Classification of large vessel vasculitis: Can we separate giant cell arteritis from Takayasu arteritis?

Role of 18F-FDG PET/CT in Large Vessel Vasculitis and Polymyalgia Rheumatica

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels, including large vessel vasculitis (LVV) and medium-sized vessel vasculitis such as giant cell arteritis (GCA) and Takayasu arteritis (TAK). GCA frequently overlaps with polymyalgia rheumatica (PMR), a rheumatic inflammatory condition affecting bursae, tendons or tendon sheaths, and joints. ¹⁸F-FDG PET/CT plays an important role in the diagnostic work-up of GCA, PMR, and TAK and is increasingly used to monitor treatment response. This continuing education article provides up-to-date guidance on the role of ¹⁸F-FDG PET/CT in patients with LVV, medium-sized vessel vasculitis, and PMR. It provides a general introduction on the clinical presentation and challenges in the diagnostic work-up of LVV and medium-sized vessel vasculitis, with a focus on the 2 major LVV subtypes: GCA, including PMR, and TAK. Next, practice points to perform and interpret the results of ¹⁸F-FDG PET/CT are described in line with the published procedure recommendations. Furthermore, the diagnostic performance and its role for treatment monitoring are discussed, taking into account recent international recommendations for the use of imaging in LVV and medium-sized vessel vasculitis in clinical practice. This is illustrated by several clinically representative PET/CT scan examples. Lastly, knowledge of limitations and pitfalls is essential to understand the role of ¹⁸F-FDG PET/CT in LVV, medium-sized vessel vasculitis, and PMR. Challenges and opportunities, as well as future research and conclusions, are highlighted. Learning objectives provide up-to-date guidance for the role of ¹⁸F-FDG PET/CT in patients with suspected LVV, medium-sized vessel vasculitis, and PMR.

Update on Imaging of Inflammatory Arthritis and Related Disorders

Arthritis and other rheumatic disorders are very frequent in the general population and responsible for a huge physical and disability burden to affected patients as well as a major cost to the society. Precise evaluation often relies on clinical data only but additional imaging may be required i) for a more objective assessment of the disease status, such as in rheumatoid arthritis (RA) or ankylosing spondyloarthritis (AS), ii) for providing prognostic information and evaluating response to treatment or iii) for establishing diagnosis, in patients with unclear clinical picture, such as polymyalgia rheumatica (PMR) and large-vessel vasculitis (LVV). Besides radiological techniques (x-rays, ultrasound, and MRI), functional and molecular imaging has emerged as a valid tool for this purpose in several disorders. Bone scanning has long been a method of choice but is now more used as a triage tool in patients with unclear complaints, including degenerative disorders (eg osteoarthritis). ¹⁸F-FDG-PET/CT (FDG) proved efficient in assessing the extent of the disease and response to treatment in RA and related disorders, and to provide accurate diagnosis in some systemic disorders, including PMR and LVV. Based on glucose metabolism, FDG-PET/CT is able to show increased metabolism in peripheral cells involved in inflammation (eg neutrophils, lymphocytes or monocytes/macrophages) but also in fibroblasts that proliferate in the pannus. The lack of specificity of FDG is a limitation and many alternative tracers were developed at the preclinical stage or applied in the clinics, especially within clinical trials. They include imaging of macrophages using translocator protein (TSPO), folate-receptors or other targets on activated cells. These new tools will undoubtedly become more and more available in the everyday clinical workup of patients with rheumatisms. Finally, it should be kept in mind that a very simple tracer, ¹⁸F-fluoride is widely more performant in AS than FDG.

