Improved cerebrospinal fluid suppression for intracranial vessel wall MRI

Purpose: To develop and assess a three-dimensional (3D) high resolution black blood MRI (BBMRI) method for evaluation of intracranial vessels with improved cerebrospinal fluid (CSF) suppression. Materials and Methods: The anti-driven-equilibrium (ADE) pulse was incorporated into a variable flip-angle TSE-based 3D BBMRI to improve CSF suppression. ADE-BBMRI was optimized in 8 participants and compared with BBMRI, with acquired 0.5 mm isotropic resolution and scan time of 5.4 min at 3 Tesla. Contrast-enhanced ADE-BBMRI protocol was implemented in nine patients with intracranial atherosclerosis. Signal and morphological measurements were compared between ADE-BBMRI and BBMRI, as well as pre- and postcontrast ADE-BBMRI. Reliability was assessed by intraclass correlations (ICC). Results: ADE-BBMRI effectively suppressed the surrounding CSF signal of intracranial vessels, with a 36–44% reduction compared with BBMRI. ADE-BBMRI also reduced the overall wall signal by 8–8.5%, but provided a significant improvement in wall-to-CSF contrast-to-noise ratio over BBMRI (middle cerebral artery, 5.93 ± 0.59 versus 3.95 ± 1.67, P < 0.01; basilar artery, 3.8 ± 1.76 versus 1.34 ± 0.54, P = 0.01, respectively). No differences were noted in morphological measurements between ADE-BBMRI and BBMRI (lumen area, 6.35 ± 2.87 versus 6.32 ± 2.84 mm²; wall area, 1.28 ± 0.52 versus 1.27 ± 0.53 mm²; mean wall thickness, 0.93 ± 0.30 versus 0.93 ± 0.32 mm; maximum wall thickness, 1.27 ± 0.33 versus 1.28 ± 0.36 mm, all P > 0.05). Contrast enhanced ADE-BBMRI improved the plaque delineation by the increased wall signal, wall-to-CSF and wall-to-blood contrast-to-noise ratio. ICC ranged from 0.54 to 0.95. Conclusion: The 3D ADE-BBMRI provides excellent blood and CSF suppression, and accurate measurements of intracranial vessels at 0.5 mm isotropic resolution in 5 min. Its clinical application may provide insight into stroke risk. J. Magn. Reson. Imaging 2016;44:665–672.