title: High proton relaxivity for gadolinium oxide nanoparticles.
abstract: OBJECTIVE
  Nanosized materials of gadolinium oxide can provide high-contrast enhancement in magnetic resonance imaging (MRI). The objective of the present study was to investigate proton relaxation enhancement by ultrasmall (5 to 10 nm) Gd(2)O(3) nanocrystals.
  
  
  METHODS
  Gd(2)O(3) nanocrystals were synthesized by a colloidal method and capped with diethylene glycol (DEG). The oxidation state of Gd(2)O(3) was confirmed by X-ray photoelectron spectroscopy. Proton relaxation times were measured with a 1.5-T MRI scanner. The measurements were performed in aqueous solutions and cell culture medium (RPMI).
  
  
  RESULTS
  Results showed a considerable relaxivity increase for the Gd(2)O(3)-DEG particles compared to Gd-DTPA. Both T (1) and T (2) relaxivities in the presence of Gd(2)O(3)-DEG particles were approximately twice the corresponding values for Gd-DTPA in aqueous solution and even larger in RPMI. Higher signal intensity at low concentrations was predicted for the nanoparticle solutions, using experimental data to simulate a T(1)-weighted spin echo sequence.
  
  
  CONCLUSIONS
  The study indicates the possibility of obtaining at least doubled relaxivity compared to Gd-DTPA using Gd(2)O(3)-DEG nanocrystals as contrast agent. The high T (1) relaxation rate at low concentrations of Gd(2)O(3) nanoparticles is very promising for future studies of contrast agents based on gadolinium-containing nanocrystals.
authors.affiliation: CMIV, Linköping University, 581 85, Linköping, Sweden. maria.engstrom@cmiv.liu.se
authors.forename: Maria
authors.initials: M
authors.lastname: Engström
authors.forename: Anna
authors.initials: A
authors.lastname: Klasson
authors.forename: Henrik
authors.initials: H
authors.lastname: Pedersen
authors.forename: Cecilia
authors.initials: C
authors.lastname: Vahlberg
authors.forename: Per-Olov
authors.initials: PO
authors.lastname: Käll
authors.forename: Kajsa
authors.initials: K
authors.lastname: Uvdal
mesh_terms: D004305:Dose-Response Relationship, Drug; D005682:Gadolinium / Q000494:pharmacology*; D019786:Gadolinium DTPA / Q000494:pharmacology; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D011108:Polymers / Q000737:chemistry; D011522:Protons; D013052:Spectrometry, X-Ray Emission; D013997:Time Factors
chemical_list: D011108:Polymers; D011522:Protons; C024617:polyol; C030581:gadolinium oxide; D005682:Gadolinium; D019786:Gadolinium DTPA