The Diagnostic Value of Systolic Acceleration Time and Resistive Index as Noninvasive Modality for Detection of Graft Rejection After Orthotopic Liver Transplantation

Abstract Background Acute cellular and chronic graft rejection are major disorders in the postoperative setting after orthotopic liver transplantation (OLT). An immediate diagnosis and successful therapy are essential for graft survival. We sought to determine whether quantitative and qualitative analysis of Doppler sonography data was predictive and sensitive as noninvasive diagnostic tools for rejection episodes. Materials and methods We prospectively recorded and retrospectively analyzed the medical records of patients who underwent OLT between January 2000 and November 2011, identifying patients with acute cellular (ACR) and chronic rejection (CR) and the grade classified the activity index according to BANFF criteria. Analyzed parameters included resistive index (R/I), systolic acceleration time (SAT) in the hepatic artery, laboratory values, histopathologic grade and therapy as well as graft and patient survival. Results Patient follow-up as of December 2011 or to the time of death ranged from 2 to 132 months (median follow- up: 79 months, mean = 83 months). We registered 29 rejection episodes (ACR n = 20 and CR n = 9) in 20 subjects. The majority of patients received a tacrolimus-based immunsuppressive regimen ( n = 14, trough level: 7–12 ng/mL) in addition to high-dose corticosteroids, and sometimes a third drug. One patient displayed a corticosteroid-resistant ACR and 4 CR cases, graft loss followed by retransplantation. R/I was calculated for all patients and SA for those who underwent OLT since 2009. As a control group we used subjects with delayed SAT and high R/I without graft rejection. In all patients with a high R/I (>0.7, range: 0.71–0.91) and in all patients who suffered graft rejection since 2009 ( n = 14), we observed a delayed SAT (>0.08, range: 0.08–0.18). The sensitivity and specificity for R/I were 82%, and 54.9%; for SAT 100% and 78%, respectively. Conclusion Delayed SAT (>0.08) and high R/I (>0.7) were sensitive indices of graft rejection episode. The limitation of these diagnostic parameters is their specificity, especially in the immediate postoperative period, where early vascular disorders trigger similar sonographic results. Nevertheless SAT and R/I may be considered to be important diagnostic tools, in combination with elevated laboratory liver values they can provide an early diagnosis of graft rejection.