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

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 detecting renal transplant perfusion defects [31].

Another future application is related to robotic-assisted partial nephrectomy, which has gained prominence recently, as this approach has a shorter learning curve and a shorter warm ischemia time as compared to laparoscopic partial nephrectomy [32]. CEUS is capable of dynamic evaluation and quantification of microvasculature blood (capillary perfusion) in real time, without affecting renal function. When used in conjunction with a robotic ultrasound probe, CEUS can facilitate better visualization of renal vasculature and tumor and ultimately improving acumen and precision. CEUS is a valuable and a cost-effective tool for the identification of renal blood flow in robotic-assisted partial nephrectomy, especially with complex, challenging tumors [32].
