**2.2.1 Liver cysts**

80 Liver Tumors

*Limitations of CEUS examination*. Harmonic contrast examination has some limitations including: a) the procedure is indicated only correlated with good 2D image; b) it has a

**2. 2D and harmonic ultrasonography in detecting and characterizing liver** 

Ultrasound diagnosis of liver tumors involves two stages: detection and characterization.

*Tumor detection* is based on the performance of the method as already presented and should include morphometric information (three axes dimensions, volume) and topographic information (number, location specifying liver segment and lobe/lobes). The specification of

Tumor characterization is a complex process based on a sum of criteria leading towards tumor nature definition. Often, other diagnostic procedures, especially interventional ones are no longer necessary. Ultrasound examination has the same morphological and hemodynamic criteria as those of CT and MRI imaging procedures. However, semiology will be adjusted to the specifics of this method. Tumor characterization using the ultrasound method will be based on the following elements: consistency (solid, liquid, mixed), echogenity, structure appearance (homogeneous or heterogeneous), delineation from adjacent liver parenchyma (capsular, imprecise), elasticity, posterior acoustic enhancement effect, the relation with neighboring organs or structures (displacement, invasion), vasculature (presence, Doppler and CEUS characteristics). The substrate on which the tumor condition develops (if the liver is normal or if there is evidence of diffuse liver disease) and the developing context (oncology, septic) are also added. Particular attention should be paid to the analysis of the circulatory bed. Microcirculation investigation allows for discrimination between benign and malignant tumors. Characteristic elements of malignant circulation are vascular density, presence of vessels with irregular paths and size, some of them intercommunicating, some others blocked in the end with "glove finger" appearance, the presence of arterio-arterial and arterio-venous shunts, lack or incompetence of arterial

precapillary sphincter made up of smooth musculatures (Weidener et al, 1991).

hematological) status are important elements that should also be considered.

status, as tumors are often asymptomatic, being incidentally discovered.

**2.2 Benign liver tumors** 

Diagnosis and characterization of liver tumors require a distinct approach for each group of conditions, using the available procedures discussed above for each of them. The correlation with the medical history, the patient's clinical and functional (biochemical and

They generally develop on normal or fatty liver, are single or multiple (generally paucilocular), have distinct delineation, with increased echogenity (hemangiomas, benign focal nodular hyperplasia) or absent, with posterior acoustic enhancement effect (cysts), have distinct delineation (hydatid cyst), lack of vascularization or show a characteristic circulatory pattern, displace normal liver structures and even neighboring organs (in case of large sizes), are quite elastic and do not invade liver vessels. The patient has a good general

relatively high cost; c) it is operator dependent examination.

these data is important for staging liver tumors and prognosis.

**2.1 Characteristics of ultrasound diagnosis** 

**tumors** 

They can be single or multiple, with variable size, generally less than 20 mm (congenital). Rarely, sizes can reach several centimeters, leading up to the substitution of a whole liver lobe (acquired, parasitic). They may be associated with renal cysts; in this case the disease has a hereditary, autosomal dominant transmission (von Hippel Lindau disease). The ultrasound appearance is a well defined lesion, with very thin, almost unapparent walls, without circulatory signal at Doppler or CEUS investigation. The content is transonic suggesting fluid composition. The presence of membranes, abundant sediment or cysts inside is suggestive for parasitic, hydatid nature. Posterior from the lesion the "acoustic enhancement" phenomenon is seen, which strengthens the suspicion of fluid mass. They typically displace normal liver vessels but no vascular or biliary invasion occurs.

Fig. 2. Liver cyst – left image. Hydatid liver cyst (2D exam) – right image. Diagnostic criteria are the presence of membranes and sediment inside.
