[Significance of PET and integrated PET/CT in the diagnostics of occult primary tumors].

BACKGROUND: In the last years (18)F-FDG-positron-emission-tomography (PET) worked satisfactorily as helpful auxiliary method in order to verify recurrency of head and neck tumors and to detect primary tumors in case of CUP syndrome especially when CT and MR imaging failed to identify the tumor accurately. Fusion of FDG hypermetabolism in PET scan and anatomical structures is achieved by integrating positron emission tomography with CT and provides improvement also in case of CUP syndrome. This retrospective study shows 47 patients with neck metastases where PET or PET/CT helped to detect primary tumor site.

PATIENTS: In a retrospective investigation 49 PET studies of 47 patients with CUP syndrome were analyzed.

RESULTS: 9 cases had positive PET findings, 1 case false-positive. 5 cases were false-negative. In 40 PET studies there couldn't be found any sign of suspicious FDG hypermetabolism.

CONCLUSION: PET and PET/CT deliver a certain improvement in localization of primary tumor site and therapeutical strategy.