The role of 18F-FDG PET in characterising disease activity in Takayasu arteritis

The Use of Shear Wave Elastography in the Diagnosis of Prestenotic Phase of Takayasu's Aortoarteritis

We report the use of shear wave elastography with dispersion imaging in diagnosing a case of prestenotic Takayasu's arteritis which presented with symptoms of fever of unknown origin with persistently raised C-reactive protein levels. Vessel wall inflammation was detected in the carotid arteries on dispersion and shear wave imaging along with increased wall stiffness which was characteristic of vasculitis seen in a prestenotic phase of Takayasu's disease. These findings preceded the sonographic finding of vessel wall thickening described as the earliest sign of the disease on routine ultrasonography and not only helped to make an early diagnosis in a patient with a fever of unknown origin but also in the posttreatment follow-up.

PET/CT Imaging of Infectious Diseases: Overview of Novel Radiopharmaceuticals

Infectious diseases represent one of the most common causes of hospital admission worldwide. The diagnostic work-up requires a complex clinical approach, including laboratory data, CT and MRI, other imaging tools, and microbiologic cultures. PET/CT with 18F-FDG can support the clinical diagnosis, allowing visualization of increased glucose metabolism in activated macrophages and monocytes; this tracer presents limits in differentiating between aseptic inflammation and infection. Novel PET radiopharmaceuticals have been developed to overcome these limits; 11C/18F-labeled bacterial agents, several 68Ga-labeled molecules, and white blood cells labeled with 18F-FDG are emerging PET tracers under study, showing interesting preliminary results. The best choice among these tracers can be unclear. This overview aims to discuss the most common diagnostic applications of 18F-FDG PET/CT in infectious diseases and, as a counterpoint, to describe and debate the advantages and peculiarities of the latest PET radiopharmaceuticals in the field of infectious diseases, which will probably improve the diagnosis and prognostic stratification of patients with active infectious diseases.

The pentraxin family in autoimmune disease

The pentraxins represent a family of multifunctional proteins composed of long and short pentamers. The latter includes serum amyloid P component (SAP) and C-reactive protein (CRP) whereas the former includes neuronal PTX1 and PTX2 (NPTX1 and NPTX2, respectively), PTX3 and PTX4. These serve as a bridge between adaptive immunity and innate immunity and a link between inflammation and immunity. Similarities and differences between long and short pentamers are examined and their roles in autoimmune disease are discussed. Increased CRP and PTX3 could indicate the activity of rheumatoid arthritis, systemic lupus erythematosus or other autoimmune diseases. Mechanistically, CRP and PTX3 may predict target organ injury, regulate bone metabolic immunity and maintain homeostasis as well as participate in vascular endothelial remodeling. Interestingly, PTX3 is pleiotropic, being involved in inflammation and tissue repair. Given the therapeutic potential of PTX3 and CRP, targeting these factors to exert a beneficial effect is the focus of research efforts. Unfortunately, studies on NPTX1, NPTX2, PTX4 and SAP are scarce and more research is clearly needed to elaborate their potential roles in autoimmune disease.

A review on the deeper understanding of inflammation and infection of the thoracic aorta

OBJECTIVE

To review the current literature regarding infection and inflammation of the thoracic aorta and to summarise its aetiologies, pathogenesis and clinical presentation. Additionally, the authors sought to compare diagnostic methods and to analyse the different management options.

METHOD

A comprehensive electronic search using PubMed, MEDLINE, Scopus and Google Scholar was conducted to find relevant journal articles with key search terms including: 'aortitis', 'thoracic aortic infection' and 'surgical management of infected thoracic aortic aneurysms'. Prominent publications from 1995 till present (2021) were analysed to achieve a deeper understanding of thoracic aorta infection and inflammation, and the information was then collated to form this review.

RESULTS

The literature review revealed that infectious causes are more prominent than non-infectious causes, with Gram positive bacteria such as Staphylococcus, Enterococcus and Streptococcus accounting for approximately 60% of the infections. The authors also noted that Staphylococcus Aureus was associated with poorer outcomes. Key diagnostic tools include MRI and multi-slice CT imaging, which are useful imaging modalities in defining the extent of the disease thus allowing for planning surgical intervention. Surgical intervention itself is extremely multifaceted and the rarity of the condition means no large-scale comparative research between all the management options exists. Until more large-scale comparative data becomes available to guide treatment, the optimal approach must be decided on a case-by-case basis, considering the benefits and drawback of each treatment option.

CONCLUSION

A high index of suspicion and a comprehensive history is required to effectively diagnose and manage infection and inflammation of the thoracic aorta. Differentiating between infectious and inflammatory cases is crucial for management planning, as infectious causes typically require antibiotics and surgical intervention. Over the years, the post treatment results have shown significant improvement due to earlier diagnosis, advancement in surgical options and increasingly specific microbial therapy.

Multimodality Evaluation of Aortic Insufficiency and Aortitis in Rheumatologic Diseases

Aortic insufficiency is commonly observed in rheumatologic diseases such as ankylosing spondylitis, systemic lupus erythematosus, antiphospholipid syndrome, Behçet's disease, granulomatosis with polyangiitis, and Takayasu arteritis. Aortic insufficiency with an underlying rheumatologic disease may be caused by a primary valve pathology (leaflet destruction, prolapse or restriction), annular dilatation due to associated aortitis or a combination of both. Early recognition of characteristic valve and aorta morphology on cardiac imaging has both diagnostic and prognostic importance. Currently, echocardiography remains the primary diagnostic tool for aortic insufficiency. Complementary use of computed tomography, cardiac magnetic resonance imaging and positron emission tomography in these systemic conditions may augment the assessment of underlying mechanism, disease severity and identification of relevant non-valvular/extracardiac pathology. We aim to review common rheumatologic diseases associated with aortic insufficiency and describe their imaging findings that have been reported in the literature.

