[Fluorodeoxyglucose (FDO) positron emission tomography (PET) in testicular germ cell tumors in adults: preliminary French clinical evaluation, development of the technique and its clinical applications].

OBJECTIVES

Metabolic positron emission tomography (PET) is a new imaging modality for the detection of tumours, which uses fluorodeoxyglucose (FDG) to demonstrate increased carbohydrate metabolism of malignant cells. The management of testicular germ cell tumours in adults raises three clinical problems poorly resolved by conventional imaging techniques: identification of suspected recurrences in a context of elevated circulating serum markers, initial staging assessment after orchidectomy, evaluation of the response to treatment.

MATERIAL AND METHODS

The authors report the data obtained in 16 patients (6 cases of seminoma and 10 cases of non seminomatous germ cell tumour [NSGCT]), investigated in the Frédéric-Joliot Department using a dedicated PET camera, 60 minutes after intravenous injection of 270 MBq of FDG.

RESULTS

In 9 cases of assessment of elevated serum markers with no tumour identified by conventional examinations, PET demonstrated images likely to correspond to tumour sites in 7 patients (5 true-positives [TP] and 2 false-positives [FP] due to postoperative inflammatory changes). PET was negative in 2 out of 9 patients, in whom subsequent follow-up showed spontaneous but delayed return to normal of tumour markers. In 3 of the 4 cases of initial staging of the disease, PET excluded an extension suspected by conventional imaging and the 4th case was a FP for PET. In 3 cases of evaluation of the response to treatment, PET concluded on the absence of viable residual tumour mass, with a false-negative result in one case.

CONCLUSIONS

These results are in line with those reported in the literature, which emphasize the diagnostic difficulties encountered in this disease. The significant contribution of FDG-PET should be confirmed by larger series of patients investigated by this new modality.