Can the greater trochanter/femoral neck signal intensity ratio on coronal t1 weighted images of the hip differentiate normal-abnormal bone mineral density?

Abstract

A simple index calculated by dividing the greater trochanter signal intensity by that of the femoral neck on coronal T1-weighted magnetic resonance images of the hip may be useful as an opportunistic screening tool to differentiate normal vs. abnormal bone mineral density.PurposeThe aim of this study is to evaluate the efficacy of the greater trochanter/femoral neck (T/N) signal intensity (SI) ratio on T1 weighted images of the hip in differentiating patients with normal vs. abnormal bone mineral density (BMD) using hip dual-energy x-ray absorptiometry (DXA) as the reference.MethodsThree BMD groups according to the T score of the femoral neck (i.e., normal, osteopenia, and osteoporosis) were created, and 20 patients were included for each group. The T/N ratio was calculated by dividing the greater trochanter SI by that of the femoral neck on coronal T1-weighted images. Receiver-operator characteristic (ROC) analysis was performed to determine diagnostic efficacy.ResultsThe mean age was 59.2 & PLUSMN;9.4; there were 57 women and 3 men. The mean BMD was 0.67 & PLUSMN;0.14 g/cm(2). The mean T/N ratio for the normal, osteopenia, and osteoporosis groups were 1.37 (& PLUSMN;0.12), 1.19 (& PLUSMN;0.10), and 1.18 (& PLUSMN;0.13), respectively. When the osteopenia and osteoporosis groups were combined into one group, i.e., low BMD group, the mean T/N ratio was 1.18 (& PLUSMN;0.11), and it was significantly different from that of the normal BMD group (p<0.00001). In ROC analysis, the area under curve (AUC) for the T/N ratio in the diagnosis of low BMD was 0.870. An optimal cutoff value of 1.28 was found for the differentiation of normal vs. abnormal BMD with 80% sensitivity and 80% specificity.ConclusionsThe T/N ratio seems to be effective at differentiating patients with normal vs. abnormal BMD and may help triage patients for additional evaluation.