Imaging features of 18F-FDG PET/CT in different types of systemic vasculitis

OBJECTIVE

To analyze ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) image features in different types of systemic vasculitis and explore its classification and diagnostic significance for systemic vasculitis.

METHODS

Clinical and ¹⁸F-FDG PET/CT imaging data of 71 consecutive patients (34 males, 37 females, mean age 53.4 ± 20.5 years) who were examined at Peking University People's Hospital and diagnosed with active systemic vasculitis were analyzed retrospectively, and ¹⁸F-FDG PET/CT imaging features of different types of systemic vasculitis were analyzed in patients with positive ¹⁸F-FDG PET/CT findings.

RESULTS

The proportions of large-, medium-, small-, and variable-vessel vasculitis were 36.6%, 15.5%, 29.6%, and 18.3%, respectively, and 93.0% of patients had positive findings on PET/CT, of which 63.6% had vascular involvement and 53.0% had extravascular involvement. Different types of vasculitis had different lesion sites, distribution patterns, and morphological changes. Large-vessel vasculitis mainly affected the aorta and its branches to the head and neck. Takayasu arteritis showed segmental involvement of the vascular and morphological changes of the vessel wall. Giant cell arteritis manifested as diffuse vascular involvement, which usually involved the temporal artery and the abdominal aorta and its branches. Medium-vessel vasculitis polyarteritis nodosa manifested as diffuse vascular involvement of both lower extremities. Small-vessel vasculitis anti-neutrophil cytoplasmic antibody-associated vasculitis manifested as granulomatous inflammation of extravascular regions. Variable-vessel vasculitis Behcet's disease involved both blood vessels and extravascular regions.

CONCLUSION

Different types of systemic vasculitis show characteristic manifestations in ¹⁸F-FDG PET/CT images, which may be useful for the diagnosis and classification of systemic vasculitis.

KEY POINTS

• Determining an early diagnosis of systemic vasculitis may be challenging. • Different types of systemic vasculitis show characteristic manifestations in ¹⁸F-FDG PET/CT images. • ¹⁸F-FDG PET/CT may be useful for the diagnosis and classification of systemic vasculitis.

Application progress of multiple imaging modalities in Takayasu arteritis

Takayasu arteritis (TA) is a chronic, idiopathic, granulomatous large vessel vasculitis of unknown etiology. The clinical manifestations of TA are incredibly variable, mainly depending on the location of the lesions. In the light of its insidious progress and the diversity of clinical manifestations, a substantial proportion of patients might experience a considerable delay in diagnosis, which leads to irreversible malignant complications, highlighting the importance of early diagnosis. There has been accumulating evidence that early identification of disease is pivotal to initiate timely therapy and ameliorate the prognosis. Therefore, this review discusses and summarizes the latest evidence on the application progress of multiple imaging modalities.

A novel model to assess disease activity in Takayasu arteritis based on 18F-FDG-PET/CT: a Chinese cohort study

OBJECTIVE

To investigate the utility of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in assessing disease activity in Takayasu arteritis (TA).

METHODS

Ninety-one patients with TA, were recruited from a Chinese cohort. Clinical data, acute-phase reactants (APRs), and 18F-FDG-PET/CT findings were simultaneously recorded. The value of using 18F-FDG-PET/CT to identify active disease was evaluated, using erythrocyte sedimentation rate (ESR) as a reference. Disease activity assessment models were constructed and concordance index (C-index), net reclassification index (NRI), and integrated discrimination index (IDI) were evaluated to compare the benefits of the new modes with ESR and Kerr score.

RESULTS

In total, 64 (70.3%) cases showed active disease. Higher levels of ESR and CRP, and lower interleukin (IL)-2R levels, were observed in active cases. 18F-FDG-PET/CT parameters, including SUVmean, SUVratio1, SUVratio2, sum of SUVmean, and sum of SUVmax, were significantly higher in active disease groups. The C index threshold of ESR to indicate active disease was 0.78 (95% CI: 0.69-0.88). The new activity assessment model combining ESR, sum of SUVmean, and IL-2R showed significant improvement in C index over the ESR method (0.96 vs 0.78, p < 0.01; NRI 1.63, p < 0.01; and IDI 0.48, p < 0.01). The new model also demonstrated modest superiority to Kerr score assessment (0.96 vs 0.87, p = 0.03; NRI 1.19, p < 0.01; and IDI 0.33 p < 0.01).

CONCLUSIONS

A novel 18F-FDG-PET/CT-based method that involves combining the sum of SUVmean with ESR score and IL-2R levels demonstrated superiority in identifying active TA compared with conventional methods.

Giant Cell Arteritis among Fevers of Unknown Origin (FUO): An Atypical Presentation

Giant cell arteritis (GCA), or Horton's arteritis, presenting solely as fever is very rare. Usually, it manifests with typical features such as visual problems, headache and jaw claudication, or it can be associated with polymyalgia rheumatica. We describe the case of a patient with GCA who presented only with prolonged fever, the cause of which was not determined by diagnostic tests.

LEARNING POINTS

Fever may be the only symptom of giant cell arteritis (GCA).It is important to consider GCA in the differential diagnosis of fever of unknown origin as early diagnosis is crucial for prompt treatment and to prevent catastrophic complications such as vision loss or stroke.Temporal artery biopsy remains the gold standard for diagnosing GCA.

Takayasu Arteritis: a Systematic Review and Meta-Analysis of Test Accuracy and Benefits and Harms of Common Treatments

Objective

Takayasu’s arteritis (TAK) is a granulomatous large‐vessel vasculitis primarily affecting the aorta and its proximal branches. TAK can be a difficult disease to diagnose and manage given the rarity of the disease as well as current limitations in biomarkers, imperfect imaging modalities, and few randomized controlled trials.

