High proton relaxivity for gadolinium oxide nanoparticles.
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.
Engström
Maria
M
CMIV, Linköping University, 581 85, Linköping, Sweden. maria.engstrom@cmiv.liu.se
Klasson
Anna
A
Pedersen
Henrik
H
Vahlberg
Cecilia
C
Käll
Per-Olov
PO
Uvdal
Kajsa
K
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
D011108:Polymers; D011522:Protons; C024617:polyol; C030581:gadolinium oxide; D005682:Gadolinium; D019786:Gadolinium DTPA