[Early contrast-enhanced MR imaging assessment of femoral head viability after femoral neck fracture].

AIMS: To evaluate the use of MR imaging, before and after i.v. administration of Magnevist, for assessing the femoral head perfusion after femoral neck fracture. Evaluation of femoral head viability is important because the outcome of internal fixation is adversely affected by the development of capital osteonecrosis. METHODS: We performed MRI of the femoral head in 48 hours of injury, on 10 patients with femoral neck fracture. Five patients underwent MR imaging of the hip utilizing fat-suppressed (STIR) sequences and the others, T1-weighted spin-echo sequences before and after i.v. contrast administration. MR findings were correlated with radiographic follow-up for at least 12 months. RESULTS: Radiographic follow-up showed femoral head osteonecrosis in two patients. On contrast-enhanced MR images of these patients, the femoral head did not enhance and was lower in signal intensity than were the enhancing femoral shaft and neck distal to the fracture and the enhancing femoral head on the unaffected side. In the patients with persistent perfusion, contrast-enhanced MR images showed a uniform increase in signal intensity in the femoral shaft and neck as well as the femoral head; the femoral head on the fractured side showed contrast enhancement similar to that on the healthy side. CONCLUSIONS: These preliminary results indicate that contrast-enhanced MR imaging may be useful for noninvasive evaluation of femoral head perfusion after femoral neck fracture. MR findings also may aid the clinician in deciding between joint-preserving therapy and hip arthroplasty.