Arjen Lindenholz

195 General Discussion 9 Increasing efforts toward strong (international) collaborations among research centers and hospitals would greatly benefit clinical acceptance of intracranial vessel wall MRI. Collaborative networks enable recruitment of larger samples (especially when investigating rare vasculopathies), while image protocols and structural image assessment can be matched across centers, facilitating sound comparisons (for example between different populations), in order to improve the understanding of vessel wall diseases using intracranial vessel wall MRI. Another significant advantage of international collaborations is the setup of larger studies and randomized controlled trials (RCTs), which are currently unavailable but crucial for answering questions regarding the relation between vessel wall findings and clinical outcome (for example risk of future cerebrovascular disease). These studies can also control for potential confounders and identify predictors with higher confidence. 1 Further, follow-up intracranial vessel wall MRI studies will become more prevalent, increasing knowledge of lesion evolution over time (with or without preventive management) or persistence of vessel wall changes after intraluminal procedures, such as IAT. 69 Conclusions Intracranial vessel wall MRI has changed our approach on how to visualize intracranial arterial pathology, and could have a significant impact on the management of cerebrovascular disease. Although image quality currently does not suffice for quantitative measurements, qualitative assessment has been proven successful in diagnosing vessel wall lesions and differentiating between major vessel wall pathologies. The work described in this thesis has provided evidence that suggests that focal intracranial vessel wall lesions truly represent atherosclerotic lesions, and that they could indeed be clinically relevant. Using intracranial vesselwallMRI togetherwithanatomicalMRI sequences furtherenables assessment of the actual status of the intracranial (and possibly extracranial) vessel wall combined with cerebral parenchymal sequelae in one session. Next steps to advance clinical translation will be (1) true histopathological validation to unravel the true nature of vessel wall lesions; (2) the setup of larger studies to identify the exact associations, predictors and potential confounders to put these lesions in clinical perspective; and (3) international collaborations and consensus guidelines for uniform acquisition and assessment of vessel wall MR images. Ultimately, intracranial vessel wall MRI has the potential to be implemented in the workup and follow-up of patients with cerebrovascular disease and in risk management, using it as non-invasive diagnostic tool to guide patient-tailored preventive and therapeutic decision-making.