The advantages of MRI in the detection of occult hip fractures

Abstract

While the displaced hip fracture can be visualized easily by plain radiography, the non-displaced fracture may be radiographically occult and require different imaging modalities, e.g., MRI for proper visualization. The accuracy of readers and cost advantages of utilizing MRI have not been assessed. Therefore, we undertook a study of these factors. The medical records of all patients who had visited the emergency room from June 2002 until May 2003 with a clinically suspected hip fracture, negative or equivocal plain film and subsequent MRI examination were retrospectively reviewed. Two senior and two junior radiologists independently evaluated both the MR images and radiographs of all 33 patients in a blinded study. One of three possible evaluations was described for the images of each modality: absence, presence or possibility of fracture. The economic consequences of using MRI in the detection of occult hip fractures were calculated. For all four doctors participating in this study, MRI proved to be far more sensitive and specific in the detection of occult hip fractures than radiography. Using the MR images, the senior radiologists identified the occult hip fracture patients with 100% accuracy and were in complete agreement. The agreement between junior and senior radiologists was high (average κ=0.75). MRI also detected soft tissue injuries in 39% of the patients that could not be identified with radiography. Adoption of the new protocol using MRI saves hospitals from €242 to 627 per patient. By shortening the time to diagnosis and permitting a superior visualization of both bone and soft tissue injuries, MR imaging prevents unnecessary hospitalization and delays in definitive treatment. MR images should be assessed by senior radiologists.