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. MATERIALS AND 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. CONCLUSION: 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.
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. MATERIALS AND 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. CONCLUSION: 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: M P Lowe; D Parker; O Reany; S Aime; M Botta; G Castellano; E Gianolio; R Pagliarin Journal: J Am Chem Soc Date: 2001-08-08 Impact factor: 15.419