PubMed · 15255418
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Gary M Kiebzak. 2004. Peripheral bone densitometry.. https://doi.org/10.1097/00007611-200406000-00005
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Evidence is accumulating that the risk of osteoporosis in later life may be determined in part by environmental influences on bone development during intrauterine and early postnatal life. A potential role for fetal leptin in mediating these effects is suggested by animal studies showing that leptin influences prenatal osteoblast growth and development, and that fetal leptin concentrations are altered by changes in maternal nutrition. In a group of term human infants we reported previously that maternal birthweight, smoking, fat mass, and exercise during late pregnancy independently predict neonatal bone mass. To investigate the potential role of leptin in mediating these effects, we now relate leptin concentrations in umbilical venous serum to neonatal bone mass and body composition in 117 infants. There were strong positive associations between umbilical venous leptin concentration and each of whole body bone mineral contents (BMC) (r = 0.42, P < or = 0.001) and estimated volumetric bone density (r = 0.21, P = 0.02); whole body lean mass (r = 0.21, P < or = 0.024); and whole body fat mass (r = 0.60, P < 0.001). The associations with neonatal BMC and fat mass, but not with lean mass, were independent of associations that we have reported previously between cord serum insulin-like growth factor 1 (IGF-1) concentrations and neonatal body composition. Among the maternal determinants of neonatal bone mass, cord leptin explained the relationship with maternal fat stores, but not those with the mother's own birthweight, smoking, or physical activity. We conclude that umbilical venous leptin predicts both the size of the neonatal skeleton and its estimated volumetric mineral density. In addition, among previously documented maternal determinants of neonatal bone mass in healthy pregnancies, maternal fat stores may mediate their effect on fetal bone accrual through variation in fetal leptin concentrations.
Manufacturer-implemented regions of interest (ROIs) to determine the bone mineral density (BMD) at the forearm are currently not standardized across dual X-ray absorptiometry (DXA) devices. We hypothesized that their differences introduce considerable variation in measurement results for forearm BMD when taken on different devices, and that a ROIs common to all devices with standardized placement and size significantly improve device comparability. The common ROI was defined to have a fixed length of 2 cm and to extend proximally from the location where the ulna and radius bones superimpose on the DXA image. The effects of universal standardization of forearm BMD were combined with and compared to those of the common ROI. They were drawn on 91 female study participants (ages 20-80 years, 10 per decade) who were scanned on Hologic QDR-4500, Aloka DCS-600EX, GE Lunar PIXI and Norland pDEXA DXA scanners. For all device combinations, manufacturer-implemented ROI root mean-square errors were significantly higher than for the common ROI, suggesting that implementing an ROI with common design on all scanners is a good way to reduce interdevice variability. When manufacturer-implemented ROIs were universally standardized root mean-square error (RMSE) values were less different from that of the nonstandardized Common ROI, suggesting that universal standardization can further improve interdevice comparability even when a common ROI such as the one implemented here is used. ROI standardization dramatically improves interdevice comparability.
Osteoporotic vertebral fracture is associated with increased morbidity and mortality. As a powerful predictor of future fracture risk, the identification of vertebral fracture helps target individuals who will benefit from anti-fracture therapy. The identification of vertebral fractures is problematic because (1) "normal" radiological appearances in the spine vary greatly both among and within individuals; (2) "normal" vertebrae may exhibit misleading radiological appearances due to radiographic projection error; and (3) "abnormal" appearances due to non-fracture deformities and normal variants are common, but can be difficult to differentiate from true vertebral fracture. Various methods of vertebral fracture definition have been proposed, but there is no agreed gold standard. Quantitative methods of vertebral fracture definition are objective and reproducible, but the major limitation of these methods is their inability to differentiate between vertebral deformity and vertebral fracture. The qualitative visual approach draws on the expertise of the reader, but it is a subjective method with poor interobserver agreement. Semiquantitative assessment of vertebral fracture is a standardized visual method, which is commonly applied in research studies as a surrogate gold standard. This method is more objective and reproducible than a purely qualitative approach, but can be difficult to apply. The established methods focus primarily on the identification of "reduced" or short vertebral height as an indication of vertebral fracture, but this is also a feature of some non-fracture deformities and normal variants. A modified visual approach known as algorithm-based qualitative assessment of vertebral fracture (ABQ) has recently been introduced, and this focuses on radiological evidence of change at the vertebral endplate as the primary indicator of fracture. Preliminary testing of the ABQ method has produced promising results, but the method requires further evaluation. Vertebral imaging by means of dual energy X-ray absorptiometry (DXA) scanner produces images of near-radiographic quality at a fraction of the radiation dose incurred by conventional radiography. There is growing interest in vertebral fracture assessment using this technique as a means of assessing a patient's fracture risk. Given the increasing availability of new technology and the importance of accurate diagnosis of vertebral fracture, there is an urgent need for better awareness of and training in the definition of vertebral fracture. Methods of vertebral fracture definition should be validated by testing the association with clinical outcomes of vertebral fracture, in particular the prediction of incident fractures.