Venous cerebral blood volume mapping in the whole brain using venous‐spin‐labeled 3D turbo spin echo.

Purpose: Venous cerebral blood volume (CBVv) is a major contributor to BOLD contrast, and therefore is an important parameter for understanding the underlying mechanism. Here, we propose a velocity‐selective venous spin labeling (VS‐VSL)‐prepared 3D turbo spin echo pulse sequence for whole‐brain baseline CBVv mapping. Methods: Unlike previous CBVv measurement techniques that exploit the interrelationship between BOLD signals and CBVv, in the proposed VS‐VSL technique both arterial blood and cerebrospinal fluid (CSF) signals were suppressed before the VS pulse train for exclusive labeling of venous blood, while a single‐slab 3D turbo spin echo readout was used because of its relative immunity to magnetic field variations. Furthermore, two approximations were made to the VS‐VSL signal model for simplified derivation of CBVv. In vivo studies were performed at 3T field strength in 8 healthy subjects. The performance of the proposed VS‐VSL method in baseline CBVv estimation was first evaluated in comparison to the existing, hyperoxia‐based method. Then, data were also acquired using VS‐VSL under hypercapnic and hyperoxic gas breathing challenges for further validation of the technique. Results: The proposed technique yielded physiologically plausible baseline CBVv values, and when compared with the hyperoxia‐based method, showed no statistical difference. Furthermore, data acquired using VS‐VSL yielded average CBVv of 2.89%/1.78%, 3.71%/2.29%, and 2.88%/1.76% for baseline, hypercapnia, and hyperoxia, respectively, in gray/white matter regions. As expected, hyperoxia had negligible effect (P >.8), whereas hypercapnia demonstrated vasodilation (P <<.01). Conclusion: Upon further validation of the quantification model, the method is expected to have merit for 3D CBVv measurements across the entire brain. [ABSTRACT FROM AUTHOR]