Variability of Standard Liver Volume by 2D Ultrasound: A Cross-sectional Study from Eastern India

Abstract

Introduction: Liver volume estimation is an essential component prior to major hepatic surgery and liver transplantation. Liver volume is evaluated with different formulae, gold standard Computed Tomography (CT) volumetry and Magnetic Resonance Imaging (MRI). As per literature review, studies comparing ultrasonography with formula based liver volume estimation are very few. Ultrasonography is non-invasive in nature and inexpensive. It is gaining popularity among clinicians as it helps in rapid evaluation of liver volumes. Aim: To compare variability of liver volume using 2D ultrasound with a standard well-established method based on formula derived by Johnson et al. Materials and Methods: This was a cross-sectional study done between August-October 2020 and patients were selected by the physician from general Outpatient Department (OPD) pool and clinically screened for further biochemical studies. Participants aged 20-60 years with normal liver function test were recruited in the study. Images were taken on a Siemens Ultrasound System. Study variables included were liver volumes estimated by two methods, age, weight, height and Body Surface Area (BSA). F test was used to compare variability between liver volumes estimated by two different methods. Bivariate correlation between ultrasonography-based liver volume and different body indices was also tested. Results: Variability comparison using F test shows no significant difference (F=1.095, df1=149, df2=149, p=0.29). Liver volumes estimated by two methods showed good correlation with each other and is significant at the 0.01 level, r=0.574. The mean difference (125 cc) in volumes between two methods were statistically significant (t=10.92, degree of freedom=149, p<0.001) and were not in agreement with each other. Body parameters were correlated with liver volume estimated by 2D ultrasound. Conclusion: Ultrasonography is a useful tool in estimating liver volume prior to major hepatic resection. Formula based calculation of Standard Liver Volume (SLV) does not agree with USG based volume and underestimates the mean liver volume obtained by USG method.