Bone Evaluation by Ultrasound Radiofrequency Echographic Multi Spectrometry (REMS) vs Dual X-ray Absorptiometry (DXA)

The study protocol was approved by the Ethics Review Boards of the Galeazzi Hospital in Milan (Comitato Etico San Raffaele, Milano, Italy). According to the protocol, only women will be enrolled because they are the vast majority of subjects usually tested for BMD using DXA. Women who voluntarily entered the study, will provide written informed consent and authorization for anonymized data publication.

To determine the short-term intra-operator precision and inter-operator repeatability of radiofrequency echographic multi-spectrometry (REMS) at the lumbar spine (LS) and proximal femur (FEM). All patients will undergo an ultrasound scan of the LS and FEM. Both precision and repeatability, expressed as root-mean-square coefficient of variation (RMS-CV) and least significant change (LSC) will be evaluated using data from two consecutive REMS acquisitions by the same operator or two different operators, respectively. The precision will be also assessed in the cohort stratified according to BMI classification.

To evaluate the comparison between REMS and DXA diagnostic results, spinal DXA reports were processed separately from femoral ones. According to spinal DXA reports, each patient was classified as osteoporotic^ if lumbar T-score≤ -2.5 and as non-osteoporotic if lumbar T-score > -2.5. An independent classification employing the same threshold was adopted on the basis of femoral neck T-score values obtained from femoral DXA reports. In both cases the non-osteoporotic patients were further classified as osteopenic if -2.5 < T-score < -1.0 or healthy^ if T-score≥ -1.0.

The whole classification process was independently repeated on the basis of the corresponding lumbar and femoral neck T-score values obtained from REMS scans.

Diagnostic accuracy of the REMS approach was then assessed by assuming DXA outputs as the standard reference. The diagnostic concordance between the two methods was assessed, by calculating the percentage of patients being classified in the same diagnostic category (osteoporotic, osteopenic, or healthy) by both DXA and REMS together with the degree of correlation between DXA and REMS T-score values.