[Can superparamagnetic contrast media improve MRI-tomographic images of experimental gliomas?].

PURPOSE

To investigate whether the margins of microscopic tumors can be delineated better with monocrystalline iron oxide nanoparticles (MION), a superparamagnetic contrast medium, than with Gd-DTPA by magnetic resonance imaging (MRI).

METHODS

MRI and histological examinations were conducted in 28 Wistar rats with sterotactically implanted gliomas (C6 gliomas). Of the 28 animals, 14 were examined after intravenous administration of MION [nine animals received 179 mmol Fe/kg body weight (dose 1), and five, 893 mmol Fe/kg (dose 2)]. The other 14 animals were examined first after i.v. administration of Gd-DTPA (0.2 mmol/kg) and then after i.v. administration of MION. The extent of the tumors as seen on MRI and at histological study were compared.

RESULTS

Iron particles were identified microscopically in tumor cells and in the tumoral interstitium. After administration of MION at dose 1, the contrast-enhanced area of tumor was 1.55-fold greater than the extent of tumor identified by histological study, at dose 2,2.15-fold. Compared with Gd-DTPA the area of contrast enhancement was greater by a factor of 1.38 with MION administration at dose 1 and by a factor of 1.91 at dose 2.

CONCLUSION

MION provides intra- and extracellular contrast enhancement. The area of the contrast-enhanced tumor is dose-dependently greater with MION than with Gd-DTPA and also greater than the extent of tumor seen at histological study.