Fluorodeoxyglucose PET in the initial staging of germ cell tumours

Testicular cancer is a rare tumour with the potential for cure at diagnosis . It is important, however, to identify those patients with metastases at p resentation so as to ensure that the optimum treatment strategy is employed . Many criteria have been used to try to place patients into high- or low-r isk groups, with variable success, Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has the potential to identify active disease and thereby influence further management. Here we report on a retrospective study of the use of FDG-PET in the detection of metastatic testicular carc inoma at diagnosis. Thirty-one patients [13 with seminoma and 18 with non-s eminomatous germ cell tumours (13 teratomas, 5 mixed)] were staged by FDG-P ET scanning. The imaging was performed using a Siemens ECAT 951 scanner. Al l results were assessed on the basis of histology or clinical follow-up. FD G-PET scan identified metastatic disease in ten and was negative in 16; the re were no false-positives and five false-negatives. There were six patient s in whom FDG-PET was negative and computed tomography was regarded as susp icious but follow-up was inconclusive. The positive predictive value was 10 0%. The negative predictive value was 76% or 91%, depending on whether the aforementioned six cases were regarded as true-negatives or false-negatives . It may be concluded that FDG-PET is capable of detecting metastatic disea se at diagnosis that is not identified by other imaging techniques. These p reliminary results are sufficient to suggest that a large prospective study should be performed to evaluate the role of FDG-PET in primary staging of disease.