高压电击伤家兔模型肢体坏死损伤的诊断:基于磁共振成像分析

目的探究磁共振成像常规序列及多b值扩散加权成像（DWI）序列对电击伤模型电击损伤的评价效果。方法选取30只普通家兔，根据电击时间将家兔随机分为3组:A组（电击0.2 s）、B组（电击0.5 s）、C组（电击1 s），10只/组；电击伤后根据标准对电击家兔进行肢体损伤分级评价；H&E染色观察家兔电击伤后24、48和72 h下肢肌肉组织病理学变化；采用磁共振T2WI平扫和T1WI-FS增强扫描观察家兔电击伤后24、48和72 h下肢损伤情况；采用DWI扫描观察不同b值下家兔电击伤不同损伤程度的表观扩散系数值。结果3种不同电击时间条件下，共计造成“轻”度损伤模型家兔为7只，“中”度损伤模型家兔为7只，“重”度损伤模型家兔为6只，“特重”度损伤模型家兔为10只（χ2=21.486，P=0.002）。组织学结果显示，电击后24 h后可见家兔下肢肌肉间质存在出血、肌细胞凝固性坏死、肌溶解及炎性浸润情况；48 h后则可观察到肌肉间质血管肿胀且有血栓形成；72 h后肌肉坏死组织进一步扩大加重；T2WI平扫及T1WI-FS增强扫描信号显示电击家兔呈渐进性坏死情况，与组织学结果一致；不同b值DWI扫描结果显示，b值在等于600 s/mm2和800 s/mm2条件下，“轻”、“中”、“重”和“特重”度损伤表观扩散系数值差异均有统计学意义（P < 0.01）。结论T2WI平扫及T1WI-FS增强MRI扫描联合多b值DWI序列扫描对于临床电击损伤的早期诊断具有重要参考意义。 

Limb necrosis of rabbit model injured by high voltage electric injury based on magnetic resonance imaging

ObjectiveTo explore the evaluation effect of conventional magnetic resonance imaging sequence and multi-B-value diffusion weighted imaging (DWI) sequence on electric shock injury model.MethodsAccording to the electric shock time, 30 rabbits were randomly divided into three groups: Group A (0.2 s), Group B (0.5 s) and Group C (1 s), with 10 rabbits in each group. After electric injury, the limb injury of rabbits was graded according to the standard. H&E staining was used to observe the histopathological changes of lower limb muscles in rabbits at 24 h, 48 h and 72 h after electric injury. The lower limb injuries of rabbits after electric injury at 24 h, 48 h and 72 h were observed by using MRI T2WI plain scan and T1WI-FS enhanced scan. Using DWI scanning, the ADC values of rabbits with different degrees of electrical injury under different B values were observed.ResultsUnder three different electric shock time conditions, 7 rabbits suffered from mild injury, 7 rabbits suffered from moderate injury, 6 rabbits suffered from severe injury and 10 rabbits suffered from severe injury (χ2= 21.486, P=0.002). Histological results showed that there were bleeding, coagulation necrosis, myolysis and inflammatory infiltration in muscle interstitium of lower limbs of rabbits 24 h after electric shock. After 48 h, swelling of muscle interstitial blood vessels and thrombosis were observed. After 72 h, the necrotic tissue of muscle was further enlarged and aggravated. The signals of T2WI plain scan and T1WI-FS enhanced scan showed progressive necrosis of rabbits after electric shock, which was consistent with the histological results. DWI scanning results with different B values showed that ADC values of "light", "medium", "heavy" and "extra-heavy" injuries were significantly different when B values were equal to 600 s/mm2 and 800 s/mm2 (P < 0.01).ConclusionT2WI plain scan and T1WI-FS enhanced MRI combined with multi-B-value DWI sequence scan have important reference significance for early diagnosis of clinical electric shock injury.