In this prospective cohort study, after obtaining the approval of local ethics committee, we evaluated patients diagnosed as obstructive jaundice by ultrasound elastography to assess the liver stiffness, referred to the diagnostic and interventional radiology department in the National Liver Institute between April 2019 and September 2020 for biliary drainage. Written informed consent was obtained from all patients.
The selected patients with confirmed diagnosis of biliary obstruction based on imaging examination, total serum bilirubin level > 2 mg/dl and clinical indications for biliary drainage. We excluded patients with liver cirrhosis, liver tumors, marked ascites, comatosed patients and contraindications to biliary drainage as bleeding disorders. All patients were subjected to routine history taking, physical examination, imaging assessment, laboratory investigations including liver biochemical tests (total bilirubin, direct bilirubin, SGOT, SGPT, GGT and ALK) and renal function tests (serum creatinine and urea).
The examination was performed using Philips Healthcare ultrasound (Bothell, WA; ElastPQ, software version 22.214.171.124) with the C5-1 curvilinear probe.
The patients were in fasting condition and examined in a supine or slight (30-degree) left lateral decubitus position with the right arm elevated to make the intercostal space wider and were asked to suspend their breath in intermediate expiration for 5–10 s during each measurement. Optimize the B-mode image for the best acoustic window to provide the best results.
All liver elasticity measurements were obtained from the right lobe with an intercostal approach, by using point shear wave elastography with acoustic radiation force impulse (ARFI) technology. The transducer was perpendicular on the liver capsule and the ROI placed in the right hepatic lobe at a depth of minimum 1 cm below the liver capsule, best at 4–5 cm from the transducer. A ROI of 0.5 × 1 cm was used. Shear wave velocity (SWV) was measured in a pre-defined ROI while performing B-mode ultrasonography.
Multiple measurements of liver elasticity were obtained in the same location by a consultant radiologist with 5 years of experience. The mean of ten valid acquisitions was considered representative for liver stiffness measurement and expressed in kilopascals (kPa). Liver elasticity values in healthy people have been reported to be less than 4.5 kPa (1.22 m/s). During examination, the stiffer the tissue was recorded with the higher the shear wave velocity.
Liver elasticity was assessed before biliary drainage (day 0), with measures repeated after 2 days (day 2) and 7 days (day 7) following successful biliary drainage. The results were recorded and considered to be reliable when there was a significant decrease in liver stiffness after biliary drainage.
The following serum markers: total bilirubin, direct bilirubin, SGOT, SGPT, ALK phosphatase and GGT, were estimated before biliary drainage and repeated on day 2 and day 7 post-biliary drainage. Then, the laboratory data were recorded to be correlated with the elastographic data.
Data were collected and tabulated using SPSS (Statistical Package for Social Science, version 26; Inc., Chicago. IL), employing descriptive statistics (quantitative data were shown as mean, SD and range; qualitative data were expressed as frequency and percent) and analytical statistics (chi-square test, Student’s t test, ANOVA test). P value was considered statistically significant when it is less than 0.05.