title: A pilot study of 4'-[methyl-11C]-thiothymidine PET/CT for detection of regional lymph node metastasis in non-small cell lung cancer.
abstract: BACKGROUND
  4'-[methyl-11C]-thiothymidine (4DST) is a novel positron emission tomography (PET) tracer to assess proliferation of malignancy. The diagnostic abilities of 4DST and 2-deoxy-2-18 F-fluoro-d-glucose (FDG) for detecting regional lymph node (LN) metastases of non-small cell lung cancer (NSCLC) were prospectively compared. In addition, the relationship between the PET result and the patient's prognosis was evaluated.
  
  
  METHODS
  A total of 31 patients with NSCLC underwent 4DST PET/computed tomography (CT) and FDG PET/CT. The PET/CT images were evaluated qualitatively and quantitatively for focal uptake of each PET tracer, according to the staging system of the American Joint Committee on Cancer. Surgical and histological results provided the reference standards. Patients were followed for up to two years to assess disease-free survival.
  
  
  RESULTS
  On a per-lesion basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for LN staging were 82%, 72%, 32%, 96%, and 73%, respectively, for 4DST, and 29%, 86%, 25%, 88%, and 78%, respectively, for FDG. The sensitivity of 4DST was significantly higher than that of FDG (P < 0.001). The disease-free survival rate with positive 4DST uptake in nodal lesions was 0.35, which was considerably lower than the rate of 0.83 with negative findings (P = 0.04). Among the factors tested, nodal staging by 4DST was the most influential prognostic factor (P = 0.05) in predicting the presence of a previously existing spread lesion or of a recurrence over the course of 2 years.
  
  
  CONCLUSIONS
  4DST PET/CT is sensitive for detecting mediastinal lymph node metastasis in NSCLC, but its low specificity is a limitation. However, it may be helpful in predicting the prognosis of NSCLC.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, National Center for Global Health and Medicine, 1-21-1, Toyama, Shinjyuku-ku, Tokyo 162-8655, Japan. ryogominamimoto@yahoo.co.jp.
authors.forename: Ryogo
authors.initials: R
authors.lastname: Minamimoto
authors.forename: Jun
authors.initials: J
authors.lastname: Toyohara
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ito
authors.forename: Ayako
authors.initials: A
authors.lastname: Seike
authors.forename: Yoko
authors.initials: Y
authors.lastname: Miyata
authors.forename: Miyako
authors.initials: M
authors.lastname: Morooka
authors.forename: Momoko
authors.initials: M
authors.lastname: Okasaki
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakajima
authors.forename: Kimiteru
authors.initials: K
authors.lastname: Ito
authors.forename: Kiichi
authors.initials: K
authors.lastname: Ishiwata
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kubota