DETECTION OF UNKNOWN PRIMARY HEAD AND NECK TUMORS BY POSITRON EMISSION TOMOGRAPHY

The purpose of this study was to investigate the potential of using po sitron emission tomography (PET) with F-18-labeled fluoro-2-deoxy-D-gl ucose (FDG) to detect unknown primary tumors of cervical metastases. T hirteen patients with various histologic types of cervical metastases of unknown primary origin were studied, Patients received 185-370 MBq FDG intravenously and were scanned from 30 min after injection onward. Whole-body scans were made with a Siemens ECAT 951/31 PET camera. PET identified The primary tumor in four patients: plasmocytoma, squamous cell carcinoma of the oropharynx, squamous cell carcinoma of the lary nx, and bronchial carcinoma, respectively. All known metastatic tumor sites were visualized. PET did not identify a primary tumor in one pat ient in whom a squamous cell carcinoma at the base of the tongue was f ound in a later phase. In the remaining eight patients, a primary lesi on was never found. The follow up ranged from Is to 30 months. A previ ously unknown primary tumor can be identified with FDG-PET in approxim ately 30% of patients with cervical metastases. PET call reveal useful information that results in more appropriate treatment, and it can be of value in guiding endoscopic biopsies for histologic diagnosis.