Noninvasive evaluation of renal allograft fibrosis by transient elastography--a pilot study.

Chronic allograft injury (CAI) is the most common cause of graft failure after the first year of transplantation. To date, only protocol biopsies can reveal subclinical disease. Transient elastography (TE) is a novel noninvasive technique that has demonstrated high reliability in the assessment of liver fibrosis. This study evaluates the feasibility of TE for the assessment of renal allograft fibrosis. Fifty-seven patients underwent TE by the FibroScan device. Biopsies were performed in 20 patients. Measurement of parenchymal stiffness by TE was successful in 55 of 57 patients (96.5%). Stiffness was significantly correlated to the extent of interstitial fibrosis (Pearson r: 0.67, P: 0.002, R(2): 0.45) and inversely related to estimated glomerular filtration rate (eGFR) (Pearson r: -0.47, P: 0.0003, R(2): 0.22). Stiffness values of patients with an eGFR >50 ml/min were significantly lower than in patients with an eGFR < or = 50 ml/min (22.2 +/- 11.0 vs. 37.1 +/- 14.2 kPa, P: 0.0005). The stiffness values of CAI Banff grades 0-1 differed significantly from grade 2 (P: 0.008) and grade 3 (P: 0.046). Parenchymal stiffness measured by TE reflects interstitial fibrosis in kidney allografts. A longitudinal assessment of parenchymal stiffness might be a powerful tool to identify patients with CAI who benefit from biopsy and consequent adaptation of the immunosuppressive regime.