title: Side-by-side reading of PET and CT scans in oncology: which patients might profit from integrated PET/CT?
abstract: OBJECTIVE
  Most early publications on integrated positron emission tomography/computed tomography (PET/CT) devices have reported the new scanner generation to be superior to conventional PET. However, few of these studies have analysed the situation where, in addition to PET, a current CT scan is available for side-by-side viewing. This fact is important, because combined PET/CT or a software-based fusion of the two modalities may improve diagnosis only in cases where side-by-side reading of PET and CT data does not lead to a definitive diagnosis. The aim of this study was to analyse which patients will profit from integrated PET/CT in terms of lesion characterization.
  
  
  METHODS
  A total of 328 consecutively admitted patients referred for PET in whom a current CT scan was available were included in the study. The localization of all pathological PET lesions, as well as possible infiltration of adjacent anatomical structures, was assessed.
  
  
  RESULTS
  Of 467 pathological lesions, 94.0% were correctly assessed with respect to localization and infiltration by either conventional PET alone (51.6%) or combined reading of PET and the already existing CT scans (42.4%). Hence, in only 6.0% of all lesions, affecting 6.7% of all patients, could evaluation have profited from integrated PET/CT.
  
  
  CONCLUSIONS
  We conclude that side-by-side viewing of PET and CT scans is essential, as in 42.4% of all cases, combined viewing was important for a correct diagnosis in our series. In up to 6.7% of patients, integrated PET/CT might have given additional information, so that in nearly 50% of patients some form of combined viewing of PET and CT data is needed for accurate lesion characterization.
authors.affiliation: Department of Nuclear Medicine, University Hospital Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany. preinartz@compuserve.com
authors.forename: Patrick
authors.initials: P
authors.lastname: Reinartz
authors.forename: Franz-Josef
authors.initials: FJ
authors.lastname: Wieres
authors.forename: Wolfram
authors.initials: W
authors.lastname: Schneider
authors.forename: Alexander
authors.initials: A
authors.lastname: Schur
authors.forename: Ulrich
authors.initials: U
authors.lastname: Buell
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013382:Subtraction Technique; D018511:Systems Integration; D014057:Tomography, X-Ray Computed / Q000379:methods*