title: Diffusion-weighted imaging can correctly identify false-positive lymph nodes on positron emission tomography in non-small cell lung cancer.
abstract: OBJECTIVE
  One of the limitations of fluorodeoxyglucose-positron emission tomography (PET) for N-staging in non-small cell lung cancer (NSCLC) is false-positive results due to lymphadenitis. This study was performed to examine whether DWI can correctly identify false-positive nodes on PET in NSCLC.
  
  
  METHODS
  Both PET and DWI were performed in 157 patients before surgery, which involved dissection of 1033 nodal stations. Of the 157 patients, 26 patients had pathological N1 or N2 disease. Each nodal station was classified as positive or negative on PET and DWI according to the cutoff value determined by the receiver operating characteristic curve. Short-axis diameters of lymph nodes were measured on computed tomography.
  
  
  RESULTS
  While hilar nodes did not show significant differences in the number of false-positives between PET and DWI, DWI showed fewer false-positives than PET in the mediastinum (p = 0.011). Of the 43 false-positive mediastinal nodes on PET, 35 (81 %) were negative on DWI. The mean size of the 43 false-positive nodes on PET was 9 ± 1 mm, which was significantly larger than mean size of 7 ± 3 mm of the 24 false-positive nodes on DWI (p = 0.002).
  
  
  CONCLUSIONS
  DWI can correctly identify false-positive nodes on PET in the mediastinum. The larger size of false-positive nodes on PET could be due to enlargement by lymphadenitis.
authors.affiliation: Department of General Thoracic Surgery, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, 296-8602, Japan. hnomori@qk9.so-net.ne.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nomori
authors.affiliation: Department of General Thoracic Surgery, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, 296-8602, Japan.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cong
authors.affiliation: Department of General Thoracic Surgery, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, 296-8602, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sugimura
authors.affiliation: Department of Diagnostic Radiology, Kameda Medical Center, Kamogawa, Chiba, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kato
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008199:Lymphadenitis / Q000000981:diagnostic imaging; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography
keywords: 18F-Fluorodeoxyglucose; Diffusion-weighted imaging; Lung cancer; Lymph node; Positron emission tomography