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E1272. Why, What, When, and How to Image the Vessel Wall! Demystifying Vessel Wall Magnetic Resonance Imaging
Authors
  1. James Loftus; University of Rochester Medical Center
  2. Thomas Marini; University of Rochester Medical Center
  3. Madalina Tivarus; University of Rochester Medical Center
  4. Edward Lin; University of Rochester Medical Center
  5. Shehanaz Ellika; University of Rochester Medical Center
Background
Common modalities for assessing intracranial vascular disease include computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA). These techniques generally focus on depicting irregularities and stenoses of the vessel lumen and do not assess changes in the vessel wall in their evaluation of cerebrovascular disease. Vessel wall magnetic resonance imaging (VW-MRI) is a technique developed over the last decade that uses high spatial resolution and blood signal nulling to better evaluate the vessel wall, providing supplemental information to more commonly utilized luminal-based forms of imaging (CTA, MRA, and DSA). Through this additional data, VW-MRI adds value to the assessment of patients with cerebrovascular disease; it potentially improves the diagnostic accuracy of cerebrovascular imaging and holds promise as a means of disease surveillance. This educational exhibit will review the why, what, when, and how of VW-MRI, including applications, physics and techniques, common imaging findings, and pitfalls.

Educational Goals / Teaching Points
After reviewing the exhibit, learners will understand the strengths of VW-MRI and added value to luminal-based imaging (CTA, MRA, and DSA). The learner should feel competent in the physics and technical specifications of the most commonly used sequences for VW-MRI. Common and uncommon indications with associated imaging findings for VW-MRI will be reviewed. Lastly, one should be able to recognize common pitfalls of VW-MRI.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Primary sequences used for VW-MRI include 3D T1 weighted variable flip angle fast spin echo (FSE), 3D T2 weighted gradient echo (GRE) or FSE, and 2D T1 or T2 weighted dual inversion recovery (DIR) FSE/GRE, all without and with contrast. Central nervous system (CNS) vasculitis most commonly presents as concentric narrowing with wall enhancement, reversible cerebral vasoconstriction syndrome (RCVS) as concentric narrowing without significant wall enhancement, and intracranial atherosclerotic disease (ICAD) as eccentric narrowing with wall enhancement. Common pitfalls of VW-MRI include enhancement secondary to vasa vasorum/perivascular venous plexuses, most commonly at the dural entry sites of major vessels, enhancement from adjacent veins, and slow flow artifacts, which can be identified utilizing pattern recognition and multiplanar reconstructions.

Conclusion
We describe the why, what, when, and how of VW-MRI; demonstrating VW-MRI is an invaluable problem-solving tool for the evaluation of cerebrovascular disease when faced with non-specific or absent findings on luminal-based cerebrovascular imaging (CTA, MRA, and DSA). The sequences utilized for VW-MRI only add approximately 10-15 minutes of additional scan time and are thus practical inclusions to standard MRI/MRA protocols dedicated to cerebrovascular disease such as ischemic stroke or cerebral aneurysm.