title: Intravoxel incoherent motion diffusion-weighted MR imaging of breast cancer at 3.0 tesla: Comparison of different curve-fitting methods.
abstract: BACKGROUND
  To compare three different curve-fitting methods for intravoxel incoherent motion (IVIM) analysis in breast cancer.
  
  
  METHODS
  Diffusion-weighted imaging was acquired in 30 patients with breast cancer using seven b-values (0-800 s/mm(2) ). Three curve-fitting methods were used for biexponential IVIM analysis: a. Direct estimation of D (diffusion coefficient), D* (pseudodiffusion coefficient) and f (perfusion fraction) (Method 1), b. Estimation of D first and then D* and f (Method 2), c. Estimation of D and f first and then D* (Method 3). Goodness-of-fit, parameter precision (coefficient of variance [CV]), parameter difference and correlation with relative enhancement ratio (RER) and initial area under the curve (IAUC) from dynamic contrast-enhanced (DCE) MRI of the three methods were determined and compared.
  
  
  RESULTS
  Among the three biexponential methods, Method 1 best described most of the pixels (63.20% based on R(2) ; 44.52% based on Akaike Information Criteria). The CV of D calculated from Method 2/3 (14.95%/13.90%), the CV of D* from Method 2 (77.04%) and the CV of f from Method 3 (80.87%) were the lowest among the three methods. Significant difference was observed for each IVIM-derived parameter calculated from all the three methods (P = 0.000-0.005). Only the perfusion-related f value calculated from Method 2 was correlated with RER (r = 0.548; P = 0.002) or IAUC (r = 0.561; P = 0.001).
  
  
  CONCLUSIONS
  IVIM-derived parameters differ depending on the calculation methods. The two-step fitting method with D value estimation first was correlated with DCE MRI perfusion.
authors.affiliation: Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Shiteng
authors.initials: S
authors.lastname: Suo
authors.affiliation: Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Naier
authors.initials: N
authors.lastname: Lin
authors.affiliation: Philips Research China, Shanghai, China.
authors.forename: He
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Liangbin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Su
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Hua
authors.affiliation: Department of Radiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Jianrong
authors.initials: J
authors.lastname: Xu
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001943:Breast Neoplasms / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D009038:Motion; D009716:Numerical Analysis, Computer-Assisted; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: breast cancer; curve-fitting; diffusion-weighted imaging; intravoxel incoherent motion