A Long-term Persistent Vascular Fluorodeoxyglucose Uptake in a Patient with Large-vessel Vasculitis

We herein report a case of large-vessel vasculitis in a 57-year-old woman who developed an intermittent fever and weight loss. While contrast-enhanced computed tomography was noncontributory, positron emission tomography-computed tomography (PET-CT) revealed the diffuse, intense uptake of fluorodeoxyglucose (FDG) in the aorta and its branches. Although she had no signs of relapse after successful oral corticosteroid therapy, PET-CT at 30 months revealed a persistent FDG uptake in the large vessels, which warranted regular follow-up imaging for vascular complications. In cases with an intense FDG uptake at the diagnosis, PET-CT follow-up after clinical remission may help predict the risk of relapse and vascular complications.

Semi-Quantitative and Quantitative [18F]FDG-PET/CT Indices for Diagnosing Large Vessel Vasculitis: A Critical Review

To confirm the diagnosis of large vessel vasculitis (LVV) with high accuracy, one of the recommended imaging techniques is [¹⁸F]Fluoro-2-deoxy-d-glucose positron emission tomography with computed tomography ([¹⁸F]FDG-PET/CT). Visual assessment of [¹⁸F]FDG uptake in the arterial wall compared to liver uptake is the mainstay for diagnosing LVV in routine clinical practice. To date, there is no consensus on the preferred semi-quantitative or quantitative parameter for diagnosing LVV. The aim of this review is to critically update the knowledge on the available evidence of semi-quantitative and quantitative [¹⁸F]FDG uptake parameters for diagnosing LVV and to provide future directions for methodological standardization and research.

Diagnostic value of [18F]FDG-PET/CT for treatment monitoring in large vessel vasculitis: a systematic review and meta-analysis

PURPOSE

Monitoring disease activity in patients with large vessel vasculitis (LVV) can be challenging. [18F]FDG-PET/CT is increasingly used to evaluate treatment response in LVV. In this systematic review and meta-analysis, we aimed to summarize the current evidence on the value of [18F]FDG-PET/CT for treatment monitoring in LVV.

METHODS

PubMed/MEDLINE and the Cochrane library database were searched from inception through October 21, 2020. Studies containing patients with LVV (i.e. giant cell arteritis, Takayasu arteritis and isolated aortitis) that received treatment and underwent [18F]FDG-PET/CT were included. Screening, full-text review and data extraction were performed by 2 investigators. The risk of bias was examined with the QUADAS-2 tool. Meta-analysis of proportions and diagnostic test accuracy was performed by a random-effects model and bivariate model, respectively.

RESULTS

Twenty-one studies were included in the systematic review, of which 8 studies were eligible for meta-analysis. Arterial [18F]FDG uptake decreased upon clinical remission in longitudinal studies. High heterogeneity (I² statistic 94%) precluded meta-analysis of the proportion of patients in which the scan normalized during clinical remission. Meta-analysis of cross-sectional studies indicated that [18F]FDG-PET/CT may detect relapsing/refractory disease with a sensitivity of 77% (95%CI 57-90%) and specificity of 71% (95%CI 47-87%). Substantial heterogeneity was observed among the cross-sectional studies. Both variation in clinical aspects and imaging procedures contributed to the heterogeneity.

CONCLUSION

Treatment of LVV leads to reduction of arterial [18F]FDG uptake during clinical remission. [18F]FDG-PET/CT has moderate diagnostic accuracy for detecting active LVV. [18F]FDG-PET/CT may aid treatment monitoring in LVV, but its findings should be interpreted in the context of the clinical suspicion of disease activity. This study underlines the relevance of published procedural recommendations for the use of [18F]FDG-PET/CT in LVV.

Patterns of Arterial Disease in Takayasu Arteritis and Giant Cell Arteritis

OBJECTIVE

To identify and validate, using computer-driven methods, patterns of arterial disease in Takayasu arteritis (TAK) and giant cell arteritis (GCA).

METHODS

Patients with TAK or GCA were studied from the Diagnostic and Classification Criteria for Vasculitis (DCVAS) cohort and a combined North American cohort. Case inclusion required evidence of large-vessel involvement, defined as stenosis, occlusion, or aneurysm by angiography/ultrasonography, or increased ¹⁸ F-fluorodeoxyglucose (FDG) uptake by positron emission tomography (PET) in at least 1 of 11 specified arterial territories. K-means cluster analysis identified groups of patients based on the pattern of arterial involvement. Cluster groups were identified in the DCVAS cohort and independently validated in the North American cohort.

