PET imaging in the management of tumors of testis and ovary: current thinking and future directions.

The role of fluoro-D-deoxyglucose positron-emission tomography (FDG-PET) in testicular malignancies has been examined in various studies primarily in three specific settings: 1) differentiation of active disease from fibrosis/mature teratoma in patients with residual mass following chemotherapy and evaluation of the response to treatment; 2) initial staging and disease assessment after orchidectomy identification of suspected recurrences in the context of elevated circulating serum markers; and 3) predicting response to treatment. Of these, the area where FDG-PET imaging has been examined the most in testicular tumors is the evaluation of postchemotherapy residual mass in both seminoma and nonseminomatous germ cell tumors (NSGCT) of the testis, a critical step in determining the subsequent management approach of these tumors that vary amongst various centers. From the available data, this should be the test of choice for the assessment of a computed tomography (CT)-visualized residual mass following chemotherapy. In patients with residual masses or raised marker levels following therapy, positron-emission tomography (PET) appears sensitive and specific for detecting recurrent disease, at suspected and unsuspected sites. Fewer studies are available investigating its usefulness for staging at diagnosis and this requires further investigation to determine its eventual place as an imaging modality in this setting. Its precise role in disease prognostification is yet to be clearly defined in this malignancy but the initial results are promising. With regard to its role in ovarian carcinoma, it appears to be particularly useful for the diagnosis of recurrence when CA125 levels are rising and conventional imaging is inconclusive or negative. The role of fluoro-D-deoxyglucose (FDG)-PET/CT for the detection of recurrent ovarian cancer appears very promising and has the potential to replace the current surveillance techniques in detecting recurrent disease.