title: Optimal reference mammography: a comparison of mammograms obtained 1 and 2 years before the present examination.
abstract: OBJECTIVE
  We assessed and compared the benefit of using images acquired 1 year or 2 years previously during mammography interpretations.
  
  
  METHODS
  Eleven radiologists and one resident reviewed 128 cases three times: once without prior mammograms for comparison, once with mammograms from the most recent (1 year) examination, and once with mammograms acquired 2 years previously. They were asked to determine whether the patient should be recalled for additional procedures. Performances under the three conditions were compared.
  
  
  RESULTS
  Radiologists were significantly more accurate (p < 0.001) when comparison mammograms (obtained 1 or 2 years previously) were available. Although sensitivity was not significantly affected between the availability of mammograms from 1 or 2 years earlier (p > 0.10), the specificity was. Specificity using mammograms from the latest examination (obtained 1 year previously) as a reference was significantly better (p = 0.03) than specificity using mammograms obtained 2 years previously.
  
  
  CONCLUSIONS
  Comparison mammograms are important for accurate diagnosis-in particular, for increasing specificity. The latest prior examination seems to be the optimal one for this purpose.
authors.affiliation: Department of Radiology, Imaging Research, Ste. 4200, University of Pittsburgh and Magee-Womens Hospital, 300 Halket St., Pittsburgh, PA 15213, USA.
authors.forename: Jules H
authors.initials: JH
authors.lastname: Sumkin
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Holbert
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Herrmann
authors.forename: Christiane A
authors.initials: CA
authors.lastname: Hakim
authors.forename: Marie A
authors.initials: MA
authors.lastname: Ganott
authors.forename: William R
authors.initials: WR
authors.lastname: Poller
authors.forename: Ratan
authors.initials: R
authors.lastname: Shah
authors.forename: Lara A
authors.initials: LA
authors.lastname: Hardesty
authors.forename: David
authors.initials: D
authors.lastname: Gur
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008327:Mammography; D015588:Observer Variation; D012680:Sensitivity and Specificity