Quantitative elastography of renal transplants using supersonic shear imaging: a pilot study

Purpose

To evaluate the reliability of quantitative ultrasonic measurement of renal allograft elasticity using supersonic shear imaging (SSI) and its relationship with parenchymal pathological changes.

Materials and methods

Forty-three kidney transplant recipients (22 women, 21 men) (mean age, 51?years; age range, 18–70?years) underwent SSI elastography, followed by biopsy. The quantitative measurements of cortical elasticity were performed by two radiologists and expressed in terms of Young’s modulus (kPa). Intra- and inter-observer reproducibility was assessed (Kruskal-Wallis test and Bland-Altman analysis), as well as the correlation between elasticity values and clinical, biological and pathological data (semi-quantitative Banff scoring). Interstitial fibrosis was evaluated semi-quantitatively by the Banff score and measured by quantitative image analysis.

Results

Intra- and inter-observer variation coefficients of cortical elasticity were 20?% and 12?%, respectively. Renal cortical stiffness did not correlate with any clinical parameters, any single semi-quantitative Banff score or the level of interstitial fibrosis; however, a significant correlation was observed between cortical stiffness and the total Banff scores of chronic lesions and of all elementary lesions (R?=?0.34, P?=?0.05 and R?=?0.41, P?=?0.03,respectively).

Conclusion

Quantitative measurement of renal cortical stiffness using SSI is a promising non-invasive tool to evaluate global histological deterioration.

Key Points

? Supersonic shear imaging elastography can measure cortical stiffness in renal transplants ? The level of cortical stiffness is correlated with the global degree of tissue lesions ? The global histological deterioration of transplanted kidneys can be quantified using elastography