中文摘要：

目的探讨锰离子增强MRI在显示大鼠视觉传导通路中的最佳时间。方法对24只SD大鼠的单侧眼球内注射氯化锰溶液（30mmol/L）3μl后,随机分为8组（注射后3、6、12、24、30、36、48、72h组）,在间隔不同时间后分别行MR T1W扫描。设定相同的ROI后,分别测量和计算视神经、外侧膝状体、上丘在各组图像中的CNR。结果 3~24h视神经、外侧膝状体和上丘的MR强化信号逐渐增高,至24h达峰值,持续至30h后逐渐下降。大鼠视神经的信号强度除在注射后6h组和72h组、24h组和30h组差异无统计学意义外（P均〉0.05）,其余各组间的差异均有统计学意义（P均〈0.05）;外侧膝状体各组间两两比较、上丘各组间两两比较差异均有统计学意义（P均〈0.05）。结论锰离子增强MRI在显示大鼠视觉传导通路中的最佳时间是24~30h。

英文摘要：

Objective To explore manganese-enhanced MRI（MEMRI）in evaluation on optimal imaging time of rat visual projections.Methods Totally 24 SD rats of unilateral intra-vitreal injection of MnCl2（30 mmol/L×3μl）underwent MEMRI,and were randomly divided into 8groups：3h,6h,12 h,24h,30 h,36h,48 h,72hgroup.The signal intensity（SI）and CNR of the optic nerve（ON）,lateral geniculate nucleus（LGN）and superior colliculus（SC）were calculated.Results The CNR of ON,LGN and SC increased from 3hto 24 hand enhanced to the peak at 24 h,but the CNR declined gradually at 30 hsince the injection.The CNR differences of ON among eight groups was significant（all P〈0.05）except for its between 6hgroup and 72 hgroup,24hgroup and 30hgroup（both P〉0.05）.CNR differences of LGN and SC between each two groups had statistically significance（all P〈0.05）.Conclusion The optimal time of MEMRI in rat visual projections is 24 hto 30hafter MnCl2 intravitreal injections.