Blood pressure dependent elasticity measurements of porcine kidney ex-vivo

Kidney transplantation is standard of care for end-stage renal failure. Monitoring graft health after transplantation to ensure graft longevity is important and usually carried out through the use of biopsy. Ultrasound elastography has the potential to allow regular non-invasive monitoring of graft health via the level of fibrosis. Results of kidney elastography research to date have been variable. It is hypothesized that the changes in blood pressure are a confounding factor in elasticity measurements and may explain the varied results. Using a controlled set-up on porcine kidneys ex-vivo, the effects of changes in pressure with flow from a peristaltic pump were examined (n=5). Each kidney was measured from 0 mmHg to 130 mmHg. It was found that the measured elasticity of the kidney was dependent on the input pressure of the pump. Increasing the input pressure resulted in an increase in the measured elasticity, from an average 21 ± 3 kPa at 0 mmHg to approximately 34 ± 9 kPa at 130 mmHg. These results suggest that the phase of the cardiac cycle be considered in kidney elastography using electrocardiogram (ECG) monitoring.