Justifying CT prior to MRI in cases of suspected occult hip fracture. A proposed diagnostic protocol

Introduction: Patients with clinical suspicion of hip fracture, but negative radiographs are suspected of having an occult hip fracture (OHF). Different diagnostic modalities are available for investigating OHF and various protocols have been suggested. MRI has the highest sensitivity and specificity, however availability is limited in many institutes. CT is readily accessible in the large majority of hospitals throughout the world but has lower sensitivity and may miss some fractures. In this article we investigate a protocol that balances these issues providing a practical and cost-effective solution. Methods: During a four-year period between 2012 and 2016 a strict diagnostic protocol was followed at our Medical Center for patients suspected of OHF. This MRI selective protocol consisted of CT initially being performed and only when negative for fracture, followed by an MRI. Retrospective analysis of all patients who followed the protocol was performed. The patients were divided into two groups: those diagnosed by CT alone and those diagnosed by MRI after having a negative CT scan. Diagnostic performance, time to diagnosis and the cost of this protocol were evaluated. Results: 103 patients were treated under the protocol. In 50 patients (49%) hip fracture was diagnosed by CT alone. In the remaining 53 patients (51%) no definitive diagnosis was reached by CT and MRI was subsequently performed. 12 of these 53 patients (23%) were diagnosed with hip fracture necessitating surgery. In the CT only group mean time from admission to diagnosis was 3 hours, in the CT + MRI group this rose to 40 hours. Cost analysis showed that this protocol was more cost-effective than performing MRI in all patients, saving an estimated 66,805 Euro during the study period. Conclusion: The clinical challenge of diagnosing OHF can be minimised by implementing a diagnostic protocol. The protocol should take into consideration the diagnostic sensitivity, availability and cost of different imaging modalities. An MRI selective strategy with initial CT scanning is recommended, as it reduces time to diagnosis and lowers overall costs.