Aortitis Workup

Updated: Dec 18, 2014
  • Author: Masato Okada, MD, FACP, FACR, FAAAAI; Chief Editor: Uchechukwu Sampson, MBBS, MPH, MBA, MSc  more...
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Workup

Laboratory Studies

Elevated acute phase reactants, such as ESR and CRP level, are nonspecific indicators of inflammation. Kerr et al questioned the value of these tests for monitoring the activity of Takayasu arteritis after seeing poor predictive value in relation to the status of surgical specimens.

In one study by Eichorn et al, [7] high titers of serum anti-endothelial cell antibodies were detected in patients with Takayasu arteritis. The value of this titer in diagnosis and its usefulness as a marker of disease activity have not been completely established.

Matrix metalloproteinase (MMP) is elastic proteinase that can degrade elastin in large vessel walls. A variety of inflammatory cytokines are known to induce the enzyme. Matsuyama et al [9] reported that plasma level of MMP-9 and MMP-3 were useful markers of activity of Takayasu arteritis.

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Imaging Studies

Early abnormalities in patients with Takayasu arteritis are limited to the arterial wall. Aortography and arteriography, which had been considered the diagnostic tests for Takayasu arteritis, can demonstrate luminal changes such as stenosis, occlusion, or aneurysmal dilatation, but they are not useful for detecting early mural findings (eg, tree-bark, endothelial wrinkling). Magnetic resonance angiography (MRA) and CT angiography (CTA) may be of similar value. CTA must be performed with a high-resolution (spiral/helical or Ultrafast) CT scanner. MRA and CTA are replacing the conventional aortography as the diagnostic tools of Takayasu arteritis.

Multimodality imaging is useful for identifying acute and chronic mural changes due to inflammation, edema, and fibrosis, and for characterizing structural luminal changes. [10] The recent advance in this field is fluorodeoxyglucose-PET (FDG-PET), which seems to have a role in early diagnosis and monitoring the activity of aortitis. [11, 12, 13] A prospective study suggests that assessment of aortitis with semi-quantitative analysis of 180-minute (18)F-FDG PET/CT acquisition images is highly accurate. [14]

CTA and MRA are less invasive than conventional angiography, and they may reveal vascular wall thickening during the early phase of disease. In a study by Yamada et al, [15] 25 patients with symptoms suggestive of Takayasu arteritis underwent both conventional angiography and CT helical scanning angiography. CT angiography was 95% sensitive and 100% specific for the diagnosis of Takayasu arteritis, and it was more sensitive than conventional angiography in detecting vessel mural changes. These modalities also can play roles in the follow-up of patients, because MRI and CT scans are able to show reduction of wall thickening after initiation of treatment.

In selected patients, conventional arteriography still may be necessary at the time of diagnosis of the late occlusive phase to provide additional information about the degree and extent of the arteritis.

Careful interpretation of the chest radiograph is also very important, because some findings, such as widened mediastinum (ie, wide aorta), can be clues to the diagnosis of Takayasu arteritis.

Ultrasonographic studies might be useful to follow the diameter and wall thickness changes in specific regions of accessible arterial vessels.

In 2002, a classification of angiographic findings in patients with Takayasu arteritis was proposed at the International Conference on Takayasu Arteritis, as follows [16] :

  • Type I involves branches of the aortic arch.
  • Type IIa involves the ascending aorta, aortic arch, and its branches.
  • Type IIb involves the type IIa region plus the thoracic descending aorta.
  • Type III involves the thoracic descending aorta, abdominal aorta, and/or renal arteries.
  • Type IV involves only the abdominal aorta and/or renal arteries.
  • Type V involves the whole aorta and its branches.

Type V is the most common finding, and type IV is observed in India and Thailand but is very rare in the United States and Japan.

Webb et al showed that FDG-PET had high sensitivity (92%) and specificity (100%) for active inflammation in Takayasu arteritis. Andrews et al [17] and Meller et al [18] concluded that FDG-PET was useful to detect active inflammation of large vessels, and that MRA was able to show progression of vascular wall thickening. See the image below.

Diffuse stenosis from the aortic arch to the abdom Diffuse stenosis from the aortic arch to the abdominal aorta. The left common carotid artery are also stenotic and the left subclavian artery is not visualized.
Dilatation of the bilateral vertebral arteries. Oc Dilatation of the bilateral vertebral arteries. Occlusion of the right internal carotid artery. Severe stenosis of the left internal carotid artery. Moderate stenosis of the left external carotid artery at the bifurcation with dilated collateral circulation.
Moderate stenosis of the external iliac artery at Moderate stenosis of the external iliac artery at the bifurcation and occlusion of the right femoral artery.

Blockmans concluded that patients with giant-cell arteritis show increased metabolic activity within the aortic wall on FDG-PET scintigraphy. This indicates inflammation of the aorta, which may be a predictor of a higher potential for aortic dilatation. [19]

The American College of Radiology has issued guidelines on the initial radiologic examination of patients with nontraumatic aortic disease. [20]

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Histologic Findings

The histologic features of arteritis are characterized as focal panarteritis. The intima is markedly thickened by accumulation of mucopolysaccharides. The media and adventitia demonstrate mixed cellular infiltration with granuloma and giant cells. The lesions usually are focal skip lesions rather than the diffuse involvement observed in patients with syphilitic aortitis. See the images below.

Leukocyte infiltration of the vasa vasorum of the Leukocyte infiltration of the vasa vasorum of the aorta accompanies arteritis obliterans and ischemic necrosis of the media in a case of syphilitic aortitis.
Granulomatous arteritis with thrombosis of a cereb Granulomatous arteritis with thrombosis of a cerebral vessel may present as a neurological defect with no obvious vascular disease by history or physical.
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Staging

A triphasic pattern of disease progression has been described, as follows:

  • Phase I is the prepulseless inflammatory period characterized by nonspecific systemic symptoms, including low-grade fever, fatigue, arthralgia, and weight loss.
  • Phase II involves vascular inflammation associated with pain (eg, carotidynia) and tenderness over the arteries.
  • Phase III is the fibrotic stage, with predominant ischemic symptoms and signs secondary to dilation, narrowing, or occlusion of the proximal or distal branches of the aorta.
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