Following intralesional resection of giant cell tumour local recurrence happens in up to 40% depending on type of treatment. Common plain radiography or Magnetic resonance tomography (MRI) often has the problem not to discriminate between scar and recurrent tumour tissue in the cement-tissue border of lesions treated with cement packing. The value of Positron emission tomography (PET) for diagnosis of tumour and recurrence was investigated in these patients. In 19 patients with giant cell tumour dynamic PET using F18-Fluordeoxyglucose for estimation of FDG turnover was carried out. PET was performed before surgery and as follow up. In all patients giant cell tumour was treated by curettage followed by burring and cement packing. Giant cell tumour was shown by histology in all patients. All giant cell tumours showed a specific PET pattern with a very high standard uptake value (SUV) of 4.8 in median. In follow up after surgery this value dropped to 0.3. In one case also pulmonary metastasis could be demonstrated. Recurrence was suspected in the follow up in 5 patients by MRI or plain radiography. In all these patients PET could show an elevated SUV above 4.0. In these 5 patients surgery was performed and recurrence could be proven by histology. In one patient MRI showed signs of recurrence but PET showed a SUV of 1.3. In the revision surgery no tumour could be found. In one patient MRI was negative but PET showed a SUV of 5.2 indicating re-recurrent tumour which could be demonstrated by histology. We conclude that PET is a very helpful tool not only in the first line diagnosis of giant cell tumour but also in diagnosis of metastatic disease and especially for detection of recurrent tumour.
