Objective To investigate multi-echo chemical shift-encoded MRI-based mapping of proton density fat fraction (PDFF) and fat-corrected R2* in bone marrow as biomarkers for osteoporosis assessment. Methods Fifty-one patients (28 female; mean age 69.7 ± 9.0 years) underwent dual energy X-ray absorptiometry (DXA). On the basis of the t score, 173 valid vertebrae bodies were divided into three groups (healthy, osteopenic and osteoporotic). Three echo chemical shift-encoded MRI sequences were acquired at 3 T. PDFF and R2* with correction for multiple-peak fat (R2*MP) were measured for each vertebral body. Kruskal–Wallis test and post hoc analysis were performed to evaluate differences between groups. Further, the area under the curve (AUC) for each technique was calculated using logistic regression analysis. Results On the basis of DXA, 92 samples were normal (53 %), 47 osteopenic (27 %) and 34 osteoporotic (20 %). PDFF was increased in osteoporosis compared with healthy (P=0.007). R2*MP showed significant differences between normal and osteopenia (P=0.004), and between normal and osteoporosis (P<0.001). AUC to differentiate between normal and osteoporosis was 0.698 for R2*MP, 0.656 for PDFF and 0.74 for both combined. Conclusion PDFF and R2*MP are moderate biomarkers for osteoporosis. PDFF and R2*MP combination might improve the prediction in differentiating healthy subjects from those with osteoporosis.

Juvenile xanthogranuloma (JXG), one of the most common forms of Langerhans-dendritic cell proliferation in young children, usually presents as spontaneously regressing cutaneous lesions. JXG with systemic (extracutaneous) involvement is a rare histiocytic disorder in which significant morbidity and death may occur. The systemic type, especially combined with multiple central nervous system lesions in young children, has a very poor prognosis. The patient described here presented with disseminated disease including lungs, liver, kidneys, ribs, scalp, and central nervous system. The patient was treated with multiagent chemotherapy based on the Langerhans cell histiocytosis II treatment protocol. The regimen used included an additional intrathecal therapy with methotrexate and prednisolone to control central nervous system lesions. The patient was treated for 28 months and has been in remission for almost 5 years.

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