Methods

In developing the American College of Rheumatology/Vasculitis Foundation guideline for the management of TAK, we performed an extensive systematic literature review to guide our recommendations. We included RCTs first. When RCTs were not available, we included observational studies that reported on patient‐important outcomes for the intervention and comparison. When studies with comparative data were not available, we included case series that present patient‐important outcomes for either the intervention or the comparison.

Results

Three hundred forty‐seven articles were included for full review to answer 27 population, intervention, comparison, and outcome questions related to TAK. Ten studies were evaluated that addressed the use of glucocorticoids (GCs), non‐GC nonbiologic therapies, as well as biologics in treating TAK. A total of 33 studies, including 8 comparative studies, were included to determine the test accuracy of commonly available diagnostic tests for TAK.

Conclusion

This comprehensive systematic review synthesizes and evaluates the benefits and harms of different treatment options and the accuracy of commonly used tests for the management of TAK.

Potential Applications of PET Scans, CT Scans, and MR Imaging in Inflammatory Diseases: Part II: Cardiopulmonary and Vascular Inflammation

Detecting inflammation is among the most important aims of medical imaging. Inflammatory process involves immune system activity and local tissue response. The role of PET with fludeoxyglucose F 18 has been expanded. Systemic vasculitides and cardiopulmonary inflammatory disorders constitute a wide range of diseases with multisystemic manifestations. PET with fludeoxyglucose F 18 is useful in their diagnosis, assessment, and follow-up. This article provides an overview of the current status and potentials of hybrid molecular imaging in evaluating cardiopulmonary and vascular inflammatory diseases focusing on the potential for PET with fludeoxyglucose F 18/MR imaging and PET/CT scans.

18F-FDG PET/CT plays a unique role in the management of Takayasu arteritis patients with atypical manifestations

OBJECTIVE

The present study aimed to evaluate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) aiding in diagnosing and evaluating disease activity in Takayasu arteritis (TA) patients with atypical clinical manifestations.

METHODS

A retrospective study of 22 TA patients was conducted. All the participants were classified into two groups. Group one including 12 patients, who did not fulfill American College of Rheumatology (ACR) criteria, were diagnosed by modified Ishikawa criteria. Group two involving ten patients, who did not satisfy the modified Ishikawa criteria or ACR criteria, were clinically diagnosed as TA after panel discussion by a combination of clinical data, excluding other diagnoses. PET/CT results were analyzed using quantitative and qualitative metrics. Disease activity was evaluated using the US National Institutes of Health (NIH) criteria.

RESULTS

In group one, nine patients in active stage and two patients in inactive stage had active FDG uptake. One patient in inactive stage had inactive PET/CT results. In group two, five patients in active stage had active FDG uptake and five patients in inactive stage had inactive FDG uptake with SUVmax values of several vascular lesions slightly lower than livermean in each person. The sensitivity of PET/CT scans for evaluating disease activity was 100.0%, specificity was 75.0%, positive predictive value was 87.5%, and negative predictive value was 100.0% compared to NIH criteria.

CONCLUSIONS

PET/CT plays a unique role in diagnosing these TA with atypical manifestation and assisting in evaluating disease activity. Key Points • Diagnosis of these TA patients with atypical manifestations may be difficult. • PET/CT plays a unique role in diagnosing these TA patients and assisting in evaluating disease activity.

Novel Biomarkers for the Precisive Diagnosis and Activity Classification of Takayasu Arteritis

BACKGROUND

Establishing the diagnosis and determining disease activity of Takayasu arteritis (TA) remains challenging. Novel biomarkers might help to solve this problem.

METHODS

In the screening phase, by using large-scale protein arrays detecting samples from 90 subjects (TA active, 29; TA inactive 31; and controls, 30). In the validation phase, by using enzyme-linked immunosorbent assay (ELISA), potential biomarkers for TA diagnosis, and activity classification were measured in independent cohorts, respectively.

RESULTS

In the screening phase, 18 cytokines significantly differentially enriched between TA patients and controls and another 15 cytokines significantly differentially enriched between TA patient in active and inactive status were identified (adjusted P<0.05). In the validation phase, TIMP (tissue inhibitor of metalloproteinases)-1 was identified as a specific biomarker for TA diagnosis that a cutoff value of 221.86 μg/L could provide a specificity of 89.58% and a positive predictive value of 0.92. Meanwhile, we found it unreliable to use a single biomarker for TA activity classification. Considering this, we further built a logistic regression model based on multiple cytokines, including CA (cancer antigen) 125, FLRG (follistatin-related protein), IGFBP (insulin-like growth factor-binding protein)-2, CA15-3, GROa (growth-regulated alpha protein), LYVE (lymphatic vessel endothelial hyaluronic acid receptor)-1, ULBP (UL16-binding protein)-2, and CD (cluster of differentiation) 99, with an area under the curve reaching 0.909 for discriminating TA activity status.

CONCLUSIONS

This study suggested TIMP-1 as a specific biomarker for TA diagnosis with a cutoff value of 221.86 μg/L. Furthermore, we provided a logistic regression model based on 8 biomarkers for the precisive activity classification of TA with an area under the curve of 0.909.

Diagnostic Role and Feasibility of 18F-FDG PET for Assessing Takayasu Arteritis: Diagnostic Efficacy of Quantifying 18F-FDG Uptake

Takayasu arteritis (TAK) is classified as large-vessel vasculitis caused by inflammation. It is often difficult to identify on clinical examination, and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) plays an indispensable role in diagnosing TAK by detecting the location and grade of the inflammatory lesions. The clinical utility of ¹⁸F-FDG PET has been established by clinical evidence, and ¹⁸F-FDG PET was added to the Japanese national health insurance listing in April 2018. In TAK, ¹⁸F-FDG uptake shows typical findings and is easily distinguished, except from physiological uptake. Particularly, the clinical significance of ¹⁸F-FDG PET is that can present not only with stenosis but also without stenosis in the arteries, which means that therapeutic intervention is possible before irreversible stenosis develops in the arteries. Additionally, ¹⁸F-FDG PET has superior diagnostic accuracy because it allows quantitative analysis using the maximum standardized uptake value. The analysis is used for the assessment of disease activity of TAK and can be utilized for therapeutic intervention in case of repeating remission during the follow-up term.

