Purpose: To improve liver iron load assessment by investigating the precision of different approaches of T2* Measurement. Background: Iron overload is a major problem in the treatment of thalassemic patients. Liver ir...Purpose: To improve liver iron load assessment by investigating the precision of different approaches of T2* Measurement. Background: Iron overload is a major problem in the treatment of thalassemic patients. Liver iron concentration (LIC) is an important index toward the management of body iron load. The accuracy of iron load estimation may suffer from the methodology of T2* measurement and there is no complete agreement upon the best approach of T2* calculation. Methods: 32 β-thallasemic patients (18 male) with the mean age of 20.0 ± 6.5 years were involved in this study. A multi-echo fast gradient-echo technique on a 1.5 T MRI system was used to measure liver iron overload and the T2* map of liver was reconstructed on a pixel-by-pixel basis. The T2* map and MRI images were utilized to deter- mine accurate location of ROI (region of interest). The mean of T2* were computed from the ROIs. The reproducibility of calculated T2* values in two methods were obtained. Moreover, the mean of the pixel’s T2* was calculated in the entire liver parenchyma of one slice. The T2* value of the entire slice was compared with the ROI approach. Results: In the ROI based method, the CoV for the intra-observer reproducibility was 8.5% and for the inter-observer was 9.78%. In the pixel based method, the CoVs for intra-observer and inter-observer reproducibility were 2.79% and 3.91%. There was an acceptable correlation (r = 0.96) between the T2* values calculated by the ROI and the entire slice. Conclusions: The pixel-based approach is more precise to determine the appropriate placement of the ROI. The assessment of T2* in the entire slice reduces the user-based errors significantly.展开更多
提出使用磁共振图像(MRI)超短回波时间(UTE)成像序列结合T2*映射技术,对耳软骨T2*值进行在体无创检测,探究既能对耳软骨进行非侵入性成像又能定量评估在体耳软骨生物成分的方法,为耳软骨再造和修复整形手术评价的标准化提供新思路。首先...提出使用磁共振图像(MRI)超短回波时间(UTE)成像序列结合T2*映射技术,对耳软骨T2*值进行在体无创检测,探究既能对耳软骨进行非侵入性成像又能定量评估在体耳软骨生物成分的方法,为耳软骨再造和修复整形手术评价的标准化提供新思路。首先,使用1个UTE和5个短回波时间(TE)的成像组合序列采集30名志愿者右侧外耳的MRI图像;然后,利用采集到的每名志愿者的图像进行组内刚性配准及手动分割耳软骨与外耳轮廓(包含耳软骨及周围组织,如皮肤、脂肪和其他软组织)的预处理;接下来,分别运用单指数和双指数衰减模型在分割出来的耳软骨和外耳区域进行T2*值测量;最后,分别使用这两种模型拟合耳软骨信号强度随回波时间变化的衰减曲线,并比较拟合模型的准确性。结果显示,在30例右耳的单成分分析(单指数模型)实验中,外耳的T2*m平均值为(49.269±16.979)ms,耳软骨的T2*m平均值为(23.799±9.629)ms。在双成分分析(双指数模型)中,外耳的短成分T2*s平均值为(11.713±3.111)ms,长成分T2*l平均值为(65.128±13.132)ms,耳软骨的短成分T2*s平均值为(5.577±1.830)ms,长成分T2*l平均值为(30.628±8.413)ms。统计分析显示,单成分分析计算得到的T2*m,和双成分分析计算得到的T2*s、T2*l,在外耳和耳软骨区域均存在显著差异(P<0.05)。在曲线拟合中,双指数模型优于单指数模型(R^2[bi]=0.999±0.001 vs R^2[mono]=0.905±0.014,P<0.05)。实验结果表明,超短回波时间成像序列结合T2*映射技术对在体耳软骨进行T2*值无创检测具备可行性,有望为软骨组织工程和3D生物打印技术制作的耳软骨-支架复合物应用在耳廓修复和再造中提供医学影像学的支撑,也为小耳畸形外科整形手术术后定量评估耳软骨提供一种可行性方案。展开更多
目的探讨1.5 T MRI T2*mapping成像定量评估腰椎间盘退变的可行性及其诊断价值。方法对195例腰腿痛患者行腰椎常规磁共振扫描及矢状位T2*mapping成像,并应用AW4.5工作站进行数据处理,采用Pfirrmann标准对纳入研究的732个椎间盘进行退变...目的探讨1.5 T MRI T2*mapping成像定量评估腰椎间盘退变的可行性及其诊断价值。方法对195例腰腿痛患者行腰椎常规磁共振扫描及矢状位T2*mapping成像,并应用AW4.5工作站进行数据处理,采用Pfirrmann标准对纳入研究的732个椎间盘进行退变分级,定量分析不同分级间椎间盘的T2*值变化特点,分析T2*值与椎间盘退变分级间的相关性。结果 732个椎间盘中,PfirrmannⅠ级26个(3.6%)、Ⅱ级47个(6.4%)、Ⅲ级233个(31.8%)、Ⅳ级390个(53.3%)、Ⅴ级36个(4.9%)。腰椎间盘髓核及纤维环T2*值均随分级增加而减小;除Ⅰ级与Ⅱ级椎间盘髓核及纤维环、Ⅱ级与Ⅲ级纤维环T2*值差异无统计学意义(P>0.05),其余各级间差异均有统计学意义(P<0.05)。椎间盘髓核及纤维环T2*值与Pfi rrmann分级呈负相关(r=-0.68,P<0.05;r=-0.54,P<0.05)。结论 1.5 T MRI T2*mapping能对腰椎间盘退变进行客观、定量评估,腰椎间盘T2*值与Pfi rrman分级负相关。展开更多
文摘Purpose: To improve liver iron load assessment by investigating the precision of different approaches of T2* Measurement. Background: Iron overload is a major problem in the treatment of thalassemic patients. Liver iron concentration (LIC) is an important index toward the management of body iron load. The accuracy of iron load estimation may suffer from the methodology of T2* measurement and there is no complete agreement upon the best approach of T2* calculation. Methods: 32 β-thallasemic patients (18 male) with the mean age of 20.0 ± 6.5 years were involved in this study. A multi-echo fast gradient-echo technique on a 1.5 T MRI system was used to measure liver iron overload and the T2* map of liver was reconstructed on a pixel-by-pixel basis. The T2* map and MRI images were utilized to deter- mine accurate location of ROI (region of interest). The mean of T2* were computed from the ROIs. The reproducibility of calculated T2* values in two methods were obtained. Moreover, the mean of the pixel’s T2* was calculated in the entire liver parenchyma of one slice. The T2* value of the entire slice was compared with the ROI approach. Results: In the ROI based method, the CoV for the intra-observer reproducibility was 8.5% and for the inter-observer was 9.78%. In the pixel based method, the CoVs for intra-observer and inter-observer reproducibility were 2.79% and 3.91%. There was an acceptable correlation (r = 0.96) between the T2* values calculated by the ROI and the entire slice. Conclusions: The pixel-based approach is more precise to determine the appropriate placement of the ROI. The assessment of T2* in the entire slice reduces the user-based errors significantly.
