The Clinical And Experimental MRI Research On High-Voltage Electrical Injuries In Limbs

Background:(1)With characristic injuried mode,the extent of tissue injury following high-voltage elecrical burns is usually quite difficult to evaluated from the external appearance of the patient.Unthorough debridment and injuries secondery blind exploration may be avoided by early,quick and accuate evluation. The extent,deepth and degree of tissue injury following high-voltage elecrical burns can not be demonstrated by routine examinations perfectly.There are only a few reports of detecting electical injuries with MRI.(2)There are always arguments about wether or not"progressive tissue necrosis"exists following high-voltage elecrical injury,and there is no report of MRI evidence for it. Objective:(1)Analyze the MRI manifestations of high-voltage electrical injury in limbs.(2)Observe the MRI manifestations of high-voltage electrical injury in hind limbs of rabbit dynamically with time lasting.Discuss whether or not"progressive tissue necrosis"exits in order to provide evidence for clinic and research.Methods:Part one:Imaging features of MRI and clinical materials in 12 cases with high-voltage electrical injury in limbs proved by operation and pathology were retrospectively analyzed.21 limbs of 12 cases had been performed with plain MR scan and contrast enhancement,and 6 cases had been performed 3D CE-MRA scan.Part two:10 hind limbs in rabbits of high-voltage electrical injury divided into MRI group and pathological group,MRI group had been performed with plain MR scan and contrast enhancement on the 24^th hour,36^th hour and 72^nd hour,pathological group evaluated morphologically and pathologically.Results:Part one:Various damages with skeletal muscle necrosis,injury and edema in 19 limbs were found,2 limbs only with injury.The extent,degree and depth of injury could be detected by MRI definitely which proved by operation and pathology.Skeletal muscle necrosis showed isointensity with or without hyperintensity signal on T1WI heterogeneously and hyperintensity with or without isointensity signal on T2WI heterogeneously,without enhancement after administration of contrast medium.â… type of muscle injury showed isointensity with or without hyperintensity signal on T1WI heterogeneously and hyperintensity on T2WI,with strong enhancement.â…¡type of muscle injury showed slight hyperintensity on T2WI,with moderate or slight enhancement. Edema in skeletal muscle showed isointensty on both T1WI and T2WI without enhancement.Sandwich-like,jump-like muscle injury with various damage of skin,tendons,joints,ligaments and bone could be demonstrated on MRI,titanic muscle damaged markedly.2 case occlusion,1 case stenosis,2 case dilation and 2 case normality in arteries were demonstrated on 3D CE-MRA proved by B type ultrasound and operation.Part two:Damaged hind limbs in MRI group showed isointensity on T1WI,slight heperintensity on T2WI with slight heterogeneous enhancement on 24^th hour.No enhanced regions were found on 48^th hour and 72^nd hour with progressive extension,which were also the same in pathological group. Conclusion:Muscle necrosis,injury and edema could be differentiated on MRI accurately,and the definite extend and depth of the electrical injury,the injury of skin,tendons,joints,ligaments and bone could also be displayed well on MRI. The situation of arteries could be detected by 3D CE-MRA exactly."One stop"solution could be supplied for the imaging diagnosis of limbs with high-voltage electrical injury,and MRI is also helpful to the decision of operation schedule, follow up,and judgment of therapeutic effect.With hind limbs with high-voltage electrical injury in rabbits observed on MRI dynamically,it could be concluded that progressive tissue necrosis occurred.This supplied imaging evidence for clinic and research.