title: Diffusion-Weighted Imaging in 3.0 Tesla Breast MRI: Diagnostic Performance and Tumor Characterization Using Small Subregions vs. Whole Tumor Regions of Interest.
abstract: BACKGROUND
  Apparent diffusion coefficient (ADC) values are increasingly reported in breast MRI. As there is no standardized method for ADC measurements, we evaluated the effect of the size of region of interest (ROI) to diagnostic utility and correlation to prognostic markers of breast cancer.
  
  
  METHODS
  This prospective study was approved by the Institutional Ethics Board; the need for written informed consent for the retrospective analyses of the breast MRIs was waived by the Chair of the Hospital District. We compared diagnostic accuracy of ADC measurements from whole-lesion ROIs (WL-ROIs) to small subregions (S-ROIs) showing the most restricted diffusion and evaluated correlations with prognostic factors in 112 consecutive patients (mean age 56.2±11.6 years, 137 lesions) who underwent 3.0-T breast MRI.
  
  
  RESULTS
  Intra- and interobserver reproducibility were substantial (κ = 0.616-0.784; Intra-Class Correlation 0.589-0.831). In receiver operating characteristics analysis, differentiation between malignant and benign lesions was excellent (area under curve 0.957-0.962, cut-off ADC values for WL-ROIs: 0.87×10-3 mm2s-1; S-ROIs: 0.69×10-3 mm2s-1, P<0.001). WL-ROIs/S-ROIs achieved sensitivities of 95.7%/91.3%, specificities of 89.5%/94.7%, and overall accuracies of 89.8%/94.2%. In S-ROIs, lower ADC values correlated with presence of axillary metastases (P = 0.03), high histological grade (P = 0.006), and worsened Nottingham Prognostic Index Score (P<0.05). In both ROIs, ADC values correlated with progesterone receptors and advanced stage (P<0.01), but not with HER2, estrogen receptors, or Ki-67.
  
  
  CONCLUSIONS
  ADC values assist in breast tumor characterization. Small ROIs were more accurate than whole-lesion ROIs and more frequently associated with prognostic factors. Cut-off values differed significantly depending on measurement procedure, which should be recognized when comparing results from the literature. Instead of using a whole lesion covering ROI, a small ROI could be advocated in diffusion-weighted imaging.
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Otso
authors.initials: O
authors.lastname: Arponen
authors.forename: Otso
authors.initials: O
authors.lastname: Arponent
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mazen
authors.initials: M
authors.lastname: Sudah
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Amro
authors.initials: A
authors.lastname: Masarwah
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Taina
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Rautiainen
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mervi
authors.initials: M
authors.lastname: Könönen
authors.affiliation: Kuopio University Hospital, Department of Pathology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Pathology and Forensic Medicine, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Cancer Center of Eastern Finland, Kuopio, Finland.
authors.forename: Reijo
authors.initials: R
authors.lastname: Sironen
authors.affiliation: Kuopio University Hospital, Department of Pathology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Pathology and Forensic Medicine, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Cancer Center of Eastern Finland, Kuopio, Finland.
authors.forename: Veli-Matti
authors.initials: VM
authors.lastname: Kosma
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Anna
authors.initials: A
authors.lastname: Sutela
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Juhana
authors.initials: J
authors.lastname: Hakumäki
authors.affiliation: Kuopio University Hospital, Diagnostic Imaging Centre, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Institute of Clinical Medicine, School of Medicine, Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland; University of Eastern Finland, Cancer Center of Eastern Finland, Kuopio, Finland.
authors.forename: Ritva
authors.initials: R
authors.lastname: Vanninen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D003937:Diagnosis, Differential; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008875:Middle Aged; D011379:Prognosis; D012680:Sensitivity and Specificity