Operator dependency of arterial input function in dynamic contrast-enhanced MRI

Objective To investigate the effect of inter-operator variability in arterial input function (AIF) definition on kinetic parameter estimates (KPEs) from dynamic contrast-enhanced (DCE) MRI in patients with high-grade gliomas. Methods The study included 118 DCE series from 23 patients. AIFs were measured by three domain experts (DEs), and a population AIF (pop-AIF) was constructed from the measured AIFs. The DE-AIFs, pop-AIF and AUC-normalized DE-AIFs were used for pharmacokinetic analysis with the extended Tofts model. AIF-dependence of KPEs was assessed by intraclass correlation coefficient (ICC) analysis, and the impact on relative longitudinal change in K-trans was assessed by Fleiss' kappa (kappa). Results There was a moderate to substantial agreement (ICC 0.51-0.76) between KPEs when using DE-AIFs, while AUC-normalized AIFs yielded ICC 0.77-0.95 for K-trans, k(ep) and v(e) and ICC 0.70 for v(p). Inclusion of the pop-AIF did not reduce agreement. Agreement in relative longitudinal change in K-trans was moderate (kappa = 0.591) using DE-AIFs, while AUC-normalized AIFs gave substantial (kappa = 0.809) agreement. Discussion AUC-normalized AIFs can reduce the variation in kinetic parameter results originating from operator input. The pop-AIF presented in this work may be applied in absence of a satisfactory measurement.

Automated summary

This study investigated the impact of inter-operator variability in arterial input function (AIF) definition on kinetic parameter estimates from dynamic contrast-enhanced MRI in patients with high-grade gliomas. Results showed that AUC-normalized AIFs can reduce the variation in kinetic parameter results originating from operator input, and the pop-AIF presented in this work may be applied in absence of a satisfactory measurement.