Resolution of vascular inflammation in patients with new-onset giant cell arteritis: data from the RIGA study

Innovations in Imaging: 18F-Fluorodeoxyglucose PET/CT for Assessment of Cardiovascular Infection and Inflammation

PURPOSE OF REVIEW

18F-Fluorodeoxyglucose positron emission tomography (PET) combined with computed tomography (CT), referred to as 18F-FDG PET/CT, plays a significant role in the diagnosis and management of patients with systemic infectious and inflammatory conditions. This review provides an overview of 18F-FDG PET/CT in systemic infectious and inflammatory conditions, including infective endocarditis (IE), cardiac implantable electrical device (CIED)/left ventricular assist device (LVAD) infection, sarcoidosis, and large-vessel vasculitis (LVV).

RECENT FINDINGS

This review highlights the past and present literature in the increasing role of 18F-FDG PET/CT in cardiovascular inflammation and infection, including diagnostic and prognostic findings. They key aspects of this paper are to highlight the importance of 18F-FDG PET/CT in cardiovascular infection and inflammation, and to provide illustrations of how it can contribute to patient diagnosis and management.

Imaging in vasculitis

PURPOSE OF REVIEW

Systemic vasculitides are characterized by inflammation of blood vessels. Their classification is based on the size of the blood vessels involved - large, medium, or small. Vasculitis early diagnosis and reliable monitoring are crucial to establish a treatment plan and prevent serious complications. Based on these considerations and depending on the location of the affected vessels, the importance of imaging modalities including ultrasonography (US), magnetic resonance Imaging (MRI), magnetic resonance angiography (MRA), computed tomography (CT), computed tomography angiography (CTA), and [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) has progressively increased. In addition to physical exam and laboratory data, these imaging tools offer complementary information about vascular changes occurring in vasculitis.This review summarizes the different imaging modalities being utilized to diagnose and monitor vasculitis.

RECENT FINDINGS

The most recent update for the use of imaging in vasculitis is referenced in the 2023 European Alliance of Associations for Rheumatology (EULAR) recommendations and the American College of Rheumatology (ACR) guidelines in 2021. Recent advances in PET imaging in large vessel vasculitis include improved technological imaging acquisition and the use of novel radiotracers for cellular and immune targets. FDG-PET has now been demonstrated to have high sensitivity and specificity to detect temporal arteritis.

SUMMARY

Imaging plays a significant role in the evaluation of vasculitis and continues to gain importance in the diagnosis and monitoring of disease activity. Differences exist between the ACR guidelines, which advocates for temporal artery biopsy, and the EULAR guidelines, which favors imaging modalities for the initial evaluation and diagnosis of large vessel vasculitis (LVV). Prerequisites for appropriate clinical management utilizing imaging in patients with vasculitis are the availability and access to skilled clinicians to interpret the images and the cost of these techniques not being prohibitive.

Advances in PET Imaging of Large Vessel Vasculitis: An Update and Future Trends

Systemic vasculitides are autoimmune diseases characterized by inflammation of blood vessels. They are categorized based on the size of the preferentially affected blood vessels: large-, medium-, and small-vessel vasculitides. The main forms of large-vessel vasculitis include giant cell arteritis (GCA) and Takayasu arteritis (TAK). Depending on the location of the affected vessels, various imaging modalities can be employed for diagnosis of large vessel vasculitis: ultrasonography (US), magnetic resonance angiography (MRA), computed tomography angiography (CTA), and [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT). These imaging tools offer complementary information about vascular changes occurring in vasculitis. Recent advances in PET imaging in large vessel vasculitis include the introduction of digital long axial field-of-view PET/CT, dedicated acquisition, quantitative methodologies, and the availability of novel radiopharmaceuticals. This review aims to provide an update on the current status of PET imaging in large vessel vasculitis and to share the latest developments on imaging vasculitides.

Faster steroid-free remission with tocilizumab compared to methotrexate in giant cell arteritis: a real-life experience in two reference centres

Glucocorticoids (GCs) are still the mainstay of treatment of giant cell arteritis (GCA). Although GCs are highly effective in GCA, the high burden of toxicity of GCs as well as the disease relapse during GC tapering is well documented. To compare the efficacy and rapidity of TCZ and MTX as steroid-sparing agents in a real-life cohort of GCA patients. A retrospective analysis was conducted including patients with newly diagnosed GCA from the Rheumatology Units of Udine and Rome. The inclusion criterion was the treatment with TCZ or MTX as first steroid-sparing drug. 112 GCA patients (81 females) with a median age of 70 (IQ 65-75) years were collected. Thirty-one out of 112 (27.7%) patients were treated with TCZ (162 mg/week), while 81/112 (72.3%) patients received MTX (up to 20 mg/week) as a GC-sparing agent. At month 6 after GCA onset, 5/31 (16.1%) patients in TCZ group and none in MTX group were in GC-free sustained remission (p value = 0.001). Similarly, at month 12, 64.5% (20/31) and 11.1% (9/81) of patients were in sustained GC-free remission in TCZ and MTX group, respectively (p value <0.001). At month 24 of follow-up, at least one relapse of the disease occurred in 7/31 (22.6%) in TCZ-treated and 28/81 (34.6%) in MTX-treated patients, respectively (p value = 0.22). TCZ allowed a faster discontinuation of steroid therapy than MTX in GCA patients, without increasing the risk of relapse.

