Arteritis is the inflammation of the walls of arteries, usually as a result of infection or autoimmune response. Arteritis, a complex disorder, is still not entirely understood. Arteritis may be distinguished by its different types, based on the organ systems affected by the disease. A complication of arteritis is thrombosis, which can be fatal. Arteritis and phlebitis are forms of vasculitis. Signs and Symptoms Symptoms of general arteritis may include: Inflammation Fever Increased production of red blood cells (erythrocytes) Limping Reduced pulse Diagnosis Diagnosis of arteritis is based on unusual medical symptoms. Similar symptoms may be caused by a number of other conditions, such as Ehlers-Danlos syndrome and Marfan syndrome (both heritable disorders of connective tissue), tuberculosis, syphilis, spondyloarthropathies, Cogans' syndrome, Buerger's, Behcet's, and Kawasaki disease. Various imaging techniques may be used to diagnose and monitor disease progression. Imaging modalities may include direct angiography, magnetic resonance angiography, and ultrasonography. Angiography is commonly used in the diagnosis of Takayasu arteritis, especially in the advanced stages of the disease, when arterial stenosis, occlusion, and aneurysms may be observed. However, angiography is a relatively invasive investigation, exposing patients to large doses of radiation, so is not recommended for routine, long-term monitoring of disease progression in patients with Takayasu arteritis. Computed tomography angiography can determine the size of the aorta and its surrounding branches, and can identify vessel wall lesions in middle to late stages of arteritis. CTA can also show the blood flow within the blood vessels. Like angiography, CTA exposes patients to high dosages of radiation. Magnetic resonance angiography is used to diagnose Takayasu arteritis in the early stages, showing changes such as the thickening of the vessel wall. Even small changes may be measured, making MRA a useful tool for monitoring disease progression without exposing patients to the radiation of direct angiography or CTA. MRA is an expensive investigation, and shows calcification of the aorta and distal branches less clearly than other imaging methods. Ultrasonography is an ideal method of diagnosing patients in early stages of arteritis when inflammation in the vessel walls occurs. It can also show the blood flow within the blood vessels. Ultrasonography is a popular first-line investigation for diagnosis because it is relatively quick, cheap, noninvasive, and does not expose patients to radiation. It is also used for long-term monitoring of disease progression in Takayasu arteritis. Not all vascular lesions are visible on ultrasound, and the accuracy