RESULTS

A total of 1,068 patients were included (DCVAS cohort: TAK = 461, GCA = 217; North American cohort: TAK = 225, GCA = 165). Six distinct clusters of patients were identified in DCVAS and validated in the North American cohort. Patients with TAK were more likely to have disease in the abdominal vasculature, bilateral disease of the subclavian and carotid arteries, or focal disease limited to the left subclavian artery than GCA (P < 0.01). Patients with GCA were more likely to have diffuse disease, involvement of bilateral axillary/subclavian arteries, or minimal disease without a definable pattern than TAK (P < 0.01). Patients with TAK were more likely to have damage by angiography, and patients with GCA were more likely to have arterial FDG uptake by PET without associated vascular damage.

CONCLUSION

Arterial patterns of disease highlight both shared and divergent vascular patterns between TAK and GCA and should be incorporated into classification criteria for large-vessel vasculitis.

Giant cell arteritis associated with inflammatory bowel disease: a case-series and review of the literature

To describe the clinical characteristics, management, and outcome of a series of patients with giant cell arteritis (GCA) and inflammatory bowel disease (IBD). Patients with both GCA and IBD evaluated between 1/1/1996 and 12/30/2018 were retrospectively identified. Clinical characteristics, laboratory parameters, radiologic features, histopathology, management and outcomes were abstracted. A systematic literature review identifying patients with IBD and GCA was performed via a Medline and EMBASE search from inception through December 31 2019. Six patients were identified with GCA and IBD (66% male). Five (83%) had ulcerative colitis (UC) and one had Crohn's disease (CD). Diagnosis of IBD preceded GCA in four patients with an average interval of 30 years (range 14-42). Average time to IBD diagnosis in those with prior GCA diagnosis was 1.5 years. During mean follow-up of 4.3 years, GCA relapse was infrequent with only one patient with relapse observed. Systematic literature review identified six additional patients with confirmed coexistence of GCA and IBD. Similar to the current series, male sex was more common and ulcerative colitis was the predominant IBD phenotype. The current study reports findings from the largest single-institution case-series of co-existent GCA and IBD. In contrast to Takayasu arteritis with co-existent IBD, which displays a predilection for female sex and Crohn's disease phenotype, both the current study and review of literature demonstrate a stronger association of GCA with male sex and ulcerative colitis. Further studies addressing a potential pathophysiologic connection between GCA and IBD are suggested.

Aortic dissection and accelerated aneurysmal degeneration in a patient with giant cell arteritis

Giant cell arteritis (GCA) is associated with nonatheromatous aortic pathology. Here we present a case in which a 76-year-old woman with a biopsy-proven history of GCA and a previous repair of her ascending aortic aneurysm presents with an acute dissection of a 4-cm aneurysm in the descending thoracic aorta. It was treated using endovascular techniques. This report adds to a growing body of evidence that GCA is a risk factor for aortic dissection and nonatheromatous aortic aneurysms.

Identification of two major autoantigens negatively regulating endothelial activation in Takayasu arteritis

The presence of antiendothelial cell antibodies (AECAs) has been documented in Takayasu arteritis (TAK), a chronic granulomatous vasculitis. Here, we identify cell-surface autoantigens using an expression cloning system. A cDNA library of endothelial cells is retrovirally transfected into a rat myeloma cell line from which AECA-positive clones are sorted with flow cytometry. Four distinct AECA-positive clones are isolated, and endothelial protein C receptor (EPCR) and scavenger receptor class B type 1 (SR-BI) are identified as endothelial autoantigens. Autoantibodies against EPCR and SR-BI are detected in 34.6% and 36.5% of cases, respectively, with minimal overlap (3.8%). Autoantibodies against EPCR are also detected in ulcerative colitis, the frequent comorbidity of TAK. In mechanistic studies, EPCR and SR-BI function as negative regulators of endothelial activation. EPCR has also an effect on human T cells and impair Th17 differentiation. Autoantibodies against EPCR and SR-BI block the functions of their targets, thereby promoting pro-inflammatory phenotype.

