpretation to avoid unnecessary further investigations.