Monocrystalline iron oxide nanoparticles: possible solution to the problem of surgically induced intracranial contrast enhancement in intraoperative MR imaging.
OBJECTIVE
Intraoperative MR imaging is increasingly being used to control the extent of surgical resection; however, surgical manipulation itself causes intracranial contrast enhancement, which is a source of error. Our purpose was to investigate the potential of monocrystalline iron oxide nanoparticles (MIONs) to solve this problem in an animal model.


METHODS
In male Wistar rats, surgical lesions of the brain were produced. The animals underwent MR examination immediately afterward. In the first group, a paramagnetic contrast agent was administered, whereas the second group of animals received MIONs 1 day before surgery. In a third group of animals, malignant glioma cells were stereotactically implanted in the caudoputamen. Two weeks later, MIONs were IV injected and the tumor was (partially) resected. Immediately after resection, MR examination was performed to determine the extent of residual tumor.


RESULTS
Surgically induced intracranial contrast enhancement was seen in all animals in which a paramagnetic contrast agent was used. Conversely, when MIONs had been injected, no signal changes that could be confused with residual tumor were detected. In the animals that had undergone (partial) resection of experimental gliomas, MR assessment of residual tumor was possible without any interfering surgically induced phenomena.


CONCLUSIONS
Because MIONs are stored in malignant brain tumor cells longer than they circulate in the blood, their use offers a promising strategy to avoid surgically induced intracranial contrast enhancement, which is known to be a potential source of error in intraoperative MR imaging.
Knauth
M
M
Department of Neuroradiology, University of Heidelberg Medical School, Germany.
Egelhof
T
T
Roth
S U
SU
Wirtz
C R
CR
Sartor
K
K
D000818:Animals; D001927:Brain Diseases / Q000601:surgery*; D001932:Brain Neoplasms / Q000601:surgery*; D003287:Contrast Media / Q000009:adverse effects; D052203:Ferrosoferric Oxide; D019786:Gadolinium DTPA / Q000009:adverse effects; D005910:Glioma / Q000601:surgery*; D007089:Image Enhancement; D007501:Iron; D008279:Magnetic Resonance Imaging; D008297:Male; D016343:Monitoring, Intraoperative; D009368:Neoplasm Transplantation; D010087:Oxides; D051381:Rats; D017208:Rats, Wistar
D003287:Contrast Media; D010087:Oxides; D007501:Iron; D019786:Gadolinium DTPA; D052203:Ferrosoferric Oxide