Sparse precontrast T1 mapping for high-resolution whole-brain DCE-MRI

Purpose: To develop and evaluate an efficient precontrast T-1 mapping technique suitable for quantitative high-resolution whole-brain dynamic contrast-enhanced-magnetic resonance imaging (DCE-MRI). Methods: Variable flip angle (VFA) T-1 mapping was considered that provides 1 x 1 x 2 mm(3) resolution to match a recent high-resolution whole-brain DCE-MRI protocol. Seven FAs were logarithmically spaced from 1.5 degrees to 15 degrees. T-1 and M-0 maps were estimated using model-based reconstruction. This approach was evaluated using an anatomically realistic brain tumor digital reference object (DRO) with noise-mimicking 3T neuroimaging and fully sampled data acquired from one healthy volunteer. Methods were also applied on fourfold prospectively undersampled VFA data from 13 patients with high-grade gliomas. Results: T-1-mapping precision decreased with undersampling factor R, althoughwhereas bias remained small before a critical R. In the noiseless DRO, T-1 bias was <25 ms in white matter (WM) and <11 ms in brain tumor (BT). T-1 standard deviation (SD) was <119.5 ms in WM (coefficient of variation [COV] similar to 11.0%) and <253.2 ms in BT (COV similar to 12.7%). In the noisy DRO, T-1 bias was <50 ms in WM and <30 ms in BT. For R <= 10, T-1 SD was <107.1 ms in WM (COV similar to 9.9%) and <240.9 ms in BT (COV similar to 12.1%). In the healthy subject, T-1 bias was <30 ms for R <= 16. At R = 4, T-1 SD was 171.4 ms (COV similar to 13.0%). In the prospective brain tumor study, T-1 values were consistent with literature values in WM and BT. Conclusion: High-resolution whole-brain VFA T-1 mapping is feasible with sparse sampling, supporting its use for quantitative DCE-MRI.