| ObjectiveTo explore the clinical application of acoustic radiation force impulse (ARFI) ultrasonic elastography in the differential diagnosis of focal liver lesions.MethodsARFI technique (Simens Acuson S2000 Ultrasonic diagnostic apparatus) was used to conduct virtual touch tissue imaging (VTI) and virtual touch tissue quantification (VTQ) of 93 patients with 96 focal liver lesions and 15 healthy volunteers to obtain elastography images of focal liver lesions and shear wave velocity (SWV) values of focal liver lesions and liver parenchyma. The tissue texture was represented by echo intensity on VTI elastography images. The stronger echo represented a softer tissue and the weaker echo, a harder tissue. The results were statistically analyzed with P<0.05 indicating significant differences.Results1. Kappa values of hardness characteristics of VTI elastography images of focal liver lesions in two postures examined by two operators were all over 0.61. Intraclass correlation coefficients (ICC) of SWV values of focal liver lesions, normal liver parenchyma and peripheral liver parenchyma of the focal lesions in two postures performed by two operators were all over 0.71. The area under ROC curve of SWV values for focal liver lesions in lateral position was higher than that in supine position.2. Of the 24 hemangioma lesions, 20 (83.33%) appeared to be hyperechogenic or isoechogenic and 16 (66.67%) displayed a clear margin on the VTI elastography images. The average value of SWV detected by VTQ was 1.53±0.58m/s. Of the 7 nodules in cirrhotic live, 2 (28.57%) appeared to be hyperechogenic, 3 (42.86%) isoechogenic, and 2 (28.57%) hypoechogenic and 2 (28.57%) displayed a clear margin on the VTI elastography images. The average value of SWV detected by VTQ was 1.74±0.44m/s. Four FNH lesions appeared to be hypoechogenic and 3 (75%) displayed a clear margin on the VTI elastography images. Four lesions with a equivalent size to that seen on conventional B-mode images and the average value of SWV detected by VTQ was 2.39±0.39m/s. Of the 54 hepatocellular carcinoma lesions, 35 (64.81%) appeared to be hypoechogenic and 44 (81.48%%) displayed a clear margin on the VTI elastography images, 41 (75.93%) demonstrated a larger size on the VTI elastography images compared with that seen on conventional B-mode images. The average value of SWV detected by VTQ was 2.59±0.51m/s. Two liver metastatic carcinoma lesions appeared to be hypoechogenic on the VTI elastography images and 1 displayed a clear margin and a larger size on the VTI elastography images compared with that seen on conventional B-mode images and 1 displayed a poor margin and an equivalent size to that seen on conventional B-mode images. The average value of SWV detected by VTQ was 2.81±1.03m/s. Five cholangiocarcinoma lesions appeared to be hypoechogenic and 3 (60%) displayed a clear margin on the VTI elastography images. The average value of SWV detected by VTQ was 3.51±0.37m/s.3. The average SWV value of malignant group was highest, followed by that of benign group and then normal group (p<0.05). There were no statistical differences of SWV values between hemangioma and nodules in cirrhotic liver or among FNH, hepatocellular carcinoma and liver metastatic carcinoma (p>0.05); The SWV values of well-differentiated, moderately differentiated and poorly differentiated hepatocellular carcinoma decreased progressively and there were significant differences between the poorly differentiated hepatocellular carcinoma and well-differentiated or moderately differentiated hepatocellular carcinoma(P<0.05). The average SWV value of the liver parenchyma in malignant group was higher than that in benign group and normal group(P<0.05), The average SWV value of the liver parenchyma in benign group was higher than that in normal group(P>0.05).There were no statistical differences of SWV values of the liver parenchyma between hemangioma and FNH, and there were also no significant differences of SWV values among liver metastatic carcinoma, hepatocellular carcinoma, nodules in cirrhotic liver and cholangiocarcinoma (p>0.05). In addition, there were no significant differences of SWV values between the lesions and peripheral liver parenchyma of nodules in cirrhotic liver and liver metastatic carcinoma (p>0.05) and there were no significant differences of SWV values between peripheral liver parenchyma and lesions of other diseases (p<0.05).4. With SWV of 1.96m/s (lateral position) as diagnosis reference value for differential diagnosis between malignant and benign groups, the accuracy, sensitivity, specificity, positive predictive value and negative predictive value was 91.7%, 98.4%, 80.0%, 89.6% and 96.6%, respectively.ConclusionsARFI elastography which can reflect the hardness of focal liver lesions is characterized by simplicity and sound reproducibility. By adopting VTI, a preliminary qualitative judgment can be made on the elasticity and hardness of lesion texture and quantitative information on the elasticity and hardness of lesion texture can be obtained by VTQ detection. ARFI elastography provides a new method of tissue characterization for the diagnosis of focal liver lesions, making it possible to improve the diagnostic accuracy in combination with the conventional and contrast-enhanced ultrasonography. |
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