title: Is there a systematic bias of apparent diffusion coefficient (ADC) measurements of the breast if measured on different workstations? An inter- and intra-reader agreement study.
abstract: OBJECTIVE
  To evaluate the influence of post-processing systems, intra- and inter-reader agreement on the variability of apparent diffusion coefficient (ADC) measurements in breast lesions.
  
  
  METHODS
  Forty-one patients with 41 biopsy-proven breast lesions gave their informed consent and were included in this prospective IRB-approved study. Magnetic resonance imaging (MRI) examinations were performed at 1.5 T using an EPI-DWI sequence, with b-values of 0 and 1000 s/mm(2). Two radiologists (R1, R2) reviewed the images in separate sessions and measured the ADC for lesion, using MRI-workstation (S-WS), PACS-workstation (P-WS) and a commercial DICOM viewer (O-SW). Agreement was evaluated using the intraclass correlation coefficient (ICC), Bland-Altman plots and coefficient of variation (CV).
  
  
  RESULTS
  Thirty-one malignant, two high-risk and eight benign mass-like lesions were analysed. Intra-reader agreement was almost perfect (ICC-R1 = 0.974; ICC-R2 = 0.990) while inter-reader agreement was substantial (ICC from 0.615 to 0.682). Bland-Altman plots revealed a significant bias in ADC values measured between O-SW and S-WS (P = 0.025), no further systematic differences were identified. CV varied from 6.8 % to 7.9 %.
  
  
  CONCLUSIONS
  Post-processing systems may have a significant, although minor, impact on ADC measurements in breast lesions. While intra-reader agreement is high, the main source of ADC variability seems to be caused by inter-reader variation.
  
  
  CONCLUSIONS
  • ADC provides quantitative information on breast lesions independent from the system used. • ADC measurement using different workstations and software systems is generally reliable. • Systematic, but minor, differences may occur between different post-processing systems. • Inter-reader agreement of ADC measurements exceeded intra-reader agreement.
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Medical University of Vienna/General Hospital Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.|Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Clauser
authors.affiliation: Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, Udine, Italy.|Department of Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Magda
authors.initials: M
authors.lastname: Marcon
authors.affiliation: SOC Fisica Sanitaria, Azienda Ospedaliero-Universitaria, S.Maria della Misericordia, Udine, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Maieron
authors.affiliation: Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Zuiani
authors.affiliation: Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, University of Udine, Udine, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Bazzocchi
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Medical University of Vienna/General Hospital Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. pascal.baltzer@meduniwien.ac.at.
authors.forename: Pascal A T
authors.initials: PA
authors.lastname: Baltzer
mesh_terms: D000328:Adult; D000368:Aged; D015982:Bias; D001940:Breast / Q000000981:diagnostic imaging / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results
keywords: Apparent Diffusion Coefficient; Breast; Diffusion-weighted Imaging; Magnetic Resonance Imaging; Observer Variation