Separating spin compartments in arterial spin labeling using delays alternating with nutation for tailored excitation (DANTE) pulse: A validation study using T2-relaxometry and application to arterial cerebral blood volume imaging

Purpose To clarify the type of spin compartment in arterial spin labeling (ASL) that is eliminated by delays alternating with nutation for tailored excitation (DANTE) pulse using T-2-relaxometry, and to demonstrate the feasibility of arterial cerebral blood volume (CBVa) imaging using DANTE-ASL in combination with a simplified two-compartment model. Method The DANTE and T-2-preparation modules were combined into a single ASL sequence. T-2 values under the application of DANTE were determined to evaluate changes in T-2, along with the post-labeling delay (PLD) and the relationship between transit time without DANTE (TTnoVS) and T-2. The reference tissue T-2 (T-2_ref) was also obtained. Subsequently, the DANTE module was embedded into the Hadamard-encoded ASL. Cerebral blood flow (CBF) and CBVa were computed using two Hadamard-encoding datasets (with and without DANTE) in a rest and breath-holding (BH) task. Results While T-2 without DANTE (T-2_noVS) decreased as the PLD increased, T-2 with DANTE (T-2_DANTE) was equivalent to T-2_ref and did not change with the PLD. Although there was a significant positive correlation between TTnoVS and T-2_noVS with short PLD, T-2_DANTE was not correlated with TTnoVS nor PLD. Baseline CBVa values obtained at rest were 0.64 +/- 0.12, 0.64 +/- 0.11, and 0.58 +/- 0.15 mL/100 g for anterior, middle, and posterior cerebral arteries, respectively. Significant CBF and CBVa elevations were observed in the BH task. Conclusion Microvascular compartment signals were eliminated from the total ASL signals by DANTE. CBVa can be measured using Hadamard-encoded DANTE-ASL in combination with a simplified two-compartment model.

Automated summary

The study demonstrates that DANTE is able to eliminate microvascular compartment signals from ASL imaging, and shows the feasibility of measuring CBVa using Hadamard-encoded DANTE-ASL in combination with a simplified two-compartment model. Significant increases in CBF and CBVa were observed in rest and breath-holding tasks.