Thoracic aorta evaluation in patients with Takayasu's arteritis by transesophageal echocardiography

EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice: 2023 update

OBJECTIVES

To update the EULAR recommendations for the use of imaging modalities in primary large vessel vasculitis (LVV).

METHODS

A systematic literature review update was performed to retrieve new evidence on ultrasound, MRI, CT and [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) for diagnosis, monitoring and outcome prediction in LVV. The task force consisted of 24 physicians, health professionals and patients from 14 countries. The recommendations were updated based on evidence and expert opinion, iterating until voting indicated consensus. The level of agreement was determined by anonymous votes.

RESULTS

Three overarching principles and eight recommendations were agreed. Compared to the 2018 version, ultrasound is now recommended as first-line imaging test in all patients with suspected giant cell arteritis, and axillary arteries should be included in the standard examination. As an alternative to ultrasound, cranial and extracranial arteries can be examined by FDG-PET or MRI. For Takayasu arteritis, MRI is the preferred imaging modality; FDG-PET, CT or ultrasound are alternatives. Although imaging is not routinely recommended for follow-up, ultrasound, FDG-PET or MRI may be used for assessing vessel abnormalities in LVV patients with suspected relapse, particularly when laboratory markers of inflammation are unreliable. MR-angiography, CT-angiography or ultrasound may be used for long-term monitoring of structural damage, particularly at sites of preceding vascular inflammation.

CONCLUSIONS

The 2023 EULAR recommendations provide up-to-date guidance for the role of imaging in the diagnosis and assessment of patients with LVV.

Mitral-aortic intervalvular fibrosa involvement by takayasu' arteritis

Takayasu's arteritis is an inflammatory disease with a variety of manifestations, such as cardiac involvement. We describe a 52-year-old woman with clinical and echocardiographic manifestations mimicking infectious endocarditis, such as periaortic and mital-aortic intervalvular fibrosa abscess with extension to the anterior mitral leaflet. However, no infective tissue was discovered intraoperatively. Pathological evaluation demonstrated Takayasu's arteritis. To the best of our knowledge, Takayasu's arteritis can involve mitral-aortic intervalvular fibrosa and imitate infectious endocarditis.

Non-invasive imaging of vascular inflammation

In large-vessel vasculitides, inflammatory infiltrates may cause thickening of the involved arterial vessel wall leading to progressive stenosis and occlusion. Dilatation, aneurysm formation, and thrombosis may also ensue. Activated macrophages and T lymphocytes are fundamental elements in vascular inflammation. The amount and density of the inflammatory infiltrate is directly linked to local disease activity. Additionally, patients with autoimmune disorders have an increased cardiovascular (CV) risk compared with age-matched healthy individuals as a consequence of accelerated atherosclerosis. Molecular imaging techniques targeting activated macrophages, neovascularization, or increased cellular metabolic activity can represent effective means of non-invasive detection of vascular inflammation. In the present review, novel non-invasive imaging tools that have been successfully tested in humans will be presented. These include contrast-enhanced ultrasonography, which allows detection of neovessels within the wall of inflamed arteries; contrast-enhanced CV magnetic resonance that can detect increased thickness of the arterial wall, usually associated with edema, or mural enhancement using T2 and post-contrast T1-weighted sequences, respectively; and positron emission tomography associated with radio-tracers such as [¹⁸F]-fluorodeoxyglucose and the new [¹¹C]-PK11195 in combination with computed tomography angiography to detect activated macrophages within the vessel wall. Imaging techniques are useful in the diagnostic work-up of large- and medium-vessel vasculitides, to monitor disease activity and the response to treatments. Finally, molecular imaging targets can provide new clues about the pathogenesis and evolution of immune-mediated disorders involving arterial vessels.

