Imaging metastatic testicular germ cell tumours with 18FDG positron emission tomography: prospects for detection and management.

The aim of this study was to investigate the role of positron emission tomography (PET) with [18F]fluoro-2-deoxyglucose (18FDG) in metastatic testicular germ cell tumours. Twenty-one patients with stage II-IV testicular germ cell tumours were imaged by PET with a multiwire proportional chamber PET system and 18FDG. Avid 18FDG uptake was seen in metastatic disease from primary seminoma and malignant teratoma. Normal tissue uptake was seen in differentiated teratoma or necrotic, fibrotic tissue. 18FDG standard uptake values and tumour to normal tissue ratios were 6.0 +/- 1.4 and 1.7 +/- 0.4 (mean +/- 1SD), respectively, for malignant tissue. Reduction of 18FDG tumour to normal tissue ratios from pre-treatment to on-treatment scans was predictive of response (n = 3). No significant reduction in 18FDG uptake was seen in patients not responding to therapy (n = 2). These results suggest a role for 18FDG PET in the detection and management of metastatic testicular germ cell tumours.