Contrast-enhanced ultrasonography in pancreas transplantation

Pancreas transplantation remains a major surgery with potential complications that require reliable imaging despite impaired kidney function. Contrast-enhanced ultrasonography (CEUS) has been proven to be an indispensable tool in the evaluation of the native pancreas. Here, CEUS studies are extended to pancreas transplants for the first time.

A total of 42 B-mode, duplex, and CEUS exams performed using 1 mL SonoVue (Bracco) on a Siemens Acuson Sequoia ultrasound machine were evaluated in 14 pancreas transplant recipients. Time-intensity curves and curve characteristics were calculated. The data were compared between normal pancreas transplants, grafts undergoing rejection, and grafts after successful treatment of the rejection episode.

All of the grafts could be well visualized in all ultrasound exams. Although the arterial resistive index did not differentiate between rejection and the absence of rejection, in CEUS, the time-intensity curves showed a significantly slower ascent and diminished maximum intensity in pancreas grafts during rejection, with significantly reduced maximum intensity and time to reach peak intensity. After the successful treatment of rejection, these parameters were almost restored to initial values.

CEUS displays the capillary perfusion of the tissue. Edema of the pancreas graft during rejection impairs capillary perfusion, reflected in the amount of contrast detected by CEUS and the dynamics of the influx of the contrast agent.

CEUS yields useful information after pancreas transplantation and has been proven a sensitive tool in the surveillance of pancreas grafts. Further studies will be needed to differentiate rejection from other posttransplantation complications using CEUS.