ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2011) 27 OC2.2

The assessment of bone microarchitecture by high resolution magnetic resonance imaging (micro MRI) in young adults with childhood onset disease

Calum Yacoubian3, Christie McComb2, Christopher Leddy3, Faisal Ahmed1 & John Foster2

1Developmental Endocrinology Research Group, Royal Hospital for Sick Children, Glasgow, UK; 2Clinical Physics, Royal Hospital for Sick Children, Glasgow, UK; 3School of Medicine, University of Glasgow, Glasgow, UK.

Introduction: Dual energy X-ray absorptiometry (DXA) scans are regarded as the gold standard for assessing bone health. However, an inability to distinguish between cortical and trabecular bone as well as the use of inapproapriate size corrections mean that this technique is of limited clinical use in conditions affecting either bone microarchitecture or patient size. We have trialled the use of high resolution MRI (micro MRI) in the measurement of bone microarchitecture in patients with different metabolic disorders.

Methods: A TrueFISP pulse sequence was optimised for high resolution imaging using a 3T Siemens Verio scanner. Images were acquired form the proximal tibia of: seven adults with osteogenesis imperfecta (OI) (ages 21–45) and seven age and sex matched controls (ages 20–45); five teenagers with childhood onset GH deficiency (GHD) (ages 16–19) and five sex matched controls (ages 21–22). Micro MRI images were analysed using in house software developed in IDL.

Results: Patients with OI were found to have a 42% reduction in apparent bone volume (appBV) (P<0.01), a 37% reduction in apparent number of trabeculae (appTbN) (P<0.01) and a 47% increase in apparent spacing between trabeculae (appTbSp) (P<0.01). GHD patients had a 14% increase in appTbSp (P=0.038) and 7.4% reduction in appBV (P=0.024). Coefficient of variation was low for both intra (appBV 0.55%, appTbTh (apparent trabecular thickness) 0.95%, appTbN 1.02%, appTbSp 1.32%) and inter (appBV 2.09%, appTbTh 2.00%, appTbN 0.87%, appTbSp 1.17%) operator reproducibility.

Conclusion: With the use of routinely available scanning equipment, we have shown there to be differences in the bone microarchitecture between volunteers with OI, where the bones are grossly affected, and controls. We have also shown that this technique is sufficiently sensitive for detecting more subtle changes in bone microarchitecture that may be found in young adults with GHD.

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