title: Evaluation of intravoxel incoherent motion fitting methods in low-perfused tissue.
abstract: To investigate the robustness of constrained and simultaneous intravoxel incoherent motion (IVIM) fitting methods and the estimated IVIM parameters (D, D* and f) for applications in brain and low-perfused tissues.
  
  
  
  Model data simulations relevant to brain and low-perfused tumor tissues were computed to assess the accuracy, relative bias, and reproducibility (CV%) of the fitting methods in estimating the IVIM parameters. The simulations were performed at a series of signal-to-noise ratio (SNR) levels to assess the influence of noise on the fitting.
  
  
  
  The estimated IVIM parameters from model simulations were found significantly different (P < 0.05) using simultaneous and constrained fitting methods at low SNR. Higher accuracy and reproducibility were achieved with the constrained fitting method. Using this method, the mean error (%) for the estimated IVIM parameters at a clinically relevant SNR = 40 were D 0.35, D* 41.0 and f 4.55 for the tumor model and D 1.87, D* 2.48, and f 7.49 for the gray matter model. The most robust parameters were the IVIM-D and IVIM-f. The IVIM-D* was increasingly overestimated at low perfusion.
  
  
  
  A constrained IVIM fitting method provides more accurate and reproducible IVIM parameters in low-perfused tissue compared with simultaneous fitting.
  
  
  
  3 J. MAGN. RESON. IMAGING 2017;45:1325-1334.
authors.affiliation: Physical Sciences of Imaging in Biomedical Sciences (PSIBS), Doctoral Training Centre, University of Birmingham, United Kingdom.|Institute of Cancer and Genomic Sciences, University of Birmingham, United Kingdom.|Department of Oncology, Birmingham Children's Hospital, Birmingham, United Kingdom.
authors.forename: Emma M
authors.initials: EM
authors.lastname: Meeus
authors.affiliation: Institute of Cancer and Genomic Sciences, University of Birmingham, United Kingdom.|Department of Oncology, Birmingham Children's Hospital, Birmingham, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Novak
authors.affiliation: Institute of Cancer and Genomic Sciences, University of Birmingham, United Kingdom.|Department of Oncology, Birmingham Children's Hospital, Birmingham, United Kingdom.|RRPPS, University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom.
authors.forename: Stephanie B
authors.initials: SB
authors.lastname: Withey
authors.affiliation: Institute of Cancer and Genomic Sciences, University of Birmingham, United Kingdom.|Department of Oncology, Birmingham Children's Hospital, Birmingham, United Kingdom.
authors.forename: Niloufar
authors.initials: N
authors.lastname: Zarinabad
authors.affiliation: Physical Sciences of Imaging in Biomedical Sciences (PSIBS), Doctoral Training Centre, University of Birmingham, United Kingdom.|School of Computer Science, University of Birmingham, United Kingdom.
authors.forename: Hamid
authors.initials: H
authors.lastname: Dehghani
authors.affiliation: Institute of Cancer and Genomic Sciences, University of Birmingham, United Kingdom.|Department of Oncology, Birmingham Children's Hospital, Birmingham, United Kingdom.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Peet
mesh_terms: D000465:Algorithms; D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D002648:Child; D003198:Computer Simulation; D003287:Contrast Media; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005910:Glioma / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009038:Motion; D016011:Normal Distribution; D010477:Perfusion; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio
chemical_list: D003287:Contrast Media
keywords: IVIM; brain tumors; diffusion weighted MRI; intravoxel incoherent motion; perfusion