正常儿童椎体骨髓转换过程中磁共振信号强度的变化

Conversion of Spinal Bone Marrow in Children:Signal Intensity Ratio Changes with Age and Sex on MR Imagings

目的分析椎体骨髓磁共振T1WI信号强度比值（SIR）与年龄、性别的关系,探讨正常儿童椎体骨髓转换的发生规律。方法回顾性分析105例正常儿童的脊柱磁共振T1加权序列图像,同时选择血液系统疾病患儿共32例作为病例组对照研究。采用GE0.2T Profile Gold永磁型开放式磁共振扫描仪行脊柱矢状面SET1WI扫描。测定椎体磁共振SIR,并对所获得的数据与年龄、性别的关系及正常组和病例组间的比较进行统计学处理。结果椎体SIR值与年龄变化的关系研究表明,颈椎、腰椎骨髓SIR值与年龄呈正相关,统计学具有显著性意义（P〈0.01）,而胸椎骨髓SIR值则与年龄无显著相关性（P=0.06）;无论是颈椎、胸椎还是腰椎的SIR值与性别均无显著相关性（P〉0.05）;病例组患儿椎体T1信号强度较正常组儿童明显减低,各年龄组病例与正常组间的SIR值差异均具有显著性意义（P〈0.01）。结论儿童年龄段（0-17岁）颈椎和腰椎骨髓转换发生较早,5岁后的骨髓信号较前发生明显增高,而且血液系统疾病患者椎体骨髓T1信号较正常显著减低。因此,利用SIR定量测定法对弥漫性骨髓疾病具有更高的敏感性。

Objective：The purpose of the study was to elucidate the signal intensity ratio （SIR） on MRI of spinal bone marrow relative to age and sex on T1-weighted images in children. Methods：We retrospectively reviewed sagittal T1-weighted MR images of the spinal vertebrae for the distribution of hematopoietic and fatty marrow. One hundred and five children aged from 3 months to 17 years old without evidence of marrow abnormality and 32 patients with hematopoietic disorders （anemia in 19 cases and leukemia in 13 cases） were examined with the 0.2T MR unit. Marrow conversion was assessed in cervical vertibrae,thoracic vertibrae and lumbar vertibrae using signal intensity ratio （SIR）. Results：Correlation analysis of age dependences showed that SIR of cervical and lumbar vertibrae correlated with age significantly （P〈0.01） while SIR of thoracic vertibrae failed to show age-related differences （P〉0.05）. Sex had no effect on the SIR of spinal vertebrae （P〉 0.05）. There were differences in SIR between the normal children and patients with hematopoietic diseases statistically, with patients having a significant lower SIR than normal children （P〈0.01）. Conclusion： Spinal bone marrow conversion in children is not related to sex. The cervical and lumbar vertibrae bone marrow conversion begins earlier than thoracic vertibrae. SIR of the vertebrae in patients with hematopoietic disorders is much less than that in normal children. As a result,SIR would be helpful to finding the diffused bone marrow abmormalities.