Prognostic value of 18 FDG-PET at diagnosis and follow-up in giant cell arteritis: An observational restrospective study

OBJECTIVES

To evaluate the ability of 18FDG PET/CT, at diagnosis of giant cell arteritis (GCA) and during follow-up, to predict occurrence of relapse in large-vessel GCA (LV-GCA).

METHODS

We conducted a retrospective study using the French Study Group for Large-Vessel Vasculitis (GEFA) network. Data from patients with LV-GCA diagnosed by PET/CT and who had PET/CT in the following year were collected. For each PET/CT, PET vascular activity score (PETVAS) and total vascular score (TVS) were assessed, and their ability to predict the occurrence of subsequent relapse was assessed.

RESULTS

A total of 65 LV-GCA patients were included, of whom 55 had undergone a follow-up PET/CT 3 to 12 months after the diagnosis of GCA. Patients for whom the second PET/CT (PET2) was performed during active GCA were excluded. PETVAS and TVS decreased between PET1 and PET2 in all patients (p < 0.001). There was no correlation between vascular activity scores in PET2 and time to prednisone taper. For relapse prediction, at PET1, the AUC of the TVS and PETVAS were respectively 51.9 and 41.9 at 6 months, 55.3 and 49.7 at 1 year, 55 and 55.7 at 2 years. For PET2, the AUC were respectively 46.1 and 46.7 at 6 months, 52.1 and 48.9 at 1 year, 58.4 and 52.3 at 2 years.

CONCLUSION

PET vascular activity scores at diagnosis and at follow-up PET/CT performed outside a period of GCA activity do not display high performance to predict the occurrence of subsequent relapse in LV-GCA patients.

Current management of giant cell arteritis and its complications

PURPOSE OF THE REVIEW

This review provides an update on current management strategies for giant cell arteritis (GCA), emphasizing the need for alternative therapies to reduce disease relapses and mitigate glucocorticoid (GC)-related morbidity.

RECENT FINDINGS

The standard of care for GCA has traditionally involved prolonged use of GC, and recent studies are exploring faster GC tapering regimens in an effort to reduce adverse effects while maintaining disease control. Randomized clinical trials have highlighted the efficacy of tocilizumab (TCZ), an interleukin-6 receptor inhibitor, in reducing disease flares and sparing GCs. However, the optimal treatment duration with TCZ is unknown and patients remain at risk of relapse after treatment discontinuation. An unmet therapeutic need persists for patients who are not candidates for TCZ, and for those who have inadequate response to this biologic. Therefore, investigations into alternative therapies such as targeting interleukin-17A, blocking T-cell activation or inhibiting the Janus kinase-signal transducer and activator of transcription pathway, showcase potential avenues for tailored treatments.

SUMMARY

While GCs remain the cornerstone of therapy, TCZ emerges as a promising GC-sparing agent. Ongoing research targeting different pathways implicated in GCA pathogenesis have led to encouraging results. However, the preliminary nature of these findings necessitates larger randomized controlled trials to establish their efficacy conclusively.

Relapses in giant cell arteritis: Updated review for clinical practice

Giant cell arteritis (GCA), the most common primary vasculitis in adults, is a granulomatous systemic vasculitis usually affecting the aorta and its major branches, particularly the carotid and vertebral arteries. Although remission can be achieved in most patients with GCA using high-dose glucocorticoids (GC), relapses are frequent, occurring in >40% of GC-only treated patients, mostly during the first two years after diagnosis. Relapsing courses lead to high GC exposure, increasing the risk of treatment-related adverse effects. Although tocilizumab is an efficacious GC-sparing therapy that allows increased sustained remission and reduced cumulative GC doses, relapses are common after drug discontinuation. This narrative review examines the most relevant features of relapses in GCA, including its definition, classification, frequency, clinical, laboratory, and imaging characteristics, chronology, probable pathophysiology, and predictive factors. In addition, we discuss treatment options for relapsing patients and the effect of relapses on patient outcomes.

Molecular imaging of large vessel vasculitis

Large vessel vasculitis (LVV) affects mainly large arteries with giant cell arteritis (GCA) and Takayasu arteritis (TAK) being the two most frequent forms. Clinical symptoms can be non-specific, including headache, fatigue, weight loss, and change in vision. Untreated, LVV may also lead to serious complications such as blindness, aortic aneurysm and dissection. Therefore, rapid recognition of the disease leading to accurate diagnosis and appropriate treatment is essential. FDG-PET/CT imaging has emerged as a sensitive marker of active vascular inflammation and its use in the management of LVV is now integrated in guidelines. In this article, we will discuss the role of FDG-PET/CT for the diagnosis of LVV and monitoring of therapy, as well as review technical and interpretation parameters.

