title: Mapping immune cell infiltration using restricted diffusion MRI.
abstract: Diffusion MRI provides a noninvasive way to assess tissue microstructure. Based on diffusion MRI, we propose a model-free method called restricted diffusion imaging (RDI) to quantify restricted diffusion and correlate it with cellularity.
  
  
  
  An analytical relation between q-space signals and the density of restricted spins was derived to quantify restricted diffusion. A phantom study was conducted to investigate the performance of RDI, and RDI was applied to an animal study to assess immune cell infiltration in myocardial tissues with ischemia-reperfusion injury.
  
  
  
  Our phantom study showed a correlation coefficient of 0.998 between cell density and the restricted diffusion quantified by RDI. The animal study also showed that the high-value regions in RDI matched well with the macrophage infiltration areas in the H&E stained slides. In comparison with diffusion tensor imaging (DTI), RDI exhibited its outperformance to detect macrophage infiltration and delineate inflammatory myocardium.
  
  
  
  RDI can be used to reveal cell density and detect immune cell infiltration. RDI exhibits better specificity than the diffusivity measurement derived from DTI. Magn Reson Med 77:603-612, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors: Department of Psychology, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
authors: Fang-Cheng
authors: FC
authors: Yeh
authors: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
authors: Li
authors: L
authors: Liu
authors: Animal Imaging Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.|Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: T Kevin
authors: TK
authors: Hitchens
authors: Rangos Research Center Animal Imaging Core, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.|Department of Developmental Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors: Yijen L
authors: YL
authors: Wu
mesh_terms: D000818:Animals; D058948:Cell Tracking / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008264:Macrophages / Q000276:immunology / Q000473:pathology*; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000000981:diagnostic imaging / Q000276:immunology / Q000473:pathology*; D020556:Neutrophil Infiltration / Q000276:immunology*; D019047:Phantoms, Imaging; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: apparent diffusion coefficient (ADC); immune cell infiltration; ischemia-reperfusion injury; restricted diffusion; restricted diffusion imaging (RDI)