Sparse precontrast T(1) 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 × 1 × 2 mm(3) resolution to match a recent high‐resolution whole‐brain DCE‐MRI protocol. Seven FAs were logarithmically spaced from 1.5° to 15°. 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] ~11.0%) and <253.2 ms in BT (COV ~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 ~9.9%) and <240.9 ms in BT (COV ~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 ~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.