Pictorial Essay | Cardiovascular Imaging https://doi.org/10.3348/kjr.2017.18.5.786 pISSN 1229-6929 · eISSN 2005-8330 Korean J Radiol 2017;18(5):786-798 CT Features of Vasculitides Based on the 2012 International Chapel Hill Consensus Conference Revised Classification Jee Hye Hur, MD1, Eun Ju Chun, MD, PhD1, Hyon Joo Kwag, MD, PhD2, Jin Young Yoo, MD3, Hae Young Kim, MD1, Jeong Jae Kim, MD1, Kyung Won Lee, MD, PhD1 1Department of Radiology, Seoul National University Bundang Hospital, Seongnam 13620, Korea; 2Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, Korea; 3Department of Radiology, Seoul National University Hospital, Seoul 03080, Korea Vasculitis, characterized by inflammation of vessel walls, is comprised of heterogeneous clinicopathological entities, and thus poses a diagnostic challenge. The most widely used approach for classifying vasculitides is based on the International Chapel Hill Consensus Conference (CHCC) nomenclature system. Based on the recently revised CHCC 2012, we propose computed tomography (CT) features of vasculitides and a differential diagnosis based on location and morphological characteristics. Finally, vasculitis mimics should be differentiated, because erroneous application of immunosuppressive drugs on vasculitis mimics may be ineffective, even deteriorating. This article presents the utility of CT in the diagnosis and differential diagnosis of vasculitides. Keywords: Vasculitis; Vasculitides; Computed tomography angiography; Computed tomography; Diagnosis INTRODUCTION and symptoms of vasculitis are nonspecific and could mimic other conditions such as infection, malignancy, Vasculitis is defined as inflammation of vessel walls. thrombotic disorders, and connective tissue diseases (1, Diagnosis of vasculitis can be challenging because signs 2). Clinical symptoms reflect the affected vessels. Limb claudication, absent pulses, and unequal blood pressure Received December 31, 2016; accepted after revision February 14, are typical symptoms of large vessel vasculitis, while 2017. palpable purpura and proteinuria are typical symptoms of This study has received funding by the National Research small vessel vasculitis. Medium vessels are defined as main Foundation (NRF) grant funded by the Korea government (MEST) (NRF-2015R1D1A1A01059717). visceral arteries and their initial branches, therefore various This pictorial essay describes CT features of vasculitis based on symptoms occur according to the involved vessels. the 2012 revised International Chapel Hill Consensus Conference, For the evaluation of vasculitis, detailed clinical history, and summarizes the differential points of vasculitis and vasculitis mimics. physical examination and focused laboratory investigation Corresponding author: Eun Ju Chun, MD, PhD, Department of are crucial. In addition, non-invasive imaging is helpful Radiology, Seoul National University Bundang Hospital, 82 Gumi- for evaluating the extent of the disease. Among them, ro 173beon-gil, Bundang-gu, Seongnam 13620, Korea. computed tomography (CT) is commonly used as the initial • Tel: (8231) 787-7609 • Fax: (8231) 787-4011 • E-mail: [email protected] imaging study for vasculitis, because it can allow evaluation This is an Open Access article distributed under the terms of of vascular wall change and localize the location and the Creative Commons Attribution Non-Commercial License extent of the lesion with excellent spatial resolution (3). (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in In this article, we describe the diagnosis and classification any medium, provided the original work is properly cited. of vasculitis with CT findings on the basis of the revised 786 Copyright © 2017 The Korean Society of Radiology CT Features of Vasculitides International Chapel Hill Consensus Conference (CHCC) 2012. Imaging Methods for the Evaluation of Vasculitis Revised 2012 CHCC Classification A non-invasive imaging approach is helpful for detecting and evaluating the extent of vasculitis. Among them, Chapel Hill Consensus Conference is a nomenclature multidetector CT is a good imaging modality for assessing system (nosology) that does not specify the criteria by vasculitis, due to its excellent spatial resolution and accurate which patients are classified for clinical studies or are cross-sectional imaging in demonstrating vessel wall change. diagnosed for clinical care. The CHCC 1994 offered names Table 2 summarizes the advantages and disadvantages of and definitions for the most common forms of vasculitis various non-invasive imaging modalities for assessment of (4, 5), and categorized vasculitis by the size of the blood vasculitis, including magnetic resonance imaging, positron