Pierre Pouponneau, Abstract Co-Author: Nothing to Disclose

Gilles P. Soulez MD, Presenter: Speaker, Bracco Group Speaker, Siemens AG Research grant, Siemens AG Research grant, Bracco Group Research grant, Cook Group Incorporated Research grant, Object Research Systems Inc

Gilles Beaudoin, Abstract Co-Author: Research grant, Siemens AG Research grant, biospace med

Jean-Christophe Leroux, Abstract Co-Author: Nothing to Disclose

Sylvain Martel, Abstract Co-Author: Nothing to Disclose

Iron-cobalt nanoparticles and doxorubicin (DOX) were co-encapsulated into therapeutic magnetic microcarriers (TMMC) designed for selective liver chemoembolization by magnetic resonance navigation (MRN). TMMC were successfully guided in the rabbit hepatic artery with an upgraded clinical magnetic resonance imaging (MRI) scanner to target the right or the left lobes of the liver. To improve MRN efficiency, tracking modalities of TMMC are investigated.

Animal experiments were approved by the local animal care committees. TMMC were loaded (w/w) with 37% of FeCo nanoparticles and 3% of DOX. Phantom studies were conducted to determine the effects of FeCo nanoparticles and TMMC (Ø = 53 µm, saturation magnetization = 72 emu/g) on MR images. 4 rabbits were used for the TMMC steering, 3 for the negative control (no steering) and 3 as blank control. Two others had respectively real-time TMMC tracking by (MRI) and computer tomography (CT). TMMC distribution in the liver lobes was determined ex vivo by MRI and cobalt level analysis.

In vitro / in vivo FeCo nanoparticles and TMMC induced significant signal loss on T2*-weighted MR images due to their high magnetic properties. In vitro, when the amount of TMMC increased from 1.1, 1.7 and 3.4 mg, the artifact volume increased from 21%, 98% and 281% respectively. TMMC signal loss was correlated with the loading of FeCo nanoparticles. The artifact volume increased with the echo-time (TE). Compared to TE = 3.5 ms, the artifact volume created by the TMMC increased of 89% and 258% with TE = 7 and 15 ms respectively. In vivo, the increase of TE was use to evaluate TMMC distribution in the untargeted and targeted liver lobes. The correlation coefficient (r) between the two methods used to determine the TMMC distribution was 0.87. TMMC accumulation was tracked in real time on T2* MR images and TMMC were detected also on CT images without artifacts.

TMMC can be easily tracked in real time by MRI and can be detected on CT-scan.

Since MRN of TMMC can target deep tissues, real time tracking of these particles by MR and CT imaging are important findings for future selective tumor treatment and monitoring.

Pouponneau, P, Soulez, G, Beaudoin, G, Leroux, J, Martel, S, MR and CT Tracking of Magnetic Nanoparticles and Doxorubicin Coencapsulated into Microcarriers Guided in the Vascular Network for Targeted Liver Chemoembolization.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11015814.html