**2.4.2 Liver abscess**

86 Liver Tumors

Fig. 7. Liver metastases (CEUS). Peripheral vascular pattern of the lesion is observed on the left in colon cancer metastasis. Lesion hyperenhancement in ovarian cancer liver metastasis

Using CEUS examination to detect metastases a sensitivity of 80-95% is obtained, similar to that of contrast CT and MRI (Quaia et al, 2006 ; Piscaglia et al, 2007). Intraoperative use of the procedure increases its performance even if it does not have a decisive contribution to change the therapeutic behavior (Konopke et al, 2005). Limitations of the method are those related to US penetration (pronounced fatty liver disease, deep lesion, excessive obesity) and to the experience of the examiner. To this the risk of confusion between hypervascular metastases, hepatocellular carcinoma and hemangioma and the confusion between hypovascular metastases and small liver cysts is added. Routine use of CEUS examination to detect liver metastases is recommended when conventional US examination is not conclusive, when precise information on some injuries (number, location) is necessary in conjunction with contrast CT/MRI and to assess the effectiveness of treatment when using a antiangiogenic therapy for hypervascular metastases (Claudon et al, 2008). The method cannot replace CT/MRI examinations which have well established indications in oncology

Besides the entities listed above inflammatory masses or even pseudo-masses can occur. Their diagnosis is quite difficult and the criteria used for differentiation are often insufficient, requiring morphologic diagnostic procedures, use of other diagnostic imaging methods or patient reevaluation from time to time. This includes lesions developed on liver parenchyma reconstruction, as occurs in cirrhosis, steatosis accumulation or in case of acute

It consists of localized accumulation of fat-rich liver cells. In some cases this accumulation can mimic a liver tumor. Sometimes the opposite phenomenon can be seen, that is an "island" of normal parenchyma in a "shining" liver. In both cases ultrasound examination identifies a well defined, un-encapsulated area, with echostructure and vasculature similar to those of normal liver parenchyma. The lesion can have different forms, most cases being oval and located in the IVth segment, anterior from the hepatic hilum. It occurs in dyslipidemic or

is seen on the right during the arterial phase.

**2.4 Pseudotumors and inflammatory masses of the liver** 

(Larsen, 2010).

or chronic inflammatory diseases.

**2.4.1 Focal steatosis** 

Liver abscess have heteromorphic ultrasound appearance, the most typical being that of a mass with irregular shapes, fringed, with fluid or semifluid content, with or without air inside. Doppler examination shows the lack of vessels within the lesion. CEUS exploration shows hyperenhancement during arterial phase close to the lesion, this being suggestive of a liver parenchymal hyperemia. During venous and sinusoidal phase the pattern is hypoechoic, and the central fluid is contrast enhanced. CEUS examination is useful because it confirms the clinical suspicion of abscess. In addition, it allows for an accurate measurement of the collection size and an indication regarding its topography inside the liver (lobe, segment).

Fig. 8. Liver abscess (2D and CEUS). 2D Examination reveals the fluid nature of the mass and imprecise delineation. CEUS examination shows congestion in the surrounding liver parenchyma and excludes a vascular tumor.
