Vascular Imaging Gotway et al. Imaging of Takayasu s rteritis Michael. Gotway 1,2 Philip. raoz 3 Thanila. Macedo 3 nthony W. Stanson 3 Charles. Higgins 1 Ernest J. Ring 1,2 Samuel K. Dawn 1,2 W. Richard Webb 1 Jessica W. T. Leung 1 Gautham P. Reddy 1 Gotway M, raoz P, Macedo T, et al. Received June 28, 2004; accepted after revision September 27, 2004. 1 Department of Radiology, University of California, San Francisco, 505 Parnassus ve., San Francisco, C 94143. 2 Department of Radiology, San Francisco General Hospital, 1001 Potrero ve., Rm. 1X 55, ox 1325, San Francisco, C 94110. ddress correspondence to M.. Gotway. 3 Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. JR 2005;184:1945 1950 0361 803X/05/1846 1945 merican Roentgen Ray Society Pictorial Essay Imaging Findings in Takayasu s rteritis OJECTIVE. The objective of our study was to evaluate the clinical usefulness of crosssectional imaging for establishing the diagnosis of Takayasu s arteritis (T), an inflammatory vascular disorder that produces arterial stenoses and aneurysms primarily involving the thoracoabdominal aorta and its branches and the pulmonary arteries. CONCLUSION. CT and MRI findings of T include vascular wall thickening and enhancement early in the disease, and arterial stenoses, occlusions, and aneurysms later in the disease. Cross-sectional imaging is useful for establishing the diagnosis of T and for showing response to nonsurgical therapy or for planning a surgical intervention. akayasu s arteritis (T) is an idiopathic inflammatory vascular dis- T order that may involve the thoracoabdominal aorta and its branches and the pulmonary arteries. T has a much higher incidence in women than in men and is most frequently found in sian patients, although the condition may occur in North merican, European, frican, and Middle Eastern patients [1]. Pathophysiology T causes arterial media destruction, leading to aneurysm formation and, uncommonly, rupture of involved arteries. Histopathologically, early T changes consist of an adventitial mononuclear infiltrate with perivascular cuffing of the vasa vasorum, followed by medullary mononuclear inflammation, occasionally accompanied by granulomatous changes [2]. ecause histopathologic specimens are seldom available as a result of the large vessels commonly affected and the fact that the histopathologic appearance of T can mimic other arteritides, the diagnosis of T is largely based on the combination of clinical information, laboratory evaluation, and diagnostic imaging. Therefore, knowledge of the radiologic features of T is essential for accurate diagnosis and early treatment. lthough angiography has been widely used for the diagnosis of T, increasingly CT and MRI are used as the diagnostic techniques of choice. Clinical Presentation T has traditionally been divided into an early, prepulseless systemic phase, and a late, occlusive phase. In the early systemic phase, diagnosis is difficult and symptoms are usually nonspecific and constitutional, including fever, myalgias, weight loss, and arthralgias. In the occlusive phase, ischemic symptoms dominate, including angina, claudication, syncope, and visual impairment [3]. Late-phase T may be further subclassified as classic pulseless disease (type 1), a mixed type (type 2), an atypical coarctation type (type 3), and a dilated type (type 4) [1]. Most patients present with a form of late-phase disease. Treatment High-dose corticosteroids are the mainstay of T therapy. Treatment of symptomatic fibrotic lesions (stenoses or occlusions) requires either interventional or surgical therapy. This can be achieved by angioplasty with or without stenting or, in severe cases, by vascular resection and surgical placement of composite grafts [4, 5] (Fig. 1). JR:184, June 2005 1945
Gotway et al. Fig. 2. 50-year-old woman with Takayasu s arteritis (T). Catheter angiography shows mild infrarenal abdominal aortic stenosis (arrow). lthough atherosclerosis commonly affects infrarenal abdominal aorta, atherosclerosis usually produces abrupt caliber changes just beyond stenosis sites; the smooth tapered nature of this stenosis favors T. Fig. 1. 45-year-old-woman with Takayasu s arteritis and graft placement for abdominal aortic occlusion. and, Coronal maximum-intensity-projection a (MIP) () and volume-rendered () images show supraceliac aorta-to-right iliac artery bypass graft (single large arrow) and supraceliac aorta-to-right renal artery bypass graft (double small arrows) with occlusion (single small arrow) of midportion abdominal aorta below superior mesenteric artery origin, best shown on MIP image (). Left renal artery is supplied via bypass graft (single arrowhead). Superior mesenteric artery is supplied from left iliac artery bypass graft (double arrowheads). Fig. 3. 45-year-old woman with Takayasu s arteritis. Catheter angiography shows severe infrarenal abdominal aortic stenosis (arrows). Fig. 4. 45-year-old woman with Takayasu s arteritis. Oblique projection catheter angiogram shows segmental stenosis of origin of right upper lobe pulmonary artery (single arrow). Other stenoses are also visible (double arrows). 1946 JR:184, June 2005
