Acoustic radiation force impulse elastography in the evaluation of focal liver pathology: a prospective study

INTRODUCTION: Determining the nature of focal liver pathology is an important issue, especially in oncological practice. Imaging methods with contrast enhancement are the main methods for diagnosing pathology of the hepatobiliary tract, however, there are limitations in the use of computed tomography, magnetic resonance imaging, and contrast-enhanced ultrasound. In recent years, acoustic radiation force impulse elastography has become a widely used method in assessing changes in the liver. This technique has been successfully used to quantify diffuse disease in the liver, and scientific research is currently being actively conducted to determine the threshold values of the stiffness of various liver lesions.OBJECTIVE: To determine the possibility of an alternative method for differential diagnosis of solid liver lesions from pseudofocal lesions using the acoustic radiation force impulse elastography technique in the context of multiparametric ultrasound examination. MATERIALS AND METHODS: The study included 64 patients with a history of cancer. In all cases, contrast-enhanced computed tomography and multiparametric ultrasound using acoustic radiation force impulse elastography technology were performed to assess quantitative indicators of lesion stiffness in the non-cirrhotic liver. The minimum, average and maximum stiffness of the lesion was assessed, expressed in m/s based on the results of 10 measurements. The results obtained were compared with accepted standards for the stiffness of the liver parenchyma for assessing diffuse changes, recommended by EFSUMB. RESULTS: In accordance with the final clinical diagnosis, the studies included focal liver lesions: hemangioma (n=16; 25.0%), focal steatosis (n=19; 29.7%), metastases (n=29; 45.3%). We assessed three subgroups of values: the minimum value, the maximum and the average. The most important parameter used for further interpretation of the data is the average stiffness value based on the results of all measurements. When assessing this indicator for hemangioma, the median was 1.63 m/s, the standard deviation was 0.36, and the range was 1.02 m/s. For these focal lesions the 25th percentile is 1.47 m/s, the 75th percentile is 2.01 m/s. For metastatic lesions, the median was 1.83 m/s. When determining the standard deviation, this indicator was 0.34 m/s, and the range was 1.58 m/s. Also, the values of the 25th percentile were 1.68 m/s, and the 75th were 2.08 m/s. When analyzing these indicators of stiffness in focal steatosis, the following values were obtained: median — 1.09 m/s; range — 0.21 m/s and standard deviation — 0.06 m/s. The 25th percentile values were 1.025 m/s, the 75th percentile — 1.105 m/s. DISCUSSION: Based on the presented data, solid lesions, such as hemangioma and metastasis, had significantly high stiffness values in comparison with unchanged liver parenchyma. Our results are close to the values described in a number of large studies, but at the moment there is no consensus regarding the threshold values, as well as the methodology for performing the study and determining the zone for assessing stiffness in the lesion, which makes this technique promising for further study. CONCLUSION: Performing a multiparametric ultrasound examination using the technique of acoustic radiation force impulse elastography to assess quantitative indicators of stiffness in the lesion makes it possible to identify changes in the liver at the screening stage, conduct constant non-invasive monitoring of cancer patients, and determine further tactics for patient management. This technique is a promising, easily accessible, economical and, most importantly, dose-free diagnostic tool for detecting and characterizing liver lesion, allowing to reduce the time of differential diagnosis at the initial stage and reduce the costs of further research.