Sclerotic Transformation

Intensely FDG-avid lytic bone lesions (or lesions visible only on the PET portion of the exam) often appear as non-avid sclerotic foci on follow-up exams. 

In these cases, we consider these lesions to have undergone “sclerotic transformation”.

If these now sclerotic lesions are non-avid, they are felt to represent successfully treated metastases and no longer reflect active malignancy. 

If metabolic activity persists within these sclerotic lesions, residual active malignancy is suspected.