MEMRI在受损视神经诊断中的应用

The Application of MEMRI in the Diagnosis of Optic Nerve Damage

目的建立大鼠视神经夹挫模型,探讨锰离子增强磁共振成像(MEMRI)在判断ON损伤不同部位、程度中的临床应用.方法健康雌性SD大鼠26只,随机分成2组,其中MEMRI组分成损伤后1 d、2 d、5 d、90 d 4个时间点,电镜组分为1 d和2 d组.利用MEMRI动态观察ON受损后1 d、2 d、5 d、90 d ON示踪成像、轴浆运输变化.电镜观察ON受损后1 d和2 d超微结构变化.结果 MEMRI检查结果:T1WI上所有对照眼ON均高信号显示,显示区域有ON、上丘、外侧膝状体部分.而损伤侧T1W1结果为:1 d组实验眼夹挫部位近眼球端T1WI上表现为高信号,远离眼球端信号有减弱;2 d组实验眼夹挫部位近眼球端T1WI上表现为高信号,远离眼球端未见显影;5 d组及90 d组实验眼T1WI上ON、上丘、外侧膝状体均未见显影.电镜下1 d部分轴突溶解,髓鞘松解、有间隙形成,线粒体肿胀;2 d组轴突溶解加重,微丝、微管溶解,大量空泡形成,线粒体肿胀、空泡形成.结论 ON损伤后Ca2+通道转运功能明显受损,并随时间推移而加重,呈不可逆改变;可考虑应用MEMRI活体观察ON受损Ca2+通道转运状况,对ON受损部位、视功能状况进行临床评价.

Objective To establish a rat model of optic nerve ON contusion after clamp injury, and investigate the application of manganese-enhanced magnetic resonance imaging （MEMRI） in detection of the location and extent of damage. Method 26 healthy female SD rats were randomly divided into two groups （MEMRI group and electron microscopy group）, then the MEMRI group was observed on 1 d, 2 d, 5 d, 90 d after injury, electron microscopy group was observed at 1 d and 2 d after injury. The MEMRI group was focused on dynamic observation of ON tractography and axoplasmic transport changes on 1 d, 2 d, 5 d, 90 d after injury, electron microscope group was focused on uhrastructural changes on 1 d and 2 d after injury. Results MEMRI findings： on T1W1 all control group eyes exhibited hyper-intensity in ON, the superior colliculus and lateral geniculate body. Injury group eyes exhibited hyper-intensity in ON proximal to eye and decreased intensity in the distal end on 1 d; hyperintensity in ON proximal to eye and no signal in the distal end on 2 d; no signal in ON, the superior co]liculus and lateral geniculate body on 5 d and 90 d. Electron microscope findings： dissolving axons, loosed myelin sheaths which separated from axolemma and swelled mitochondria were observed on 1 d; Furtherdissolved axons, dissolving microfilament and microtubule, abundance of bulb-like degeneration, swelled mitochondria with bulb-like degeneration inside were observed on 2 d. Conclusion The transport function of neuronal calcium channel can be significantly damaged after ON injury and irreversibly deteriorate with time. MEMRI may be used to evaluate the transport function of damaged neuronal calcium channel in ON and detect the location and extent of damage.