iShim-DWI与SS-EPI在肺部占位性病变MR检查中的应用价值比较

Comparison of iShim-DWI and SS-EPI in MR of Space-Occupying Lesion of the Lung

目的对比逐层匀场技术(iShim-DWI)与单次激发平面回波成像(SS-EPI)应用于肺部占位性病变MR检查中成像质量的差异。方法前瞻性收集2017年9月至2023年3月经CT检查证实存在肺占位病变的患者的MR图像。所有患者均使用3.0 T MRI检查仪行SS-EPI、iShim-DWI及T 2WI扫描。以T 2WI-haste图像为参考,由2名放射科医生采用五分法对2种DWI图像整体质量评分,Kappa检验用来评价2名医生评分的一致性,Wilcoxon秩和检验比较两种DWI序列对图像整体质量显示的差异。2名放射科诊断医生共同对肺占位性病变进行定量参数的测量,计算肺占位性病变图像的信噪比(SNR)、对比噪声比(CNR)及病变的前后径(AP)、左右径(RL)的几何变形率(GDR),另测量肺占位性病变的表观扩散系数值(ADC),使用配对样本t检验比较两序列测得定量参数的差异。结果共收集肺占位病变的患者56例,其中肺癌23例,转移瘤33例。2名放射科医生对2种DWI序列图像整体质量评分的一致性较好(Kappa>0.75)。两序列得分之间的差异有统计学意义(P<0.001)。iShim-DWI和SS-EPI显示肺占位性病变的SNR、CNR分别为23.683、39.803和15.525、21.261,2种序列间SNR、CNR差异有统计学意义(P<0.001)。iShim-DWI和SS-EPI测量肺占位性病变前后、左右方向的GDR分别为6.914、6.879和27.827、25.859,iShim-DWI对肺占位性病变GDR较SS-EPI显著降低(P<0.001)。在iShim-DWI和SS-EPI中测量病变的ADC值分别为1.097×10^(-3)、1.105×10^(-3) mm 2·s^(-1),差异无统计学意义(P>0.05)。结论在肺占位性病变的检查中,iShim-DWI可以明显提高DWI的图像质量。

Objective To compare the difference in imaging quality between integrated shimming diffusion weighted imaging(iShim-DWI)and single-shot echo planar imaging(SS-EPI)applied to MR examination of lung occupying lesions.Methods MR images of patients with CT-confirmed space-occupying lesions of the lung between September 2017 and March 2023 were prospectively collected.All patients performed SS-EPI,iShim-DWI and T 2WI sequences using 3.0 T MRI.T 2WI were used as a reference and two radiologists scored the overall quality of two DWI using a five-point scale.Kappa test was used to evaluate the consistency of two radiologists’scores,Wilcoxon test was used to compare the differences in image quality between the two DWI sequences.Two radiologists measured quantitative parameters of the lesion together,calculating the signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR)and genmetric distortion ration(GDR)of the anterior and posterior(AP)and left and right(RL)of lesion,and measuring the lesion’s ADC value.Results A total of 56 patients with space-occupying lesions of the lung were collected,including 23 cases of lung cancer,33 cases of metastases.The consistency of two radiologists on the images quality scored was very well(Kappa>0.75),and the differences between the image quality scores of both sequences were statistically significant(P<0.001).The SNR and CNR measured by iShim-DWI and SS-EPI were 23.683、39.803 and 15.525、21.261,respectively,and the differences were statistically significant(P<0.001).The GDR of lesions’AP and RL measured by iShim-DWI and SS-EPI were 6.914、6.879 and 27.827、25.859,respectively,the GDR of iShim-DWI was significantly lower than SS-EPI(P<0.001).The mean ADC of the lesions measured by the two sequences were 1.097×10^(-3),1.105×10^(-3) mm 2·s^(-1),respectively,and the difference was not statistically significant(P>0.05).Conclusion Compared with SS-EPI,iShim-DWI could significantly improve image quality of DWI sequences in space-occupying lesion of the lung.