(a) Single hypoechoic intrahepatic space-occupying lesion with clear boundary and regular shape. (b) Multiple hypoechoic intrahepatic space-occupying lesions (arrow) with the same size and round or oval shape
The echo of lesion is higher than that of the liver parenchyma with the internal area presents hyperechoic area (Figs. 7.2a and 7.3), and the echo is either even or uneven both with commonly seen clear boundaries. Hyperechoic type is often found in gastrointestinal tract or urinary tract tumor metastasis.
(a) Hyperechoic intrahepatic space-occupying lesion with clear boundary and hypoechoic dark rings in surrounding area (arrow). (b) Liver lesion (arrow), observing dotted color blood flow signals in surrounding area (curved arrow). (c) The same patient showing conglomeration of swelling lymph nodes (arrow) behind the pancreas (arrow). SPV splenic vein, SMA superior mesenteric artery
Diffusely distributed hypoechoic intrahepatic space-occupying lesions (arrow) of different sizes and bereaving hypoechoic dark rings in surrounding area with some of them being integrated
The echo of lesion is similar with that of the endovascular (it’s black in screen), called anechoic lesion. It mainly refers to the situation that large areas of liquefaction necrosis are observed in lesions and often seen in metastatic adenocarcinoma with secretory function. It has multilocular inner structure; the separate walls of different thicknesses may have papillary projections with clear boundary (Fig. 7.4). Anechoic type is often found in metastatic adenocarcinoma with secretory function or malignant stromal tumor in the nasopharynx, ovary, gastrointestinal organ, etc.
Intrahepatic cystic space-occupying lesion, observing material echo (arrow), low-differentiated adenocarcinoma metastasis of ovarian tumor
The lesion is often large with mainly high echo in internal, irregular anechoic area around the center and clear boundary. This type may also show a high and low echo mix.
It is mainly found in hyperechoic lesions of different shapes with attenuation in the rear and may also be found in larger metastatic lesions, often seen in liver metastasis of gastrointestinal tract or ovarian tumor.
Mild attenuation of tumor posterior echo can be caused in metastatic liver cancer of large sound attenuation; while in tumors with greater necrosis and liquefaction, tumor posterior echo can be enhanced.
Intrahepatic Pipeline Structure
When the metastatic liver cancer is small or less, there will be no obvious change in the intrahepatic pipeline structure. But, when the lesions are larger and more, changes, such as compression, development, and an unclear display of portal vein, hepatic vein, and inferior vena cava, can occur. However, intravascular thrombosis is rarely seen. In addition, lesions in the hilar region often lead to expansion of intrahepatic bile duct.
Lymph Node Metastasis
Multiple enlarged lymph nodes can be presented near the hilum, pancreas (Fig. 7.2c), and abdominal aorta, which mainly belong to hypoechoic type that can be conglomerated.
Often shows liver parenchyma with homogeneous and fine echo because of having no liver cirrhosis background.
If primary tumors are observed in the kidney, pancreas, bladder, accessories, etc., masses with abnormal echo can be found in these organs, which will provide positive support to decide that intrahepatic space-occupying lesions are metastatic lesions.
7.2.2 Color Doppler Ultrasound
Metastatic liver cancer often has a blood supply feature that the primary tumor has. Metastatic liver cancer derived from varied tissues with different levels of differentiation will present different color Doppler ultrasound manifestations, because of different blood supplies. Color Doppler ultrasound can show blood supply of hepatic tumors, manifesting as color blood in the shape of point, linear, or branch. Generally speaking, commonly seen metastatic liver cancer often manifests bypass blood flow in peripheral tumor (Fig. 7.2b), which is then detected by pulsed Doppler as arterial blood flow with often high resistance indexes, in which most of them are above 0.6. As the blood supply of metastatic liver cancer is usually less than that of the primary liver cancer, the color Doppler blood flow detection rate of metastatic liver cancer is usually less than that of the primary liver cancer with the former more abundant than the latter. Based on the blood flow of tumor lesions, color Doppler can often determine whether the lesion is benign or malignant, but, it is difficult to identify a primary lesion from a metastatic one, and the preliminary diagnoses should be made by combining with conventional gray-scale ultrasound.
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7.2.3 Contrast-Enhanced Ultrasound
Hepatic malignant tumors often seen in contrast-enhanced ultrasound present rapid enhancement and rapid decline (against liver parenchyma) and are referred to as “rapid in and rapid out.” Metastatic liver cancer is also usually manifested in contrast-enhanced ultrasound as “rapid in and rapid out” hepatic malignant tumors characterized by enhancement (Fig. 7.5). Different from primary hepatocellular carcinoma in which the characteristic enhancement way of the former is mostly peripheral enhancement in the manner of ring, and after that the decline often begins from the center toward the around area with hypoechoic change. Sometimes, the center of the lesion begins to decline before completion of the enhancement. Comparing with primary liver cancer, the blood supply to metastatic liver cancer is less, which may contribute to the above situation. In addition, the enhancement way of metastatic liver cancer is different with that of the primary liver cancer.
(a) Hypoechoic hepatic lesion (arrow). (b) Color Doppler ultrasound showing linear color blood flow in surrounding area of the lesion (arrow). (c) Contrast-enhanced ultrasound showing arterial phase of liver lesion (17 s after injection of contrast agent) with obvious enhancement of surrounding area (arrow). (d) Decrease of portal phase showing obvious hypoechoic change (47 s after injection of contrast agent)
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