Angiotensin-converting enzyme 2 is a critical determinant of angiotensin II-induced loss of vascular smooth muscle cells and adverse vascular remodeling

Angiotensin-converting enzyme (ACE) 2 is a key negative regulator of the renin-angiotensin system and metabolizes angiotensin II (Ang II) into Ang 1 to 7. Ang II is a vasoactive peptide, which plays an important role in vascular disease. The objective of the present study was to define the role of ACE2 in pathological vascular remodeling. We found upregulation of ACE2 in dilated human aorta with bicuspid aortic valve and in murine aorta in response to Ang II. Ex vivo pressure myography showed increased vascular stiffness in ACE2 knockout (KO) mesenteric arteries in response to Ang II (1.5 mg/kg per day) and with aging. Histological analyses revealed reduced media-to-lumen ratio in ACE2KO mesenteric arteries with loss of vascular smooth muscle cells. Aortic vascular smooth muscle cells from ACE2KO mice showed markedly increased reactive oxygen species and apoptosis in response to Ang II along with increased cleaved caspase-3 and cleaved caspase-8 levels in the ACE2KO aorta. Ang II type 1 receptor blockade and Ang 1 to 7 supplementation prevented the increase in Ang II-induced reactive oxygen species and apoptotic cell death. In the aorta, Ang II resulted in thoracic and abdominal aortic dilation with loss of vascular smooth muscle cell density in ACE2KO aorta as revealed by α-smooth muscle actin, calponin staining, and electron microscopy with increased promatrix metalloproteinase 2, matrix metalloproteinase 2, and matrix metalloproteinase 9 levels. ACE2 is upregulated in vascular diseases, and ACE2 deficiency exacerbates Ang II-mediated vascular remodeling driven by increased reactive oxygen species and vascular smooth muscle cell apoptosis. In conclusion, the key counter-regulatory role of ACE2 against an activated renin-angiotensin system provides novel insights into the role of ACE2 in vascular diseases.

Loss of Timp3 gene leads to abdominal aortic aneurysm formation in response to angiotensin II

Aortic aneurysm is dilation of the aorta primarily due to degradation of the aortic wall extracellular matrix (ECM). Tissue inhibitors of metalloproteinases (TIMPs) inhibit matrix metalloproteinases (MMPs), the proteases that degrade the ECM. Timp3 is the only ECM-bound Timp, and its levels are altered in the aorta from patients with abdominal aortic aneurysm (AAA). We investigated the causal role of Timp3 in AAA formation. Infusion of angiotensin II (Ang II) using micro-osmotic (Alzet) pumps in Timp3(-/-) male mice, but not in wild type control mice, led to adverse remodeling of the abdominal aorta, reduced collagen and elastin proteins but not mRNA, and elevated proteolytic activities, suggesting excess protein degradation within 2 weeks that led to formation of AAA by 4 weeks. Intriguingly, despite early up-regulation of MMP2 in Timp3(-/-)Ang II aortas, additional deletion of Mmp2 in these mice (Timp3(-/-)/Mmp2(-/-)) resulted in exacerbated AAA, compromised survival due to aortic rupture, and inflammation in the abdominal aorta. Reconstitution of WT bone marrow in Timp3(-/-)/Mmp2(-/-) mice reduced inflammation and prevented AAA in these animals following Ang II infusion. Treatment with a broad spectrum MMP inhibitor (PD166793) prevented the Ang II-induced AAA in Timp3(-/-) and Timp3(-/-)/Mmp2(-/-) mice. Our study demonstrates that the regulatory function of TIMP3 is critical in preventing adverse vascular remodeling and AAA. Hence, replenishing TIMP3, a physiological inhibitor of a number of metalloproteinases, could serve as a therapeutic approach in limiting AAA development or expansion.

Single stage multiple stenting in Takayasu's arteritis. Case report

A 32-year-old Filipino female presented with Takayasu's arteritis manifesting as an abrupt onset of syncope. Physical examination revealed diminished consciousness, right hemiparesis, and a large discrepancy in blood pressure between the upper and lower extremities. Magnetic resonance imaging revealed cerebral infarcts in the left basal ganglia and the left temporal lobe. Angiography revealed complete occlusion of the left common carotid artery and severe stenosis of the brachiocephalic artery, the right common carotid artery, and the left subclavian artery. Based on the clinical examination and studies, the diagnosis was Takayasu's arteritis, type I. The patient's condition stabilized after 2 months of prednisone and anti-platelet therapy. Single stage multiple stenting in the brachiocephalic artery, the right common carotid artery, and the left subclavian artery was then performed using high pressure inflation to dilate the arteries due to the remarkably rigid lesions that resulted from extensive and diffuse fibrosis throughout the vessel walls. Although a small intimal flap occurred during inflation of the left subclavian artery, re-dilation was possible with the stent. Even with evidence of notable recovery in blood pressure and cerebral blood flow, no further neurological improvement was observed. In view of the favorable short- and intermediate-term results, single stage multiple stenting may be the optimum treatment option for first-line stent-supported angioplasty in patients with Takayasu's arteritis.

[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.

[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.

Aortic vessel wall magnetic resonance imaging at 3.0 Tesla: a reproducibility study of respiratory navigator gated free-breathing 3D black blood magnetic resonance imaging

The purpose of this study was to evaluate a free-breathing three-dimensional (3D) dual inversion-recovery (DIR) segmented k-space gradient-echo (turbo field echo [TFE]) imaging sequence at 3T for the quantification of aortic vessel wall dimensions. The effect of respiratory motion suppression on image quality was tested. Furthermore, the reproducibility of the aortic vessel wall measurements was investigated. Seven healthy subjects underwent 3D DIR TFE imaging of the aortic vessel wall with and without respiratory navigator. Subsequently, this sequence with respiratory navigator was performed twice in 10 healthy subjects to test its reproducibility. The signal-to-noise (SNR), contrast-to-noise ratio (CNR), vessel wall sharpness, and vessel wall volume (VWV) were assessed. Data were compared using the paired t-test, and the reproducibility of VWV measurements was evaluated using intraclass correlation coefficients (ICCs). SNR, CNR, and vessel wall sharpness were superior in scans performed with respiratory navigator compared to scans performed without. The ICCs concerning intraobserver, interobserver, and interscan reproducibility were excellent (0.99, 0.94, and 0.95, respectively). In conclusion, respiratory motion suppression substantially improves image quality of 3D DIR TFE imaging of the aortic vessel wall at 3T. Furthermore, this optimized technique with respiratory motion suppression enables assessment of aortic vessel wall dimensions with high reproducibility.

What the practising rheumatologist needs to know about the technical fundamentals of ultrasonography

A transducer generates ultrasound waves and emits them into the body. Boundaries in or between tissues reflect the waves, and the transducer receives the reflected waves. A computer converts the information into images that are displayed on a monitor. Image resolution is greater with higher frequencies, and penetration is greater with lower frequencies. Linear probes with frequencies between 5 and 20 MHz are mainly used for musculoskeletal ultrasound. Image quality and resolution have improved significantly. Tissue harmonic imaging and cross-beam technology aid in differentiating between anatomical structures, although borders appear artificially thickened. Three-dimensional ultrasound provides additional coronary planes, and contrast agents increase the sensitivity for synovial blood flow in inflamed joints. This chapter provides further information regarding which ultrasound technology is the best for purchase by a rheumatology unit, how to organize ultrasound clinics, and how best to perform ultrasonography in daily practice, including the most important indications for ultrasound in rheumatology.

Imaging studies in the diagnosis and management of vasculitis

The term vasculitis encompasses a number of distinct clinicopathologic disease entities. Final diagnosis should be supported by histologic study in most cases. However, different imaging modalities offer the potential for an early visualization of inflammatory vascular abnormalities, provide some diagnostic clues, and allow for an adequate assessment of therapeutic response. This review discusses recent advances in imaging techniques and refinements in vascular imaging methods, as well as a brief mention of research modalities that are increasingly used in studies of pathogenesis or in the assessment of disease progression.

Outpatient assessment of systemic vasculitis

The vasculitides are complex, multisystem diseases, the natural history of which has been transformed by the use of immunosuppressive therapy. In many cases, survival is characterized by the presence of ongoing low-grade disease activity and, now that patients can survive acute, life-threatening manifestations of vasculitis, the new challenge is to provide accurate descriptions of these problems so as to plan appropriate changes in therapy to ensure optimal control of disease, with minimal toxicity, damage, and impairment of function. To achieve these aims, it is necessary to undertake structured evaluation of patients, with a significant dependence on careful clinical observation, supported by appropriate laboratory investigation at all stages from diagnosis to long-term care of these patients. This chapter reviews the important aspects of disease assessment and recommends a strategy for managing these complex patients. We can make use of standardized disease assessment instruments, such as the Birmingham Vasculitis Assessment Score and the Vasculitis Damage Index, to serve as an aide memoire in documenting the clinical features of disease. Routine monitoring for drug toxicity in the short-term and long-term is essential. Above all, however, it is very important to review these patients regularly and see them urgently in case of flares or complications, which are a common problem in most forms of vasculitis.