Objective To characterize the MRI features of demyelinating pseudotumors(DPTs).Methods MR data of 10 cases clinically proved with DPTs were retrospectively analyzed .All cases were underwent MRI scan ,9 of 10 cases were performed with enhanced MRI,7 cases were underwent diffusion weight imaging(DWI),2 cases were performed with single voxel short echo 1 H-MRS.Results 8 cases showed lesions with mild to moderate edema,5 cases showed multiple lesions,3 cases were solitary nodular lesions,2 cases were solitary flaky lesions.On enhanced MRI,4 cases presented with open ring like enhancement,3 cases presented ring like enhancement,1 case with nodular enhancement,and 1 case showed patchy enhancement.All lesions showed high signal in DWI.In 1 H-MRS,2 cases demonstrated varying decrease in peaks heights of Nacetylaspartate(NAA),elevation of the choline(Cho),the lactate(Lac)and lipids(1ip).1 case demonstrated evident elevation in peaks height of glutamate/glutamine(Glx).Conclusion DPTs has some characteristics on MRI, especially as open ring like enhancement.It is helpful to identified DPTs from other lesions when together with DWI and 1 H-MRS.

Objective To establish a rat model of Cryptococcus neoformans meningitis. Methods Sprague-Dawley rats were divided into four groups (group A to D). The load of Cryptococcus neoformans was inoculated by intracisternal injection to the animals in Group A (1×105 cfu), Group B (1×106 cfu), Group C (1×107 cfu), and 0.9％ NaCl solution to Group D. The rats were observed after inoculation for their clinical symptoms. On day 14 and day 21 after inoculation, cerebrospinal fluid was sampled and cultured for counting of bacterial colonies. The 28-day mortality of the animals was calculated. Results All the animals in group A (1×105 cfu) survived without any apparent clinical symptoms, and associated with decreasing bacteria load. The animals in group B (1×106 cfu) had mild symptoms associated with low mortality rate and slightly increased bacterial load. The animals in group C (1×107 cfu) showed a lot of symptoms and associated with high mortality rate and significantly increased bacteria load. All the animals in group D (0.9％ NaCl solution) survived with normal activity. No bacterial colony was cultured from the cerebrospinal fluid. Conclusions Intracisternal injection of 1×107 cfu Cryptococcus neoformans to rats could cause apparent clinical symptoms of meningitis. The 28-day mortality rate of such a rat model of Cryptococcus neoformans meningitis is greater than 80％. An ideal rat model of Cryptococcus neoformans meningitis is established successfully.