Renal Allograft Dysfunction: Evaluation with Shear-wave Sonoelastography

Purpose To evaluate whether shear-wave sonoelastography can help differentiate stable renal allograft from acute allograft dysfunction and chronic allograft dysfunction and to correlate shear-wave sonoelastography measurements with resistive index (RI), serum creatinine level, estimated glomerular filtration rate (eGFR) obtained with the Nankivell equation, and biopsy findings. Materials and Methods A prospective study of 60 patients who had undergone renal transplantation was conducted between October 2014 and March 2016. Patients were classified as having stable allograft, acute allograft dysfunction, or chronic allograft dysfunction on the basis of clinical parameters. Mean parenchymal stiffness was compared. The Banff score was used wherever applicable. Receiver operating characteristic curves were drawn to evaluate the feasibility of differentiation. Results Thirty patients had graft dysfunction (acute in 19 patients and chronic in 11). Mean parenchymal stiffness values in stable allograft, acute allograft dysfunction, and chronic allograft dysfunction were 8.51 kPa ± 2.44, 11.06 kPa ± 2.91, and 24.50 kPa ± 4.49, respectively (stable vs acute dysfunction, P = .010; stable vs chronic dysfunction, P < .001; acute sysfunction vs chronic dysfunction, P < .001). The allograft parenchymal stiffness values for patients with Banff grade I (mild interstitial fibrosis and tubular atrophy) differed significantly from those with Banff grade II (moderate interstitial fibrosis and tubular atrophy) (P = .02). Parenchymal stiffness showed a negative correlation with eGFR (r = -0.725; P < .001) and a positive correlation with RI (r = 0.562; P < .001) and serum creatinine level (r = 0.714; P < .001). The sensitivity was 73.68% and specificity was 80% in the differentiation of stable graft from acute graft dysfunction (threshold value, 10.11 kPa). Conclusion Shear-wave sonoelastographic evaluation of renal parenchymal stiffness may help differentiate stable allograft from acute and chronic allograft dysfunction. The inverse correlation of parenchymal stiffness with eGFR and positive correlation with RI and serum creatinine level show that shear-wave sonoelastography may reflect functional status of the renal allograft.