Use of magnetite particles as a contrast agent for MR imaging of the liver.

Abstract

To evaluate the potential of dextran-coated magnetite (DM) particles in enhancing the detection of hepatocellular carcinoma with magnetic resonance (MR) imaging, the authors induced liver tumors in rats by oral administration of diethylnitrosamine and examined the rats before and after intravenous injections of DM with various iron concentrations. Because of the intense and preferential T2 relaxativity of DM, use of DM with an iron concentration of 10 mumol/kg yielded effective MR signal reduction in each normal liver at 1 hour after the injection. Because no significant signal change in the tumors was observed on DM-enhanced MR images, the contrast between hepatocellular carcinoma and adjacent uninvolved liver increased remarkably on even relatively T1-weighted images. The detection rate for the 89 tumors, including small tumors less than 2 mm in diameter, increased from 10% (nine of 89) before DM administration to 65% (58 of 89) with DM-enhanced T1-weighted imaging. Iron staining of rat liver performed about 1 hour after DM administration showed sparse deposits of DM selectively in reticuloendothelial cells but not in liver tumors.

Relaxation effects of clustered particles

“…It has been shown that a negative charge on the particle surface accelerates phagocytosis (22). The surface of carboxylate-modified latex beads is negatively charged due to a hydroxyl group (-OH) (23), and SPIOs are also negatively charged by the hydroxyl group of dextran (24). The selected size and surface structure of latex beads were analogous to SPIO, and it was expected that RES phagocytosis of latex beads could simulate that of SPIO (22).…”

“…The selected size and surface structure of latex beads were analogous to SPIO, and it was expected that RES phagocytosis of latex beads could simulate that of SPIO (22). Thus, we used intravital microscopy using latex beads (10 -11) instead of previously used histologic iron staining after SPIO injection for animals (24).…”

The in vivo performance of biomagnetic hydroxyapatite nanoparticles in cancer hyperthermia therapy

“…Recently, the functional properties of the magnetic nanoparticles have been modified individually so that they could be used in different biological applications, such as cell label and separation [4][5][6][7], immunoassay [8,9], drug delivery [10][11][12], MRI contrast agents [13][14][15][16][17][18], and hyperthermia [19][20][21].…”

Eisenoxide (einatembare Fraktion) [MAK Value Documentation in German language, 2011]

“…Eisenoxidpartikel besitzen darüber hinaus adsorptive Eigenschaften und können die Toxizität, die Aufnahme und den Metabolismus adsorbierter Stoffe infolge Kombinationswirkung beeinflussen (u. a. Cheu et al 1996;Garcon et al 2000;Haguenoer et al1996 (Kawamura et al 1990). …”