MR imaging findings of high-voltage electrical burns in the upper extremities: correlation with angiographic findings.

BACKGROUND: A high-voltage electrical burn is often associated with deep muscle injuries. Hidden, undetected deep muscle injuries have a tendency for progressive tissue necrosis, and this can lead to major amputations or sepsis. MRI has excellent soft tissue contrast and it may aid in differentiating the areas of viable deep muscle from the areas of non-viable deep muscle.
PURPOSE: To describe the MR imaging findings of a high-voltage electrical burn in the upper extremity with emphasis on the usefulness of the gadolinium-enhanced MRI and to compare the MR imaging findings with angiography.
MATERIAL AND METHODS: We retrospectively reviewed the imaging studies of six patients with high-voltage electrical burns who underwent both MRI and angiography at the burn center of our hospital from January 2005 to December 2009. The imaging features were evaluated for the involved locations, the MR signal intensity of the affected muscles, the MR enhancement pattern, the involved arteries and the angiographic findings (classified as normal, sluggish flow, stenosis or occlusion) of the angiography of the upper extremity. We assessed the relationship between the MR imaging findings and the angiographic findings.
RESULTS: The signal intensities of affected muscles were isointense or of slightly high signal intensity as compared with the adjacent unaffected skeletal muscle on the T1-weighted MR images. Affected muscles showed heterogenous high signal intensity relative to the adjacent unaffected skeletal muscle on the T2-weighted images. The gadolinium-enhanced T1-weighted images showed diffuse inhomogeneous enhancement or peripheral rim enhancement of the affected muscles. The angiographic findings of the arterial injuries showed complete occlusion in three patients, severe stenosis in two patients and sluggish flow in one patient. Of these, the five patients with complete occlusion or severe stenosis on angiography showed non-perfused and non-viable areas of edematous muscle on MRI. On the other hand, one patient with sluggish flow on angiography showed a perfused and viable area of edematous muscle on MRI.
CONCLUSION: Gadolinium-enhanced MRI is a useful non-invasive imaging modality to detect the site and extent of hidden, undetected deep muscle injuries in a group of patients with high-voltage electrical burns of the upper extremities.