Vessel Wall Imaging at 7T: State of the Art

ABSTRACT

Intracranial vessel wall imaging (VWI) has emerged as a critical tool in neurovascular diagnostics, enabling direct assessment of the vessel wall, which conventional luminal imaging techniques cannot fully address. While commonly available 3T MRI systems have been valuable for VWI, limitations in spatial resolution and signal-to-noise ratio hinder their ability to visualize medium and smaller caliber vessels. Ultra-high-field 7T-MRI, given its improved spatial resolution, contrast, and signal-to-noise ratio, can help address these limitations. This review highlights the historical development of VWI at 7T, tracing its evolution from early attempts to key technical advancements, development of pulse sequences such as MPIR-TSE, SPACE, and CUBE, along with the later incorporation of CSF suppression techniques to further enhance lesion conspicuity. It also discusses the pitfalls and clinical applications of 7T-VWI in cerebrovascular diseases, including atherosclerosis, vasculitis, and aneurysms, demonstrating its ability to improve plaque characterization, monitor disease progression, and assist in treatment planning. Despite challenges, such as B1 field inhomogeneity and the lack of standardized protocols, 7T-MRI's potential for clinical application is evident, with ongoing innovations like deep learning-based reconstructions promising to further improve its feasibility in routine clinical practice. ABBREVIATIONS: VWI= Vessel Wall Imaging; CoW= Circle of Willis; MPIR-TSE= magnetization-prepared inversion recovery turbo spin echo; SNR= Signal-to-noise ratio; CNR= Contrast-to-noise ratio; SPACE= Sampling Perfection with Application-optimized Contrasts using different flip angle Evolutions; DANTE= Delay Alternating with Nutation for Tailored Excitation; ICAD= Intracranial Atherosclerotic Disease; UIA= Unruptured intracranial aneurysm.