# Renal Ultrasound Elastography: A Review of the Previous Reports on Chronic Kidney Diseases
## 4 Ultrasound Elastography of a Renal Malignancy  
The feasibility of ultrasound elastography for the assessment of renal neoplasms has been investigated in several studies. [PERSON] et al. investigated the renal elasticities of 28 patients with angiomyolipomas and 19 patients with renal cell carcinomas. They reported that renal angiomyolipomas could be differentiated from renal cell carcinomas based on the elasticity patterns obtained using strain elastography [34]. Similarly, strain elastography revealed the differences between the strain index values of benign and malignant cells [35]. Others have investigated the usefulness of SWE in assessing renal masses. In a study with 197 patients with renal lesions, the SWV in renal cell carcinomas was significantly higher than that in angiomyolipomas and the tumor-to-cortex SWV ratio was significantly higher in patients with renal cell carcinomas [36]. Another study by [PERSON] et al. investigated the ability to differentiate between benign and malignant renal tumors [37]. They showed that the SWVs in normal parenchyma were different from those in benign lesions, malignant tumors, and infectious lesions. Among them, the SWV in the hematoma was significantly lower than that in the adjacent renal parenchyma. The SWVs in malignant tumors were significantly higher than those in benign lesions. However, there were no significant differences between the SWVs of infectious and malignant tumors.  
Although the SWV in renal malignant tumors tends to be higher than that in benign lesions and normal parenchyma, contradictory results have also been reported. [PERSON] et al. investigated the elasticity in renal malignant masses with respect to the lesion size. They recruited patients with malignant and solid renal tumors < 4 cm. The elasticity values in the malignant masses, mostly composed of clear cell carcinomas, showed lower elasticity values compared to benign angiomyolipomas [38]. They suggested that the heterogeneity within the tumor influenced the SWE values. Clear renal cell carcinomas frequently present with cystic lesions such as a hemorrhage or necrosis causing decreased SWE values.  
\begin{table}
\begin{tabular}{c p{341.4 pt}} \hline \hline
1. & Measure with patients placed in prone or unilateral position \\
2. & Measurement should be performed during holding the breath \\
3. & Depth of the target region of interest should be limited to less than 8 cm \\
4. & Renal cysts or vasculature need to be avoided within the target region of interest \\
5. & Parenchymal stiffness rather than medullary stiffness is recommended in terms of reliability \\
6. & Push-pulse should be irradiated perpendicular to the renal capsule \\
7. & Ten repeated measurements should be obtained \\
8. & Results can be reported in meters per second or kilopascals \\
9. & Final result should be expressed as the median together with the interquartile range-to-median ratio \\ \hline \hline \end{tabular}
\end{table}
Table 1: Proposal for measuring renal elasticity with the SWE technique.  
Considering these results, the application of ultrasound elastography in differentiating renal solid lesions is limited.