title: [F-18 FDG PET for detection of occult primary tumor in patients with lymphatic metastases of the neck region].
abstract: BACKGROUND
  The occult primary tumor remains an important diagnostic problem in patients with lymph node metastases despite a large variety of imaging modalities. Therefore, the aim of our study was to evaluate the impact of F-18-FDG-positron-emission-tomography (PET) in these patients.
  
  
  METHODS
  The study group included a total of 28 patients aged 39 to 84 years with cervical lymph node metastases of a histologically confirmed squamous cell carcinoma (n = 24) or an undifferentiated carcinoma (n = 4). All patients received 370 MBq F-18-FDG intravenously, and whole-body images were acquired at 60 min p.i. with an ECAT EXACT 47 (921) (Siemens, CTI). All lesions were evaluated either by histology or by CT/MRI.
  
  
  RESULTS
  In 12 patients PET did not reveal suspected tumorous lesions. In contrast in 16/28 patients PET showed focal tracer accumulations corresponding to potential primary tumor sites located in the lungs (n = 7), in the region of the tonsilla palatina (n = 5), in the submandibular gland (n = 1), in the nasopharynx (n = 1), in the larynx (n = 1), or at the base of the tongue (n = 1). In nine out of these 16 patients, the primary was confirmed in the lungs in 5 patients, in the larynx, at the base of the tongue, in the nasopharynx, and the tonsilla palatina in one patient each, respectively. Moreover, in 6 out of 16 patients, PET was false-positive. One patient refused further evaluation of PET findings.
  
  
  CONCLUSIONS
  In approximately one third of all patients, PET detected the primary tumor site, which significantly influenced further therapeutic procedures. Thus, F-18-FDG-PET may be a valuable diagnostic tool in the detection of the primary tumor in patients with cervical lymph node metastases.
authors.affiliation: Abteilung für Nuklearmedizin, Universitätskrankenhauses Eppendorf, Hamburg.
authors.forename: K H
authors.initials: KH
authors.lastname: Bohuslavizki
authors.forename: S
authors.initials: S
authors.lastname: Klutmann
authors.forename: U
authors.initials: U
authors.lastname: Sonnemann
authors.forename: J
authors.initials: J
authors.lastname: Thoms
authors.forename: S
authors.initials: S
authors.lastname: Kröger
authors.forename: J A
authors.initials: JA
authors.lastname: Werner
authors.forename: J
authors.initials: J
authors.lastname: Mester
authors.forename: M
authors.initials: M
authors.lastname: Clausen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000556:secondary*; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D006801:Humans; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary / Q000000981:diagnostic imaging*; D010039:Otorhinolaryngologic Neoplasms / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed
chemical_list: D019788:Fluorodeoxyglucose F18