Multiparametric ultrasound imaging: attenuation imaging (ATI) and dispersion imaging role in quantitative evaluation of steatosis and viscosity in patients with chronic liver disease.

Purpose: The prevalence of steatosis in patients with chronic liver disease is growing worldwide [2]. Hepatic fibrosis staging has been used as a prognostic factor by clinicians to measure clinical outcomes and as an index to establish therapeutic plans in patients with chronic liver disease (CLD) [1;2]. Multiparametric approach using the new ultrasound technique as attenuation imaging (ATI) and dispersion imaging for quantitative evaluation of steatosis and viscosity in cases of diffuse chronic diseases, helps to detect the changes without using the invasive methods. [3;4;5]. The aim of the study is to analyze the diagnostic value of liver ultrasound attenuation imaging (ATI) and dispersion imaging in quantitative evaluation of steatosis and viscosity in cases of diffuse chronic diseases. Methods and materials: Total 154 patients were enrolled in a prospective study between April 2019 and December 2020, where 98 patients with the confirmed diffuse liver disease, 17 healthy patients (63 women and 52 men, median age 52.0) and additionally 56 patients with proven SARS-CoV-19. Patients with the severe liver parenchymal changes due to rare disease as Budd-Chiari and Wilson disease were excluded. For fibrosis, steatosis detection and viscosity quantification the multiparametric measurements were performed by three radiologists, experienced in abdominal ultrasound: B-mode imaging, 2D shear-wave elastography measurements, attenuation imaging (ATI) and dispersion imaging on Ultrasound machine Aplio i800, Canon Medical Systems, Japan. Average 5-13 (+/-2.3 SD) numbers of Elasto - measurements in 2D-SWE were registered with IQR/median values, including patients with ascites. The laboratory results as ALAT and ASAT were taken for a correlation. Chronic liver parenchymal changes were caused by different etiology - virus hepatitis B (n=3), hepatitis C (n=31), autoimmune hepatitis (n=6), steatohepatosis (n=37), alcohol related (n=13) and patients of other etiology (n=8).
Patients with confirmed SARS-CoV-19 infection in the last 3-9 months were scanned. Multiparametric ultrasound measurements were performed with the liver biochemical damage and inflammation marker control (LDH, GGT, AlAT, CRP, ESR), where in higher grade of steatosis a more severe disease course was found. Results: There was a statistically significant difference among etiology groups and ATI (p=0.0001) with predominantly high attenuation intensity range dB/cm/MHz >0.65-0.8 in steatohepatosis (strong correlation r=0.71; p=0.0001). Relatively high attenuation intensity range was detected in toxic hepatitis group up to 0.55-0.65 dB/cm/MHz with steatosis qualitative assessment on B mode image (normal or hyperechogenic liver structure) (rs=0.5; p=0.0001). Alterations in liver tissue viscosity to the stage of fibrosis were revealed with positive correlation (rp=0.40; p=0.005) with higher value towards higher fibrosis stage, but no correlation to steatosis was found (p=0.051).
Attenuation (ATI) median values had moderate correlation with steatosis qualitative assessment on B mode image (normal or hyperechogenic liver structure) (rs=0.5; p=0.0001). Post Covid-19 patients showed the higher dispersion values (median 12.4 (m/s)/KHz) as moderate viscosity (50%) with reference of <12 (m/s)/KHz as normal values as well as no changes in ATI results [6]. It is possible that shear wave dispersion alone may provide interesting information on tissue organization at the microscopic level and give information on necro-inflammatory activity. A third part of study group of Covid-19 patients have been hospitalised and in cases of severe disease - the steatosis grades were significantly higher (F= 9.1, p<0.01) after 3-6 months after onset. In Covid-19 patients with no previous history of liver disease 2D shear wave results showed F0-F1 stage of fibrosis, that indicates initial changes. According to the results of our study and analyzing the study performed in 2017 by F.Piscaglia et al. [7] multiparametric ultrasound approach can be a good non-invasive measurement tool for evaluating the stage of liver fibrosis and inflammatory activity. The accuracy of the method is examinator dependent, although some limitations as ascites in big volume or patient non-contribution may be present. In our study we didn’t find the correlation of the stage of fibrosis to the degree of steatosis, also this effect was not confirmed during the previous studies as Bota et al. 2011 [8] and J.Yoo et al.2019 [9]. The results of our study showed that laboratory confirmed inflammatory changes in liver gave higher numbers in dispersion and therefore in viscoelasticity. Further research is required with the liver tissue biopsy, to detect the relationship between the fibrosis, viscosity and pathological changes. Conclusion: Multiparametric ultrasound evaluation of liver can be helpful in chronic liver disease as well as post Covid-19 patients as added value with reliable quantitative measurements in steatohepatosis, viscosity and fibrosis.