OBJECTIVETo explore the sensitivity of magnetic resonance contrast agent ultrasmall superparamagnetic iron oxide (USPIO) enhancement scan in detecting experimental allergic encephalopathy (EAE) lesions and the change of magnetic transfer of USPIO enhancement lesions in the animal model of EAE.

METHODSThe routine T1-weighted imaging, T2-weighted imaging, three dimensional T1 magnetic transfer, three dimensional T1 no magnetic transfer, Dimeglumine Gadopentetate injection (Gd-DTPA) enhancement, and USPIO enhancement scan were performed in 11 EAE rats and 10 control rats respectively. The sensitivity of USPIO and Gd-DTPA enhancement in detecting the lesions in EAE rats was calculated. Magnetic transfer ratio (MTR) of USPIO enhancement area for the first time in EAE rats and MTR of the same area of the last scan were calculated respectively. HE and myelin staining of brain tissues were performed.

RESULTSNo abnormally enhanced lesions were showed in EAE rats' brain in Gd-DTPA enhancement scan, while abnormally enhanced lesions were showed in 11 EAE rats' brain in USPIO enhancement scan. The MTR value of USPIO enhancement area for the first time was significantly different from MTR of the same area of the last scan in EAE rats (P < 0.05). Inflammation cells and demyelination lesions were found in USPIO enhancement area histopathologically. There were no positive findings in control rats.

CONCLUSIONSThe sensitivity of USPIO enhancement scan in detecting EAE lesions was high. Magnetic transfer imaging, together with USPIO enhancement scan, was helpful to determine the features of the EAE lesions.