双层探测器光谱CT电子密度图像对腰椎间盘退行性变性的诊断价值研究

Diagnostic value of dual-detector spectral CT electron density map for evaluating lumbar intervertebral disc degeneration

目的以磁共振成像(MRI)T2加权图像为标准,探讨双层探测器光谱计算机断层扫描(DLCT)电子密度图像(EDM)评估腰椎间盘退行性变性的可行性。方法回顾性分析65例行腰椎MRI及DLCT扫描患者的影像资料,将感兴趣区放置在椎间盘轴位的髓核(NP)区域,得到NP的平均计算机断层扫描(CT)值及平均电子密度值(ED),对椎间盘退行性变性行改良Pfirrmann分级(mPG),在彩色编码EDM图像上对椎间盘视觉分级。采用Kappa检验分析2位医师对椎间盘mPG及EDM视觉分级的一致性。使用Spearman相关性分析比较各mPG及总体NP的平均CT值与ED值的相关性、椎间盘EDM视觉分级与mPG的相关性,组间两两比较用Tambane's T2检验。结果椎间盘NP的CT值与ED值呈正相关关系(r=0.788,P<0.001),NP平均ED值与mPG呈正相关关系(r=0.052,P<0.001),较高级别与较低级别退行性变性椎间盘NP的ED值存在差异。EDM视觉分级与mPG呈正相关关系(r=0.772,P<0.001),不同视觉分级间对应的平均ED值及mPG两两对比均有差异。结论基于DLCT重建的EDM具有评价椎间盘退行性变性的潜力。

Objective To investigate the feasibility of double-layer detector spectral CT(DLCT)electron density map(EDM)in the evaluation of lumbar disc degeneration based on magnetic resonance imaging(MRI)T2-weighted images.Methods The image data of 65 patients who underwent lumbar MRI and DLCT scan were retrospectively collected and analyzed.The average CT value and average electron density(ED)were obtained by placing the region of interest in the nucleus pulposus(NP)area of the axial position of the intervertebral disc.Intervertebral disc degeneration was graded by modified Pfirrmann grades(mPG)grading on MRI and visual grading on color coded electron density maps.Kappa test was used to analyze the consistency of mPG grading and EDM visual grading between the two physicians.Spearman correlation analysis was used to compare the correlation between the average CT value and ED value of mPG grades,and to compare the correlation between the EDM visual grade and the mPG grade.Tambane's T2 test was used for a pairwise comparison between groups.Results The CT value of NP was positively correlated with the ED value(r=0.788,P<0.001).The average ED value of NP was positively correlated with the mPG grade(r=0.052,P<0.001).There was a difference in the ED value of NP between the higher grade and the lower grade and a positive correlation between EDM visual grading and mPG grading(r=0.772,P<0.001).There were differences in the average ED value and mPG grading between different visual gradings.Conclusion EDM based on DLCT reconstruction has the potential in the evaluation of intervertebral disc degeneration.