Relapsing polychondritis (RP) is a rare progressive autoimmune disease. The cardiovascular system is rarely involved. The authors report the case of a young woman with RP aortic arch aneurysm and symptomatic cerebral vessels stenosis. A positron emission tomography-computed tomography (PET-CT) indicated areas with activity and guided the surgery. Aortic arch with proximal vessels was successfully replaced. The PET-CT may be useful to assess the risks and determine healthy zones for potential anastomotic sites.