Clinical research of features of magnetic resonance imaging of high-voltage electrical burns in limbs at early stage
-
摘要: 目的 分析患者四肢高压电烧伤早期的磁共振成像(MRI)特点。 方法 2013年3月—2016年8月,笔者单位收治符合入选标准的高压电烧伤患者38例,共78只患肢,其中上肢56只、下肢22只,伤后72 h内均行MRI T1加权成像(T1WI)、T2WI、压脂T2WI平扫及压脂T1WI增强扫描。分析四肢皮肤及皮下组织、骨骼肌、肌腱、关节韧带及骨骼电烧伤的MRI信号特点,观察骨骼肌是否存在"夹心样"坏死及损伤,是否存在肌腱、关节韧带及骨骼损伤;分析截肢上肢和保肢患肢MRI信号特点。所有患者均在MRI检查后24 h内接受手术,术中对肌肉活力进行判断。分别对MRI显示完全坏死但对电刺激无反应的肌肉组织,MRI显示损伤有血运但对电刺激反应微弱的肌肉组织,以及MRI显示水肿的肌肉组织进行取材,HE染色观察肌肉组织病理特点。 结果 (1)本组患者电流入口处缺损面积大于出口处缺损,患肢皮肤及皮下组织广泛不均匀增厚,T2WI表现为高信号,T1WI表现为等信号,压脂T1WI增强后不均匀强化;皮下水肿严重区域可见条带状积液。(2)骨骼肌完全坏死,T2WI表现为低信号、等信号或稍高信号,T1WI表现为等信号、稍高信号或等信号及稍高混杂信号,压脂T1WI增强表现为大部分边界清楚的无强化区。骨骼肌损伤信号分为2型。Ⅰ型信号,紧邻完全坏死区的部分坏死肌肉,T2WI呈不均匀高信号或稍高信号,边界不清;T1WI呈等信号或略高信号;压脂T1WI增强后呈带状或花边状显著强化。Ⅱ型信号,远离完全坏死区的深部肌肉组织,T2WI呈高信号,T1WI呈等信号或等信号为主夹杂高信号,压脂T1WI增强呈不均匀中等程度或轻度强化。正常肌肉信号和Ⅰ、Ⅱ型信号内夹杂坏死信号,表现为"夹心样"改变。骨骼肌水肿,T2WI表现为稍高信号,边界不清;T1WI表现为低信号;压脂T1WI增强后无明显强化。(3)肌腱完全坏死,T2WI表现为等信号或稍高信号,T1WI表现为等信号,压脂T1WI增强后无强化。肌腱损伤,T2WI表现为等信号,T1WI表现为等信号或低信号,压脂T1WI增强后轻度强化。(4)腕关节损伤较重,关节周围软组织完全坏死,T2WI表现为稍高信号或等信号,T1WI表现为低信号,压脂T1WI增强后无强化或轻度不均匀强化。腕关节完全毁损,由外至内各层结构不清,T2WI表现为稍高信号或等信号,T1WI表现为低信号或等信号,压脂T1WI增强后无任何强化。肘关节损伤,T2WI呈高信号,T1WI呈等信号或低信号,压脂T1WI增强后不均匀强化。膝关节损伤,T2WI呈高信号,T1WI呈低信号,压脂T1WI增强后轻度强化。(5)骨质水肿,T2WI呈等信号,压脂T2WI呈稍高信号,T1WI呈等信号,压脂T1WI增强后呈斑片状强化。(6)截肢上肢的MRI表现为骨骼肌呈坏死信号、Ⅰ型信号和Ⅱ型信号及Ⅰ、Ⅱ型混杂信号,其中较远端的坏死信号和Ⅰ型信号面积大于病灶的50%以上;间生态组织范围较大,边界不清,其前后群肌肉均有弥漫性损伤;上肢尺、桡动脉搏动消失。保肢患肢的MRI表现为骨骼肌呈Ⅰ型信号、Ⅱ型信号和Ⅰ、Ⅱ型混杂信号及局部坏死信号,以Ⅰ型信号为主,远端为Ⅱ型信号。(7)MRI显示骨骼肌完全坏死区,手术探查证实肌肉活力丧失,病理检查显示横纹肌组织完全坏死。MRI显示骨骼肌损伤区,手术探查证实为间生态肌肉,活力较正常肌肉差;病理检查显示正常肌细胞和肌纤维与核固缩的坏死横纹肌细胞相混杂,损伤程度不一。MRI显示骨骼肌水肿区,手术探查证实骨骼肌肿胀,肌肉活力正常;病理检查显示横纹肌间质水肿伴大量炎性细胞浸润。MRI表现与手术探查结果及病理检查结果相符。 结论 MRI能够较好地区分骨骼肌完全坏死、损伤及水肿,判断损伤范围和深度,并能够显示皮肤、肌腱、关节韧带及骨骼的损伤情况,可为四肢高压电烧伤早期的诊断、临床手术预案的制订、术中组织活力判断提供客观的影像学依据。Abstract: Objective To analyze the features of magnetic resonance imaging (MRI) of patients with high-voltage electrical burns in limbs at early stage. Methods Thirty-eight patients with high-voltage electrical burns, conforming to the study criteria, were hospitalized in our unit from March 2013 to August 2016. T1 weighted imaging (T1WI), T2WI, fat-suppression T2WI plain scan, and fat-suppression T1WI enhanced scan of MRI were performed in 78 limbs, including 56 upper limbs and 22 lower limbs at post injury hour 72. The MRI signal characteristics of electrical burns in skin and subcutaneous tissue, skeletal muscle, tendon, joint ligament, and skeleton of limbs were analyzed. " Sandwich-like" necrosis and injury in skeletal muscle, injuries of tendon, joint ligament, and skeleton were observed. MRI signal characteristics of amputated upper limbs and salvaged limbs were also analyzed. All patients underwent surgery within 24 h after MRI examination, and the muscle vitality was judged during operation. Muscle tissue without reaction to electrical stimulation which was completely necrotic as shown by MRI, muscle tissue with weak reaction to electrical stimulation which was injured with blood supply as shown by MRI, and muscle tissue with edema as shown by MRI were collected, and then the pathological characteristics of muscle tissue were observed with HE staining. Results (1) The defect area of patients at entrance of current was bigger than that at exit. The skin and subcutaneous tissue extensively unevenly thickened. T2WI manifested hyperintensity, and T1WI manifested isointensity, while fat-suppression enhanced T1WI manifested uneven enhancement. Zonal effusion was seen in the region of serious subcutaneous edema. (2) For complete necrosis of skeletal muscle, T2WI manifested hypointense, isointensity, or slight hyperintensity, and T1WI manifested isointensity, slight hyperintensity, or mixed signal of isointensity and slight hyperintensity, while fat-suppression enhanced T1WI manifested most no enhancement area with clear boundary. The MRI signals of injured skeletal muscle could be divided into two types. Type Ⅰ signal was for partial necrotic muscle adjacent to the completely necrotic zone. T2WI manifested uneven hyperintensity or slight hyperintensity, with unclear boundary. T1WI manifested isointensity or slight hyperintensity. Fat-suppression enhanced T1WI manifested significant banding or laciness enhancement. Type