Role of shear wave elastography in assessment of chronic allograft nephropathy

Background The principal cause of renal graft loss after the first year is chronic allograft nephropathy which is represented histologically by tubulo-interstitial fibrosis. Its early diagnosis and treatment are crucial to prevent late graft failure. Ultrasound is unequivocally the first-line imaging modality for the evaluation of renal transplants in the immediate postoperative period and for long-term follow-up. Ultrasound shear wave elastography is an imaging technique based on estimation of the elastic properties of tissues. Elastography is performed in the same clinical setting with conventional B-mode ultrasonography. Tissue elasticity is displayed as an absolute number and color-coded real-time estimation. So, it can be used in screening and diagnosing chronic allograft nephropathy. However, the accurate diagnosis and prognosis of renal parenchymal complications still relies on tissue biopsy. Many studies have proved the high specificity of ultrasound elastography in decreasing the number of unnecessary biopsies. Results In our study, we included 36 patients with biopsy-proven chronic allograft nephropathy. All patients had a B-mode ultrasound examination and followed by ultrasound shear wave elastography in the same session. The results were compared to the histopathological results. Time since transplantation was directly correlated with mean renal stiffness, revealing that with longer time of transplantation renal stiffness and interstitial fibrosis and tubular atrophy (IF/TA) percentage increased with r = 0.72, 0.90 and p value