title: A Simplified Model for Intravoxel Incoherent Motion Perfusion Imaging of the Brain.
abstract: Despite a recent resurgence, intravoxel incoherent motion MRI faces practical challenges, including limited SNR and demanding acquisition and postprocessing requirements. A simplified approach using linear fitting of a subset of higher b-values has seen success in other organ systems. We sought to validate this method for evaluation of brain pathology by comparing perfusion measurements using simplified linear fitting to conventional biexponential fitting.
  
  
  
  Forty-nine patients with gliomas and 17 with acute strokes underwent 3T MRI, including DWI with 16 b-values (range, 0-900 s/mm2). Conventional intravoxel incoherent motion was performed using nonlinear fitting of the standard biexponential equation. Simplified intravoxel incoherent motion was performed using linear fitting of the log-normalized signal curves for subsets of b-values >200 s/mm2. Comparisons between ROIs (tumors, strokes, contralateral brain) and between models (biexponential and simplified linear) were performed by using 2-way ANOVA. The root mean square error and coefficient of determination (R2) were computed for the simplified model, with biexponential fitting as the reference standard.
  
  
  
  Perfusion maps using simplified linear fitting were qualitatively similar to conventional biexponential fitting. The perfusion fraction was elevated in high-grade (n = 33) compared to low-grade (n = 16) gliomas and was reduced in strokes compared to the contralateral brain (P < .001 for both main effects). Decreasing the number of b-values used for linear fitting resulted in reduced accuracy (higher root mean square error and lower R2) compared with full biexponential fitting.
  
  
  
  Intravoxel incoherent motion perfusion imaging of common brain pathology can be performed by using simplified linear fitting, with preservation of clinically relevant perfusion information.
authors: From the Department of Medical Imaging (J.C., C.H.), Sunnybrook Health Sciences Centre and University of Toronto, Toronto, Ontario, Canada.
authors: J
authors: 0000-0001-9921-2086
authors: J
authors: Conklin
authors: From the Department of Medical Imaging (J.C., C.H.), Sunnybrook Health Sciences Centre and University of Toronto, Toronto, Ontario, Canada.
authors: C
authors: 0000-0002-3226-5199
authors: C
authors: Heyn
authors: Department of Diagnostic and Interventional Radiology (M.R., M.C., C.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland.
authors: M
authors: 0000-0002-4126-9722
authors: M
authors: Roux
authors: Department of Diagnostic and Interventional Radiology (M.R., M.C., C.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland.
authors: M
authors: 0000-0001-5033-7507
authors: M
authors: Cerny
authors: Department of Radiology (M.W.), University of Virginia, Charlottesville, Virginia.|Department of Radiology (M.W., C.F.), Stanford University, Stanford, California.
authors: M
authors: 0000-0002-6726-3951
authors: M
authors: Wintermark
authors: Department of Diagnostic and Interventional Radiology (M.R., M.C., C.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland christian.federau@gmail.com.|Department of Radiology (M.W., C.F.), Stanford University, Stanford, California.
authors: C
authors: 0000-0002-3803-6602
authors: C
authors: Federau
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D001932:Brain Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D005910:Glioma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009038:Motion; D055420:Perfusion Imaging / Q000379:methods; D015203:Reproducibility of Results; D020521:Stroke / Q000000981:diagnostic imaging / Q000473:pathology