Role of Shear Wave Elastography for Assessment of Renal-Allograft Fibrosis and its Correlation With Histopathology

Objectives

To investigate whether shear wave elastography (SWE) can accurately identify interstitial fibrosis and tubular atrophy (IFTA) in chronic renal allograft injury (CRAI) and whether it can differentiate between different grades of IFTA.

Materials and Methods

Prospective observational study on renal transplant recipients who presented with CRAI. Patient selection was done on the basis of clinical presentation, serum creatinine, and eGFR levels. Biopsy and SWE were performed and SWE values were correlated with histopathological findings according to Banff schema. Receiver operating characteristic (ROC) was also analyzed to assess the diagnostic efficacy of SWE.

Results

Sxity-one patients were evaluated. Ten patients had no IFTA, 33 patients had mild IFTA, 16 patients had moderate IFTA, and 2 patients had severe IFTA. Mean parenchymal stiffness values in no IFTA, mild IFTA, moderate IFTA and severe IFTA were 39.86 ± 2.17 kPa (3.64 ± 0.09 m/s), 41.59 ± 3.36 kPa (3.71 ± 0.15 m/s), 47.59 ± 3.34 kPa (3.98 ± 0.14 m/s), and 53.83 ± 1.41 kPa (4.25 ± 0.03 m/s), respectively. SWE values of parenchymal stiffness reached statistical significance to differentiate between mild, moderate, and severe IFTA. ROC analysis revealed cut-off values of 45.09 kPa (3.89 m/s) to differentiate between mild IFTA and moderate IFTA, 52.06 kPa (4.18 m/s) to differentiate between moderate IFTA and severe IFTA with acceptable sensitivity and specificity.

Conclusion

SWE is a non-invasive and cost-effective imaging tool to evaluate the disease status of renal allografts affected by CRAI. Thus, it can be of paramount importance if added to the regular follow-up imaging protocol of renal allograft along with grayscale and Doppler imaging.