Dynamic MRI Positive Enhancement Integral Color Mapping in Femoral Neck Fracture

Introduction: The most important factor affecting the outcome of osteosynthesis is not the degree of displacement, but femoral head perfusion after femoral neck fracture. Classifications based on plane radiography including Garden’s classification cannot reflect perfusion of the femoral head. We estimated femoral head perfusion in patients with femoral neck fracture using dynamic magnetic resonance imaging positive enhancement integral color mapping (PEICM). Materials and Methods: Subjects in this prospective study comprised 64 patients with femoral neck fracture. Mean age was 78 years. All patients underwent PEICM with a 1.5-T unit before surgery. The examination protocol included coronal fast spoiled gradient echo imaging (SPGR) of the femoral head before and after intravenous gadopentetate dimeglumine administration. The integral signal intensity value of each pixel was displayed as color mapping, with the highest value displayed as red and the lowest value as black. Color mapping was then classified into 3 grades: Grade 1, same color as unaffected side; Grade 2, darker than unaffected side; and Grade 3, black. Patients showing Grade 1 or 2 underwent osteosynthesis using 3 cannulated screws. Patients showing Grade 3 underwent primary hemiarthroplasty. Patients were followed for 6 months (median, 16 months; range, 6 38 months). Results: Color mapping was classified as Grade 1 in 15 patients, Grade 2 in 32 patients and Grade 3 in 17 patients. Union was achieved without complications in 40 of 47 patients who underwent osteosynthesis (union rate, 85.1%). In the remaining 7 patients, late collapse occurred in 3 patients and non-union occurred in 4 patients. Histological studies of the extirpated femoral head from patients showing Grade 3 revealed avascular necrosis in 16 of 17 specimens. Conclusion: PEICM is a reliable method for estimating femoral head perfusion in femoral neck fractures. Deciding therapeutic strategies based on the results of PEICM is valid.