DUSTER: Dynamic contrast enhance up-sampled temporal resolution analysis method

Dynamic contrast enhanced (DCE) MRI using Tofts' model for estimating vascular permeability is widely accepted, yet inter-tissue differences in bolus arrival time (BAT) are generally ignored. In thisworkwe propose a method, incorporating the BAT in the analysis, demonstrating its applicability and advantages in healthy subjects and patients. A method for DCE Up Sampled TEmporal Resolution (DUSTER) analysis is proposed which includes: baseline T₁ map using DESPOT₁ analyzed with flip angle (FA) correction; preprocessing; raw-signal-to-T₁-to-concentration time curves (CTC) conversion; automatic arterial input function (AIF) extraction at temporal super-resolution; model fitting with model selection while incorporating BAT in the pharmacokinetic (PK)model, and fits contrast agent CTCwhile using exhaustive search in the BAT dimension in super-resolution. The method was applied to simulated data and to human data from 17 healthy subjects, six patients with glioblastoma, and two patients following stroke. BAT values were compared to time-to-peak (TTP) values extracted fromdynamic susceptibility contrast imaging. Results show that the method improved the AIF estimation and allowed extraction of the BAT with a resolution of 0.8 s. In simulations, lower mean relative errorswere detected for all PK parameters extracted using DUSTER compared to analysiswithout BAT correction (v_p:5% vs. 20%, K^trans: 9% vs.24% andKep: 8% vs. 17%, respectively), and BAT estimates demonstrated high correlations (r = 0.94, p < 1e^-10) with true values. In real data, high correlations between BAT values were detected when extracted from data acquired with high temporal resolution (2 s) and sub-sampled standard resolution data (6 s) (mean r = 0.85,p < 1e^-10). BAT and TTP valueswere significantly correlated in the different brain regions inhealthy subjects(mean r = 0.72,p = <1e^-3), aswere voxel-wise comparisons in patients (mean r = 0.89, p < 1e^-10). In conclusion, incorporating BAT in DCE analysis improves estimation accuracy for the AIF and the PK parameters while providing an additional clinically important parameter.