探讨look-locker序列和B1-corrected VFA序列在上腹部组织T1值定量分析中的价值

Quantitative T1 Mapping in Upper Abdomen: Comparison of Look-Locker and B1-corrected VFA Variable-flip-angle(VFA) Methods

目的评估两种平扫T1mapping的成像方法(自由呼吸Look-locker序列和屏气B1-correctedVFAvariable-flipangle(VFA)序列)在上腹部组织(脾脏、胰腺、双肾皮质及髓质、腹直肌及竖脊肌)所得T1值的定量特征,并评价其变异度。方法对66名患者行Look-locker序列和B1-correctedVFA序列;测量两种序列在上腹部组织所得T1值,并比较所得T1值的差异,以P<0.05为差异有统计学意义,应用变异系数(coefficientof variation,CV)来评价两种成像方法的变异度,采用Bland-Altman法对两名医师间的测量结果进行对比。结果 2名阅片者采用两种序列所得T1值得相关系数分别为0.973、0.924,P值<0.001。两种序列在双肾皮质、髓质所得T1值比较,差异无统计学意义(P>0.05)。同侧肾皮、髓质之间所得T1值存在差异(t=10.27、13.45、12.44、17.24;P<0.05)。脾脏、胰腺、双肾皮髓质、腹直肌及竖脊肌所得T1值之间差异有统计学意义(P<0.05)。Looklocker序列在腹部组织所得T1值的变异系数低于B1-correctedVFA序列。BlandAltman散点图显示Look-locker序列测定的f值分布相对更集中。结论对腹部各组织采用Look-locker序列和B1-corrected VFA序列所得T1值是不同的,采用Looklocker序列测量的T1值一致性评估变异度小,稳定性高,临床实用价值更高。

Objective Assess non-enhanced T1 mapping in the upper abdomen(spleen, pancreas, bilateral kidneys Cortical and medulla, rectus abdominis, and erector spinae), and also compare two T1 mapping methods, namely free-breathing whole liver looklocker and breath-hold B1-corrected VFA variable-flip-angle(VFA)T1 mapping sequence. Methods Sixty-six patients underwent free breathing Look-locker sequence and breath-holding B1-corrected VFA sequence. The T1 values obtained in the upper abdominal tissues of the two sequences were measured and the differences in T1 values were compared. P<0.05 was considered statistically significant. The coefficient of variation(CV) was used to evaluate the variability of the two imaging methods, and the BlandAltman method was used to compare the measurement results between two physicians. Results The correlation coefficients of the T1 value were 0.973 and 0.924 respectively in Look-locker and B1-corrected VFA, P<0.001. There was no significant difference in T1 values between the two sequences in the renal cortex and medulla(P>0.05). There were differences in T1 values between ipsilateral renal skin and medulla(t=10.27, 13.45, 12.44, 17.24, P<0.05). T1 values are significant different between look-locker and B1-corrected VFA T1 mapping in the upper abdomen(spleen、pancreas、bilateral kidney renal cortex and medulla, rectus abdominis muscle、erector spinae muscles, P<0.05). The coefficient of variation of the T1 value obtained by Look-locker sequence in abdominal tissue is lower than that of B1-corrected VFA sequence. The Bland-Altman scatter plot shows that the distribution of f-values determined by the Look-locker sequence is relatively more concentrated. Conclusion The T1 values obtained by using the Looklocker sequence and the B1-corrected VFA sequence for abdominal tissues are different. The consistency of T1 values measured by the Look-locker sequence is less variability, higher stability, and higher clinical value.