Application of Ultrasound Elastography for Chronic Allograft Dysfunction in Kidney Transplantation

Abstract

Interstitial fibrosis is the main characteristic of chronic allograft dysfunction, which remains the key factor affecting long‐term allograft survival after kidney transplantation. Ultrasound elastography (UE), including real‐time elastography, transient elastography, and acoustic radiation force impulse, has been applied widely in breast, thyroid, and liver diseases, especially in the assessment of liver fibrosis. Recently, numerous studies have reported the efficacy of UE methods in evaluating renal allograft fibrosis. This review aims to investigate the clinical applications, limitations, and future roles of UE in current clinical practice in light of changing management paradigms. In current clinical practice, UE methods, especially transient elastographic measurement, appear to be useful for ruling out fibrosis but do not have sufficient accuracy to distinguish between various stages of allograft fibrosis. Moreover, there remain considerable issues to be solved for the application of UE in kidney transplantation. Thus, UE methods cannot replace the crucial role of renal allograft biopsy in the diagnosis and evaluation of allograft fibrosis in kidney transplantation. Perhaps UE methods could be of more importance in the long‐term observation and evaluation of allograft fibrosis during follow‐up.

Editorial Comment to Non‐invasive assessment of kidney allograft fibrosis with shear wave elastography: A radiological‐pathological correlation analysis

“…1,2 The most common cause of late allograft failure is chronic allograft nephropathy (CAN), which is a consequence of various immune-dependent and immune-independent factors. Despite major improvements in surgical techniques and immunosuppression therapy, today, long-term allograft survival after kidney transplantation remains a major clinical issue.…”

“…1 Biopsy remains the "gold standard" for the evaluation of kidney allograft dysfunction, thus some transplant units carry out protocol biopsies for CAN detection. [1][2][3] 1,3 In contrast, some transplant centers monitor changes in serum creatinine values in order to detect CAN, but this occurs late in the course of the disease when significant and irreversible histological changes have already developed, precluding timely interventions in order to prevent further damage to the kidney transplant.…”

“…Despite major improvements in surgical techniques and immunosuppression therapy, today, long-term allograft survival after kidney transplantation remains a major clinical issue. 1,2 The most common cause of late allograft failure is chronic allograft nephropathy (CAN), which is a consequence of various immune-dependent and immune-independent factors. 1 Aside from other histological findings (glomerulopathy, tubular atrophy, vasculopathy), the most prominent histological characteristic of CAN is interstitial fibrosis, which is a strong predictor of kidney allograft failure, and the early appearance of CAN is an independent predictor for poor long-term kidney transplant survival.…”

“…1,3 In contrast, some transplant centers monitor changes in serum creatinine values in order to detect CAN, but this occurs late in the course of the disease when significant and irreversible histological changes have already developed, precluding timely interventions in order to prevent further damage to the kidney transplant. [1][2][3] Therefore, non-invasive methods for early CAN detection are required. Ultrasound elastography (UE) methods determine tissue stiffness, and have been extensively evaluated in the context of liver fibrosis in the past two decades.…”

“…As other authors also suggested, the main role of UE methods could be in the long-term observation and evaluation of allograft fibrosis during follow up, possibly selecting patients for timely (re)evaluation with kidney biopsy. [1][2][3]…”