title: Rapid multicomponent relaxometry in steady state with correction of magnetization transfer effects.
abstract: OBJECTIVE
  To study the effects of magnetization transfer (MT) on multicomponent T2 parameters obtained using mcDESPOT in macromolecule-rich tissues and to propose a new method called mcRISE to correct MT-induced biases.
  
  
  METHODS
  The two-pool mcDESPOT model was modified by the addition of an exchanging macromolecule proton pool to model the MT effect in cartilage. The mcRISE acquisition scheme was developed to provide sensitivity to all pools. An incremental fitting was applied to estimate MT and relaxometry parameters with minimized coupling. The interaction between MT and relaxometry parameters, efficacy of MT correction, and feasibility of mcRISE in vivo were investigated in simulations and in healthy volunteers.
  
  
  RESULTS
  The MT effect caused significant errors in multicomponent T1/T2 values and in fast-relaxing water fraction fF , which is consistent with previous experimental observations. fF increased significantly with macromolecule content if MT was ignored. mcRISE resulted in a multifold reduction of MT biases and yielded decoupled multicomponent T1/T2 relaxometry and quantitative MT parameters.
  
  
  CONCLUSIONS
  mcRISE is an efficient approach for correcting MT biases in multicomponent relaxometry based on steady state sequences. Improved specificity of mcRISE may help to elucidate the sources of the previously described high sensitivity of noncorrected mcDESPOT parameters to disease-related changes in cartilage and the brain.
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Walter F
authors.initials: WF
authors.lastname: Block
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Kijowski
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.|Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Alexey
authors.initials: A
authors.lastname: Samsonov
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000000981:diagnostic imaging; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007717:Knee / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging
keywords: cartilage imaging; magnetization transfer; multicomponent relaxometry; steady-state sequences