**16. Conclusions**

Renal cysts from second category, II, are characterized by septa thinner than 1 mm, which might have fine calcifications. No contrast enhancement or very discrete enhancement is

In the third category, called IIF, the cysts have multiple septa, minimally thickened walls, thin or thick calcifications. On CEUS, a discrete enhancement of the walls and septa is depicted. The malignant potential is 5%, and these lesions need regular monitoring for 6 months [8, 25]. Renal cysts from the fourth category, called III, present homogeneous of irregular thickening of the walls and/or septa and irregular calcifications. The CEUS examination reveals multiple

In the last category, called IV, the cysts present solid components together with homogeneous of irregular thickening of the walls and/or septa and irregular calcifications. The CEUS examination depicts multiple contrast enhancing septa and irregular contrast enhancing soft tissue

The accuracy of CEUS in differentiating renal cystic lesions as benign or malignant is similar to CE-CT [11]. The sensitivity of CEUS for depicting the vascular signal at the level of the cystic components (septa, walls, and nodules) is superior to CE-CT [26]. However, CEUS does not have the same sensitivity as CT in detecting calcifications, a confounding factor for the

CEUS is a very accurate method to depict blood extravasation after kidney surgery.

**15. Future expectations and developments in the field of kidney** 

In the last years, CEUS became a useful tool for monitoring during and after radiofrequency ablations (RFA) and cryoablation (CA). The CEUS score system for monitoring after these interventions was proposed by Wink et al. [28] in which 0 = no enhancement, 1 = rim enhancement, 2 = diffuse enhancement, 3 = localized enhancement, and 4 = no defect in enhancement. The accuracy of CEUS compared to CE-CT or MRI was lower at 3 months post-treatment, but

A better quantification of blood flow could be achieved using contrast enhanced threedimensional (3D) harmonic ultrasound imaging (HI) and subharmonic ultrasound imaging (SHI) [30]. In this preliminary study, 3D contrast-enhanced nonlinear ultrasound was able to quantify perfusion in vivo, in canine kidneys. Three-dimensional SHI resulted in better overall agreement with the reference standard than 3D HI did and was superior to previously reported 2D SHI results. Three-dimensional SHI outperformed the other methods for estimating blood perfusion because of the improved visualization of the complete perfused vascular networks [30]. This 3D technique based on CEUS proved an accurate examination for

observed. The malignant potential is 0% [8, 25].

130 Evolving Trends in Kidney Cancer

contrast enhancing septa. The malignant potential is 50% [8, 25].

components. These lesions are considered malignant [8, 25].

measurement of wall thickness and septum [27].

similar to these procedures at 12 month after [29].

detecting renal transplant perfusion defects [31].

**CEUS**

**14. CEUS for monitoring renal interventions**

The CEUS examination is an important progress for ultrasonography. The procedure depicts dynamic angio-perfusion. It is valuable in strengthening the diagnosis of renal cancer by evidencing neo-angiogenesis. It is useful in detecting tumor and nontumor circulatory abnormalities.
