TAKAYASU ARTERITIS : A less common presentation

Patient is a 20 year old female, who presented with complaints of lower limb claudication.

CT ANGIOGRAM : CASE FINDINGS 

Click on the images to view in full-size

The branches of aortic arch showed no involvement. There was circumferential wall thickening of the thoracic aorta starting distal to the origin of left subclavian artery, extending in a contiguous fashion with increasing severity to involve the abdominal aorta. Involvement of iliac arteries were also seen.

The above image shows the progressive increase in the wall thickness of abdominal aorta, with maximal involvement of the infra-renal segment, where the lumen was almost a thread like / non-existent.

Celiac trunk, SMA, Bilateral renal arteries showed significant stenosis origin/ proximal portion. IMA origin was completely blocked, which got collateral blood supply from a large tortuous branch from SMA (meandering mesenteric artery / wandering artery of Drummond).

Above the 3D-VRT image shows the engorged Superior Epigastric arteries (branch of Internal Thoracic / Internal Mammary artery) bilaterally, with tortuous anastomosis within the bilateral rectus abdominis muscles - where it anastomose with the corresponding Inferior Epigastric Arteries.

3D- VRT images showing the gradual smooth tapering of abdominal aorta; Rat-tail appearance.

Coronal MPR images showing marked wall thickening of infra-renal Abdominal Aorta.

DIAGNOSIS :

Since the wall thickening is seen involving the descending thoracic aorta and abdominal aorta, but sparing the ascending aorta and arch, the diagnosis is more fitting into a Type III Takayasu Arteritis.

Midaortic dysplastic syndrome cannot be distinguished from late-phase Takayasu arteritis on the basis of radiologic findings alone. The two disease entities can be differentiated only by histopathologic exclusion of inflammatory change, which is present in Takayasu arteritis but not in midaortic dysplastic syndrome. (Radiographics, 2003).

TAKAYASU ARTERITIS 

Takayasu arteritis is a chronic, idiopathic, inflammatory disease that primarily affects large vessels, such as the aorta and its major branches and the pulmonary and coronary arteries. The non-specific inflammation of involved vessels usually leads to concentric wall thickening, fibrosis and thrombus formation. Diseased arteries become stenotic or occluded, undergo vascular remodelling or develop aneurysms.

Disease occurs primarily in young women with associated rheumatic complaints including arthritis, myalgia, pleuritis, pericarditis, fever and rash, none of which was present in any of our patients. The ESR is usually raised.

Sharma criteria for diagnosis of Takayasu arteritis

Major criteria

1. Left mid-subclavian artery lesion
2. Right mid-subclavian artery lesion
3. Characteristic signs and symptoms of at least one month duration [a]

Minor criteria

1.  High erythrocyte sedimentation [b]
2. Carotid artery tenderness
3. Hypertension [c]
4. Aortic regurgitation or annuloaortic ectasis
5. Pulmonary artery lesion
6. Left mid-common carotid lesion
7. Distal brachiocephalic trunk lesion
8. Descending thoracic aorta lesion
9. Abdominal aorta lesion
10. Coronary artery lesion

Presence of two major, or one major and two minor criteria, or four minor criteria suggests a high probability of Takayasu arteritis.

[a] Including limb claudication, pulselessness or pulse differences in limbs, an unobtainable or significant blood presence difference, fever, neck pain, transient amaurosis, blurred vision, syncope, dyspnea or palpitations.
[b] Higher than 20mm per hour (Westergren method).
[c] Higher than 140/90mmHg brachial or 160/90mmHg popliteal.

 Disease has two phases of progression:

The Early phase / Systemic phase / Pre-pulseless phase : where the steroid therapy can affect prognosis.

Late phase or Pulseless phase or Occlusive phase symptoms depend upon the site of occlusion. The interval between the early and late phase can vary between 1 to 8years.

Early-phase arteritis is limited to the arterial wall. Therefore, absence of stenotic or occlusive changes in the aorta, its branches, and the pulmonary artery on conventional angiograms of a young female patient with fever of unknown origin does not exclude the possibility of early phase Takayasu arteritis. So CT/MRI is required to assess the aortic wall to know the presence of inflammation in early phase.

According to the vessels involved, the most recently proposed angiographic classification divides TA into six types :- (See the image below)

Type I involves only the branches of the aortic arch.
Type IIa involves ascending aorta, aortic arch and its branches.
Type IIb affects ascending aorta, aortic arch and its branches, and thoracic descending aorta.
Type III involves the descending thoracic aorta, the abdominal aorta and/or the renal arteries. The ascending aorta, the aortic arch and its branches are not affected.
Type IV involves only the abdominal aorta and/or renal arteries.
Type V has combined features of Type IIb and IV.

Additionally, involvement of the coronary and pulmonary arteries should be indicated as C (+) or P (+), respectively. Type V has been documented as the most common type.

CT angiography features

1. Mural thickening

a. typical manifestation for Takayasu is the concentric mural thickening of the involved arteries.
b. Calcification (27%, Often transmural) in the thickened wall is another important sign of Takayasu.

c. Double ring enhancement pattern (See the above image) on CECT – inner hypodense rim – due to intimal edema and outer enhancing wall due to medial and adventitial inflammation.

2. Luminal changes

a. Stenosis is the most common finding associated with wall thickening (in 90%).
b. Abdominal and thoracic aorta stenosis in up to 60%.
c. Branches showing stenosis : Subclavian and Common carotids > Renal.
d. Occlusion, ectasis(ascending) and aneurysm(abdominal) formation seen less often.
e. Sometimes, the normal or dilated proximal vessels associated with tapered narrowing of distal segments exhibit a characteristic ‘‘rat tail’’-like configuration, especially in patients with both thoracic and abdominal aorta involved (as in this case).

3. Collateral vessels : (MIP is useful for assessment of collaterals.)

a. When the superior mesentenc artery is stenotic or occluded, excellent collateral flow via a meandering mesenteric artery reconstitutes the distal portion. Blood flow is retrogradely directed from the inferior mesenteric artery to the distal superior mesenteric artery branches via the meandering mesenteric artery.

b. When the infrarenal portion of the abdominal aorta is nearly or totally occluded, blood flow is directed antegradely from the superior mesenteric artery to the inferior mesenteric artery via the meandering mesenteric artery ( As in this case). In this situation, the meandering mesenteric artery is dilated as much as the aorta.[2]

4. Other findings

a. Pulmonary and coronary artery involvement can be seen in ~60% and ~40% of patients, respectively.

Differential diagnosis

 

1. Midaortic dysplastic syndrome.

2. Atherosclerosis : Atherosclerotic plaques are more common in patients aged 45 years and above, and not usually associated with long segment luminal stenosis.

3. Giant cell arteritis : >50yrs, branches of the external and internal carotid arteries are most frequently diseased.

4. Polyarteritis nodosa :30–50 years, males more than females, and it also more commonly affects patients with hepatitis B. Gastrointestinal and renal arteries are the primary sites diseased. Multiple small aneurysm formation in the involved artery is the characteristic manifestation on CTA.

Treatment

TA is a rare entity with poor prognosis.Corticosteroids have been considered to be the mainstay of treatment for TA, with a remission rate up to 60%. In patients with symptomatic stenotic or occlusive lesions, percutaneous transluminal angioplasty and stenting or bypass surgery is the most common palliative treatment



References :
[1]Takayasu arteritis: imaging spectrum at multidetector CT angiography, BJR -2012.
[2] Takayasu Arteritis – Radiographics,1997.