Abstract
Purpose: To determine the in vivo precision and accuracy of magnetic resonance imaging (MRI) in evaluating the thin (˜mm) femoral neck cortex.
Material and Methods: Hip regions of 30 volunteers were scanned with standard 1.5T MRI twice with repositioning, and the images of the narrow-neck cross-sections were obtained. Two radiologists independently delineated periosteal and endosteal cortical boundaries, and several structural variables were determined. For precision, 95% limits of agreement and coefficients of variation were calculated. Accuracy was determined with phantoms.
Results: In vivo precision of the directly delineated measurements varied from 0.9% (periosteal circumference) to 1.6% (total area), while the precision of the calculated variables remained poorer, from 7.3% (cortical to total area ratio) to 15.1% (torsional rigidity). The root-mean-square error of the cortical thickness measurement was 0.15 mm.
Conclusion: Thin cortical bone at the narrowest location of the femoral neck can be delineated precisely and accurately with a standard clinical 1.5T MRI device. MRI provides a feasible tool for the assessment of mechanically important cortical bone at the femoral neck and may be of clinical utility in assessing hip fragility.