Large vessel giant cell arteritis

Giant cell arteritis is the principal form of systemic vasculitis affecting people over 50. Large-vessel involvement, termed large vessel giant cell arteritis, mainly affects the aorta and its branches, often occurring alongside cranial giant cell arteritis, but large vessel giant cell arteritis without cranial giant cell arteritis can also occur. Patients mostly present with constitutional symptoms, with localising large vessel giant cell arteritis symptoms present in a minority of patients only. Large vessel giant cell arteritis is usually overlooked until clinicians seek to exclude it with imaging by ultrasonography, magnetic resonance angiography (MRA), computed tomography angiography (CTA), or [18F]fluorodeoxyglucose-PET-CT. Although the role of imaging in treatment monitoring remains uncertain, imaging by MRA or CTA is crucial for identifying aortic aneurysm formation during patient follow up. In this Series paper, we define the large vessel subset of giant cell arteritis and summarise its clinical challenges. Furthermore, we identify areas for future research regarding the management of large vessel giant cell arteritis.

PET/CT in Inflammatory and Auto-immune Disorders: Focus on Several Key Molecular Concepts, FDG, and Radiolabeled Probe Perspectives

Chronic immune diseases mainly include autoimmune and inflammatory diseases. Managing chronic inflammatory and autoimmune diseases has become a significant public health concern, and therapeutic advancements over the past 50 years have been substantial. As therapeutic tools continue to multiply, the challenge now lies in providing each patient with personalized care tailored to the specifics of their condition, ushering in the era of personalized medicine. Precise and holistic imaging is essential in this context to comprehensively map the inflammatory processes in each patient, identify prognostic factors, and monitor treatment responses and complications. Imaging of patients with inflammatory and autoimmune diseases must provide a comprehensive view of the body, enabling the whole-body mapping of systemic involvement. It should identify key cellular players in the pathology, involving both innate immunity (dendritic cells, macrophages), adaptive immunity (lymphocytes), and microenvironmental cells (stromal cells, tissue cells). As a highly sensitive imaging tool with vectorized molecular probe capabilities, PET/CT can be of high relevance in the management of numerous inflammatory and autoimmune diseases. Relying on key molecular concepts of immunity, the clinical usefulness of FDG-PET/CT in several relevant inflammatory and immune-inflammatory conditions, validated or emerging, will be discussed in this review, together with radiolabeled probe perspectives.

Development of the Takayasu Arteritis Integrated Disease Activity Index

OBJECTIVE

Accurate clinical assessment of disease activity in Takayasu arteritis (TAK) can be challenging. 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) can directly measure vascular inflammation. This study details the development of a new type of disease activity index called the Takayasu's Arteritis Integrated Disease Activity Index (TAIDAI).

METHODS

Clinical symptoms for TAIDAI were identified from a literature review. Each symptom was paired with FDG-PET findings in corresponding arterial territories. Constitutional symptoms were paired with acute phase reactant levels. One point was given for each clinical symptom paired with supporting FDG-PET or laboratory abnormalities and summed into the TAIDAI score. A TAIDAI of ≥1 defined active disease. To assess performance of TAIDAI, face validity, content validity, and sensitivity to change were evaluated within a prospective observational cohort study of patients with TAK.

RESULTS

Seventeen clinical symptoms were paired with imaging or laboratory abnormalities. In a cohort of 96 patients contributing 204 study visits, TAIDAI showed excellent sensitivity (96.3%) and good specificity (79.2%) compared to physician's clinical assessment. TAIDAI significantly correlated with physician global assessment, PET Vascular Activity Score, patient global assessment, and acute phase reactant levels. In patients treated with either tumor necrosis factor inhibitors or tocilizumab, a TAIDAI of 0 was achieved in 21 (91%) of 23 patients who met a predefined definition of clinical response.

CONCLUSION

TAIDAI is new type of disease activity index in TAK in which clinical symptoms are integrated with specific laboratory and imaging findings. TAIDAI should be validated in future randomized controlled trials in TAK.

Establishing clinical remission criteria for giant cell arteritis: Results of a Delphi exercise carried out by an expert panel of the Japan Research Committee of the Ministry of Health, Labour, and Welfare for Intractable Vasculitis

OBJECTIVE

To develop a proposal for giant cell arteritis remission criteria in order to implement a treat-to-target algorithm.

METHODS

A task force consisting of 10 rheumatologists, 3 cardiologists, 1 nephrologist, and 1 cardiac surgeon was established in the Large-vessel Vasculitis Group of the Japanese Research Committee of the Ministry of Health, Labour and Welfare for Intractable Vasculitis to conduct a Delphi survey of remission criteria for giant cell arteritis. The survey was circulated among the members over four reiterations with four face-to-face meetings. Items with a mean score of ≥4 were extracted as items for defining remission criteria.

RESULTS

An initial literature review yielded a total of 117 candidate items for disease activity domains and treatment/comorbidity domains of remission criteria, of which 35 were extracted as disease activity domains (systematic symptoms, signs and symptoms of cranial and large-vessel area, inflammatory markers, and imaging findings). For the treatment/comorbidity domain, ≤5 mg/day of prednisolone 1 year after starting glucocorticoids was extracted. The definition of achievement of remission was the disappearance of active disease in the disease activity domain, normalization of inflammatory markers, and ≤5 mg/day of prednisolone.