Imaging of Takayasu s rteritis Fig. 5. 52-year-old woman with Takayasu s arteritis. Catheter angiogram shows severe infrarenal abdominal aortic stenosis, ending in aortic occlusion (arrow), with extensive collateral vessel formation. Imaging Findings ngiography ngiography, particularly digital subtraction angiography, has traditionally been the procedure of choice for the diagnostic evaluation of T [6, 7]. ngiography often shows long, smooth, tapered stenoses ranging from mild (Fig. 2) to severe (Figs. 3 and 4) or frank occlusions (Fig. 5); collateral vessels (Fig. 6), or the subclavian steal phenomenon [4], are also well shown. ngiography is useful in guiding interventional procedures such as angioplasty or stent placement. However, angiography is invasive, carries a substantial radiation dose, may require a large amount of iodinated contrast material, and can be difficult to perform in patients with long-segment stenoses or heavy arterial calcification. Furthermore, angiography does not depict wall architecture changes as effectively as cross-sectional techniques and cannot differentiate vascular narrowing due to acute mural inflammation from stenoses due to chronic Fig. 6. 38-year-old woman with Takayasu s arteritis. Catheter angiogram shows severe infrarenal abdominal aortic stenosis (arrowhead) with extensive collateral vessel formation by enlarged pancreaticoduodenal artery between superior mesenteric and celiac arteries (arrows). transmural fibrosis. Finally, the frequency of ischemic complications resulting from angiography in patients with T has been shown to be high, and cross-sectional techniques are therefore attractive for diagnosis and disease monitoring [8]. Sonography Sonography reveals homogeneous circumferential thickening of affected vessels (indistinguishable from atherosclerotic plaque), vascular occlusions and dilation, and flow velocity elevations beyond stenotic lesions in patients with T. Limitations of sonography include lack of a consistent acoustic window to allow visualization of the root of the great vessels, obscuration of abdominal vasculature by overlying bowel gas, and technically limited studies in obese patients. Invasive imaging with transesophageal echocardiography and intravascular sonography provides extremely high spatial resolution and allows recognition of subtle wall changes in aortic segments that appear normal with other imaging techniques. CT ecause the basic pathologic feature of early-phase T is great vessel wall thickening, CT is useful for early diagnosis because it allows evaluation of wall thickness rather than merely the luminal diameter [6], which is especially important because early diagnosis and treatment are associated with improved prognosis. The spectrum of findings on CT angiography includes stenoses; occlusions; aneurysms (Figs. 7 9); and concentric arterial wall thickening affecting the aorta and its branches, the pulmonary arteries, and occasionally the coronary arteries [1 3, 5 8] (Fig. 9). In the later stage of disease, extensive vascular calcification may occur (Fig. 10). Limitations of CT include the need for iodinated contrast material and ionizing radiation; the latter may limit the utility of CT for following up patients undergoing treatment. MRI MRI advantages include the lack of need for ionizing radiation and iodinated contrast material; therefore, MRI is ideal for serial evaluation of patients with T who are undergoing treatment. Furthermore, MRI provides the ability to view vessels in any desired plane, and techniques like cine MRI can detect cardiovascular functional and hemodynamic changes, such as aortic regurgitation, in patients with T [2]. s with CT, MRI is useful for early diagnosis because of its ability to evaluate wall thickness rather than just the luminal narrowing [1, 2, 8]. Findings of T on MRI include mural thrombi, signal alterations within and surrounding inflamed vessels (Figs. 11 and 12), fusiform vascular dilation, thickened aortic valvular cusps, multifocal stenoses (Figs. 13 and 14), and concentric thickening of the aortic wall [1, 2, 8] (Fig. 12). MRI may also reveal pericardial effusions and signal alterations within the pericardial sac, representing fluid and granulation tissue. Disadvantages of MRI include difficulty in visualizing small branch vessels and poor visualization of vascular calcification. MRI is also expensive and is often less available in regions where T is most prevalent. MR angiography provides detailed vascular information, including the location, degree, extent of stenoses and dilation, and patency of collateral vessels and surgical bypass grafts (Fig. 15). Limitations of MR angiography include the possibility that vascular branch points may be improperly interpreted as occlusions (breath-hold techniques have lessened this problem) and that maximum-intensity-projection images may JR:184, June 2005 1947
