Ultrasonography Parameters and Histopathology Findings in Transplanted Kidney

BackgroundUntil now studies have shown conflicting results about morphologic and hemodynamic parameters in predicting histopathology results in renal graft malfunction. We sought to analyze whether parenchymal thickness relative to graft length and resistive index (RI) measured by ultrasonography can predict histopathology findings on renal biopsy.Patients and MethodsWe retrospectively analyzed 72 deceased donor renal allograft biopsies and respective allograft ultrasounds, performed on 68 patients (57% men) with mean age of 50 years (range, 21–73), with kidney graft dysfunction in 2010 and 2011. Parenchymal thickness relative to graft length and RI were compared with different histopathology diagnoses: Acute rejection, chronic rejection, chronic kidney changes, acute tubular necrosis (ATN), and other diagnoses.ResultsThe mean value of the RI and of the parenchymal thickness/graft length ratio (parenchyma size index [PSI]) was 0.81 ± 0.10 (SD) and 1.48 ± 0.27 (SD), respectively. Enlarged PSI was significantly higher in ATN (mean 1.72 ± 0.26) compared with no ATN (mean 1.39 ± 0.23; P < .001), and lower when chronic changes were present (mean 1.40 ± 0.25 for chronic changes vs mean 1.62 ± 0.28 for no chronic changes; P = .004). In the group without ATN, PSI was enlarged in acute graft rejection compared with no graft rejection (mean 1.50 ± 0.24 vs 1.24 ± 0.13, respectively; P < .001), whereas in the whole group, including ATN, PSI showed no differentiating power for acute rejection (P = .526). RI was significantly higher in ATN than without it (mean 0.91 ± 0.10 vs 0.79 ± 0.08, respectively; P < .001), whereas the RI was not increased (but was actually lower) in acute graft rejection compared with no graft rejection, neither in the whole group (mean 0.81 ± 0.09 vs 0.82 ± 0.12, respectively; P = .611).ConclusionsEnlarged parenchymal thickness/graft length ratio on ultrasonography was observed in ATN and acute allograft rejection. The RI was increased in ATN, but not in acute allograft rejection. Decreased parenchymal thickness/graft length ratio was observed in chronic kidney changes.