title: Diagnosing left lower lobe pneumonia: usefulness of the 'spine sign' on lateral chest radiographs.
abstract: BACKGROUND
  Left lower lobe pneumonia may be obscured by the heart on the postero-anterior (PA) chest radiograph. In such cases, the lateral projection may be helpful, especially if it exhibits the "spine sign", which is an interruption in the progressive increase in lucency of the vertebral bodies from superior to inferior. We investigated whether the spine sign would help family physicians diagnose left lower lobe pneumonia on chest radiographs.
  
  
  METHODS
  We selected the chest radiographs of all patients with left lower lobe pneumonia who were seen between 1983 and 1995 at a family practice training program (N = 78) and an equal number of chest radiographs of patients without pneumonia. Six family physicians read these radiographs under two viewing conditions: PA only vs PA and lateral. We used receiver operating characteristic (ROC) curve methodology to compare the two viewing conditions.
  
  
  RESULTS
  There was no significant difference in performance between the two viewing conditions. The lateral view was helpful in some patients but misleading in others. Among patients with pneumonia, the lateral view was helpful when the spine sign was present, but it was misleading when the spine sign was absent.
  
  
  CONCLUSIONS
  In this study of family physicians, the lateral chest radiograph did not improve overall diagnostic accuracy in patients with left lower lobe pneumonia. Among pneumonia patients with the spine sign, however, the lateral view was often helpful.
authors.affiliation: Department of Radiology, University of Iowa Hospitals and Clinics, Iowa City 52242, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Ely
authors.forename: K S
authors.initials: KS
authors.lastname: Berbaum
authors.forename: G R
authors.initials: GR
authors.lastname: Bergus
authors.forename: B H
authors.initials: BH
authors.lastname: Thompson
authors.forename: B T
authors.initials: BT
authors.lastname: Levy
authors.forename: M A
authors.initials: MA
authors.lastname: Graber
authors.forename: E R
authors.initials: ER
authors.lastname: Evans
authors.forename: D A
authors.initials: DA
authors.lastname: Bedell
authors.forename: D S
authors.initials: DS
authors.lastname: Fick
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005194:Family Practice; D005260:Female; D006801:Humans; D007484:Iowa; D008297:Male; D008875:Middle Aged; D010821:Physicians, Family / Q000592:standards; D011014:Pneumonia / Q000000981:diagnostic imaging*; D012372:ROC Curve; D013902:Radiography, Thoracic / Q000379:methods* / Q000592:standards; D012680:Sensitivity and Specificity; D013131:Spine / Q000000981:diagnostic imaging