Advanced vascular imaging techniques

This chapter outlines recent advances in imaging of disorders of the cervicocerebral vasculature that permit evaluation of the lumen, the vessel wall, and the patterns of blood flow within the vessel. Noninvasive MR techniques to evaluate the vessel lumen, such as noncontrast time-of-flight magnetic resonance angiography and contrast-enhanced magnetic resonance angiography (CEMRA) are routinely used in diagnosis, planning, and posttreatment follow-up. More recently, high-resolution vessel wall imaging MRI (VWMRI) has been developed, which provides additional information about the vessel wall or aneurysm wall. VWMRI wall signal and enhancement patterns may permit differentiation between vasculopathies and between stable and unstable unruptured aneurysms. In addition, the study of blood flow patterns using phase-contrast MRI (4D flow MRI) and image-based computational fluid dynamics has been used to characterize flow and wall shear stress within aneurysms, flow within arteriovenous malformations (AVMs) and pulsatile tinnitus. Digital subtraction angiography (DSA), however, remains the gold standard in the evaluation and treatment of neurovascular diseases. New adjunctive DSA techniques, such as 4D-DSA reconstruction and color flow analysis, are also covered. These new MRI and DSA techniques increase diagnostic accuracy, improve understanding of the pathophysiology and natural history of neurovascular disease, inform and guide treatment, and may provide risk stratification for patients being considered for therapy.