This lecture provides an overview of imaging strategies for the diagnosis and assessment of vasculitis across different vessel sizes, including large-, medium-, and small-vessel vasculitides. The session reviews the pathophysiology and classification of vasculitis and examines the strengths and limitations of contemporary imaging modalities, including ultrasound, CT angiography, MR angiography, and FDG PET/CT. Through representative clinical cases, the lecture demonstrates how imaging findings evolve from vessel wall inflammation to luminal narrowing, aneurysm formation, and end-organ complications. Particular emphasis is placed on the imaging appearance of giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, and Kawasaki disease, as well as the complementary role of molecular imaging in detecting active vascular inflammation.

Learning Objectives

By the end of this lecture, participants will be able to:

• Classify vasculitis according to vessel size and recognize the major clinical entities affecting large, medium, and small vessels.
• Compare the roles of ultrasound, CT angiography, MR angiography, and FDG PET/CT in the evaluation of vascular inflammation.
• Identify key imaging features of vasculitis, including vessel wall thickening, edema, contrast enhancement, stenosis, occlusion, and aneurysm formation.
• Recognize characteristic imaging patterns associated with giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, and Kawasaki disease.
• Understand the value of FDG PET/CT for detecting active vessel wall inflammation and differentiating inflammatory vascular disease from structural vascular abnormalities.
• Appreciate important differential diagnoses and clinical factors, including atherosclerosis, infectious arteritis, IgG4-related disease, trauma, and the effects of corticosteroid therapy on imaging findings.