**5. Precautions**

**3. Equipment**

122 Evolving Trends in Kidney Cancer

harmonic echoes at the tissue level and the artifacts.

contrast media assessment (for ROI characterization).

nance of the area of interest in the ultrasound examination plan.

after injection), corticomedullary (36–120 s), and delayed (>120 s) [10].

**4. The examination technique**

and reduce "Gain" function.

the patient weight [7].

tice [7].

For CEUS technique, the ultrasound device must be capable of functioning in harmonic mode and benefit from the acoustic power adjustment. The transducers, similar to those currently used for B and Doppler mode examinations, differ in the ability to operate in contrast mode. The harmonic mode allows a real and effective discrimination of the echoes from the blood column to those from the tissues. The acoustic power regulation is set to a value of 0.09–0.11, which leads to the generation of harmonic echoes at the microbubble level, minimizing the

Prior to the examination, a peripheral vein (preferably the antecubital vein) is catheterized with a 20–22 Gauge needle. The examination methodology goes through the following steps: gray scale (for ROI detection), Doppler technique (for circulatory specificity assessment), and

The patient's position is adapted for examination of the organ of interest. For retroperitoneal organs, it is recommended that the patient adopts a shallow breath to facilitate the mainte-

After activating the contrast mode, the following settings of the ultrasound equipment must be done: the "Focus" position below the region of interest, the mechanical index at 0.09–0.11,

The injection of the contrast agent (at an average dose of 2.4 ml) is followed by 10 ml of saline solution is bolus. At the time of injection, the ultrasound timer and record videos are started. The region of interest is dynamically tracked for up to 5 min postinjection. Theoretically, a second injection can be made immediately, although this is rarely necessary in clinical prac-

The quality of the CEUS image is limited, as in the case of the B mode ultrasound, by the localization of the region of interest, the presence of the intestinal gas or bone margins, and

For kidney CEUS examination, the literature proposed various contrast phase terminologies. One is similar to the terminology used by multiphase contrast-enhanced computer tomography (CE-CT) and magnetic resonance imaging (MRI) [8]. This terminology uses three phases: corticomedullary (enhancing cortex with medullary pyramids not yet perfused, approximately 15–30 s after contrast agent injection), nephrographic (homogenously enhancing renal parenchyma, approximately 30–70 s postinjection), and delayed (>70 s postinjection) [8]. Other groups used the following terminology: arterial phase <30 s postinjection and delayed phase 30–90 s postinjection [9]. Other authors proposed other terminologies: cortical (8–35 s The sulfur hexafluoride, the gaze part of the contrast agent is inert, nontoxic, with biocompatible membranes and easily eliminated by breathing. The metabolism of the membranes covering the microbubbles is done in the liver. These features make CEUS exploration independent of renal or thyroid functions, being an alternative to computer tomography in cases of renal failure or patients with history of thyrotoxicosis.

Very rare side effects are possible due to the interaction of ultrasound with microbubbles. These interactions may be mechanical or chemical. Mechanical features include bubble expansion and capillary rupture. Transient hyperthermia during bubbles recovering after expansion can generate free radicals. The precipitating factor for these reactions is the use of a mechanical index of about 0.4 [11]. Anaphylactic reactions were reported in 0.002% of examinations [12, 13].
