title: Dynamic contrast-enhanced MR imaging kinetic parameters and molecular weight of dendritic contrast agents in tumor angiogenesis in mice.
abstract: OBJECTIVE
  To evaluate the relationship between dynamic contrast agent-enhanced magnetic resonance (MR) imaging-derived kinetic parameters and contrast agents of equal chemical composition and configuration but with different molecular weights in a tumor angiogenesis model.
  
  
  METHODS
  This study was approved by the ethical review committee. Maintenance and care of animals was in compliance with guidelines set by the institutional animal care committee. Dynamic contrast-enhanced MR imaging was performed with dendritic contrast agents in 16 mice with tumor xenografts; mice were placed in groups of four for each molecular weight of the contrast agent. The magnitude and spatial distribution of kinetic parameters (transfer coefficient [K(PS)] and plasma fraction [f(PV)]) were compared with molecular weight of the contrast agent by determining the Spearman correlation coefficient (r) and the quantitative relationship between the endothelial K(PS) and molecular weight.
  
  
  RESULTS
  Inverse relationships between molecular weight of contrast agent and K(PS) and f(PV) of tumor rim (r = -0.8, P < .001 and r = -0.5, P = .04, respectively) and core (r = -0.7, P = .004 and r = -0.6, P = .01, respectively) were observed. The quantitative relationship between K(PS) and molecular weight (MW) was K(PS) = 0.4/MW(0.44). A decreasing stepwise pattern in f(PV) was noted between contrast agents with low (0.7- and 3.0-kDa) molecular weight and those with high (12- and 51-kDa) molecular weight.
  
  
  CONCLUSIONS
  Macromolecular permeability is best measured with high-molecular-weight contrast agents; endothelial K(PS) values measured with low-molecular-weight contrast agents incorporate tissue perfusion and permeability and demonstrate heterogeneous microcirculatory flow.
authors.affiliation: Department of Radiology and Angiogenesis Laboratory, Departments of Pathology and Internal Medicine, Maastricht University Hospital, P. Debyelaan 25, 6202 AZ Maastricht, the Netherlands. qdlu@rdia.azm.nl
authors.forename: Quido G
authors.initials: QG
authors.lastname: de Lussanet
authors.forename: Sander
authors.initials: S
authors.lastname: Langereis
authors.forename: Regina G H
authors.initials: RG
authors.lastname: Beets-Tan
authors.forename: Marcel H P
authors.initials: MH
authors.lastname: van Genderen
authors.forename: Arjan W
authors.initials: AW
authors.lastname: Griffioen
authors.forename: Jos M A
authors.initials: JM
authors.lastname: van Engelshoven
authors.forename: Walter H
authors.initials: WH
authors.lastname: Backes
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D019786:Gadolinium DTPA / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D051379:Mice; D008819:Mice, Nude; D008970:Molecular Weight; D009374:Neoplasms, Experimental / Q000098:blood supply* / Q000473:pathology*; D009389:Neovascularization, Pathologic
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA