In vivo MRI measurements of bone quality in the calcaneus: A comparison with DXA and ultrasound

Magnetic resonance imaging (MRI) has shown promise in the assessment of bon e architecture. The precision and feasibility of MRI measurements in osteop orosis in vivo have been assessed in this study. T2' was calculated from me asurements of T2 and T2* in the calcaneus of 32 postmenopausal women using a gradient-echo sequence PRIME (Partially Refocused Interleaved Multiple Ec ho). This sequence allows the measurement of T2 and T2* in one acquisition. In vivo measurements of bone mineral density (BMD) by dual-energy X-ray ab sorptiometry (DXA) were made in the calcaneus, spine and femoral neck. The ultrasound parameters broadband ultrasound attenuation (BUA) and speed of s ound (SOS) were also measured in the calcaneus. These three techniques have not previously been compared in the same study population. The precision o f the MRI technique was poor relative to the DXA and ultrasound techniques, with a CV of 6.9% +/- 4.4% for T2' and 5.5% +/- 3.6% for T2*. Approximatel y 4% of this is due to system error as determined by phantom measurements. The postmenopausal women were classified as having low BMD if they had a lu mbar spine (L2-4) BMD of less than 0.96 g/cm(2) (more than 2 standard devia tions below normal peak bone mass). Calcaneal T2' was significantly correla ted with calcaneal BMD (r = -0.79, p < 0.0001), BUA (r = -0.59, p = 0.0004) and SOS (r= -0.58, p = 0.0006). T2' was significantly different in postmen opausal women with normal BMD and those with low BMD (p < 0.01). However, t he difference was of only borderline significance (p < 0.06) after adjustme nt for age and years since menopause.