文摘目的应用T2加权成像观察多发性硬化大脑深部灰质核团(丘脑,尾状核,壳核,苍白球)病变的特点,对MRI T2信号强度进行定量分析,并探讨多发性硬化患者颅内深部灰质核团改变与临床指标(病程,有无行走障碍,有无视神经受累,脑脊液寡克隆带是否为阳性)的相关性。经过糖皮质激素治疗后,对比治疗前后颅内深部灰质核团T2信号强度。方法依据Mc Donald 2010诊断标准,收集多发性硬化患者17例为实验组,选取17例同性别、同年龄的健康人作为对照组,实验组及对照组均行核磁共振,应用测量T2相对信号值的方法,对两组颅内深部灰质核团(丘脑,尾状核,壳核,苍白球)的MRI T2信号强度进行定量分析,对比组间是否有差异,同时搜集病程,有无行走障碍,有无视神经受累,脑脊液寡克隆带结果等临床指标,评价颅内深部灰质核团改变与临床指标是否有相关性。对比糖皮质激素治疗前后颅内深部灰质核团T2信号强度。结果与对照组相比,MS组各灰质核团的T2信号均有所减低,差异有统计学意义:丘脑(P=0.001),尾状核(P=0.047),壳核(P=0.041),苍白球(P=0.009)。行走受限与各灰质核团T2信号强度具有相关性,spearman相关系数分别为丘脑0.566(P=0.018),尾状核0.51(P=0.037),苍白球0.538(P=0.026),壳核0.481(P=0.051>0.05)。其余临床指标与T2信号相关系数差异无统计学意义(P>0.05)。糖皮质激素治疗前后,颅内深部灰质核团T2信号强度差异无统计学意义(P>0.05)。结论多发性硬化患者的灰质核团相比于正常组,T2信号值普遍偏低,提示灰质核团铁质沉积。行走障碍与各个灰质核团的T2低信号有显著相关性,而病程、脑脊液寡克隆带和视神经受累等临床指标均与T2低信号无关。激素治疗对灰质核团铁沉积无即时影响。
文摘提出使用磁共振图像(MRI)超短回波时间(UTE)成像序列结合T2*映射技术,对耳软骨T2*值进行在体无创检测,探究既能对耳软骨进行非侵入性成像又能定量评估在体耳软骨生物成分的方法,为耳软骨再造和修复整形手术评价的标准化提供新思路。首先,使用1个UTE和5个短回波时间(TE)的成像组合序列采集30名志愿者右侧外耳的MRI图像;然后,利用采集到的每名志愿者的图像进行组内刚性配准及手动分割耳软骨与外耳轮廓(包含耳软骨及周围组织,如皮肤、脂肪和其他软组织)的预处理;接下来,分别运用单指数和双指数衰减模型在分割出来的耳软骨和外耳区域进行T2*值测量;最后,分别使用这两种模型拟合耳软骨信号强度随回波时间变化的衰减曲线,并比较拟合模型的准确性。结果显示,在30例右耳的单成分分析(单指数模型)实验中,外耳的T2*m平均值为(49.269±16.979)ms,耳软骨的T2*m平均值为(23.799±9.629)ms。在双成分分析(双指数模型)中,外耳的短成分T2*s平均值为(11.713±3.111)ms,长成分T2*l平均值为(65.128±13.132)ms,耳软骨的短成分T2*s平均值为(5.577±1.830)ms,长成分T2*l平均值为(30.628±8.413)ms。统计分析显示,单成分分析计算得到的T2*m,和双成分分析计算得到的T2*s、T2*l,在外耳和耳软骨区域均存在显著差异(P<0.05)。在曲线拟合中,双指数模型优于单指数模型(R^2[bi]=0.999±0.001 vs R^2[mono]=0.905±0.014,P<0.05)。实验结果表明,超短回波时间成像序列结合T2*映射技术对在体耳软骨进行T2*值无创检测具备可行性,有望为软骨组织工程和3D生物打印技术制作的耳软骨-支架复合物应用在耳廓修复和再造中提供医学影像学的支撑,也为小耳畸形外科整形手术术后定量评估耳软骨提供一种可行性方案。
