Imaging in vasculitis




Vasculitides may involve small, medium-sized or large arteries. In small-vessel vasculitides imaging studies of lungs, nasal sinuses, cerebrum, heart and other organs are important for determining disease extension and disease activity.


Aneurysms are a hallmark of medium-sized artery vasculitides.


In large-vessel vasculitis, imaging studies depict homogeneous, circumferential wall swelling and smoothly tapered luminal narrowing. Ultrasound and high-resolution magnetic resonance imaging (MRI) show characteristic wall abnormalities in temporal and occipital arteries whereas ultrasound, MRI, MR angiography, computed tomography (CT), CT angiography and positron emission tomography delineate characteristic features in extra-cranial arteries that are affected in large-vessel giant cell arteritis, Takayasu arteritis and idiopathic aortitis. Conventional angiography has still its place for therapeutic interventions.


Imaging has led to a better understanding of the nature and distribution of vasculitides. It significantly facilitates diagnosis of patients with suspected vasculitis.


Introduction


The role of imaging in the diagnosis of the vasculitides has tremendously increased during the last decade because of improved quality of imaging techniques and increasing scientific work in this field.


Primary vasculitides have been classified according to the size of vessels that are predominantly involved .


Imaging studies in small-vessel vasculitides are important for determining disease extension and disease activity. Examples include chest radiography for detecting pulmonary granulomas or pleural effusion in granulomatosis with polyangiitis (GPA; formerly, Wegener’s granulomatosis), computed tomography (CT) for evaluating fibrosing alveolitis in microscopic polyangiitis (MPA), echocardiography and cardiac magnetic resonance imaging (MRI) in search for pericardial effusion or myocarditis in eosinophilic granulomatosis with polyangiitis (EGPA; formerly, Churg–Strauss syndrome), cranial MRI for detecting cerebral vasculitis and musculoskeletal ultrasound for detecting concomitant arthritis in clinically ambivalent cases.


In vasculitides that mainly involve medium-sized vasculitides such as polyarteritis nodosa and Kawasaki disease, aneurysms frequently occur. Imaging studies allow delineating the involved arteries with the aneurysms directly.


Imaging is particularly useful in the diagnosis of the large-vessel vasculitides. Several imaging techniques such as conventional angiography, MRI, MRI angiography (MRA), CT, CT angiography (CTA), colour Doppler ultrasound, positron emission tomography (PET) and PET–CT are delineating characteristic anatomical abnormalities. Imaging displays characteristic homogeneous artery wall swelling and characteristic stenoses with smoothly tapered luminal narrowing. Histology has been the gold standard for the diagnosis of the vasculitides. However, discussion has aroused if imaging can replace histology due to highly specific findings at least in cases with definite findings on clinical examination and imaging. In many cases, histology cannot be obtained, particularly if large arteries such as the aorta or the proximal arm arteries are involved. Imaging studies allow documenting the anatomic distribution of vasculitis. Imaging helps differentiate subgroups such as temporal arteritis, large-vessel giant cell arteritis (GCA), idiopathic aortitis and Takayasu arteritis.

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Nov 11, 2017 | Posted by in RHEUMATOLOGY | Comments Off on Imaging in vasculitis

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