Noncontrast MR Imaging of Blood-Brain Barrier Permeability: Halving Scan Time With Velocity-Selective Preparation for Vessel Isolation.

PURPOSE: This study aims to develop and evaluate a noncontrast MRI method, Water-Extraction-with-Fourier-transform-velocity-selective-Arterial-Spin-Tagging (WEFAST), for accelerated and robust measurement of blood-brain barrier (BBB) permeability to water.

METHODS

The proposed WEFAST sequence incorporates Fourier-Transform Velocity-Selective (FTVS) preparation into the Water-Extraction-with-Phase-Contrast-Arterial-Spin-Tagging (WEPCAST) MRI framework, enabling single-shot acquisition without the need for double-subtraction measurement. The imaging parameters of WEFAST were optimized for maximizing spatial and temporal SNR. Its reproducibility and evaluation against the established WEPCAST technique were performed.

RESULTS

Optimal scan parameters were determined to be velocity cut-off = 2 cm/s and FTVS flip angle = 90°, and the spatial SNR reached 10.42 ± 1.30 which is significantly higher than that of other imaging protocols (all p < 0.01). The scan time of WEFAST was significantly reduced (WEFAST vs. WEPCAST: 3 min 50 s vs. 6 min 54 s). The WEFAST sequence preserved robust reproducibility (intrasession CoV: extraction fraction (E) = 3.11% ± 0.67%, permeability surface area product (PS) = 11.08% ± 1.29%; intersession CoV: E = 3.17% ± 0.76%, PS = 12.33% ± 2.04%) and achieved good agreement with the WEPCAST in quantitative measurements (R = 0.59, p < 0.001 for E; R = 0.74, p < 0.001 for PS). Multidelay experiments further confirmed reliable quantification of venous water extraction signals in multiple venous structures such as the transverse sinus and straight sinus.

CONCLUSION

The proposed WEFAST sequence achieved significant acceleration in noncontrast BBB MR imaging by providing rapid and reliable quantification of BBB water permeability, with the potential for clinical applications.