CONCLUSION

We developed proposals for remission criteria to guide the implementation of a treat-to-target algorithm for giant cell arteritis.

Effectiveness and safety of a 26-week taper regimen of glucocorticoid in GCA patients: Results from a prospective cohort study

OBJECTIVES

To assess the effectiveness and safety of the 26-week tapering regimen of glucocorticoids (GC) used in the GiACTA trial in a prospective cohort of treatment-naive, biopsy-proven GCA patients.

METHODS

Patients with a new diagnosis of biopsy-proven GCA enrolled in the GC arm of the START project (molecular stratification of patients with GCA to tailor GC and tocilizumab therapy) were included. All patients were treated with the 26-week taper regimen of GC used in the GiACTA trial. The primary endpoint was the rate of relapse-free remission at week 52. The secondary endpoints were the proportion of patients with incident aortic damage, cumulative GC doses and GC-related adverse events (AE).

RESULTS

22 patients were included between December 2018 and February 2022. At week 52, 10 patients (45 %, 95 % CI 24-68) were in relapse-free remission. After a median (IQR) follow-up of 35 (22-40) months, 7 patients (32 %, 95 % CI 14-55) were in relapse-free remission. 18 patients with baseline large-vessel imaging underwent CT angiography at the end of the follow-up. No patients had evidence of new aortic dilation, significant progression of aortic damage or large vessel stenosis. 15/22 patients (68 %) had at least one relapse during follow-up. No patients developed visual or cerebrovascular manifestations during relapses. 15/22 (68 %) patients had at least one GC-related AE.

CONCLUSIONS

A 26 week taper regimen of GC was effective and safe in inducing and maintaining remission in a sizeable proportion of newly diagnosed GCA patients. However, the frequency of GC-related adverse events was high.

Treatment of giant cell arteritis with ultra-short glucocorticoids and tocilizumab: the role of imaging in a prospective observational study

OBJECTIVES

To assess the impact of tocilizumab (TCZ) monotherapy after ultra-short-pulse glucocorticoids (GCs) on clinical manifestations, and vessel inflammation and damage in large vessel-GCA (LV-GCA).

METHODS

In this prospective observational study, we enrolled patients with active LV-GCA. All patients received 500 mg per day i.v. methylprednisolone for three consecutive days and weekly s.c. TCZ injections from day 4 until week 52. PET/CT was performed on all patients at baseline and at weeks 24 and 52. The primary end points were the reduction in the PET vascular activity score (PETVAS) at weeks 24 and 52 compared with baseline, and the proportion of patients with relapse-free remission at weeks 24 and 52. The secondary end point was the proportion of patients with new aortic dilation at weeks 24 and 52.

RESULTS

A total of 18 patients were included (72% female, mean age 68.5 years). Compared with the baseline value, a significant reduction in the PETVAS was observed at weeks 24 and 52, mean (95% CI) reductions -8.6 (-11.5 to -5.7) and -10.4 (-13.6 to -7.2), P = 0.001 and 0.002, respectively. The proportion of patients with relapse-free remission at weeks 24 and 52 was 10/18 (56%, 95% CI 31-78) and 8/17 (47%, 95% CI 23-72), respectively. At weeks 24 and 52, no patient had shown new aortic dilation. However, 4 patients who had shown aortic dilation at baseline showed a significant increase in aortic diameter (≥5 mm) at week 52.

CONCLUSION

TCZ monotherapy after ultra-short-pulse GCs controlled the clinical symptoms of GCA and reduced vascular inflammation.

TRIAL REGISTRATION

ClinicalTrials.gov, https://clinicaltrials.gov, NCT05394909.

Association between the patterns of large-vessel lesions and treatment outcomes in patients with large-vessel giant cell arteritis

OBJECTIVES

We aimed to identify associations between patterns of large-vessel lesions of large-vessel giant cell arteritis (LV-GCA) and treatment outcomes.

METHODS

We extracted data on 68 newly diagnosed patients with LV-GCA from a retrospective, multi-centric, nationwide registry of GCA patients treated with glucocorticoids between 2007 and 2014. Patients with aortic lesions were identified based on the findings from contrast-enhanced computed tomography, magnetic resonance imaging, or positron emission tomography-computed tomography (Group 2, n = 49). Patients without aortic lesions were subdivided into LV-GCA with or without subclavian lesions defined as Group 1 (n = 9) or Group 3 (n = 10), respectively. The primary outcome evaluation was failure to achieve clinical remission by Week 24 and/or relapse within 104 weeks.

RESULTS

The mean age and proportion of patients with cranial lesions and polymyalgia rheumatica in Group 2 were numerically lower than in the other two groups. Large-vessel lesions in Group 3 included carotid, pulmonary, renal, hepatic, or mesenteric lesions. The cumulative rate of poor treatment outcomes >2 years was 11.1%, 55.3%, and 88.0% in Groups 1, 2, and 3, respectively (by Kaplan-Meier analysis). The mean time to poor outcome was significantly different between the groups.

CONCLUSIONS

Classification by subclavian and aortic lesions may be useful to determine treatment strategy.

