Detection of toxoplasmic lesions in mouse brain by USPIO-enhanced magnetic resonance imaging.
The objective of this study was to examine the feasibility of detecting toxoplasmic brain lesions in a mouse model of cerebral toxoplasmosis by ultrasmall superparamagnetic particles of iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI). Toxoplasmosis encephalitis was induced in Kunming mice by intracerebral injection of Toxoplasma gondii tachyzoites. T2- and T2*--weighted MRI was performed 1, 3, 4, 5 and 6 days after infection before USPIO injection; immediately after USPIO injection; and 24 h later. A comparison of USPIO enhancement and Gd-DTPA enhancement was made in three toxoplasmic mice 4 days after infection. Hematoxylin and eosin staining and Prussian blue staining were performed to detect inflammatory reactions and presence of iron in and around the toxoplasmic brain lesions. Nonenhanced T2-/T2*-weighted imaging detected few abnormalities in the brain up to 5 days. Most mice developed prominent hydrocephalus at 6 days. Gd-DTPA-enhanced imaging showed prominent enhancement of the cerebral ventricles but revealed only few space-occupying lesions in the parenchyma. USPIO-enhanced T2*-weighted imaging showed improved detection of toxoplasmic brain lesions that were invisible to nonenhanced T2-/T2*-weighted imaging and gadolinium-enhanced imaging. Most of the enhancing lesions showed nodular enhancement immediately after USPIO injection, some of which changed appearance 24 h later, having a ring enhancement at the outer rim. It can be concluded that USPIO enhancement of the toxoplasmic lesions may reflect blood-brain barrier impairment and/or inflammatory reactions associated with these lesions. USPIO-enhanced imaging may be used in combination with gadolinium-enhanced imaging to provide better characterization of toxoplasmic brain lesions and, potentially, improve the differential diagnosis of toxoplasmosis encephalitis.
Wei
Li
L
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, PR China.
Zhou
Gang
G
Li
Zhen
Z
He
Li
L
Gao
Mingyuan
M
Tan
Jinquan
J
Lei
Hao
H
D000818:Animals; D001921:Brain / Q000473:pathology*; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D007089:Image Enhancement / Q000379:methods*; D007501:Iron; D058185:Magnetite Nanoparticles; D008297:Male; D051379:Mice; D010087:Oxides; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016781:Toxoplasmosis, Cerebral / Q000175:diagnosis*
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide