Reconstructive Ultrasound Elasticity Imaging for Renal Transplant Diagnosis: Kidney Ex Vivo Results

Abstract

It may be possible to diagnose and monitor scarring, inflammation and edema in transplant kidney using reconstructive ultrasound elasticity imaging. Kidney elasticity is expected to change dramatically with scar, and to a lesser degree, with acute inflammation and edema. The hypothesis that changes in kidney elasticity can be imaged using a clinical ultrasound scanner was experimentally tested with an ex vivo canine kidney model, and results on a single pair of kidneys are reported in this paper. A cross-linking agent affected kidney elasticity both globally and locally. Elasticity changes were monitored with accurate estimates of internal displacement and strain followed by Young's modulus reconstruction. The results of this study strongly suggest that ultrasound elasticity imaging can detect elasticity changes in complex structures such as the kidney. Moreover, it has the potential to become an important clinical tool for renal transplant diagnosis.

Quantification of Kidney Fibrosis Using Ultrasonic Shear Wave Elastography

“…12,24,25 However, a human study using transient elastography and an ex vivo study of canine kidneys showed similar mean stiffness values as our study. 21,28 In fact, the Young modulus used in this study could be measured differently according to the radio frequency of shear waves even in the same tissue or organ. 29 Magnetic resonance elastography uses mechanical vibration to create shear waves in the organs and quantifies the shear modulus.…”

Renal Advances in Ultrasound Elasticity Imaging: Measuring the Compliance of Arteries and Kidneys in End-Stage Renal Disease

“…The clinical situation is exacerbated by the fact that substantial renal parenchymal loss may occur before there is any change in functional measurements of renal function [24] . Previous ex vivo studies have suggested that ultrasound elasticity imaging may be able to detect localized elastic changes within the kidney [25,26] . Since the fi brosis associated with CAN may be accompanied by an increase in measurable elastic tissue properties, such as shear or Young's modulus, elasticity imaging may provide a means of measuring renal fi brosis and diagnosing or monitoring CAN [25,26] .…”

“…Previous ex vivo studies have suggested that ultrasound elasticity imaging may be able to detect localized elastic changes within the kidney [25,26] . Since the fi brosis associated with CAN may be accompanied by an increase in measurable elastic tissue properties, such as shear or Young's modulus, elasticity imaging may provide a means of measuring renal fi brosis and diagnosing or monitoring CAN [25,26] . Therefore, we applied ultrasound elasticity imaging to several renal transplant recipients to see if this method could practically detect differences in the elastic properties of renal parenchymal tissues.…”

Comparison of Ultrasound Corticomedullary Strain with Doppler Parameters in Assessment of Renal Allograft Interstitial Fibrosis/Tubular Atrophy

“…Furthermore, speckle tracking was optimized by largely constraining tissue motion to the area along the beam because along-beam (axial) resolution was finer than across-beam (lateral) resolution for the images used in this study. The finer axial resolution provides better tracking accuracy and noise robustness along the beam compared with tracking across the beam (Emelianov et al 2000). To improve speckle tracking, we used a high frame rate (.30 frames/s), emphasized temporal resolution (space-time setting as T2 on Sequoia ultrasound scanner) and used low grayscale frequency (2-3.5 MHz) as standard parameters in the study.…”