Use of CT vs. MRI for diagnosis of hip or pelvic fractures in elderly patients after low energy trauma
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Background: Elderly patients who fall account for more than two million emergency department visits each year. In 4-10 % of these patients, initial plain radiographs do not identify a hip or pelvis fracture later diagnosed with advanced imaging. No consensus exists about what type of imaging, CT or MRI, should be obtained in elderly patients with hip or pelvic pain after a low energy trauma. The purpose of this study was to determine whether CT or MRI is more likely to result in a definitive fracture diagnosis in elderly patients with hip or pelvic pain after low energy trauma. Methods: A retrospective chart review was conducted of all patients who presented to the ED at a single level one trauma center over a 4.5 year period. Inclusion criteria were age greater than fifty years old, presentation with hip and/ or pelvis pain due to a low energy trauma, and radiographic imaging including both plain radiographs and at least one pelvis MRI or CT. Results: Of the 218 patients who met inclusion criteria and had negative initial plain radiographs, CT or MRI later diagnosed a fracture in 69 patients (32%). Seventy eight patients underwent MRI (24 fractures, 32%), 132 underwent CT imaging (41 fractures, 31%), and eight had both CT and MRI (5 fractures, 63%). Patients who underwent CT spent less time in the ED on average (430 minutes) than those who underwent MRI, or MRI and CT (502 minutes and 620 minutes respectively). Patients who underwent CT were just as likely to be diagnosed with a fracture as those who underwent MRI (p= 0.002). We encountered no cases where CT imaging did not identify a fracture that was later identified on MRI. Fifty six patients (26%) had at least one contraindication to MRI. Conclusions: Our study suggests CT may be adequate to rule out hip and pelvic fractures in this patient population. CT may be preferable to MRI based on decreased time spent in the ED and the large percentage of elderly patients with contraindications to MRI.Level of Evidence: III.