Vessel-specific quantification of cerebral venous oxygenation with velocity-encoding preparation and rapid acquisition.

Purpose: Non-invasive measurement of cerebral venous oxygenation (Y _v ) is of critical importance in brain diseases. The present work proposed a fast method to quantify regional Y _v map for both large and small veins.
Methods: A new sequence was developed, referred to as TRU-VERA (T ₂ relaxation under velocity encoding and rapid acquisition, which isolates blood spins from static tissue with velocity-encoding preparation, modulates the T ₂ weighting of venous signal with T ₂ -preparation and utilizes a bSSFP readout to achieve fast acquisition with high resolution. The sequence was first optimized to achieve best sensitivity for both large and small veins, and then validated with TRUST (T ₂ relaxation under spin tagging), TRUPC (T ₂ relaxation under phase contrast), and accelerated TRUPC MRI. Regional difference of Y _v was evaluated, and test-retest reproducibility was examined.
Results: Optimal Venc was determined to be 3 cm/s, while recovery time and balanced SSFP flip angle within reasonable range had minimal effect on SNR efficiency. Venous T ₂ measured with TRU-VERA was highly correlated with T ₂ from TRUST (R ²  = 0.90), and a conversion equation was established for further calibration to Y _v . TRU-VERA sequences showed consistent Y _v estimation with TRUPC (R ²  = 0.64) and accelerated TRUPC (R ²  = 0.79). Coefficient of variation was 0.84% for large veins and 2.49% for small veins, suggesting an excellent test-retest reproducibility.
Conclusion: The proposed TRU-VERA sequence is a promising method for vessel-specific oxygenation assessment.
(© 2024 International Society for Magnetic Resonance in Medicine.)