Current Controversies in Large-Vessel Inflammatory Vasculitis and Thoracic Aortic Aneurysm Disease

Large-vessel vasculitis encompasses the spectrum of vasculitides, which pathologically cause chronic granulomatous inflammatory changes, primarily in the aorta and its major branches. These patients are at risk of developing life-threatening aortic lesions that, without recognition and prompt treatment, can cause detrimental effects. Many provocative issues surrounding large-vessel vasculitis and its surgical treatment still remain, spanning from recognition to management. In this review, we discuss the main large-vessel vasculitides, Takayasu's arteritis and giant cell arteritis. We include the key points and current controversies surrounding diagnostic imaging, timing of interventions, and patient outcomes.

Takayasu arteritis: clinical importance of extra-vessel uptake on FDG PET/CT

Background

[F-18]fluorodeoxyglucose positron emission tomography/computed tomography is routinely used for assessing Takayasu arteritis patients. However, extra-vessel [F^-18]fluorodeoxyglucose uptake has not been evaluated in detail in these patients. We aimed to describe the extent and distribution of extra-vascular [F-18]fluorodeoxyglucose uptake on positron emission tomography/computed tomography in Takayasu arteritis patients. Seventy-three [F-18]fluorodeoxyglucose positron emission tomography/computed tomography scans from 64 consecutive Takayasu arteritis patients (59 women, mean age, 35.4 years; range, 13 to 71 years) and 40 scans from age-matched controls (36 women, mean age, 37.8 years; range, 13 to 70 years) were examined. We graded [F-18]fluorodeoxyglucose uptake in large vessels using a 4-point scale and evaluated extra-vessel findings. Factors correlated with disease activity were examined. We evaluated the relationship between disease activity according to the National Institutes of Health score with extra-vessel findings, as well as other inflammatory markers (e.g., white blood cell count and C-reactive protein level).

Results

Extra-vessel involvement was present in 50 of 73 (68.4%) scans, specifically at the following sites: lymph nodes, 1.4%; thyroid glands, 17.8%; thymus, 11.0%; spleen, 1.4%; vertebrae, 45.2%; and pelvic bones, 9.6%. Takayasu arteritis patients had higher [F-18]fluorodeoxyglucose uptake in the spine (P = 0.03) and thyroid glands (P = 0.003) than did controls; uptake in other regions was comparable between groups. Compared with inactive patients, those with active Takayasu arteritis had a higher number of [F-18]fluorodeoxyglucose uptake sites in the vasculature (P = 0.001). Finally, patients with a National Institutes of Health score of ≥ 1 had significantly higher extra-vascular involvement (P = 0.008).

Conclusions

Extra-vessel [F-18]fluorodeoxyglucose uptake may be present in the context of Takayasu arteritis-related inflammatory processes. Information on extra-vascular [F-18]fluorodeoxyglucose uptake may be useful for detecting and evaluating inflammatory processes when interpreting positron emission tomography/computed tomography scans obtained from Takayasu arteritis patients.

Vasculo-Behçet disease complicated by conversion disorder diagnosed with 18F-fluoro-deoxy-glucose positron emission tomography combined with computed tomography (PET/CT)

Vasculitis in Behçet's disease, termed "vasculo-Behçet's disease," is a major cause of mortality and morbidity. We report a case of vasculo-Behçet's disease complicated by conversion disorder, in which ¹⁸F-fluoro-deoxy-glucose positron emission tomography combined with computed tomography (FDG PET/CT) was useful for the diagnosis. A twenty-two-year-old woman recently diagnosed with tonsillitis presented with fever, right foot pain, left equinovarus foot, and numbness in both hands and feet. Laboratory data showed elevated levels of c-reactive protein (CRP). The patient was positive for HLA B51; pathergy testing was also positive. Nerve conduction velocity and electromyography were normal. MRI showed swelling of the left crural muscle group. PET/CT showed intense FDG uptake in the left popliteal artery, demonstrating active vasculitis. The patient was diagnosed with vasculo-Behçet's disease and treated with corticosteroids, colchicine, and infliximab, which led to obvious improvement of the MRI findings and reduction in CRP. However, left equinovarus foot and numbness in the extremities persisted. She also developed aphonia. They were attributed to psychogenic dystonia and conversion disorder, and psychiatric treatment was effective in relieving those symptoms. We suggest that PET/CT may be useful for the early diagnosis of medium-sized vessel vasculitis in patients with Behçet's disease.

Diffusion-weighted Whole-body Imaging with Background Body Signal Suppression (DWIBS) as a Novel Imaging Modality for Disease Activity Assessment in Takayasu's Arteritis

A 26-year-old woman with Takayasu's arteritis (TAK) experienced back and neck pain during tocilizumab (TCZ) treatment. The levels of C-reactive protein were normal, and ultrasonography revealed no significant changes. Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) showed signal enhancement in the walls of several arteries. Contrast computed tomography showed arterial inflammation in the same lesion. After increasing the dose of prednisolone and TCZ, all signal enhancements decreased and continued to decrease, as observed on days 76 and 132. Thus, DWIBS may be a novel imaging modality for assessing the disease activity of TAK, particularly during follow-up.

F-18 FDG PET for assessment of disease activity of large vessel vasculitis: A systematic review and meta-analysis

BACKGROUND

The aim of this study is to investigate the performance of F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) or positron emission tomography/computed tomography (PET/CT) for the assessment of disease activity in patients with large vessel vasculitis (LVV) through a meta-analysis.

