title: [Quantitative calculation of drugs distribution parameter in the brain extracellular space by using MRI tracer].
abstract: OBJECTIVE
  To build a mathematical model to simulate the drug distribution accompanying with diffusion, distribution and clearance in the brain extracellular space (ECS).
  
  
  METHODS
  Magnetic resonance imaging (MRI) technology was used to monitor changes in the signal-intensity-related tracer gadolinium-diethylene triamine pentaacetic acidm(Gd-DTPA), as an external drug which was injected into the rat brain, and then the mathematical model was built by using the data to establish the diffusion, distribution and clearance process of Gd-DTPA in the brain ECS. The model equation was resolved by Laplace transform. In the sphere coordinates, the linear regressive model was adopted to obtain the estimation method of diffusion coefficient, clearance rate of drugs distribution in the brain ECS.
  
  
  RESULTS
  The diffusion coefficient D and the clearance rate k were obtained as (2.73±0.364)×10(-4) mm(2)/s and (1.40±0.206)×10(-5) /s, respectively.
  
  
  CONCLUSIONS
  The proposed method can accurately reflect the isotropic drug distribution in the brain ECS, and can serve as the foundation to further solve problems about the orthotropic distribution in the brain ECS.
authors.affiliation: Department of Radiology, Peking University Third Hospital, Beijing, China.
authors.forename: Qing-yuan
authors.initials: QY
authors.lastname: He
authors.forename: Dong-qi
authors.initials: DQ
authors.lastname: He
authors.forename: Hong-bin
authors.initials: HB
authors.lastname: Han
authors.forename: Lan
authors.initials: L
authors.lastname: Yuan
authors.forename: Xiao-hong
authors.initials: XH
authors.lastname: Yang
authors.forename: Yun
authors.initials: Y
authors.lastname: Peng
authors.forename: Wei-bo
authors.initials: WB
authors.lastname: Ka
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Hai-long
authors.initials: HL
authors.lastname: Zhang
authors.forename: Ke-jia
authors.initials: KJ
authors.lastname: Li
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Jin
authors.initials: J
authors.lastname: Tian
authors.forename: Xiao-hua
authors.initials: XH
authors.lastname: Liu
authors.forename: Xiao-qi
authors.initials: XQ
authors.lastname: Xue
mesh_terms: D000818:Animals; D001921:Brain; D004058:Diffusion; D005110:Extracellular Space; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D051381:Rats
chemical_list: D019786:Gadolinium DTPA