Magnetic resonance imaging of the femoral neck cortex.
OBJECTIVE
To determine the in vivo precision and accuracy of magnetic resonance imaging (MRI) in evaluating the thin (approximately mm) femoral neck cortex.


METHODS
Hip regions of 30 volunteers were scanned with standard 1.5 T 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.


CONCLUSIONS
Thin cortical bone at the narrowest location of the femoral neck can be delineated precisely and accurately with a standard clinical 1.5 T 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.
Sievänen
H
H
Bone Research Group, UKK Institute, Tampere, Finland. harri.sievanen@uta.fi
Karstila
T
T
Apuli
P
P
Kannus
P
P
D000328:Adult; D005260:Female; D005272:Femur Neck / Q000033:anatomy & histology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results