1. Peritoneal examination
Hepatocellular carcinoma nodules with a diameter of 3cm or more often have intact peritoneum. The envelope is composed of fibrous tissue, and its "acoustic impedance" is higher than that of the surrounding liver tissues and cancer, so it generates interface reflection, which can show a thin hyperechoic membrane surrounding the whole cancerous nodule on two-dimensional acoustic image. The thickness of the envelope is estimated to be <0.5mm, and the envelope is relatively smooth and even on the sonogram, with a regular pattern, round or oval in shape. It reflects the characteristic of expansive growth of small hepatocellular carcinoma. However, the envelope on the sonogram always shows abortive on both sides of the nodule, which is the echogenic loss efficacy of the large interface. When the volume of hepatocellular carcinoma is large, its envelope is usually confused. However, there are cases when the diameter of the cancer nodule is more than 5cm, the periphery is still particularly complete, and in this case, the inner echoes are often accompanied by acoustic halos.
2. Internal echography
The internal echoes of cancerous nodules are of different heights and have a tendency to change. Except for the uniform hypoechoic nodules, the echoes of other cancer nodules are unevenly distributed. The detection rate of ultrasound for liver cancer nodules of <1cm was 33%-37%. Cancer nodules were classified according to the level of echo as follows:
1. Hypoechoic nodules 2. Hypoechoic nodules 3. Mixed nodules 4. Isoechoic nodules 5. Relationship between the level of nodal echo and blood supply.
3. Color blood flow in cancerous nodules
Hepatocellular carcinoma nodules and their surroundings are rich in blood supply, which can obtain all kinds of information about blood flow. Color Doppler ultrasound with second harmonic acoustic imaging has high sensitivity in examining tissue blood flow and can accurately reflect the blood supply of hepatocellular carcinoma. Color Doppler ultrasound can identify the inflow vessels, outflow vessels, and intratumoral vessels of hepatocellular carcinoma nodules, and the inflow vessels can be the hepatic artery or portal vein. Outflow vessels can be hepatic veins or portal veins. Intratumoral vessels show trunk-like, dotted, or color-mosaicked "clustered" plaques, which can be hepatic artery, portal vein, or hepatic vein flow on spectral Doppler analysis. Blood flow around a cancerous nodule may be symptomatic as a complete circle or as an arcuate tangle, which can be measured by spectral Doppler as persistent portal or pulsatile arterial flow.
4. Lymph node metastasis
①First hilar lymph node metastasis: sonogram shows round or oval hypoechoic foci of 0.5-2cm in size around the neck of the gallbladder, the common bile duct, and the portal vein, single or several. Several enlarged lymph nodes may cause pressure on the common bile duct and jaundice. ② Lymph node metastasis in the second hepatoportal region: the liver depends on the lymphatic vessels in the cephalic and transverse septum that converge to the inferior vena cava. (iii) Peripheral lymph nodes at the place where the branch hepatic veins flow into the liver (second hepatic hilar). It is often difficult to detect enlarged lymph nodes in this place because of its deep location. ④ Retroperitoneal lymph node metastasis: lymph node metastasis around the periphery of the abdominal aorta and inferior vena cava and around the periphery of the pancreas shows round or oval hypoechoic foci, single or several.