Persistent aortic inflammation in patients with giant cell arteritis

OBJECTIVES

To investigate the clinicopathologic features of patients with giant cell arteritis (GCA) who had thoracic aorta aneurysm or dissection surgery.

METHODS

Patients who had thoracic aorta surgery between January 1, 2000, and December 31, 2021, at the Mayo Clinic, Rochester, Minnesota, were identified with current procedural terminology (CPT) codes. The identified patients were screened for a prior diagnosis of GCA with diagnostic codes and electronic text search. The available medical records of all the patients of interest were manually reviewed. Thoracic aorta tissues obtained during surgery were re-evaluated in detail by pathologists. The clinicopathologic features of these patients were analyzed. Overall observed survival was compared with lifetable rates from the United States population.

RESULTS

Of the 4621 patients with a CPT code for thoracic aorta surgery, 49 had a previous diagnosis of GCA. Histopathologic evaluation of the aortic tissue revealed active aortitis in most patients with GCA (40/49, 82%) after a median (IQR) of 6.0 (2.6-10.3) years from GCA diagnosis. All patients were considered in clinical remission at the time of aortic surgery. The overall mortality compared to age and sex-matched general population was significantly increased with a standardized mortality ratio of 1.55 (95% CI, 1.05-2.19).

CONCLUSION

Histopathologic evaluation of the thoracic aorta obtained during surgery revealed active aortitis in most patients with GCA despite being considered in clinical remission several years after GCA diagnosis. Chronic, smoldering aortic inflammation likely contributes to the development of aortic aneurysm and dissection in GCA.

PET-Derived Increased Inflammation in Large Vessels is linked to Relapse-Free Survival in Patients with Giant Cell Arteritis

BACKGROUND

 Despite anti-inflammatory treatment, patients with giant cell arteritis (GCA) experience relapse. We aimed to determine respective relapse predictors focusing on [18F]fluorodeoxyglucose ([18F]FDG)-PET-based parameters.

MATERIAL AND METHODS

 21 therapy-naïve GCA patients received [18F]FDG-PET/CT. Patients were divided in two groups: those who relapsed during course of disease and those who did not. Median follow up was 15 months. [18F]FDG-PET/CT was analyzed for visual (PET vascular activity score [VAS]) and quantitative parameters, including Target-to-background-Ratio with liver (TBRliver) and jugular vein (TBRjv) serving as reference tissues. In addition, clinical parameters were tested.

RESULTS

 8/21 (38.1 %) had relapse. Clinical parameters could not significantly discriminate between relapse vs no-relapse, including age (p = 0.9) or blood-based inflammatory markers (white blood cell counts [WBC] and c-reactive protein [CRP], p = 0.72, each). PETVAS score could also not differentiate between respective subgroups (p = 0.59). In a quantitative assessment, TBRjv demonstrated a trend towards significance (p = 0.28). TBRliver, however, separated between patients with and without relapse (p = 0.03).

CONCLUSION

 [18F]FDG PET quantification of vessels may be useful to identify GCA patients prone to relapse during follow-up.

Measuring treatment outcomes and change in disease activity in giant cell arteritis: a systematic literature review informing the development of the EULAR-ACR response criteria on behalf of the EULAR-ACR response criteria in giant cell arteritis task force

OBJECTIVES

To identify criteria and descriptors used to measure response to treatment and change in disease activity in giant cell arteritis (GCA).

METHODS

A systematic literature review (SLR) to retrieve randomised controlled trials (RCTs) and longitudinal observational studies (LOS). Criteria and descriptors of active disease, remission, response, improvement, worsening and relapse were extracted. RCTs, LOS with >20 subjects, and qualitative research studies were included.

RESULTS

10 593 studies were retrieved, of which 116 were included (11 RCTs, 104 LOS, 1 qualitative study). No unified definition of response to therapy was found. Most RCTs used composite endpoints to assess treatment outcomes. Active disease was described in all RCTs and 19% of LOS; and was largely defined by a combination of clinical and laboratory components. Remission was reported in 73% of RCTs and 42% of LOS; It was predominantly defined as the combination of clinical and laboratory components. One LOS reported response with a definition resembling the definition of remission from other studies. Improvement was rarely used as an endpoint and it was mostly a surrogate of remission. No study specifically defined worsening. Relapse was reported in all RCTs and 86% of LOS. It was predominantly defined as the combination of clinical, laboratory and treatment components.

CONCLUSIONS

The results of this SLR demonstrate that definitions of response used in clinical studies of GCA are scant and heterogeneous. RCTs and LOS mainly used remission and relapse as treatment outcomes. The descriptors identified will inform the development of the future European Alliance of Associations for Rheumatology-American College of Rheumatology response criteria for GCA.

The role of PET/CT in disease activity assessment in patients with large vessel vasculitis

PURPOSE OF REVIEW

The aim of this article was to review the recent contributions on the role of PET in assessing disease activity in patients with large-vessel vasculitis (giant cell arteritis and Takayasu arteritis).

