title: Correcting partial volume effects in biexponential T2 estimation of small lesions.
abstract: OBJECTIVE
  T2 mapping provides a quantitative approach for focal liver lesion characterization. For small lesions, a biexponential model should be used to account for partial volume effects (PVE). However, conventional biexponential fitting suffers from large uncertainty of the fitted parameters when noise is present. The purpose of this work is to develop a more robust method to correct for PVE affecting small lesions.
  
  
  METHODS
  We developed a region of interest-based joint biexponential fitting (JBF) algorithm to estimate the T2 of lesions affected by PVE. JBF takes advantage of the lesion fraction variation among voxels within a region of interest. JBF is compared to conventional approaches using Cramér-Rao lower bound analysis, numerical simulations, phantom, and in vivo data.
  
  
  RESULTS
  JBF provides more accurate and precise T2 estimates in the presence of PVE. Furthermore, JBF is less sensitive to region of interest drawing. Phantom and in vivo results show that JBF can be combined with a reconstruction method for highly undersampled data, enabling the characterization of small abdominal lesions from data acquired in a single breath hold.
  
  
  CONCLUSIONS
  The JBF algorithm provides more accurate and stable T2 estimates for small structures than conventional techniques when PVE is present. It should be particularly useful for the characterization of small abdominal lesions.
authors.affiliation: Department of Mathematics, University of Arizona, Tucson, Arizona, USA; Department of Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Chuan
authors.initials: C
authors.lastname: Huang
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Galons
authors.forename: Christian G
authors.initials: CG
authors.lastname: Graff
authors.forename: Eric W
authors.initials: EW
authors.lastname: Clarkson
authors.forename: Ali
authors.initials: A
authors.lastname: Bilgin
authors.forename: Bobby
authors.initials: B
authors.lastname: Kalb
authors.forename: Diego R
authors.initials: DR
authors.lastname: Martin
authors.forename: Maria I
authors.initials: MI
authors.lastname: Altbach
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008107:Liver Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: MR parameter estimation; T2 estimation; lesion classification; partial volume effect
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