ARFI应用中射频及嵌入深度对肝脏弹性成像诊断准确性的影响

目的:分析应用声辐射力脉冲成像(Acoustic Radiation Force Impulse Imaging,ARFI)技术进行肝病诊断过程中不同探针及不同嵌入深度对其诊断准确性的影响。方法:于2012~2014年,选取经ARFI诊断过的98例丙型肝炎(Hepatitis C Virus,HCV)患者,对两种探针(凸阵探头C4-1 MHz和线阵探头L9-4 MHz)诊断下的相关数据进行前瞻性研究分析,并与瞬时弹性成像(Fibroscan)进行对比。对不同嵌入深度的ARFI弹性成像的变异性进行了系统评估。结果:根据Fibroscan成像结果,33例患者(34%)患有肝硬化,其余患者中27例(27%)患有严重的肝纤维化,38例(39%)未患。C4-1的传播速率平均为1.68±0.59 m/s,L9-4为1.93±0.76 m/s。两种探针检测结果彼此相关显著(P0.001,r=0.71),且二者均与Fibroscan结果显著相关(P0.001,r分别为0.79和0.81)。对于肝硬化或严重肝纤维化患者而言,L9-4探针诊断结果高于C4-1探针,差异具有统计学意义(P0.001)。在诊断肝硬化疾病中,C4-1和L9-4探针的AUROC值分别为0.97和0.91,截断水平分别为1.68和2.01 m/s。C4-1和L9-4嵌入深度分别为3~6 cm和2~3.5 cm。结论:线阵探头和凸阵探头在应用ARFI成像评估肝脏硬度中具有较高的准确性,相较而言,线阵探头诊断结果更高。且ARFI的测量操作不宜靠近肝被膜。

Effects of Frequency and Depth on Liver Elastography: Implication for Acoustic Radiation Force Impulse Imaging

Objective:To explore the effect of different probes and insertion depths on diagnostic accuracy of liver elastography during the clinical application of acoustic radiation force impulse imaging (ARFI).Methods:98 patients with hepatitis C virus (HCV) were examined by ARFI using two probes (convex 4-1 MHz and linear 9-4 MHz). The obtained data were analyzed by comparing to Fibroscan.Results:According to the results of Fibroscan, 33 patients (34 %) were diagnosed with liver cirrhosis, while 27 patients (27 %) had significant liver fibrosis and 38 patients (39 %) had no significant fibrosis. The mean propagation rate of C4-1 and L9-4 were 1.68 ± 0.59 m/s and 1.93± 0.76 m/s, respectively. There was significant correlation between the results of two probes. Meanwhile, a significant correlation was also observed between the results of probes and Fibroscan (r=0.79 for C4-1, r=0.81 for L9-4, P<0.001). The results of ARFI using L9-4 were significantly higher than that using using C4-1 for the patients with cirrhosis or significant fibrosis (P<0.001). During detection of liver cirrhosis, AUROC values of C4-1 and L9-4 were 0.97 and 0.91 respectively, the best cut-off levels were 1.68 and 2.01 m/s respectively. The insertion depth in the measurements of ARFI was 3~6 cm for C4-1 and 2~3.5 cm for L9-4.Conclusion:Convex and linear probes are feasible in ARFI in comparison with Fibroscan, and the linear probes can get the higher diagnostic results. Furthermore, the measurement of ARFI should not be close to liver capsule.