METHODS

The MEDLINE via PubMed and EMBASE were searched for the studies evaluating the performance of F-18 FDG PET or PET/CT in the assessment of disease activity in patients with LVV. Pooled sensitivity, specificity, diagnostic odds ratios (DORs), and summary receiver-operating characteristic (sROC) curve were estimated across the included studies. Possible publication bias was assessed by Deek's funnel plot asymmetry tests.

RESULTS

A total of 439 PET images from 298 patients pooled from nine studies showed that the pooled sensitivity was 0.88 [95% confidence interval (CI) 0.79-0.93] without heterogeneity (χ2 = 14.42, P = .07) and the pooled specificity was 0.81 (95% CI 0.64-0.91) with heterogeneity (χ2 = 63.72, P = .00) for the detection of active LVV. The pooled DOR was 30 (95% CI 8-107). Hierarchical sROC curve indicates that the area under the curve was 0.91 (95% CI 0.89-0.94). There was no significant publication bias (P = .42), and meta-regression analysis revealed that none of the variables was the source of the study heterogeneity.

CONCLUSIONS

F-18 FDG PET has a good performance for the detection of active disease status in patients with LVV. Revised criteria for the assessment of disease activity incorporated with F-18 FDG PET or PET/CT should be introduced and validated. Further studies are warranted to determine if PET-based treatment of LVV can improve outcomes.

Role of PET/CT in the Evaluation of Aortic Disease

Positron emission tomography (PET) /computed tomography (CT) has been established as a standard imaging modality in the evaluation of malignancy. Although PET/CT has played a major role in the management of oncology patients, its clinical use has also increased for various disorders other than malignancy. Growing evidence shows that PET/CT images have many advantages in aortic disease as well. This review article addresses the potential role of PET/CT in diseases involving the aorta, emphasizing its usefulness with regard to acute thoracic aortic syndromes, aortic aneurysm, atherosclerotic lesions, aortitis and aortic tumors.

Comparison of magnetic resonance angiography and 18F-fluorodeoxyglucose positron emission tomography in large-vessel vasculitis

OBJECTIVES

To assess agreement between interpretation of magnetic resonance angiography (MRA) and 18F-fluorodeoxyglucose positron emission tomography (PET) for disease extent and disease activity in large-vessel vasculitis (LVV) and determine associations between imaging and clinical assessments.

METHODS

Patients with giant cell arteritis (GCA), Takayasu's arteritis (TAK) and comparators were recruited into a prospective, observational cohort. Imaging and clinical assessments were performed concurrently, blinded to each other. Agreement was assessed by per cent agreement, Cohen's kappa and McNemar's test. Multivariable logistic regression identified MRA features associated with PET scan activity.

RESULTS

Eighty-four patients (GCA=35; TAK=30; comparator=19) contributed 133 paired studies. Agreement for disease extent between MRA and PET was 580 out of 966 (60%) arterial territories with Cohen's kappa=0.22. Of 386 territories with disagreement, MRA demonstrated disease in more territories than PET (304vs82, p<0.01). Agreement for disease activity between MRA and PET was 90 studies (68%) with Cohen's kappa=0.30. In studies with disagreement, MRA demonstrated activity in 23 studies and PET in 20 studies (p=0.76). Oedema and wall thickness on MRA were independently associated with PET scan activity. Clinical status was associated with disease activity by PET (p<0.01) but not MRA (p=0.70), yet 35/69 (51%) patients with LVV in clinical remission had active disease by both MRA and PET.

CONCLUSIONS

In assessment of LVV, MRA and PET contribute unique and complementary information. MRA better captures disease extent, and PET scan is better suited to assess vascular activity. Clinical and imaging-based assessments often do not correlate over the disease course in LVV.

TRIAL REGISTRATION NUMBER

NCT02257866.

Pulmonary vasculitis: diagnosis and endovascular therapy

Pulmonary vasculitides are caused by a heterogeneous group of diseases with different clinical features and etiologies. Radiologic manifestations depend on the predominant type of vessel involved, which are grouped into large, medium, or small-sized vessels. Diagnosing pulmonary vasculitides is a challenging task, and radiologists play an important role in their management by providing supportive evidence for diagnosis and opportunities for minimally invasive therapy. This paper aims to present a practical approach for understanding the vasculitides that can affect the pulmonary vessels and lungs. We will describe and illustrate the main radiologic findings, discussing opportunities for minimally invasive treatment.

FDG-PET/CT(A) imaging in large vessel vasculitis and polymyalgia rheumatica: joint procedural recommendation of the EANM, SNMMI, and the PET Interest Group (PIG), and endorsed by the ASNC

Large vessel vasculitis (LVV) is defined as a disease mainly affecting the large arteries, with two major variants, Takayasu arteritis (TA) and giant cell arteritis (GCA). GCA often coexists with polymyalgia rheumatica (PMR) in the same patient, since both belong to the same disease spectrum. FDG-PET/CT is a functional imaging technique which is an established tool in oncology, and has also demonstrated a role in the field of inflammatory diseases. Functional FDG-PET combined with anatomical CT angiography, FDG-PET/CT(A), may be of synergistic value for optimal diagnosis, monitoring of disease activity, and evaluating damage progression in LVV. There are currently no guidelines regarding PET imaging acquisition for LVV and PMR, even though standardization is of the utmost importance in order to facilitate clinical studies and for daily clinical practice. This work constitutes a joint procedural recommendation on FDG-PET/CT(A) imaging in large vessel vasculitis (LVV) and PMR from the Cardiovascular and Inflammation & Infection Committees of the European Association of Nuclear Medicine (EANM), the Cardiovascular Council of the Society of Nuclear Medicine and Molecular Imaging (SNMMI), and the PET Interest Group (PIG), and endorsed by the American Society of Nuclear Cardiology (ASNC). The aim of this joint paper is to provide recommendations and statements, based on the available evidence in the literature and consensus of experts in the field, for patient preparation, and FDG-PET/CT(A) acquisition and interpretation for the diagnosis and follow-up of patients with suspected or diagnosed LVV and/or PMR. This position paper aims to set an internationally accepted standard for FDG-PET/CT(A) imaging and reporting of LVV and PMR.

