磁共振IDEAL-IQ序列对急性胰腺炎状态下胰腺脂肪沉积和铁沉积的评估

Potential role of IDEAL-IQ sequence for quantitative assessment of fat and iron deposition in pancreas with acute pancreatitis

目的:探讨磁共振非对称回波与最小二乘法估算铁定量的迭代水脂分离(IDEAL-IQ)序列评估急性胰腺炎状态下胰腺脂肪沉积和铁沉积的临床价值。方法:对37例急性胰腺炎患者和22例健康志愿者(对照组)进行上腹部常规及IDEAL-IQ序列MRI扫描,在工作站经图像重建获得脂肪分量(FF)图、弛豫率(R_2~*)图、水像和脂像,在各组图像上分别测量胰腺的信号值。按照MRSI评级标准,将急性胰腺炎患者分为轻度15例、中度15例、重度7例。比较急性胰腺炎组和对照组中胰腺的脂肪分量(FF)、弛豫率(R_2~*)、水和脂肪像上的信号值(SI_水,SI_脂);对两组间差异有统计学意义的参数,进一步分析其在不同严重程度的急性胰腺炎组间的差异。结果:急性胰腺炎组胰腺的FF值大于对照组,而弛豫率(R_2~*)和SI水小于对照组,差异均有统计学意义(P=0.011、0.002和0.016),但两组间胰腺SI脂的差异无统计学意义(P>0.05)。急性胰腺炎组中不同MRSI分级间R_2~*值的差异有统计学意义(ChiSquare=7.020,P=0.03);进一步组间两两比较,轻度与中度和重度组间R_2~*值的差异有统计学意义(P=0.041和0.043),中度与重度组间R_2~*值的差异无统计学意义(P=0.612)。结论:急性胰腺炎状态下胰腺实质内可有脂肪沉积,磁共振IDEAL-IQ技术对急性胰腺炎的诊断及分级有一定的临床意义。

Objective:To explore the potential role of IDEAL-IQ MRI technique for quantitative assessment of fat and iron deposition in pancreas with acute pancreatitis.Methods:37 patients with acute pancreatitis and 22 control subjects were scanned with both routine sequences and iterative decomposition of water and fat with echo asymmetry and the least squares estimation-iron quantification(IDEAL-IQ)sequence.Fat fraction(FF),R 2*,water and fat maps were obtained by postprocessing,and values of pancreatic quantitative parameters including FF,R 2*,signal intensity on water and fat images(SI water and SI fat)were measured.According to the MRSI standard,all patients were classified into mild(n=15),moderate(n=15)and severe(n=7)gourp.The differences of the four quantitative parameters between patient group and control group,and in groups with different severity were analyzed.Results:There were significant differences in FF,R 2*and SI water values between acute pancreatitis group and control group(P=0.011,0.002 and 0.016,respectively),but no significant difference in SI fat value.Compared with the control group,the average FF value of acute pancreatitis group was higher,but average R 2*and water value were lower.The difference of R 2*values among the three acute pancreatitis subgroups with different MRSI grades was statistically significant(Chi-Square=7.020,P=0.03);the further pairwise comparison showed significant difference between mild and moderate,mild and severe acute pancreatitis(P=0.041 and 0.043,respectively);and there was no statistically significant difference between moderate and severe groups in R 2*values.Conclusion:Pancreatic parenchyma may have fat deposits in acute pancreatitis.IDEAL-IQ technique can be used to diagnose acute pancreatitis.R 2*especially has the highest diagnostic efficiency and can be able to differentiate mild and moderate to severe acute pancreatitis.