title: Clinical relevance of imaging proliferative activity in lung nodules.
abstract: OBJECTIVE
  Recently, the thymidine analogue 3'-deoxy-3'[18F]fluorothymidine (FLT) has been introduced for imaging proliferation with positron emission tomography (PET). In this prospective study, we examined the accuracy of FLT for differentiation of benign from malignant lung lesions and for tumour staging.
  
  
  METHODS
  A total of 47 patients with newly diagnosed pulmonary nodules on chest CT suspicious for malignancy were examined with FLT-PET in addition to routine staging procedures. A total of 43 patients also underwent 2-[18F]fluoro-2-deoxy-D-glucose (FDG) PET imaging. Within 2 weeks, patients underwent resective surgery or core biopsy of the pulmonary lesion.
  
  
  RESULTS
  Histopathology revealed malignant lung tumours in 32 patients (20 non-small cell lung cancer, 1 small cell lung cancer, 1 pulmonary carcinoid, 1 non-Hodgkin's lymphoma, nine metastases from extrapulmonary tumours) and benign lesions in 15 patients. Increased FLT uptake was exclusively related to malignant tumours. FLT-PET was false negative in two patients with non-small cell lung cancer, in the patient with a pulmonary carcinoid and in three patients with lung metastases. The sensitivity of FLT-PET for detection of lung cancer was 90%, the specificity 100% and the accuracy 94%. Fifteen out of 21 patients with lung cancer had mediastinal lymph node metastases. FLT-PET was true positive in 7/15 patients, resulting in a sensitivity of 53% for N-staging (specificity 100%, accuracy 67%). Clinical TNM stage was correctly identified in 67% (20/30) patients, compared to 85% (23/27) with FDG-PET.
  
  
  CONCLUSIONS
  FLT-PET has a high specificity for the detection of malignant lung tumours. Compared with FDG, FLT-PET is less accurate for N-staging in patients with lung cancer and for detection of lung metastases. FLT-PET therefore cannot be recommended for staging of lung cancer.
authors.affiliation: Department of Nuclear Medicine, University of Ulm, Robert-Koch-Strasse 8, 89081, Ulm, Germany. andreas.buck@medizin.uni-ulm.de
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Buck
authors.forename: Martin
authors.initials: M
authors.lastname: Hetzel
authors.forename: Holger
authors.initials: H
authors.lastname: Schirrmeister
authors.forename: Gisela
authors.initials: G
authors.lastname: Halter
authors.forename: Peter
authors.initials: P
authors.lastname: Möller
authors.forename: Clemens
authors.initials: C
authors.lastname: Kratochwil
authors.forename: Andreas
authors.initials: A
authors.lastname: Wahl
authors.forename: Gerhard
authors.initials: G
authors.lastname: Glatting
authors.forename: Felix M
authors.initials: FM
authors.lastname: Mottaghy
authors.forename: Torsten
authors.initials: T
authors.lastname: Mattfeldt
authors.forename: Bernd
authors.initials: B
authors.lastname: Neumaier
authors.forename: Sven N
authors.initials: SN
authors.lastname: Reske
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015224:Dideoxynucleosides; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D003074:Solitary Pulmonary Nodule / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*
chemical_list: D015224:Dideoxynucleosides; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C002854:alovudine