Arjen Lindenholz

194 CHAPTER 9 enhancement may differentiate between unstable and stable aneurysms, which could guide their therapeutic management. 15,82,83 Other examples of vessel wall pathology and vasculopathy-associated diseases in which intracranial vessel wall MRI has been suggested to be helpful are dissections, moyamoya disease, Fabry disease, giant cell arteritis, and cerebral amyloid angiopathy; however, sample sizes are small and the additional value of vessel wall MRI in their management remains to be seen. 2,5,84-87 Future perspectives Considering the high demands in SNR, CNR and spatial resolution of intracranial vessel wall MRI and the generally limited clinically applicable acquisition times, further technical developments in sequence design will be inevitable. Next to methods that shorten acquisition times as discussed above and in Chapter 3 , new and promising CSF suppression techniques such as delay alternating with nutation for tailored excitation (DANTE), double inversion recovery, antidriven-equilibrium and motion-sensitizing preparation pulses may improve vessel wall delineation by increasing CNR. 4,8-10,88-90 In addition, recent improvements in hardware, such as a higher number of receiver channels and extended coil sizes, may open up new avenues for clinical application by enabling visualization of both extracranial and intracranial arteries in a single session, providing a complete assessment of both cervical and brain vasculature. 14,91,92 As these and other technical developments follow each other rapidly, minimal technical requirements and assessment of intracranial vessel wall MRI change at a similar pace, hindering clear guidelines on how to perform intracranial vessel wall MRI in clinical practice. Nevertheless, although the ideal trade-off in sequence parameters may depend on the clinical question, and newer techniques may overrule existing sequence performances and image quality, some general uniform agreements on technique and image assessment are of utmost importance for efficient clinical implementation and setup of comparison studies. A few manuscripts addressing this implementation issue (e.g., Chapter 3 ) have recently been published; however, most studies to date have single-center experience and a limited sample size, thereby limiting translation of their protocols to generally applicable clinical guidelines. 1,2,4,8 In addition, there are no standardized scoring systems that can be applied for structural or segmental assessment of the intracranial arterial vessel wall. Some approaches include individual assessment of all large intracranial arteries, further subdivided into segments: 4,32,93 however, these approaches do not include individual lesion severity (e.g., level of stenosis or plaque vulnerability) nor do they result in a clinically validated ‘final vessel wall score’ that is linked to practical implications. Also, these approaches are time-consuming and less feasible for assessment of inflammatory vasculopathies in which the identification of typical enhancement patterns not limited to one vessel segment is oftenmore important. 4