18F-FDG PET/MRI in the diagnosis of an infected aortic aneurysm

We report a case where an integrated whole body ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) is performed in the diagnostic work-up of a saccular aortic aneurysm. The integrated whole body ¹⁸F-FDG PET/MRI study answered all relevant diagnostic questions, clearly marking an infected aortic aneurysm, depicting the extent of the infected area in relation to the aortic branch vessels, and indicating the aortic lesion as the primary site of infection. The patient was successfully treated by open type V TAAA repair and pericardial graft replacement. Aortic wall infection was proven in cultures of the surgical specimen.

18 F-Fluorodeoxyglucose-Positron Emission Tomography As an Imaging Biomarker in a Prospective, Longitudinal Cohort of Patients With Large Vessel Vasculitis

OBJECTIVE

To assess the clinical value of ¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in a prospective cohort of patients with large vessel vasculitis (LVV) and comparator subjects.

METHODS

Patients with Takayasu arteritis and giant cell arteritis were studied, along with a comparator group consisting of patients with hyperlipidemia, patients with diseases that mimic LVV, and healthy controls. Participants underwent clinical evaluation and FDG-PET imaging, and patients with LVV underwent serial imaging at 6-month intervals. We calculated sensitivity and specificity of FDG-PET interpretation for distinguishing patients with clinically active LVV from comparator subjects and from patients with disease in clinical remission. A qualitative summary score based on global arterial FDG uptake, the PET Vascular Activity Score (PETVAS), was used to study associations between activity on PET scan and clinical characteristics and to predict relapse.

RESULTS

A total of 170 FDG-PET scans were performed in 115 participants (56 patients with LVV and 59 comparator subjects). FDG-PET distinguished patients with clinically active LVV from comparator subjects with a sensitivity of 85% (95% confidence interval [95% CI] 69, 94) and a specificity of 83% (95% CI 71, 91). FDG-PET scans were interpreted as active vasculitis in most patients with LVV in clinical remission (41 of 71 [58%]). Clinical disease activity status, disease duration, body mass index, and glucocorticoid use were independently associated with activity on PET scan. Among patients who underwent PET during clinical remission, future clinical relapse was more common in patients with a high PETVAS than in those with a low PETVAS (55% versus 11%; P = 0.03) over a median follow-up period of 15 months.

CONCLUSION

FDG-PET provides information about vascular inflammation that is complementary to, and distinct from, clinical assessment in LVV. FDG-PET scan activity during clinical remission was associated with future clinical relapse.

Takayasu Arteritis

Takayasu arteritis is an idiopathic granulomatous vasculitis of the aorta and its main branches and it constitutes one of the more common vasculitides in children. Inflammation and intimal proliferation lead to wall thickening, stenotic or occlusive lesions, and thrombosis, while destruction of the elastica and muscularis layers originates aneurysms and dissection. Carotid artery tenderness, claudication, ocular disturbances, central nervous system abnormalities, and weakening of pulses are the most frequent clinical features. The diagnosis is usually confirmed by the observation of large vessel wall abnormalities: stenosis, aneurysms, occlusion, and evidence of increased collateral circulation in angiography, MRA or CTA imaging. The purpose of this revision is to address the current knowledge on pathogenesis, investigations, classification, outcome measures and management, and to emphasize the need for timely diagnosis, effective therapeutic intervention, and close monitoring of this severe condition.

Effect of CRP value on 18F-FDG PET vascular positivity in Takayasu arteritis: a systematic review and per-patient based meta-analysis

PURPOSE

The aim of this study was to quantify the association between the CRP value and ¹⁸F-FDG PET vascular positivity in Takayasu arteritis (TAK) through a structured dedicated systematic review and meta-analysis.

METHODS

From January 2000 to December 2016, the PubMed/MEDLINE database was searched for articles specifically dealing with the assessment of vascular inflammation using ¹⁸F-FDG PET and CRP biomarkers in TAK. Inclusion criteria for the qualitative analysis were (1) ¹⁸F-FDG PET used to assess the disease activity, (2) The use of the ACR criteria for the diagnosis of TAK, (3) No case mixed vasculitis (i.e., no giant cell arteritis), and (4) CRP concentration and clinical disease activity available. For the meta-analysis, PET-positive and PET-negative subgroups with the corresponding CRP concentrations were generated based on per patient data. The standard mean difference, which represents the effect of the CRP concentrations on the ¹⁸F-FDG PET vascular uptake, was computed for all studies, and then the results were pooled together.

RESULTS

Among the 33 initial citations, nine complete articles including 210 patients fulfilled the inclusion criteria. Five studies found a significant correlation between the ¹⁸F-FDG PET and CRP concentration, one provided a trend towards association and three did not find any association between the two biomarkers. Six studies found a significant association between ¹⁸F-FDG PET and clinical disease activity, one found a trend towards association and the last two studies did not evaluate this correlation. The meta-analysis (121 patients) provided the following results: Standard Mean Deviation = 0.54 [0.15;0.92]; Chi² = 3.35; I² = 0%; Test for overall effect: Z = 2.70 (P = 0.007).

CONCLUSION

The CRP concentration only moderately reflects the ¹⁸F-FDG PET vascular positivity in TAK, suggesting dissociated information. Standardized longitudinal prospective studies are necessary to assess the value of ¹⁸F-FDG PET as an independent biomarker for subtle vascular wall inflammation detection.

