Pancreatic transplant rejection: assessment with duplex US

Area of Science:

• Transplant Surgery
• Diagnostic Imaging
• Nephrology

Background:

• Pancreatic transplantation is a vital treatment for select patients with type 1 diabetes.
• Monitoring transplant function and detecting rejection are critical for graft survival.
• Duplex ultrasonography offers a non-invasive method for vascular assessment.

Purpose of the Study:

• To evaluate the diagnostic accuracy of duplex ultrasonography (US) in assessing pancreatic transplant function.
• To correlate Doppler arterial resistive indexes (RIs) with clinical outcomes, particularly rejection.
• To determine the utility of RI in differentiating rejection from other post-transplant complications.

Main Methods:

• A prospective study involving 22 patients undergoing pancreatic transplantation over 1.5 years.
• Ninety-eight duplex US examinations were performed, focusing on parenchymal vessel Doppler parameters.
• Arterial resistive indexes (RIs) were calculated and correlated with clinical events and diagnoses.

Main Results:

• A resistive index (RI) of 0.70 or less was consistently observed in normally functioning transplants.
• An RI greater than 0.70 was detected in 87.5% of clinical rejection episodes.
• The positive predictive value of RI > 0.70 for rejection was 100%, with a negative predictive value of 90% for excluding rejection.

Conclusions:

• Duplex US, specifically the arterial resistive index (RI), is a valuable tool for diagnosing pancreatic transplant rejection.
• Elevated RI values are highly specific for rejection and not typically associated with cyclosporine toxicity, pancreatitis, or infection.
• Duplex US may be more accurate for pancreatic than renal transplant rejection due to fewer confounding factors.