Role Of Doppler Evaluation Of Portal Vein Hemodynamics In Patients With Non-Alcoholic Fatty Liver Disease (A Prospective Study Of 100 Subjects)

Aim: To evaluate the hemodynamics of portal vein in patients with non-alcoholic fatty liver disease (NAFLD) with help of Doppler sonography. Materials and Methods: In a prospective case-control study carried out in the Department of Radio-diagnosis SSG hospital, Vadodara between April 2016 to November 2016 on an outpatient basis, 100 subjects with previous 4-6 hours of fasting were assessed by senior radiologists with many years of experience in the field of abdominal sonography and Doppler on a Mylab-40 ultrasound machineusing a low frequency, 3-5 MHz convex transducer. They were examined with help of Gray-scale and Doppler (color and spectral wave) sonography for evaluating the hemodynamics of the main portal vein. These subjects were divided into 2 groups of test (64 subjects with various grades of fatty infiltration of liver) and control (36 healthy subjects) based on presence or absence of fatty infiltration of the liver. The test group was further divided into 3 subgroups (group 1, 2 and 3) on the basis of the degree of fatty infiltration of the liver assessed on the gray-scale images. The fatty infitration of the liver was assessed on Gray-scale images by comparing its echogenicity with that of the right renal cortex and was graded as mild moderate and severe. The portal vein pulsatility index (VPI) and time-averaged mean flow velocity (MFV) were calculated for each subject. VPI was calculated as (peak maximum velocity - peak minimum velocity) /peak maximum velocity). Results: VPI and MFV values were, respectively, 0.32 +/- 0.06 and 16.8 +/- 2.6 cm/second in the control group, 0.27 +/- 0.07 and 14.2 +/- 2.2 cm/second in the group with grade 1 fatty infiltration, 0.22 +/- 0.06 and 12.2 +/- 1.8 cm/second in the group with grade 2 fatty infiltration, and 0.18 +/- 0.04 and 10.8 +/- 1.5 cm/second in the group with grade 3 fatty infiltration. There was a negative inverse correlation between the grade of fatty infiltration and both VPI (f - 55.3, p <0.001) and MFV (f - 43.9, p <0.001). Conclusion: The pulsatility index and the mean flow velocity decreases as the degree of fatty infiltration increases indicating that fatty infiltration leads to impedance to blood flow in the hepatic parenchyma and can later cause changes of chronic hepatitis and cirrhosis. The exact pathology of liver cirrhosis is incompletely understood. However, few suggest it may be due to increasing fibrosis consequent to increased lipid deposition.