腰椎 MR 弥散成像与定量CT 骨密度测量的相关性研究

目的：探讨腰椎椎体表观弥散系数（ apparent diffusion coefficient ，ADC）值与定量CT（ quantitative compu-ted tomography，QCT）所测骨密度（bone mineral density，BMD）的相关性。方法对121例腰腿痛患者进行腰2～4椎体QCT检查，并根据骨密度分为骨密度正常组、骨密度减少组及骨质疏松组。再对患者进行腰椎MR检查，先行常规矢状面T2WI、T1 WI和横轴面T2WI扫描；弥散加权成像（diffusion weighted imaging，DWI）采用自旋回波单次激发回波平面成像序列（ b值为0和600 s/mm2），行椎体矢状位DWI扫描，在ADC图上测量腰2～4椎体ADC值。最后分析ADC值与骨密度的相关性。结果男性各组间ADC值差异无统计学意义（ P ＞0）．05）；女性骨密度正常组ADC（0．45＆#177;0．13）＆#215;10-3 mm2/s，与骨量减少组（0．302＆#177;0．0677）＆#215;10-3 mm2s/及骨质疏松组（0．2869＆#177;0．0475）＆#215;10-3 mm2/s比较，差异有统计学意义（ P ＜0．05）。 Spearman相关分析发现，男性BMD与ADC值无相关性，女性BMD与ADC值呈正相关（ r ＝0．545， P ＜0．01）。结论 DWI可从骨髓分子运动水平研究骨质疏松的病理生理变化，对骨质疏松进行无创性定量评估。

Correlation between apparent diffusion coefficient and bone mineral density measured by quantitative computed tomography in human lumbar spine

Objective To investigate the correlation between apparent diffusion coefficient （ ADC ） detected by magnetic resonance （ MR） diffusion weighted imaging （ DWI ） and bone mineral density （ BMD ） measured by quantitative computed tomography （ QCT） in human lumbar spine .Methods 121 patients with lumbocrural pain underwent volumetric bone mineral density measured by QCT at the site of lumbar spine （ L2~4 ） .According to the bone mineral density , all the subjects were divided into three groups：normal bone density group , osteoporosis group , osteopenia group .After routine MRI examination （Sagittal T2WI,T1WI and Axial T2WI）,DWI was performed with single shot spin -echo planar imaging sequence （ b =0,600 s/mm2 ） and ADC values were measured .Finally the correlation between ADC and BMD was analyzed . Results There were no significant differences in ADC values among different male groups .As compared with those in normal bone density group,ADC values were significantly decreased in osteoporosis group [（0.2869 ＆#177;0.0475） ＆#215;10 -3 mm2/s vs （0.45 ＆#177;0.13） ＆#215;10 -3 mm2/s, P ＆lt;0.01）] and in osteopenic group [（0.302 ＆#177;0.0677） ＆#215;10 -3 mm2/s vs （0.45 ＆#177;0.13） ＆#215; 10 -3 mm2/s, P ＆lt;0.01）] in females.ADC values were positively correlated with BMD values （ r =0.545, P ＆lt;0.01） in females,but ADC values were not related to BMD values in males .Conclusion DWI can quantitatively evaluate osteoporosis noninvasively by observing the pathological changes of vertebral bone marrow at molecular movement level .