Investigation and optimization of parameter accuracy in dynamic contrast-enhanced MRI

Purpose: To present a modified pharmacokinetic model for improved parameter accuracy and to investigate the influ- ence of an inaccurate arterial input function (AIF) on dy- namic contrast-enhanced (DCE)-MRI parameter estimates of the transfer constant (K trans ), blood volume (v p ), and interstitial volume (v e ). Materials and Methods: Tissue uptake curves were simu- lated over a large range of physiological values and ana- lyzed for different AIF measurement errors and temporal resolutions. The AIF measurement was assumed to be in- accurate in the bolus amplitude (rapid sampling) or sus- ceptible to unknown temporal offsets (slow sampling with biexponential decay fit). Results: The modified model adequately reduces errors in parameter estimates arising from transit time effects. An error in the AIF bolus amplitude results in an inversely proportional error in K trans and v p ; v e remains robust. More consistent error in K trans (⬇20% underestimation) was ob - tained using a biexponential AIF, at the expense of severely underestimating v p . Conclusion: While an accurate, high temporal resolution AIF is essential for estimating v p , a biexponential AIF ac - quired at low temporal resolution (⬍20 seconds) provides robust estimates of v e and results in a K trans underestima - tion comparable to that from a 25% error in the initial AIF bolus amplitude. Key Words: dynamic contrast-enhanced (DCE)-MRI; phar- macokinetic modeling; arterial input function (AIF); bolus arrival delay; mean transit time; parameter accuracy