Malich Ansgar, Freesmeyer Martin G, Mentzel Hans-Joachim, Sauner Dieter, Boettcher Joachim, Petrovitch Alexander, Behrendt Werner, Kaiser Werner A
Institute of Diagnostic and Interventional Radiology, Friedrich-Schiller-University Jena, Jena, Germany.
J Clin Densitom. 2003 Summer;6(2):103-11. doi: 10.1385/jcd:6:2:103.
To verify whether estimation of bone mineral density (BMD) using digital X-ray radiogrammetry (DXR) is possible on children and to determine normative values of both such a DXR-BMD estimate and a corresponding metacarpal index (DXR-MCI) on.
In retrospect, X-rays were selected of the hands of 200 healthy Caucasian children (120 boys and 80 girls, aged 4-18 yr). The involved children were selected among a larger group of children submitted to the surgical department of our institute for evaluation of a suspected fracture after an occurred trauma. All children with a verified fracture or a chronic bone-related disease, including bone age retardation or acceleration, were excluded from the study. Furthermore, only conventional X-rays with the same film and capture parameters were included. The images were scanned and analyzed using the Pronosco X-posure system V.2 (Sectra Pronosco, Denmark). DXR-BMD, DXR-MCI, and a porosity index (DXR-PI) were automatically calculated using the midshafts of the metacarpals II-IV. Mean values of DXR-BMD and DXR-MCI were calculated separately for girls and boys in 2-yr intervals.
In the present study the system has been demonstrated to be capable of calculating DXR-BMD from conventional X-rays of the hand from children down to approx 6 yr of age. This ability depended somewhat on the diameter and the length of the involved metacarpals. The success rate was higher for large bones than for small bones. The system succeeded in analyzing the images of 110 boys and 68 girls. Values of DXR-BMD were observed to increase with age from 0.40 g/cm2 to 0.62 g/cm2 in the male group and from 0.39 g/cm2 to 0.54 g/cm2 in the female group. Girls aged 11-12 yr had a higher DXR-BMD than did boys, corresponding to the earlier entry to puberty of girls. Standard deviations (SDs) reached values of up to 0.05 g/cm2. DXR-MCI increased with age from 0.36 to 0.47 for boys and from 0.34 to 0.49 for girls with a maximum SD of 0.06. The correlation between DXR-BMD and age was r=0.83 and r=0.84 for boys and girls, respectively. The corresponding correlations for DXR-MCI was lower, with observed correlations of r=0.63 (boys) and r=0.68 (girls), respectively, with p<0.01 in all cases. The DXR-PI did not reveal a significant correlation to age (r=-0.31 and r=0.04. respectively) and showed SDs marginally higher than the calculated mean values.
The newly available DXR-methodology seems to offer the ability to determine DXR-BMD and DXR-MCI in children starting with a bone age of 6. This possibility may be of special relevance for children suffering from chronic bone diseases that require repeated X-rays of the hand (e.g. to determine bone age). The acquired normative data suggest that the measurements are of clinical value owing to low age-dependent variability (SDs) relative to an observed high increase with age. The clinical value of the porosity index (DXR-PI) remains uncertain and is limited owing to a high inter-individual variability.
验证使用数字X线摄影测量法（DXR）估算儿童骨密度（BMD）是否可行，并确定这种DXR-BMD估算值及相应掌骨指数（DXR-MCI）的正常参考值。
回顾性选取200名健康白种儿童（120名男孩和80名女孩，年龄4 - 18岁）手部的X线片。这些儿童是从我院外科接收的一大组因外伤后疑似骨折前来评估的儿童中选取的。所有确诊骨折或患有慢性骨相关疾病（包括骨龄延迟或加速）的儿童均被排除在研究之外。此外，仅纳入具有相同胶片和采集参数的传统X线片。使用Pronosco X-posure系统V.2（丹麦Sectra Pronosco公司）对图像进行扫描和分析。利用第二至第四掌骨的骨干自动计算DXR-BMD、DXR-MCI和孔隙率指数（DXR-PI）。分别按2岁间隔计算男孩和女孩的DXR-BMD和DXR-MCI的平均值。
在本研究中，已证明该系统能够从儿童手部的传统X线片中计算出DXR-BMD，年龄下限约为6岁。这种能力在一定程度上取决于所涉及掌骨的直径和长度。大骨骼的成功率高于小骨骼。该系统成功分析了110名男孩和68名女孩的图像。观察到男性组的DXR-BMD值随年龄从0.40 g/cm²增加到0.62 g/cm²，女性组从0.39 g/cm²增加到0.54 g/cm²。11 - 12岁的女孩DXR-BMD高于男孩，这与女孩青春期开始较早相符。标准差（SD）最高达到0.05 g/cm²。男孩的DXR-MCI随年龄从0.36增加到0.47，女孩从0.34增加到0.49，最大标准差为0.06。男孩和女孩的DXR-BMD与年龄的相关性分别为r = 0.83和r = 0.84。DXR-MCI的相应相关性较低，观察到的相关性分别为r = 0.63（男孩）和r = 0.68（女孩），所有情况下p < 0.01。DXR-PI与年龄未显示出显著相关性（分别为r = -0.31和r = 0.04），且显示出的标准差略高于计算出的平均值。
新的DXR方法似乎能够从骨龄为6岁的儿童开始确定DXR-BMD和DXR-MCI。对于患有需要反复拍摄手部X线片（如确定骨龄）的慢性骨疾病的儿童，这种可能性可能具有特殊意义。所获得的正常参考数据表明，由于相对于观察到的随年龄的高增长，年龄依赖性变异性（标准差）较低，这些测量具有临床价值。孔隙率指数（DXR-PI）的临床价值仍不确定，且由于个体间变异性高而受到限制。
