常规MRI信号评价腰椎骨质疏松的意义

Significance of routine magnetic resonance imaging examination in evaluating osteoporosis of the lumbar spine

背景:腰椎MRI成像在腰痛患者中的应用越来越广泛,临床上发现老龄女性腰椎常规MRI信号常常较高,可能与骨质疏松有一定关系。目的:探讨常规MRI成像腰椎椎体信号变化在腰椎骨质疏松评估中的意义。方法:收集在前后1个月内进行过L1-L4椎体双能X射线吸收法-骨矿物质密度测定和腰椎MRI成像者194例,其中男50例,女144例。分析双能X射线吸收法骨矿物质密度值和腰椎矢状面MRI-T1加权(T_1WI)、T2加权(T_2WI)、脂肪抑制T_2WI及T_2WI与脂肪抑制T_2WI信号差值。以1 g/cm^2为分界,对椎体双能X射线吸收法-骨矿物质密度值和椎体MRI信号值进行对照比较。结果与结论:(1)女性被检者所有4个腰椎体的骨矿物质密度均显著低于男性,除L4的P=0.003外,其余均P <0.001;(2)男女性腰椎体MRI信号除脂肪抑制T_2WI差异无显著性意义(P均> 0.05)外,女性T_1WI、T_2WI信号强度和T_2WI与脂肪抑制T_2WI强度差值均显著高于男性(P均≤0.001);(3)不同年龄段双能X射线吸收法骨矿物质密度和MRI-T_1WI、T_2WI信号和T_2WI与脂肪抑制T_2WI信号差值差异均有显著性意义;(4)经两两比较,除L4外,60岁以下患者的双能X射线吸收法-骨矿物质密度值显著大于60岁以上患者(P<0.05),且随年龄增加而降低;(5)而MRI-T_1WI、T_2WI和T_2WI与脂肪抑制T_2WI差值均显著低于60岁以上患者,且随年龄增加而升高;(6)各年龄段脂肪抑制T_2WI序列椎体信号差异均无显著性意义;(7)双能X射线吸收法骨矿物质密度值≥1 g/cm2者的年龄、MRI-T_1WI、T_2WI信号和T_2WI与脂肪抑制T_2WI信号差值均显著低于<1 g/cm2者(P <0.001),而脂肪抑制T_2WI序列椎体信号差异均无显著性意义(P> 0.05);(8)结果表明,双能X射线吸收法能定量测定骨矿物质密度含量,MRI成像通过多序列信号变化反映了骨脂肪和水的含量,对间接判断骨矿物质和骨基质含量具有重要意义。

BACKGROUND:MRI of lumbar spine has been more and more extensively applied in patients with low back pain.The conventional MRI signal of lumbar spine is high in older females,which may be related to osteoporosis.OBJECTIVE:To investigate the significance of conventional signal changes on MRI of lumbar spine in evaluating lumbar osteoporosis.METHODS:One hundred and ninety-four cases were collected whose bone mineral density was determined by dual-energy X-ray absorptiometry and MRI in the L1-L4 within 1 month,including 50 males and 144 females.Dual-energy X-ray absorptiometry-bone mineral density value and MRI signal of lumbar vertebrae in the sagittal plane MRI-T1WI,T2WI and FS-T2WI and signal difference between T2WI and FS-T2WI were analyzed.With 1 g/cm2 as the dividing line,the dual-energy X-ray absorptiometry-bone mineral density value and the value of MRI signal of vertebral bodies were compared.RESULTS AND CONCLUSION:(1)Bone mineral density of female subjects in all four vertebral bodies were significantly lower than that of males,in addition to P=0.003 in L4,the rest P<0.001.(2)The FS-T2WI was not significantly different between males and females(P>0.05).In females,the signals of MR-T1WI,T2WI and signal difference between MR-T2WI and FS-T2WI in the sagittal plane of lumbar vertebrae were significantly higher than those in males(P≤0.001).(3)Among different age groups,dual-energy X-ray absorptiometry-bone mineral density and signals of MRI-T1WI,T2WI and signal difference between MRI-T2WI and FS-T2WI were significantly different.(4)In addition to the L4,dual-energy X-ray absorptiometry-bone mineral density of patients under 60 years old was significantly higher than that of patients over 60 years old(P<0.05),and decreased with age increasing.(5)While the signals of MRI-T1WI,T2WI and signal difference between MR-T2WI and FS-T2WI of patients under 60 years old were significantly lower than that of patients over 60 years old(P<0.05),and increased with age increased.(6)There were no significant differences in the signal of MRI-FS-T2WI of all age groups.(7)The age and signals of MRI-T1WI,T2WI and signal difference between MRI-T2WI and FS-T2WI of subjects of dual-energy X-ray absorptiometry-bone mineral density≥1 g/cm2 were significantly lower than that<1 g/cm2(P<0.001),while vertebral signals were not significantly different in FS-T2WI(P>0.05).(8)These results indicate that dual-energy X-ray absorptiometry can quantitatively determine the bone mineral density.MRI can reflect the content of bone fat and water by changes of signal by multi-sequences.It has important significance to judge the content of bone minerals and bone matrix indirectly.