Ⅱ signal was for deep muscle tissue far from the complete necrotic zone. T2WI manifested hyperintensity, and T1WI manifested isointensity or main isointensity mixed with hyperintensity, while fat-suppression enhanced T1WI manifested uneven moderate or slight enhancement. Normal muscle signal, type Ⅰ signal, and type Ⅱ signal were all mixed with necrotic signal, showing " sandwich-like" change. For skeletal muscle edema, T2WI manifested slight hyperintensity and unclear boundary, and T1WI manifested hypointense, while fat-suppression enhanced T1WI manifested no obvious enhancement. (3) For complete necrosis of tendon, T2WI manifested isointensity or slight hyperintensity, and T1WI manifested isointensity, while fat-suppression enhanced T1WI manifested no enhancement. For tendon injury, T2WI manifested isointensity, and T1WI manifested isointensity or hypointense, while fat-suppression enhanced T1WI manifested slight enhancement. (4) Severe injury of wrist joint were manifested as complete necrosis of soft tissue around joint. T2WI manifested slight hyperintensity or isointensity, and T1WI manifested isointensity, while fat-suppression enhanced T1WI manifested no enhancement or slightly uneven enhancement. For completely destroyed wrist joints, the structures were not clear from outside to inside. T2WI manifested slight hyperintensity or isointensity, and T1WI manifested hypointense or isointensity, while fat-suppression enhanced T1WI manifested no enhancement. For elbow injury, T2WI manifested hyperintensity, and T1WI manifested isointensity or hypointense, while fat-suppression enhanced T1WI manifested uneven enhancement. For knee injury, T2WI manifested hyperintensity, and T1WI manifested hypointense, while fat-suppression enhanced T1WI manifested slight enhancement. (5) For bone edema, T2WI manifested isointensity, while fat-suppression T2WI manifested slight hyperintensity. T1WI manifested isointensity, and fat-suppression enhanced T1WI manifested patchy enhancement. (6) MRI of amputated upper limbs showed necrosis signals, type Ⅰ signals, type Ⅱ signals, and mixed signals of type Ⅰ and type Ⅱ in skeletal muscle. The necrosis signal and type Ⅰ signal area of the distal end were more than 50% greater than those of the lesion. The scope of the ecological tissue was large and the boundary was not clear. There were diffuse injuries in both anterior and posterior muscles, and the ulnar and radial artery pulsation disappeared in the upper limbs. The MRI of salvaged limbs were type Ⅰ signal, type Ⅱ signal, mixed signals of type Ⅰ and type Ⅱ, and local necrosis signals of skeletal muscle. The type Ⅰ signal was the main type, and the distal end showed type Ⅱ signal. (7) For completely necrotic skeletal muscle as shown by MRI, surgical exploration showed loss of muscle viability, and pathological examination showed complete necrosis of striated muscle tissue. For injury area of skeletal muscle as shown by MRI, surgical exploration showed interecological muscle with activity worse than mormal muscle, and pathological examination showed normal muscle cells and muscle fiber mixed with necrotic striated muscle cells having karyopyknosis, with different degree of injury. For edema area of skeletal muscle as shown by MRI, surgical exploration showed swelling skeletal muscle and normal muscle vitality, and pathological examination showed striated muscle interstitial edema with a large number of inflammatory cells infiltration. The manifestions of MRI were consistent with the results of surgical exploration and pathological examination. Conclusions Skeletal muscle complete necrosis, injury, and edema could be preferably differentiated by MRI, and the definite scope and depth of electrical injury, the injury of skin, tendon, joint ligament, and bone could also be displayed well on MRI. It can provide objective imaging basis for the diagnosis of high-voltage electrical burns in limbs at early stage, the establishment of clinical operation plan, and the judgment of intraoperative tissue vitality.
-
Key words:
- Burns, electric /
- Magnetic resonance imaging /
- Extremities
点击查看大图
计量
- 文章访问数: 105
- HTML全文浏览量: 19
- PDF下载量: 5
- 被引次数: 0