分析1.5T与3.0TMR定量评价体外铁浓度模型比较研究

Quantitative measurement of iron concentration in vitro model:a comparative study between 1.5T and 3.0T MRI

目的:探讨MRI对体外不同铁浓度模型定量测量的可靠性,并比较1.5T和3.0T MR对体外铁浓度模型定量测定的准确性。方法:制作2组不同铁浓度体外模型,一组铁浓度范围为0~5.0mg/mL。另一组铁浓度范围为0~1.0mg/mL。两组铁浓度模型分别在1.5T及3.0T MR上进行扫描。扫描序列包括短轴面FSE/T1WI、FRFSE/T2WI、T2map和T2*map。评价测量指标包括T1WI和T2WI信噪比、T2、R2、T2*和R2*值。评价指标的一致性采用组内相关系数分析。铁浓度与T1WI信噪比、T2WI信噪比、T2、R2、T2*和R2*值的关系应用Pearson相关分析。结果:两位研究者对体外铁浓度模型MR图像测量指标T1WI信噪比、T2WI信噪比、T2、R2、T2*和R2*值一致性评价的组内相关系数均大于0.900(P<0.001)。T2WI信噪比、T2和T2*值与铁浓度在1.5T和3.0T MR上均呈非线性相关。在1.5T MR上,当铁浓度≤1.5mg/mL时,T1WISNR、R2与铁浓度呈显著性正相关(P<0.05)。R2*则在铁浓度≤2.5mg/mL时,与铁浓度呈显著正性线性相关(P<0.001)。而在3.0T MR上,当铁浓度≤0.90mg/mL时,R2和R2*值与铁浓度呈正相关(P<0.05)。结论:MRI定量测定体外不同铁浓度模型的可重复性好;在1.5T或3.0T MR各测量参数中,R2*值可准确定量反映体外铁浓度,且1.5T MR检测铁浓度范围宽于3.0T MR。

Objective:To investigate the reliability of quantitative measurement of iron concentration in vitro model using MRI and compare the accuracy between 1.5 Tand 3.0 T.Methods:Two sets of iron concentration in vitro models were made,ranging from 0 mg/mL to 5.0 mg/mL and from 0 mg/mL to 1.0 mg/mL,respectively.The scanning protocol included FSE/T1 WI,FRFSE/T2 WI,T2 map and T2*map on axial section.Two radiologists independently evaluated the MR images of the models.T1 WI signal to noise ratio(SNR),T2 WI SNR,T2,R2,T2*and R2*values were evaluated.Intraclass correlation coefficient(ICC)was used to evaluate the agreements of the parameters and Pearson correlation analysis was used to calculate the correlation between iron concentration and MR measurement indexes.Results:The ICCs of T1 WI SNR,T2 WI SNR,T2,R2,T2*and R2*values evaluated by two radiologists were all more than 0.900(P<0.001).The relation between iron concentration and T2 WI SNR,T2 and T2*values demonstrated function relation on 1.5 T or 3.0 T MR scanner.At 1.5 T MR scanner,when iron concentration was less than 1.5 mg/mL,T1 WI SNR and R2 correlated positively with iron concentration(P<0.05).At 3.0 T MR scanner,when iron concentration was less than 2.5 mg/mL,R2*had a positive correlation with it(P<0.001).When iron concentration was less than 0.900 mg/mL,R2 and R2*were positively correlated with it(P<0.05).Conclusion:MRI is able to quantitatively evaluate iron concentration in vitro model reproducibly.R2*value is the best index to evaluate the iron concentration at either 1.5 Tor 3.0 T MR.The measureable range at 1.5 T MR is wider than that at 3.0 T MR.