vessels affected (6). With advances in the understanding emission tomography and ultrasonography (7). of the pathophysiology of vasculitis, the CHCC 2012 added four new categories: variable vessel vasculitis, single-organ Characteristic CT Findings of Vasculitis Based vasculitis, vasculitis associated with systemic disease, and on the Revised CHCC 2012 vasculitis associated with probable etiology (Table 1). Recently, depending on the trend to avoid using eponym, In CHCC 2012 nomenclature, the first approach to CHCC 2012 replaced some eponyms with descriptive terms identifying vasculitis is evaluation of the size of affected (4, 6). However, some eponyms such as Takayasu arteritis vessels (i.e., large, medium, and small vessel vasculitis) (TA) or Kawasaki disease (KD) were retained, because these (4). If all sizes of vessels are present or additional veins are were deemed more effective than any alternatives that were affected, variable vessel vasculitis, a new category in the proposed (4). CHCC 2012, can be suspected. Figure 1 shows a diagram of vasculitis, based on the affected vessel size and types. Table 1. Various Vasculitides Based on 2012 International Chapel Hill Consensus Conference Large vessel vasculitis Takayasu arteritis Giant cell arteritis Medium vessel vasculitis Polyarteritis nodosa Kawasaki disease Small vessel vasculitis Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis Microscopic polyangiitis Granulomatosis with polyangiitis (formerly Wegener granulomatosis) Eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome) Immune-complex small vessel vasculitis Anti-glomerular-basement-membrane (anti-GBM) disease Cryoglobulinemic vasculitis IgA vasculitis (formerly Henoch-Schönlein purpura) Hypocomplementemic urticarial vasculitis (anti-C1q vasculitis) Variable vessel vasculitis Behçet’s disease Cogan syndrome Vasculitis associated with systemic disease Lupus vasculitis Rheumatoid vasculitis Sarcoid vasculitis Others Modified from Jennette et al. Arthritis Rheum 2013;65:1-11 (4). IgA = immunoglobulin A kjronline.org Korean J Radiol 18(5), Sep/Oct 2017 787 Hur et al. Large Vessel Vasculitis syndrome” and “pulseless disease”, is an idiopathic By the CHCC 2012 definition, “large vessels” are the aorta inflammatory disease that primarily affects large vessels and its major branches, except for the most distal branches. such as the aorta, major branches of the aorta, and coronary and pulmonary arteries. Pathologically, TA is characterized Takayasu Arteritis by panarteritis affecting all three arterial layers (8, 9), and Takayasu arteritis, which is also known as “aortic arch subsequent scarring of media leading to luminal occlusion (10). Table 2. Advantages and Disadvantages of Each Imaging Modality for Evaluation of Vasculitis Modalities Advantages Disadvantages Lesion extent Accurate cross-sectional imaging in demonstrating vessel wall change Exposure to ionizing radiation CT Evaluation of other organs which was helpful for differential Contrast media diagnosis Excellent high spatial resolution Multiple planes and three-dimensional views Limited field of view US Lack of exposure to ionizing radiation Operator dependence High cost Demonstration of early wall thickening even before luminal MRI Long scan time narrowing occurs Difficult in detecting calcification in vessel wall Poor spatial resolution PET Evaluation of metabolism (activity evaluation) Less information of anatomy CT = Computed tomography, MRI = magnetic resonance imaging, PET = Positron emission tomography, US = Ultrasonography Immune-complex small vessel vasculitis Cryoglobulinemic vasculitis IgA vasculitis (Henoch-Schönlein) Hypocomplementemic urticarial vasculitis Anti-GBM disease Medium vessel vasculitis Polyarteritis nodosa Kawasaki disease ANCA-associated small vessel vasculitis Microscopic polyangiitis Granulomatosis with polyangiitis (Wegener’s) Large vessel vasculitis Eosinophilic granulomatosis with polyangiitis (Churg-Strauss) Takayasu arteritis Giant cell arteritis Variable vessel vasculitis Behçet’s disease Fig. 1. Diagram of vasculitides categorized based on frequently affected vessel size and types. Drawing shows aorta, large artery, medium arteries, and small arteries or arterioles, capillaries, venules, and veins, in sequence from left to right. Modified from Jennette et al. Arthritis Rheum 2013;65:1-11 (4). ANCA = anti-neutrophil cytoplasmic antibody, Anti-GBM = anti-glomerular basement membrane, IgA = immunoglobulin A 788 Korean J Radiol 18(5), Sep/Oct 2017 kjronline.org CT Features of Vasculitides Takayasu arteritis occurs worldwide, but is much more CT findings of TA differ depending on the stage (1, 2, 17). common in Asia (11, 12). Women