Purpose
Quantitative analysis of dynamic contrast‐enhanced MRI (DCE‐MRI) requires an arterial input function (AIF) which is difficult to measure. We propose the reference region and input function tail (RRIFT) approach which uses a reference tissue and the washout portion of the AIF.
Methods
RRIFT was evaluated in simulations with 100 parameter combinations at various temporal resolutions (5‐30 s) and noise levels (σ = 0.01‐0.05 mM). RRIFT was compared against the extended Tofts model (ETM) in 8 studies from patients with glioblastoma multiforme. Two versions of RRIFT were evaluated: one using measured patient‐specific AIF tails, and another assuming a literature‐based AIF tail.
Results
RRIFT estimated the transfer constant and interstitial volume with median errors within 20% across all simulations. RRIFT was more accurate and precise than the ETM at temporal resolutions slower than 10 s. The percentage error of had a median and interquartile range of −9 ± 45% with the ETM and −2 ± 17% with RRIFT at a temporal resolution of 30 s under noiseless conditions. RRIFT was in excellent agreement with the ETM in vivo, with concordance correlation coefficients (CCC) of 0.95 for , 0.96 for , and 0.73 for the plasma volume using a measured AIF tail. With the literature‐based AIF tail, the CCC was 0.89 for , 0.93 for and 0.78 for .
Conclusions
Quantitative DCE‐MRI analysis using the input function tail and a reference tissue yields absolute kinetic parameters with the RRIFT method. This approach was viable in simulation and in vivo for temporal resolutions as low as 30 s.