Usefulness of real-time sonoelastography for assessment of renal allograft fibrosis

Background: Currently, allograft renal biopsy is the only reliable tool available to detect fibrosis in the transplanted kidney. However, it is an invasive procedure and is associated with complications. Therefore, a noninvasive tool to detect renal allograft fibrosis is needed. Aims: The aim of the study was to evaluate the usefulness of real-time sonoelastography (RTS) in the diagnosis of renal allograft fibrosis. Subjects and Methods: We studied 15 renal allograft recipients who had chronic allograft nephropathy. RTS was performed by an experienced radiologist to semi-quantitatively determine cortical and medullary stain ratio. These parameters were compared with the degree of fibrosis as assessed by allograft renal biopsy. For comparison, patients were divided into two groups based on the degree of fibrosis: those with mild fibrosis (interstitial fibrosis and tubular atrophy [IFTA] <25%) and those with moderate-to-severe fibrosis (IFTA >25%). A receiver operating characteristic (ROC) curve analysis was performed to evaluate the accuracy of cortical strain ratio to discriminate between patients with mild fibrosis versus patients with moderate-to-severe fibrosis. Results: The mean cortical strain ratio was significantly higher in those who had mild fibrosis as compared to those who had moderate-to-severe fibrosis (2.46 +/- 0.55 vs. 1.78 +/- 0.15, P = 0.01), while the medullary strain ratio was comparable between the two groups. The diagnostic accuracy of cortical strain ratio, as evaluated by area under the curve of ROC analysis, was 0.96. Conclusion: RTS can differentiate between mild fibrosis and moderate-to-severe fibrosis with high accuracy.