Imaging kidney in conscious rats with high-frequency ultrasound and detection of two cases of unilateral congenital hydronephrosis.

A quick noninvasive screen of laboratory animal organ phenotype by high-resolution ultrasound is useful in biomedical research and new drug discovery. During new drug testing, imaging animal at the conscious state avoiding anaesthesia does not only speed up the screening process, but also avoids the potential compounding interaction of anaesthetic agents with the new drugs. The feasibility of imaging kidney in conscious rats with high-frequency ultrasound was explored in this study. Two operators were involved with the procedure, with one operator holding the rat and the other operator doing the imaging process. A VisualSonics ultrasound system was used, with a 30 MHz central frequency probe at the resolution of 115 x 55 microm. It was feasible to hold the conscious rats still, allowing ultrasound imaging of kidneys, without causing stress to the animals. In a group of 12 male Han Wistar rats (Charles River, UK), two cases of unilateral congenital hydronephrosis of the right kidney were identified. The right kidneys with hydronephrosis showed an echolucent dilated pelvis and overall parenchymal hypotrophy.