Autoantibodies against endothelium have been recognized in Takayasu arteritis (TAK). Here the authors identify endothelial protein C receptor and scavenger receptor class B type 1 as major autoantigens in TAK, and find autoantibodies inhibit the negative regulation of endothelial activation.

Gender differences in clinical presentation and vascular pattern in patients with Takayasu arteritis

Objective: To compare clinical characteristics and pattern of vascular involvement at disease onset according to gender specificity in patients with Takayasu arteritis (TA).Methods: Data from 117 TA patients (11 male, 106 female), diagnosed according to the American College of Rheumatology criteria, from our centre were retrospectively collected. Differences between men and women regarding demographic features, diagnostic delay, signs and symptoms attributed to TA, and arteries involved at diagnosis were compared. Data were obtained from three published articles describing gender differences in TA. A global analysis of these three cohorts plus ours (a total of 578 patients; 108 men, 470 women) was performed.Results: In our TA cohort, age at disease onset and age at diagnosis were not significantly different between genders. Diagnostic delay was higher in men. Male patients showed higher involvement of iliac arteries (right, p = 0.016; left, p = 0.021); females suffered more frequently from upper limb claudication (p = 0.026). In the overall analysis, men had higher prevalence of arterial hypertension (p = 0.007) and more frequent involvement of abdominal aorta (p = 0.026), renal arteries (right, p < 0.001; left, p < 0.001), and iliac arteries (right, p = 0.009; left, p = 0.002). Women more frequently exhibited upper limb claudication (p = 0.042) and involvement of left subclavian artery (p = 0.005), carotid arteries (right, p < 0.001; left, p < 0.001), and supradiaphragmatic aorta (ascending, p = 0.050; arch, p < 0.001; descending, p = 0.003). Inflammatory markers were more frequently raised in women (p = 0.005).Conclusions: In TA patients, gender has a strong influence on pattern of vascular involvement and consequently on clinical presentation. Specifically, women have a higher involvement of the supradiaphragmatic vessels, whereas in men the abdominal vessels are more frequently affected.

Takayasu's disease effects on the kidneys: current perspectives

Takayasu arteritis (TA) is a chronic vasculitis disease of unknown etiology. Clinically significant renal disease is relatively common, and renovascular hypertension is the major renal problem. The assessment of TA activity is usually challenging because vascular inflammation may progress to fixed vascular injury without findings of active disease. Until now, the best therapeutic options have not been identified. This review highlights the current perspectives of renal involvement in TA.

Large-vessel giant cell arteritis: diagnosis, monitoring and management

GCA is a chronic, idiopathic, granulomatous vasculitis of medium and large arteries. It comprises overlapping phenotypes including classic cranial arteritis and extra-cranial GCA, otherwise termed large-vessel GCA (LV-GCA). Vascular complications associated with LV-GCA may be due, in part, to delayed diagnosis, highlighting the importance of early identification and prompt initiation of effective therapy. Advancements in imaging techniques, including magnetic resonance angiography, CT angiography, PET and colour duplex ultrasonography, have led to improvements in the diagnosis of LV-GCA; however, the role imaging modalities play in the assessment of disease activity and long-term outcomes remains unclear. Glucocorticoids are the mainstay of therapy in LV-GCA, but their prolonged use is associated with multiple, sometimes serious, adverse effects. Recent data suggest that biologic therapies, such as tocilizumab, may be effective and safe steroid-sparing options for patients with GCA. However, data specifically evaluating the management of LV-GCA are limited.