Opportunistic Evaluation of Trabecular Bone Texture by MRI Reflects Bone Mineral Density and Microarchitecture

CONTEXT

Many individuals at high risk for fracture are never evaluated for osteoporosis and subsequently do not receive necessary treatment. Utilization of magnetic resonance imaging (MRI) is burgeoning, providing an ideal opportunity to use MRI to identify individuals with skeletal deficits. We previously reported that MRI-based bone texture was more heterogeneous in postmenopausal women with a history of fracture compared to controls.

OBJECTIVE

The present study aimed to identify the microstructural characteristics that underlie trabecular texture features.

METHODS

In a prospective cohort, we measured spine volumetric bone mineral density (vBMD) by quantitative computed tomography (QCT), peripheral vBMD and microarchitecture by high-resolution peripheral QCT (HRpQCT), and areal BMD (aBMD) by dual-energy x-ray absorptiometry. Vertebral trabecular bone texture was analyzed using T1-weighted MRIs. A gray level co-occurrence matrix was used to characterize the distribution and spatial organization of voxelar intensities and derive the following texture features: contrast (variability), entropy (disorder), angular second moment (ASM; uniformity), and inverse difference moment (IDM; local homogeneity).

RESULTS

Among 46 patients (mean age 64, 54% women), lower peripheral vBMD and worse trabecular microarchitecture by HRpQCT were associated with greater texture heterogeneity by MRI-higher contrast and entropy (r ∼ -0.3 to 0.4, P < .05), lower ASM and IDM (r ∼ +0.3 to 0.4, P < .05). Lower spine vBMD by QCT was associated with higher contrast and entropy (r ∼ -0.5, P < .001), lower ASM and IDM (r ∼ +0.5, P < .001). Relationships with aBMD were less pronounced.

CONCLUSION

MRI-based measurements of trabecular bone texture relate to vBMD and microarchitecture, suggesting that this method reflects underlying microstructural properties of trabecular bone. Further investigation is required to validate this methodology, which could greatly improve identification of patients with skeletal fragility.

Night waking among 1-year olds: a study of maternal separation anxiety

The relationships between aspects of parenting and infants' sleep patterns were studied longitudinally with 81 mother-child pairs. Mothers' parenting orientation at 6 months was defined using the Facilitator-Regulator distinction. When the infants were 12 months old, mother and child participated in a laboratory-based developmental assessment which involved a brief separation episode. Upon reunion, mothers reported on their concerns during separation; they also described their child's sleep. It was found that high maternal separation anxiety was related to night waking. In addition, night waking was more frequent among first born babies of Facilitators compared with Regulators. How maternal separation anxiety and care-giving orientation regulate aspects of the child's sleep awaits further explanation.

Facilitators and regulators: cross-cultural and methodological considerations

In a model of motherhood Raphael-Leff (1983) delineated two basic orientations: the Facilitator who adapts to the baby and the Regulator who expects the baby to adapt. The FR questionnaire was completed by 97 Israeli mothers of six-month-old infants; 34 per cent were classified as Facilitators, 34 per cent Regulators, 15 per cent Intermediates and 17 per cent were labelled Bipolars. Future research should explore the characteristics of this latter group and its prevalence in other societies.