Application of imaging techniques for Takayasu arteritis

Arterial injury with subsequent remodelling and predisposition to arterial stenosis and/or dilation are the hallmarks of Takayasu arteritis. The degree of arterial damage closely aligns with prognosis and therefore its prevention is the predominant aim of therapy. Non-invasive imaging has greatly improved our ability to identify the extent and severity of disease and to monitor its progress. However, many questions remain concerning the optimal use of individual modalities at different stages of disease. Imaging methods for the quantification of arterial damage are lacking. Likewise, no single technique can accurately determine disease activity within the arterial wall or distinguish inflammatory and non-inflammatory disease progression. The aim of this review is to outline current imaging strategies in Takayasu arteritis, their individual roles in diagnosis and disease monitoring and potential future advances.

Monitoring Disease Activity in Patients with Aortitis and Chronic Periaortitis Undergoing Immunosuppressive Therapy by Perfusion CT

RATIONALE AND OBJECTIVES

To evaluate the role of perfusion CT for monitoring inflammatory activity in patients with aortitis and chronic periaortitis undergoing immunosuppressive therapy.

MATERIALS AND METHODS

Seventeen symptomatic patients (median age 68.5 years) who underwent perfusion-based computed tomography (CT) monitoring after diagnostic contrast-enhanced CT were retrospectively included in this study. Blood flow (BF), blood volume (BV), volume transfer constant (k-trans), time to peak, and mean transit time were determined by setting circular regions of interest in prominently thickened parts of the vessel wall or perfused surrounding tissue at sites where the perfusion CT color maps showed a maximum BF value. Differences in CT perfusion and, morphological parameters, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were tested for significance during therapy.

RESULTS

In all patients BF and BV dropped at second perfusion CT (P < 0.05). In aortitis patients, CRP dropped from 3.86 ± 5.31 mg/dL to 0.9 ± 1.37 mg/dL and in periaortitis patients from 1.78 ± 2.25 mg/dL to 0.79 ± 1.55 mg/dL, whereas ESR dropped from 45.71 ± 37.59 seconds to 8.57 ± 3.1 seconds and 36.78 ± 34.67 seconds to 17.22 ± 21.82 seconds in aortitis and in periaortitis, respectively.

CONCLUSIONS

The course of perfusion CT parameters in aortitis and chronic periaortitis undergoing immunosuppressive therapy dropped at different extent after therapy.

18F-FDG-PET/CT in unexplained elevated inflammatory markers. Joining entities

The diagnostic strategy in patients with fever or inflammation of unknown origin remains a major clinical challenge. The aim of this study was to evaluate the role of ¹⁸F-FDG-PET/CT in patients with unexplained elevated C-reactive protein with or without fever. Contribution of ¹⁸F-FDG-PET/CT to the final diagnosis was evaluated. In addition we determined whether a differentiation between patients with or without fever is clinically reasonable.

PATIENTS, METHODS

We retrospectively analysed 72 consecutive patients with unexplained elevated C-reactive protein levels (above 8mg/l) that underwent ¹⁸F-FDG-PET/CT in our facility between 10/2009 and 11/2012. ¹⁸F-FDG-PET/CT was considered a so-called diagnostic scan when results decisively led to a final diagnosis and adequate therapy with a response of symptoms was initiated due to the PET/CT result.

RESULTS

In 60/72 patients (83%) a final diagnosis was established. Diagnoses included infections (58%), non-infectious inflammatory diseases (29%) and malignancies (8%). ¹⁸F-FDG-PET/CT was true positive in 47 cases (65%) and the diagnostic scan in 29 patients (40%). Sensitivity of ¹⁸F-FDG-PET/CT was 81% and specificity was 86%. Diagnostics, final diagnoses, ¹⁸F-FDG-PET/CT results, SUVmax, C-reactive protein levels and the diagnostic scan did not differ significantly between patients with fever and patients without fever.

CONCLUSION

¹⁸F-FDG-PET/CT is a useful method in the diagnostic workup of patients with inflammation of unknown origin. In our series there was no significant difference between patients with or without fever. Regarding ¹⁸F-FDG-PET/CT-imaging inflammation of unknown origin and unexplained fever can be joined to one entity.

Assessment of Therapy Response by FDG PET in Infection and Inflammation

Positron emission tomography (PET) is a well-known imaging modality in assessing the treatment response to chemotherapy or radiotherapy in various malignancies. A systematic review of the literature reveals a few publications reporting evaluation of the treatment response in benign conditions using PET/computed tomography. PET holds a promising future role in the follow-up of inflammatory or infectious diseases. In this article, [(18)F]Fluorodeoxyglucose PET as a tool in the evaluation, treatment, and follow-up of infectious and inflammatory diseases is discussed.

Cardiovascular magnetic resonance in rheumatology: Current status and recommendations for use

Targeted therapies in connective tissue diseases (CTDs) have led to improvements of disease-associated outcomes, but life expectancy remains lower compared to general population due to emerging co-morbidities, particularly due to excess cardiovascular risk. Cardiovascular magnetic resonance (CMR) is a noninvasive imaging technique which can provide detailed information about multiple cardiovascular pathologies without using ionizing radiation. CMR is considered the reference standard for quantitative evaluation of left and right ventricular volumes, mass and function, cardiac tissue characterization and assessment of thoracic vessels; it may also be used for the quantitative assessment of myocardial blood flow with high spatial resolution and for the evaluation of the proximal coronary arteries. These applications are of particular interest in CTDs, because of the potential of serious and variable involvement of the cardiovascular system during their course. The International Consensus Group on CMR in Rheumatology was formed in January 2012 aiming to achieve consensus among CMR and rheumatology experts in developing initial recommendations on the current state-of-the-art use of CMR in CTDs. The present report outlines the recommendations of the participating CMR and rheumatology experts with regards to: (a) indications for use of CMR in rheumatoid arthritis, the spondyloarthropathies, systemic lupus erythematosus, vasculitis of small, medium and large vessels, myositis, sarcoidosis (SRC), and scleroderma (SSc); (b) CMR protocols, terminology for reporting CMR and diagnostic CMR criteria for assessment and quantification of cardiovascular involvement in CTDs; and (c) a research agenda for the further development of this evolving field.

