Sc6 1

The Aixplorer (SuperSonic Imagine) system was used to obtain images with a convex probe (SC6–1) within 3 days before hepatic surgery. Measurements were performed in the right lobe of the liver through the intercostal spaces. The patients maintained an overnight fast before examination. The US imaging settings including the depth, overall gain, time gain compensation, and compression were optimized. In the elastography examination, the maximum color scale of elastogram was set as 40 kPa. All gray scale and elastogram imaging settings remained constant in all patients. Assisted by a real-time gray scale US image, the ROI was positioned 1–2 cm under the liver capsule and at least 2 cm from lesion margin, avoiding large blood vessels and acoustic shadowing. Once a color map with complete and homogeneous filling was obtained in the SWE box, a Q-box (mean diameter, 20 mm) was used to obtain the LSM. The mean value of the five LSMs was used as the representative measurement of each patient [10 ].

Ultrasound elastography examinations were performed using supersonic shear wave elastography (SWE, Aixplorer, SuperSonic Imagine, Aix-en-Provence, France; software version of 9.2) with a 1–6 MHz convex transducer (model number of SC6-1). Examinations were performed by one of two experienced pediatric radiologists. Prior to SWE examination, routine abdominal ultrasound was performed to exclude children who might have any abnormalities in the abdomen, including the liver. After that, hepatic SWVs were obtained while the children were in the supine position with regular free breathing (FB) status. The transducer was held at a perpendicular angle to the skin. We used a right intercostal approach and obtained hepatic SWVs fifteen times from fifteen color-coded maps at the right lobe, avoiding hepatic vessels and bile ducts, at a 4 cm depth from the dermis. A round ROI with an 8 mm diameter (the automatically set size for routine abdominal study for SWE) was placed on each color-coded map of elasticity in the targeted liver (Fig 1). The machine automatically provided values in units of both kPa and m/sec simultaneously. We recorded the mean value of the ROI in the unit of kPa for each acquisition. When the children were able to hold their breath for a moment, hepatic SWVs were obtained fifteen times repeatedly in breath hold (BH) status using the same method above.

Liver stiffness was assessed by two-dimensional shear wave elastography (2D-SWE) in real time using B-mode ultrasound imaging with potential to select the region of interest. During the 2-week preoperative period, liver stiffness (2D-SWE) was measured. Aixplorer ultrasound system (Supersonic Imagine, France) and a convex broadband probe (SC6-1, 1–6 MHz) were used based on instructions provided by manufacturer. The ideal position—hold the arm completely abducted in the right dorsal decubitus—was proposed after 6-h fasting. An acceptable liver stiffness measurement was based on 10 acquisitions measured in each participant. The mean (M) of valid measurements in kilopascals (kPa) was considered as a result of liver stiffness evaluation for each subject. The single operator was blinded to the study data.