Ultrafast Blood T₁ Measurement Using Golden Angle Rotated Spiral k-t Sparse Parallel Imaging (GASSP): Evaluations in...

Blood T₁ is a key parameter for hemodynamic quantification in both non-contrast- and contrast-enhanced imaging. Individual vessel T₁ has been measured using a modified Look-Locker scheme with multi-shot EPI or FLASH in high spatial resolution, requiring ∼1 min. Here, by exploiting the temporal sparsity from the excessive number of inversion delays, we apply Golden Angle rotated Spiral k-t Sparse Parallel imaging (GASSP) to enable blood T₁ measurement in a single shot of 10 s.

The pulse sequence with single-shot GASSP reconstruction was developed for T₁ measurement from the internal jugular vein (IJV) with 1 × 1 mm² in-plane resolution. On nine healthy volunteers, the single-shot GASSP was compared to the segmented EPI readout and was repeated to assess its intra-scan reproducibility. Another experiment was performed on three patients, during which the 10 s GASSP was obtained at different time points prior to and following the Gadolinium (Gd) administration to assess dynamic changes in blood T₁.

The blood T₁ values measured with the highly undersampled GASSP method were strongly correlated (r = 0.83) with those using the multi-shot EPI readout and exhibited high reproducibility (r = 0.88) within the session. The baseline IJV T₁ values measured were 1700-2000 ms. Following the Gd injection, the T₁ values of IJVs gradually recovered from ∼300-400 to ∼500 ms within 10-15 min.

The feasibility of an ultrafast blood T₁ measurement was demonstrated with high spatial resolution in a single shot of 10 s, applicable to both pre- and post-contrast conditions.