Role of elastography and dynamic contrast-enhanced ultrasound in the evaluation of pancreas transplantation rejection.

Abstract

Rejection is the leading cause of graft failure, and its diagnosis remains a challenge. Elastography and dynamic contrast-enhanced ultrasound (DCE-US) are novel non-invasive techniques for quantifying tissue elasticity and perfusion. Their role in pancreas graft rejection has not yet been defined. From October 16 to January 20, all pancreas transplantations performed at our institution were prospectively studied with elastography and DCE-US at 1 week, 3 weeks, and 12 months post-transplantation. Surveillance biopsies were performed at 3 weeks and 12 months. Elastography and DCE-US were also conducted in all requested biopsies during this period (regardless of the date of transplantation). Patients were categorized according to the biopsy result: normal/rejection. Grafts with other complications were excluded. Cut-off values were established. One hundred twenty-one elastography and 127 DCE-US in 56 patients were included. All parameters showed a high dispersion during the first 90 days post-transplantation. After this period, the rejection group presented higher stiffness (0.97 vs 1.46 m/s, p < 0.001) and lower perfusion. The optimal cut-off value for elastography was 1.27 m/s (AUC 0.80), and for DCE-US were: peak enhancement 601 a.u. (AUC 0.67), wash-in AUC 2748 a.u. (AUC 0.70), wash-in rate 118 a.u. (AUC 0.65), wash-in perfusion index 369 a.u. (AUC 0.67), wash-out AUC 5181 a.u. (AUC 0.69) and total AUC 6388 a.u. (AUC 0.68). A combined predictive score showed that alteration of elastography and DCE-US was associated with a 23.2-fold probability of rejection. After the first 90 days post-transplantation, pancreas graft rejection is associated with higher stiffness and lower graft perfusion. Question Pancreas graft rejection remains a clinical challenge, as there are currently no reliable non-invasive tests for its diagnosis. Findings After the first 90 days post-transplantation, elastography and DCE-US show higher stiffness and lower pancreas graft perfusion in the presence of rejection. Clinical relevance These non-invasive tools, which can be easily integrated into daily routine practice, may be useful in identifying grafts at higher risk of rejection, allowing closer follow-up or early biopsy to establish early rejection treatment, improving graft and patient survival.