[Imaging procedures in rheumatology: imaging in vasculitis]

Imaging in Vasculitis

Purpose of Review

Vasculitides are characterized by mostly autoimmunologically induced inflammatory processes of vascular structures. They have various clinical and radiologic appearances. Early diagnosis and reliable monitoring are indispensable for adequate therapy to prevent potentially serious complications. Imaging, in addition to laboratory tests and physical examination, constitutes a key component in assessing disease extent and activity. This review presents current standards and some typical findings in the context of imaging in vasculitis with particular attention to large vessel vasculitides.

Recent Findings

Recently, imaging has gained importance in the management of vasculitis, especially regarding large vessel vasculitides (LVV). Recently, EULAR (European League Against Rheumatism) has launched its recommendations concerning the diagnosis of LVVs. Imaging is recommended as the preferred complement to clinical examination. Color-coded duplex sonography is considered the first choice imaging test in suspected giant cell arteritis, and magnetic resonance imaging is considered the first choice in suspected Takayasu’s arteritis.

Summary

Due to diversity of clinical and radiologic presentations, diagnosis and therapy monitoring of vasculitides may constitute a challenge. As a result of ongoing technological progress, a variety of non-invasive imaging modalities now play an elemental role in the interdisciplinary management of vasculitic diseases.

[Imaging techniques in the evaluation of primary large vessel vasculitides: Part 2: duplex ultrasound, positron emission tomography, computed tomography, and ophthalmological methods]

This article focuses on the clinical application and technical aspects of imaging methods which are used alternatively or additionally to angiography or magnetic resonance imaging in patients with Takayasu's arteritis or giant cell arteritis. Providing a high spatial resolution, duplex ultrasound is particularly suitable for the evaluation of peripheral arteries. With the exception of cranial arteries, positron emission tomography as a whole body examination is the best imaging modality for the assessment of inflammatory activity. Computed tomography is used for angiographic examinations and enables evaluation of wall thickening in large arteries. It is the method of choice in the case of emergencies due to aortic aneurysm or dissection. In addition to angiographic and ultrasound techniques, ophthalmological methods comprise biomicroscopy, including funduscopy and optical coherence tomography.

[Myalgia in polymyalgia rheumatica, temporal arteritis and other vasculitides]

Myalgias most commonly occur in polymyalgia rheumatica (PMR). About 45% of patients with giant cell arteritis present with symptoms of PMR. Other vasculitides may also lead to arthralgia and myalgia. While shoulder and pelvic pain is characteristic for PMR pain often also occurs in the back of the neck and in the region of the thoracic spine. In addition, patients often present with malaise, morning stiffness and weight loss. CRP and ESR are elevated. Ultrasound and MRI delineate minor synovitis, tenosynovitis and bursitis in the shoulder. Hip joint synovitis and trochanteric bursitis are also commonly seen. PMR should be distinguished from rheumatoid arthritis. The initial treatment comprises a prednisolone dose of 15-25 mg/day, followed by a weekly decrease of 1-2.5 mg. Once 10 mg/day has been reached the dose should be reduced more slowly.

[Large-vessel vasculitis. Imaging and interventional therapy]

Giant cell arteritis and Takayasu's arteritis are classified as primary large-vessel vasculitides. Inflammatory cell infiltrates and cytokines induce destruction and hyperplasia of the vessel wall, leading to stenoses or aneurysms. When extracranial large arteries are involved, there is often a similar clinical and radiologic disease pattern of an inflammatory aortic arch syndrome. Rare causes of large-vessel vasculitis include Behçet's disease, association with other autoimmune diseases, and infection. Depending on the localization, imaging is usually performed by means of duplex ultrasound, magnetic resonance imaging, computed tomography, or positron emission tomography. These imaging modalities are used not only to establish the diagnosis but also to determine the disease extent and activity and to perform follow-up in the course of medical therapy. Angiography offers the option to perform interventional therapy for vascular stenoses and occlusions.

Role of imaging in vasculitis and connective tissue diseases

Imaging techniques play a pivotal role in securing the diagnosis of large vessel vasculitis, and in demonstrating internal organ involvement in connective tissue diseases. In large vessel vasculitis, angiography is useful in demonstrating vessel stenoses or aneurysms. However, angiography is unable to reveal initial lesions such as vessel wall oedema and thickening, and is thus not useful to make an early diagnosis. In contrast, colour Doppler ultrasonography, computerized tomography angiography, and magnetic resonance imaging/angiography are able to delineate both the vessel wall and the lumen. Therefore, they may show vessel wall alterations when the lumen is still unaffected on angiography. 18fluorodeoxyglucose positron emission tomography does not visualize the vessel wall, but is very sensitive in revealing inflamed vessels. All of these investigations have also been used to follow up patients over time and to monitor response to treatment. In connective tissue diseases, imaging techniques are particularly useful to study internal organs, especially the brain and lung. Magnetic resonance imaging is the investigation of choice to detect and monitor brain disease, while computerized tomography is the best procedure for lung disease. However, since most imaging findings are not entirely specific for any given condition, it is important to interpret the results of imaging in the broader clinical context.

A case of polyarteritis nodosa presenting initially as peripheral vascular disease

Polyarteritis nodosa is a rare necrotizing vasculitis that can be progressive and fatal, and its initial presenting symptom may be leg claudication due to peripheral vascular ischemia. To date, there have been fewer than ten case reports of polyarteritis nodosa presenting as peripheral vascular disease. We report a case of a 38-year-old man initially diagnosed to have premature peripheral vascular disease who presented 1 year later with symptoms consistent with giant cell arteritis and subsequently developed bowel ischemia leading to a fatal outcome. Based on the autopsy and the patient's clinical course, the final diagnosis was polyarteritis nodosa. This case illustrates the challenges in diagnosing polyarteritis nodosa and the importance of considering vasculitis in young patients presenting with atypical presentations of diseases such as peripheral vascular disease or giant cell arteritis.