title: Breast masses: computer-aided diagnosis with serial mammograms.
abstract: OBJECTIVE
  To retrospectively evaluate effects of computer-aided diagnosis (CAD) involving an interval change classifier (which uses interval change information extracted from prior and current mammograms and estimates a malignancy rating) on radiologists' accuracy in characterizing masses on two-view serial mammograms as malignant or benign.
  
  
  METHODS
  The data collection protocol had institutional review board approval. Patient informed consent was waived for this HIPAA-compliant retrospective study. Ninety temporal pairs of two-view serial mammograms (depicting 47 malignant and 43 benign biopsy-proved masses) were obtained from 68 patient files and were digitized. Biopsy was the reference standard. Eight Mammography Quality Standards Act of 1992-accredited radiologists and two breast imaging fellows assessed digitized two-view temporal pairs (in preselected regions of interest only) by estimating likelihood of malignancy and Breast Imaging Reporting and Data System (BI-RADS) category without and with CAD. Observers' rating data were analyzed with Dorfman-Berbaum-Metz (DBM) multireader multicase method. Statistical significance of differences was estimated with the DBM method and Student two-tailed paired t test.
  
  
  RESULTS
  Average area under the receiver operating characteristic curve for likelihood of malignancy across the 10 observers was 0.83 (range, 0.74-0.88) without CAD and improved to 0.87 (range, 0.80-0.92) with CAD (P < .05). The average partial area index above a sensitivity of 0.90 for likelihood of malignancy was 0.35 (range, 0.13-0.54) without CAD and 0.49 (range, 0.18-0.73) with CAD--a nonsignificant improvement (P = .11). For BI-RADS assessment, it was estimated that with CAD, six radiologists would correctly recommend additional biopsies for malignant masses (range, 4.3%-10.6%) and five would correctly recommend reduction of biopsy (ie, fewer biopsies) for benign masses (range, 2.3%-9.3%). However, five radiologists would incorrectly recommend additional biopsy for benign masses (range, 2.3%-14.0%), and one would incorrectly recommend reduction of biopsy (4.3%).
  
  
  CONCLUSIONS
  CAD involving interval change analysis of preselected regions of interest can significantly improve radiologists' accuracy in classifying masses on digitized screen-film mammograms as malignant or benign.
authors.affiliation: Department of Radiology, University of Michigan Medical Center, CGC B2102, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0904, USA. lhadjisk@umich.edu
authors.forename: Lubomir
authors.initials: L
authors.lastname: Hadjiiski
authors.forename: Berkman
authors.initials: B
authors.lastname: Sahiner
authors.forename: Mark A
authors.initials: MA
authors.lastname: Helvie
authors.forename: Heang-Ping
authors.initials: HP
authors.lastname: Chan
authors.forename: Marilyn A
authors.initials: MA
authors.lastname: Roubidoux
authors.forename: Chintana
authors.initials: C
authors.lastname: Paramagul
authors.forename: Caroline
authors.initials: C
authors.lastname: Blane
authors.forename: Nicholas
authors.initials: N
authors.lastname: Petrick
authors.forename: Janet
authors.initials: J
authors.lastname: Bailey
authors.forename: Katherine
authors.initials: K
authors.lastname: Klein
authors.forename: Michelle
authors.initials: M
authors.lastname: Foster
authors.forename: Stephanie K
authors.initials: SK
authors.lastname: Patterson
authors.forename: Dorit
authors.initials: D
authors.lastname: Adler
authors.forename: Alexis V
authors.initials: AV
authors.lastname: Nees
authors.forename: Joseph
authors.initials: J
authors.lastname: Shen
mesh_terms: D000328:Adult; D001706:Biopsy; D001941:Breast Diseases / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods*; D015588:Observer Variation; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies