Chronic kidney disease (CKD) incidence and prevalence are increasing in Western countries, due particularly to diabetes mellitus and hypertension-related nephropathies. CKD may lead to end-stage renal failure, with extensive morbidity, mortality and increasing health costs. Primary and secondary prevention requires a better knowledge of mechanisms underlying renal scarring, the development of specific therapies to slow down the progression of the disease and the development of non-invasive diagnostic tools to characterize the process. Ultrasound elastography is a new imaging technique under development that provides information about renal stiffness. Kidney elasticity measurements with ultrasound should be performed with a quantitative technique, such as Shearwave techniques. However kidney stiffness is not only related to fibrosis, as it also sensitive to mechanical and functional parameters such as anisotropy, vascularization, hydronephrosis and external pressure. This paper reviews the existing ultrasound elastography techniques. Elastography is a new tool under development for renal tissue characterization and needs further validation in clinical practice.

Purpose: The goal of this study was to develop and evaluate a volumetric three-dimensional (3D) approach to improve the accuracy of ablation margin assessment following thermal ablation of hepatic tumors. Methods:The 3D margin assessment technique was developed to generate the new 3D assessment metrics: volumes of insufficient coverage (VICs) measuring volume of tissue at-risk post-ablation. VICs were computed for the tumor and tumor plus theoretical 5-and 10-mm margins. The diagnostic accuracy of the 3D assessment to predict two-year local tumor progression (LTP) was compared to that of manual 2D assessment using retrospective analysis of a patient cohort that has previously been reported as a part of an outcome-centered study. Eighty-six consecutive patients with 108 colorectal cancer liver metastases treated with radiofrequency ablation (2002 -2012) were used for evaluation. The 2-year LTP discrimination power was assessed using receiver operating characteristic area under the curve (AUC) analysis.Results: A 3D assessment of margins was successfully completed for 93 out of 108 tumors. The minimum margin size measured using the 3D method had higher discrimination power compared with the 2D method, with an AUC value of 0.893 vs. 0.790 (P = 0.01). The new 5 mm VIC metric had the highest 2-year LTP discrimination power with an AUC value of 0.923 (P = 0.004). Conclusions:Volumetric semi-automated 3D assessment of the ablation zone in the liver is feasible and can improve accuracy of 2-year LTP prediction following thermal ablation of hepatic tumors.