RECENT FINDINGS

18 FDG (fluorodeoxyglucose) vascular uptake in large-vessel vasculitis at PET shows moderate correlation with clinical indices, laboratory markers and signs of arterial involvement at morphological imaging. Limited data may suggest that 18 FDG (fluorodeoxyglucose) vascular uptake could predict relapses and (in Takayasu arteritis) the development of new angiographic vascular lesions. PET appears to be in general sensitive to change after treatment.

SUMMARY

While the role of PET in diagnosis large-vessel vasculitis is established, its role in evaluating disease activity is less clear-cut. PET may be used as an ancillary technique, but a comprehensive assessment, including clinical, laboratory and morphological imaging is still required to monitor patients with large-vessel vasculitis over time.

Effectiveness of a two-year tapered course of tocilizumab in patients with giant cell arteritis: A single-centre prospective study

OBJECTIVE

To evaluate the feasibility of tocilizumab tapering and withdrawal in patients with giant cell arteritis (GCA).

METHODS

GCA patients eligible for tocilizumab were prospectively enrolled. Tocilizumab was administered weekly for the first 12 months, every-other-week for an additional 12 months, then discontinued. Relapses on tocilizumab were managed with temporary increases in systemic glucocorticoids or addition of methotrexate. Primary outcome was relapse-free survival at month 6 after tocilizumab suspension. Relapse-free survival on tocilizumab, imaging response, and adverse events were evaluated.

RESULTS

23 GCA patients were enrolled. Reasons for tocilizumab start were relapse (n = 14), persistence of activity (n = 5), or steroid-related adverse events (n = 4). At tocilizumab start, two patients were on methotrexate, which was maintained. Fourteen patients had extracranial vascular involvement on 18FDG-PET/CT. During the first 12 months, four patients (17%) had clinical relapse. At every-other-week tocilizumab start, all patients were in clinical remission, two patients had active vasculitis on 18FDG-PET/CT; two patients were on steroid therapy, and four patients were taking methotrexate. Two patients (9%) relapsed while on every-other-week tocilizumab. At tocilizumab suspension, no patient was on steroid therapy and no patient had signs of active vasculitis on 18FDG-PET/CT. In the 6 months after tocilizumab discontinuation, six patients (26%) relapsed. No new or unexpected safety findings were identified.

CONCLUSION

Tocilizumab tapered over a two-year period was effective to induce and maintain remission in GCA. Relapses on tocilizumab were minor and responded to incremental changes in therapy. A significant proportion of patients relapsed in the 6 months after therapy suspension.

Efficacy and safety of leflunomide in the management of large vessel vasculitis: A systematic review and metaanalysis of cohort studies

OBJECTIVE

The search for new glucocorticoid-sparing disease-modifying anti-rheumatic drugs continues to be an unmet need in large vessel vasculitis (LVV). This report aims to assess the effectiveness and safety of leflunomide (LEF) in Takayasu arteritis (TA) and giant cell arteritis (GCA).

METHODS

We systematically reviewed the literature, searching for studies evaluating the efficacy of LEF in LVV. A meta-analysis was conducted using the random-effects method.

RESULTS

The literature search identified eight studies that assessed LEF in TAK and seven in GCA. All were uncontrolled observational studies with a high risk of bias, implying a low or very-low certainty of evidence. In TAK, the pooled proportion of patients achieving at least a partial remission was 75% (95% CI: 0.64-0.84), angiographic stabilization was observed in 86% (0.77-0.94) and relapses in 12% (0.05-0.21). The mean reduction in the prednisolone dose (MRPD) after LEF treatment was 15.7 mg/d (10.28-21.16). Adverse events were observed in 8% of patients (0.02-0.16). Comparison of LEF with methotrexate (MTX) or cyclophosphamide revealed LEF to be superior in terms of remission induction, relapse prevention, and tolerance. When compared with tofacitinib, both drugs demonstrated comparable efficacy. In GCA, the pooled proportion of patients achieving at least a partial remission was 60% (0.17-0.95). The MRPD after LEF treatment was 15.63 mg/d (1.29-32.55) and 53% of the patients were able to discontinue glucocorticoids (0.25 - 0.80). Relapses were observed in 21% of cases (0.14- 0.28) and adverse events in 28% (0.12-0.46). Comparison of LEF with MTX showed similar efficacy and tolerance.

CONCLUSION

LEF is well tolerated and might be effective for patients with TAK and GCA.

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.

Recent advances in the treatment of giant cell arteritis

Giant cell arteritis (GCA) is a systemic, granulomatous, large-vessel vasculitis that affects individuals over the age of 50 years. Morbidity from disease includes cranial manifestations which can cause irreversible blindness, while extra-cranial manifestations can cause vascular damage with large-artery stenosis, occlusions, aortitis, aneurysms, and dissections. Glucocorticoids while efficacious are associated with significant adverse effects. Furthermore, despite treatment with glucocorticoids, relapses are common. An understanding of the pathogenesis of GCA has led to the discovery of tocilizumab as an efficacious steroid-sparing therapy while additional therapeutic targets affecting different inflammatory pathways are under investigation. Surgical treatment may be indicated in cases of refractory ischemia or aortic complications but data on surgical outcomes are limited. Despite the recent advances, many unmet needs exist, including the identification of patients or subsets of GCA who would benefit from earlier initiation of adjunctive therapies, patients who may warrant long-term immunosuppression and medications that sustain permanent remission. The impact of medications like tocilizumab on long-term outcomes, including the development of aortic aneurysms and vascular damage also warrants investigation.

