MRI study of acute high voltage electric injury in forearm muscle / 中华放射学杂志

ABSTRACT

Objective To investigate the features of MR imaging of acute high voltage electric injury in forearm muscle. Methods Nine patients (17 forearms, 8 males and 1 female, 15～36 years of age) with clinically and pathological proved acute high voltage electric injury were studied on MRI retrospectively. MRI studies were obtained within 72 hours on Siemens 1 0 T MR scanner. 2 forearms were examined with body coil, and 15 with head coil. The severe area was placed as near as possible to the isocenter in the magnet and was used as the center of the MR imaging acquisition. Spin echo T 1 weighted images, spin echo and fast spin echo T 2 weighted images were acquired in all patients. 14 out of 17 were performed with Ⅳ administration of Gd DTPA. Results All 17 forearms had fascistomy after MRI. 11 had only debridement. The lesions were mainly observed in the flexor digitorum supericialis or profunduds muscle appearing as isointense on T 1 weighted images, hyperintense on T 2 weighted images, and strongly enhanced after Ⅳ administration of Gd DTPA in 8. The proximal aspect of the lesion appeared as sharp knife in 11. There was a weaker twitch response to electrocauterization in the injury muscle than in healthy muscle. It was variably necrotic in histopathology. Two transitional zones accompanied with the suffered forearm in 2, and one transitional zone in 6. Both of them had well defined margin. 6 forearms had amputation after debriding. There was Ⅰ,Ⅱ,and Ⅲ mixture signal all over the forearms. The proximal lesions showed type Ⅰ changes. Distal to the zone of forearm showed type Ⅱ and Ⅲ pattern appearing as isointense on T 1 weighted images, hyperintense and hypointense on T 2 weighted images. It was hardly enhanced after Ⅳ administration of Gd DTPA. There was no twitch response to electrocauterization in the injury muscle. It was almost completely necrotic in histopathology. ALL amputated forearms had two transitional zones and ill defined margin. The second transitional zone was enhanced something like flower border. Conclusion MR imaging of acute high voltage electric injury in forearm appeared as three kinds of signal mode, which was closely related with histopathology. MRI was useful in dealing with clinic problem and in judging the prognosis.