Hepatic magnetic resonance imaging with T2* mapping of ovariectomized rats: correlation between iron overload and postmenopausal osteoporosis.

OBJECTIVE

To explore the correlation between liver iron overload and bone mineral density (BMD) in an ovariectomy (OVX) rat model, using liver magnetic resonance (MR)-T2* and dual-energy X-ray absorptiometry (DEXA).

METHODS

Sprague-Dawley rats received deferoxamine (DFO) or phosphate-buffered saline 3 months after bilateral OVX. MRI and DEXA were performed pre- and postoperatively. Five rats per group were killed every month for micro-CT, histopathology and biochemical examinations. Statistical analysis was performed with independent-samples t tests, box plots and Pearson's correlation analysis.

RESULTS

At 2 months postoperatively, BMD was significantly lower in the OVX group than in the control group (P < 0.01), corresponding to the increased serum ferritin concentration (SFC; P < 0.01) and liver iron concentration (LIC; P < 0.01). Liver T2* values significantly differed between the two groups at 1 month postoperatively (P < 0.001) and improved 1 month after DFO injection (P < 0.05). These values were significantly and positively correlated with BMD in the control (r = 0.527, P < 0.001) and OVX (r = 0.456, P < 0.001) groups.

CONCLUSION

Liver MRI T2* changed markedly earlier than BMD, LIC and SFC, and correlated well with osteoporosis; it may thus be a valuable early indicator of osteoporosis.

KEY POINTS: • Iron overload plays a vital role in the pathogenesis of postmenopausal osteoporosis. • Liver T2* relaxation time is a sensitive value in reflecting iron overload. • Liver T2* mapping elucidates changes in postmenopausal osteoporosis earlier than BMD. • Iron chelation increases BMD in ovariectomized rats. • Liver T2* has a moderate positive correlation with BMD.