Imaging of giant cell arteritis - recent advances

Imaging is increasingly being used to guide clinical decision-making in patients with giant cell arteritis (GCA). While ultrasound has been rapidly adopted in fast-track clinics worldwide as an alternative to temporal artery biopsy for the diagnosis of cranial disease, whole-body PET/CT is emerging as a potential gold standard test for establishing large vessel involvement. However, many unanswered questions remain about the optimal approach to imaging in GCA. For example, it is uncertain how best to monitor disease activity, given there is frequent discordance between imaging findings and conventional disease activity measures, and imaging changes typically fail to resolve completely with treatment. This chapter addresses the current body of evidence for the use of imaging modalities in GCA across the spectrum of diagnosis, monitoring disease activity, and long-term surveillance for structural changes of aortic dilatation and aneurysm formation and provides suggestions for future research directions.

Advanced molecular imaging in large-vessel vasculitis: Adopting FDG-PET into a clinical workflow

The use of fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging to detect vascular inflammation is increasingly common in the clinical management of patients with large-vessel vasculitis (LVV). In this review, the role of FDG-PET imaging to diagnose and monitor vascular disease activity will be detailed. Suggestions on incorporation of FDG-PET imaging into a clinical workflow will be provided with emphasis on patient preparation, image acquisition, and image interpretation. If FDG-PET imaging is obtained, multimodal imaging assessment, whereby FDG-PET imaging and non-invasive angiography are obtained concurrently, and correlation of imaging findings with clinical assessment is generally advisable. Considering the clinical scenario and treatment status of the patient is important when interpreting vascular FDG-PET image findings.

Impact of previous glucocorticoid therapy on diagnostic accuracy of [18F] FDG PET-CT in giant cell arteritis

OBJECTIVE

To evaluate the impact of prior glucocorticoid (GC) treatment on the diagnostic accuracy of ¹⁸F-FDG PET-CT in giant cell arteritis (GCA).

METHODS

Retrospective study of a consecutive cohort of 85 patients with proven GCA who received high-dose GC before PET-CT.

RESULTS

Thirty-nine patients previously treated with methylprednisolone (MP) boluses, of whom 37% were PET-CT (uptakes grade 3 or 2) positive. The positivity rate was 80% with MP doses of 125 mg, 33% with 250 or 500 mg, and 0% with doses of 1 g.  If we also classify as positive those cases with a grade 1 uptake (with a circumferencial uptake and smooth linear or long segmental pattern, possibly indicative of "apparently inactive" vasculitis), the positivity rate increases to 62% (100%, 50-60%, and 33% for the different MP doses, respectively). In patients with new-onset GCA treated with high-dose oral GC, PET-CT positivity was 54.5% in patients treated for less than two weeks, 38.5% in those treated for 2 to 4 weeks, and 25% in those treated for 4 to 6 weeks (increasing to 91%, 77%, and 50%, respectively, if we include cases with grade 1 uptake and these characteristics). In patients with relapsing/refractory GCA, or who developed GCA having a prior history of PMR, PET-CT positivity reached 54% despite long-term treatment with low-to-moderate doses of GC (68% including cases with a grade 1 uptake).

CONCLUSION

A late ¹⁸F-FDG PET-CT (beyond the first 10 days of treatment) can also be informative in a considerable percentage of cases.

What is a response in randomised controlled trials in giant cell arteritis?

Glucocorticoids (GCs) are the gold standard for treatment of giant cell arteritis (GCA); however, there is a need for studies on GC-sparing agents, given that up to 85% of patients receiving GC only develop adverse events. Previous randomised controlled trials (RCTs) have applied different primary endpoints, limiting the comparison of treatment effects in meta-analyses and creating an undesired heterogeneity of outcomes. The harmonisation of response assessment is therefore an important unmet need in GCA research. In this viewpoint article, we discuss the challenges and opportunities with the development of new, internationally accepted response criteria. A change of disease activity is a fundamental component of response; however, it is debatable whether the ability to taper GC and/or the maintenance of a disease state for a specific time period, as applied in recent RCTs, should be part of response assessment. The role of imaging and novel laboratory biomarkers as possible objective markers of disease activity needs further investigation but might be a possibility when drugs directly or indirectly influence the levels of traditional acute-phase reactants such as erythrocyte sedimentation rate and C reactive protein. Futures response criteria might be constructed as a multidomain set, but the questions about which domains will be included and what their relative weights will be still need to be answered.

Positron Emission Tomography Imaging in Vasculitis

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels. [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) plays an important role in the diagnosis and therapeutic monitoring of vasculitides affecting large-sized and medium-sized vessels. FDG-PET/CT also provides complementary information to other vascular imaging tools. The resolution and sensitivity of newer generation scanners continues to increase, hereby improving the ability of FDG-PET/CT to accurately assess the full disease extent in patients with vasculitis. Novel tracers targeting specific immune cells will allow for more detailed detection of vascular infiltrates.

