title: Low dose non-enhanced CT versus standard dose contrast-enhanced CT in combined PET/CT protocols for staging and therapy planning in non-small cell lung cancer.
abstract: OBJECTIVE
  To evaluate low dose non-enhanced CT and standard dose contrast-enhanced CT in combined PET/CT protocols for staging and therapy planning of non-small cell lung cancer (NSCLC).
  
  
  METHODS
  Retrospective analysis was performed of 50 consecutive patients with proven NSCLC who had been referred for primary staging (n=41) or restaging (n=9). All patients underwent a multi-phase PET/CT consisting of a low dose non-enhanced attenuation scan and an arterial and portal-venous contrast-enhanced CT scan followed by whole-body PET. Fused datasets of non-enhanced and contrast-enhanced PET/CT were compared per patient by using the TNM staging system, and per lesion regarding localisation, characterisation and delineation of tumour lesions. The staging results were validated either by histopathology or by clinical-radiological follow-up for >or=6 months.
  
  
  RESULTS
  In 47/50 patients, the results of T staging did not differ between the two PET/CT protocols. Three patients could only be correctly classified as having T4 tumours after contrast application. Regarding N staging, both protocols yielded the same results. In M staging, there was only one patient with an improvement of the results as a result of contrast application. The lesion-based analysis of 92 sites showed no difference in the accuracy of lesion localisation and only one revision of lesion characterisation by contrast-enhanced PET/CT. The assessment of tumour delineation was altered by contrast application in 58/92 sites (p<0.0001). In 10/50 patients, contrast-enhanced PET/CT detected additional clinically important findings.
  
  
  CONCLUSIONS
  In patients with advanced NSCLC, contrast-enhanced CT as part of the PET/CT protocol more accurately assessed the TNM stage in 8% of patients compared with non-contrast PET/CT. However, for planning of 3D conformal radiotherapy and non-conventional surgery, contrast-enhanced PET/CT protocols are indispensable owing to their superiority in precisely defining the tumour extent.
authors.affiliation: Department of Diagnostic Radiology, Eberhard-Karls-University, Tübingen, Germany. christina.pfannenberg@med.uni-tuebingen.de
authors.forename: Anna C
authors.initials: AC
authors.lastname: Pfannenberg
authors.forename: Philip
authors.initials: P
authors.lastname: Aschoff
authors.forename: Klaus
authors.initials: K
authors.lastname: Brechtel
authors.forename: Mark
authors.initials: M
authors.lastname: Müller
authors.forename: Roland
authors.initials: R
authors.lastname: Bares
authors.forename: Frank
authors.initials: F
authors.lastname: Paulsen
authors.forename: Jutta
authors.initials: J
authors.lastname: Scheiderbauer
authors.forename: Godehard
authors.initials: G
authors.lastname: Friedel
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Eschmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000532:radiotherapy*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011829:Radiation Dosage; D011881:Radiotherapy, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media