Gotway et al. C Fig. 7. 40-year-old woman with aneurysmal form of Takayasu s arteritis., Thoracic CT angiogram shows aneurysm of left subclavian artery (arrow) at origin of left vertebral artery., Thoracic CT angiogram obtained caudal to shows large aneurysm (arrow) of brachiocephalic artery and proximal right subclavian artery. C, Volume-rendered image shows right subclavian artery aneurysm (arrowheads) to advantage. Fig. 8. 45-year-old woman with aneurysmal form of Takayasu s arteritis. xial CT image shows aneurysm of proximal descending thoracic aorta (arrow). Differential diagnosis should include atherosclerosis, mycotic aneurysm, and ehçet's syndrome. Fig. 9. 40-year-old woman with aneurysmal form of Takayasu s arteritis., Thoracic CT angiogram obtained through heart shows aneurysm (arrow) of left anterior descending coronary artery., Thoracic CT angiogram obtained caudal to shows aneurysm (arrow) of left circumflex coronary artery. 1948 JR:184, June 2005
Imaging of Takayasu s rteritis Fig. 10. 50-year-old woman with Takayasu s arteritis in late stage of disease. Unenhanced CT scan shows extensive calcification (arrow) composing abdominal aortic lumen. Fig. 11. 19-year-old man with early Takayasu s arteritis., xial T1-weighted MR image (TR/TE, 500/20) obtained through superior mediastinum shows thickening of right brachiocephalic artery wall (arrowheads)., xial T1-weighted gadolinium-enhanced MR image (500/20) shows extensive enhancement of abnormally thickened right brachiocephalic artery wall (arrowheads). Fig. 12. 32-year-old woman with Takayasu s arteritis., xial T1-weighted MR image (TR/TE, 500/20) shows concentric thickening of infrarenal abdominal aorta (arrow)., xial T1-weighted MR image (500/20) with fat saturation after gadolinium administration shows extensive enhancement of thickened abdominal aorta (arrow). JR:184, June 2005 1949
Gotway et al. Fig. 13. 50-year-old woman with Takayasu s arteritis. Coronal MR angiogram shows short-segment occlusion of infrarenal abdominal aorta (long arrow). Occlusion of right common femoral artery (short arrows) is also evident. falsely accentuate the degree of vascular stenoses. Regarding the latter, we believe it is advisable to assess the degree of vascular stenoses from the MR angiography source images. Conclusion ngiographic and cross-sectional imaging findings of T include vascular stenoses, occlusions, and aneurysm formation. Familiarity with the demographic and imaging features of T will facilitate accurate diagnosis and allow early treatment, improving patient outcome. Fig. 14. 59-year-old woman with multifocal great vessel stenoses due to Takayasu s arteritis (T). Maximum-intensity-projection coronal MR angiogram shows occlusion of right brachiocephalic artery (arrow), severe stenosis of right subclavian artery (single arrowhead), and occlusion of proximal left subclavian artery (double arrowheads). Subclavian arteries are reconstituted by collateral vessel formation bilaterally. Note relatively proximal great vessel involvement; whereas giant cell arteritis may have imaging appearance similar to that of T, lesions are usually located more distally in latter disorder. References 1. Matsunaga N, Hayashi K, Sakamoto I, Ogawa Y, Matsumoto T. Takayasu arteritis: protean radiologic manifestations and diagnosis. RadioGraphics 1997;17:579 594 2. Matsunaga N, Hayashi K, Sakamoto I, et al. Takayasu arteritis: MR manifestations and diagnosis of acute and chronic phase. J Magn Reson Imaging 1998;8:406 414 3. Kerr GS, Hallahan CW, Giordano J, et al. Takayasu arteritis. nn Intern Med 1994;120:919 929 4. Park JH, Han MC, Kim SH, Oh H, Park Y, Seo JD. Takayasu arteritis: angiographic findings and results of angioplasty. JR 1989;153:1069 1074 Fig. 15. 55-year-old woman with Takayasu s arteritis, infrarenal abdominal aortic occlusion, and surgical arterial bypass graft. Coronal maximum-intensity-projection MR angiogram shows occluded infrarenal abdominal native aorta (arrow) and surgical bypass graft (arrowheads) with reimplanted abdominal vasculature. 5. Miyata T, Sato O, Koyama H, Shigematsu H, Tada Y. Long-term survival after surgical treatment of patients with Takayasu s arteritis. Circulation 2003;108:1474 1480 6. Park JH, Chung JW, Lee KW, Park Y, Han MC. CT angiography of Takayasu arteritis: comparison with conventional angiography. J Vasc Interv Radiol 1997;8:393 400 7. Paul JF, Fiessinger JN, Sapoval M, et al. Followup electron beam CT for the management of early phase Takayasu arteritis. J Comput ssist Tomogr 2001;25:924 931 8. Yamada I, Numano F, Suzuki S. Takayasu arteritis: evaluation with MR imaging. Radiology 1993; 188:89 94 1950 JR:184, June 2005