Department of Radiology, Bone and Breast Density Research Group, University of California, San Francisco, San Francisco, CA, USA.
J Bone Miner Res. 2011 Nov;26(11):2745-52. doi: 10.1002/jbmr.473.
The monitoring time interval (MTI) is the expected time in years necessary to identify a change between two measures that exceeds the measurement error. Our purpose was to determine MTI values for dual-energy X-ray absorptiometry (DXA) scans in normal healthy children, according to age, sex, and skeletal site. 2014 children were enrolled in the Bone Mineral Density in Childhood Study and had DXA scans of the lumbar spine, total hip, nondominant forearm, and whole body. Measurements were obtained annually for seven visits from 2002 to 2010. Annualized rates of change were calculated by age and sex for all bone regions. A subgroup of 155 children ages 6 to 16 years (85 boys) had duplicate scans for calculation of scan precision. The bone mineral density (BMD) regions of interest included the spine, total body less head (TBLH), total hip, femoral neck, and one-third radius. Bone mineral content (BMC) was also evaluated for the spine and TBLH. The percent coefficient of variation (%CV) and MTI were calculated for each measure as a function of age and sex. The MTI values were substantially less than 1 year for the TBLH and spine BMD and BMC for boys ≤ 17 years and girls ≤ 15 years. The hip and one-third radius MTIs were generally 1 year in the same group. MTI values as low as 3 months were found during the peak growth years. However, the MTI values in late adolescence for all regions were substantially longer and became nonsensical as each region neared the age for peak bone density. All four DXA measurement sites had reasonable (< 1 year) MTI values for boys ≤ 17 years and girls ≤ 15 years. MTI was neither useful nor stable in late adolescence and young adulthood. Alternative criteria to determine scan intervals must be used in this age range.
监测时间间隔（MTI）是指在识别两次测量值之间超过测量误差的变化所需的预期年数。我们的目的是根据年龄、性别和骨骼部位，确定正常健康儿童的双能 X 射线吸收法（DXA）扫描的 MTI 值。2014 名儿童参加了儿童骨密度研究，并在 2002 年至 2010 年期间进行了 7 次腰椎、全髋、非优势前臂和全身的 DXA 扫描。每年测量一次，共测量 7 次。根据年龄和性别计算所有骨骼区域的年度变化率。一个由 155 名年龄在 6 至 16 岁的儿童（85 名男孩）组成的亚组进行了重复扫描，以计算扫描精度。感兴趣的骨密度（BMD）区域包括脊柱、全身（不包括头部）（TBLH）、全髋、股骨颈和三分之一半径。还评估了脊柱和 TBLH 的骨矿物质含量（BMC）。作为年龄和性别的函数，计算了每个测量值的%变异系数（%CV）和 MTI。对于男孩≤17 岁和女孩≤15 岁的 TBLH 和脊柱 BMD 和 BMC，MTI 值明显小于 1 年。在同一组中，髋部和三分之一半径的 MTI 通常为 1 年。在生长高峰期发现的 MTI 值低至 3 个月。然而，在青春期后期，所有区域的 MTI 值都明显延长，并且随着每个区域接近骨密度峰值年龄，变得毫无意义。对于男孩≤17 岁和女孩≤15 岁的所有四个 DXA 测量部位，MTI 值都在合理范围内（<1 年）。在青春期后期和成年早期，MTI 既没有用也不稳定。在这个年龄段，必须使用其他标准来确定扫描间隔。