MRI parametric monitoring of biological therapies in primary large vessel vasculitides: a pilot study

OBJECTIVE

To evaluate the development of characteristic MRI changes in patients with primary large-vessel vasculitis (LVV) when treated with biological therapies.

METHODS

12 patients with primary LVV (8 patients with Takayasu arteritis and 4 patients with giant-cell arteritis) received biological therapy with tumour necrosis factor-α blockers (n = 9) or an interleukin-6 inhibitor (n = 3). MRI investigations were performed at baseline (pre-treatment) and follow-up. All patients underwent the same MRI/MR angiography (MRA) protocol. Laboratory parameters (C-reactive protein and erythrocyte sedimentation rate) and clinical response (Birmingham Vasculitis Activity Score) were assessed.

RESULTS

Wall thickness was 4.2 ± 0.3 mm pre-treatment and significantly decreased to 3.2 ± 0.3 mm post treatment in 9/12 patients. Mural enhancement was increased in all 12/12 patients with LVV, and subsided with therapy in 5/12 patients. Mural oedema or ill-defined contour were less prevalent but also improved with biological treatment. C-reactive protein and erythrocyte sedimentation rate levels decreased, and clinical assessment revealed a significant improvement from pre-treatment to post-treatment. However, the course of imaging characteristics often did not parallel that of laboratory or clinical parameters. In all three patients receiving interleukin-6 blockade, laboratory markers and clinical scores normalized despite persistent vascular inflammation in one patient which was disclosed by MRI.

CONCLUSION

Contrast-enhanced MRI/MRA may be useful when evaluating the development of disease activity in primary LVV under biological therapies. A high degree of suspicion and regular imaging follow-up is needed to detect persistent inflammation.

ADVANCES IN KNOWLEDGE

This is the first study investigating the applicability of different MRI/MRA parameters for monitoring biological therapy in patients with primary LVV.

Outcome assessment in Takayasu arteritis

Takayasu arteritis (TAK) is a systemic granulomatous large-vessel vasculitis with a phenotype that overlaps with GCA and defined by the 1993 and 2012 Chapel Hill Consensus Conference statements. However, the diagnosis of TAK is often delayed since TAK patients may be asymptomatic or have non-specific symptoms. Once a diagnosis is made, it is difficult to judge remission or recurrence since there are no reliable assessment tools. With the availability of newer agents, such as cytokine blockade, which are being evaluated in GCA, there is the potential for real advances in TAK patient management. Without reliable assessment tools it will be difficult to introduce newer agents in an organized way or to optimally benefit patients in the future. In this article we review the use and performance of disease indicators in TAK clinical trials as a basis for the further development of assessment tools for this disease.

(18)F-Fluorodeoxyglucose positron emission tomography and serum cytokines and matrix metalloproteinases in the assessment of disease activity in Takayasu's arteritis

OBJECTIVE

To evaluate (18)F-fluorodeoxyglucose ((18)F-FDG) uptake on positron emission tomography-computed tomography (PET-CT) and serum levels of different cytokines and matrix metalloproteinases (MMPs) in patients with Takayasu arteritis (TA) and associations with disease activity.

METHODS

Serum levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-2, IL-6, IL-8, IL-12, IL-18, MMP-3 and MMP-9 were measured in 36 TA patients and 36 controls. Maximum standard uptake value (SUVmax) of (18)F-FDG in arterial walls was determined by PET-CT scans. TA patients were classified as active disease, inactive disease and possible active disease.

RESULTS

Serum IL-6 and MMP-3 levels were higher in TA patients than in controls (p<0.001). Serum IL-6 was higher in patients with active disease and in patients with possible active disease than in inactive disease (p<0.0001). Patients with active disease had higher serum TNFα levels than patients with inactive disease (p=0.049) while patients with possible active disease presented higher IL-18 levels than patients with inactive disease (p=0.046). Patients with active disease had higher SUVmax values than those with inactive disease (p=0.042). By receiver operating characteristic (ROC) curve SUVmax was predictive of active disease in TA and values ≥1.3 were associated with disease activity (p=0.039). Serum TNF-α levels were higher in patients with SUVmax≥1.3 than <1.3 (p=0.045) and controls (p=0.012). Serum IL-6 levels were higher in patients with SUVmax≥1.3 than in controls (p<0.001). No differences regarding other biomarkers were found between TA patients and controls.

CONCLUSIONS

Higher serum IL-6 and TNFα levels as well as higher (18)F-FDG uptake in arterial wall are associated with active TA.

Use of positron emission tomography (PET) for the diagnosis of large-vessel vasculitis

The term vasculitis encompasses a heterogeneous group of diseases that share the presence of inflammatory infiltrates in the vascular wall. The diagnosis of large-vessel vasculitis is often a challenge because the presenting clinical features are nonspecific in many cases and they are often shared by different types of autoimmune and inflammatory diseases including other systemic vasculitides. Moreover, the pathogenesis of large-vessel vasculitis is not fully understood. Nevertheless, the advent of new imaging techniques has constituted a major breakthrough to establish an early diagnosis and a promising tool to monitor the follow-up of patients with largevessel vasculitis. This is the case of the molecular imaging with the combination of positron emission tomography with computed tomography (PET/CT) using different radiotracers, especially the (18)F-fluordeoxyglucose ((18)F-FDG). In this review we have focused on the contribution of (18)F-FDG PET in the diagnosis of large-vessel vasculitis.