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Background

In absence of pharmacological toxicity, allograft dysfunction is usually due to parenchymal inflammation and tubulointerstitial fibrosis, but its clinical signs are often non-specific and tend to appear when advanced damage has been established. We investigated whether Shear Wave Elastography (SWE), a new non-invasive ultrasound (US) based technique that estimates tissue stiffness, could provide early confident diagnosis of acute allograft dysfunction compared to biopsy (gold standard technique).

Methods

We designed a single Centre, case-controls, prospective, longitudinal and analytical study that included all kidney transplanted patients with acute allograft dysfunction referred for biopsy at our Institution for 21 months. Within 24 hours after laboratory tests an initial US and Doppler examination was performed. If non-parenchymal, urinary or vascular complications were encountered, the patient was considered as case. We gathered consecutive normal-functioning transplanted patients referred for routine follow-up. If no US abnormalities were encountered, they were classified as controls. 7 quantitative SWE measurements at each allograft´s cortical region were acquired (kilopascals (kPa). Within 24 hours, same-point allograft biopsies were performed by Nephrologists in cases. Once Pathology results were available statistical analysis were subsequently performed.

Results

26 patients (13 cases and 13 controls) were enrolled. Creatinine serum mean values were 4,18mEq/dL in cases and 1,84 in controls. SWE mean values were of 21,45 kPa in cases and 13,73 in controls. Biopsies were evaluable in all cases. Statistical analysis showed a positive relation between SWE and creatinine levels. No significance was found of SWE with anatomopathological results in terms of rejection/others, neither with rejection type.

Conclusions

SWE is a helpful, non-invasive tool for early diagnosis of kidney allograft dysfunction. Patients with higher elasticity values, in absence of clinical or analytical manifestations, should be included in an increased surveillance program since parenchymal disorders may be incipient. However further studies, with larger cohorts, are necessary to validate these findings.