18-Fluorodeoxyglucose positron emission tomography/computed tomography for large vessel vasculitis in clinical practice

Diagnosis, prognostic assessment, and monitoring disease activity in patients with large vessel vasculitis (LVV) can be challenging. Early recognition of LVV and treatment adaptation is essential because vascular complications (aneurysm, dilatations, ischemic complications) or treatment related side effects can occur frequently in these patients. 18-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG-PET/CT) is increasingly used to diagnose, follow, and evaluate treatment response in LVV. In this review, we aimed to summarize the current evidence on the value of 2-[18F]FDG-PET/CT for diagnosis, follow, and treatment monitoring in LVV.

The role of PET/CT in large vessel vasculitis and related disorders: diagnosis, extent evaluation and assessment of therapy response

Large vessel vasculitides (LVV) are defined as chronic inflammatory disorders that affect the arteries with two major variants being distinguished: giant cell arteritis (GCA) and Takayasu's arteritis (TAK). These often present with nonspecific constitutional symptoms which makes an accurate diagnosis often challenging. Nevertheless, timely diagnosis is of utmost importance to initiate treatment and to avoid potential life-threatening complications. [¹⁸F]FDG-PET/CT is nowadays widely accepted as useful tool to aid in the diagnosis of large vessel vasculitis. However, its role to monitor disease activity and to predict disease relapse during follow-up is less obvious since vascular [¹⁸F]FDG uptake can be detected in the absence of clinical or biochemical signs of disease activity. In addition to the two major variants, [¹⁸F]FDG-PET/CT has shown promise in (peri-)aortitis and related disorders. This article aims to provide an update on the current knowledge and limitations of [¹⁸F]FDG-PET/CT for the diagnosis and assessment of treatment response in LVV. Furthermore, other radiopharmaceuticals targeting key components of the vascular immune system are being discussed which could provide an interesting alternative to image vascular inflammation in LVV.

Comparing treatment options for large vessel vasculitis

INTRODUCTION

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are the major forms of large vessel vasculitis (LVV).Glucocorticoids represent the cornerstone of LVV treatment, however, relapses and recurrences frequently occur when they are tapered or stopped, determining a prolonged exposure to glucocorticoids and a subsequent increased risk of glucocorticoid-related side effects. Therefore, conventional and biologic immunosuppressive drugs have been proposed to obtain a glucocorticoid-sparing effect.

AREAS COVERED

We searched PubMed® using the keywords "giant cell arteritis/drug therapy" and "Takayasu Arteritis/drug therapy" OR "Takayasu Arteritis/surgery". This review focuses on the management of LVV, based on the current evidence while highlighting the differences in terms of therapeutic management of TAK and GCA.

EXPERT OPINION

Conventional disease modifying anti-rheumatic drugs, such as methotrexate or azathioprine, are recommended in association to glucocorticoids for selected GCA and all TAK patients. Two randomized placebo-controlled trials recently demonstrated the efficacy of tocilizumab in reducing relapses and cumulative prednisone dosage in GCA patients with newly diagnosed or relapsing disease. Observational evidence and two small randomized controlled trials support the use of TNF-alpha inhibitors and tocilizumab as glucocorticoid-sparing agents in relapsing TAK, albeit high-quality evidence regarding the management of TAK is still lacking.

2-deoxy-2[18F]fluoro-D-glucose positron emission tomography-computed tomography in rheumatological diseases

2-deoxy-2[18F]fluoro-D-glucose (FDG) PET-CT has revolutionized oncological imaging. The cellular processes that make cancer cells visible on FDG PET-CT also occur in a number of inflammatory cells. Exploiting this phenomenon has led to a growth of evidence supporting the use of FDG PET-CT in a wide range of infective and inflammatory diseases. Rheumatological diseases can affect multiple sites within the musculoskeletal system alongside multi-organ extra-articular disease manifestations. Inflammation is central to these diseases, making FDG PET-CT a logical choice. In this review article we describe the various applications of FDG PET-CT in rheumatological diseases using illustrative examples to highlight the beneficial role of FDG PET-CT in each case.

The role of PET/CT in disease activity assessment in patients with large vessel vasculitis

OBJECTIVES

To evaluate the accuracy of PET/CT and of PET vascular activity score (PETVAS) in assessing disease activity and the ability of PETVAS in predicting relapses in a large single-centre cohort of patients with large vessel vasculitis (LVV).

METHODS

We conducted a retrospective cohort study of prospectively collected data of consecutive patients diagnosed with LVV who underwent at least one PET/CT scan between 2007 and 2020. The nuclear medicine physician's interpretation of each PET/CT scan (active/inactive vasculitis) was compared with disease activity clinical judgement (active disease/remission). For each PET/CT scan, the PETVAS score was calculated and its accuracy in assessing disease activity was evaluated. The ability of PETVAS in predicting subsequent relapses was evaluated.

RESULTS

A total of 100 consecutive LVV patients (51 large vessel GCA, 49 Takayasu arteritis) underwent a total of 476 PET/CT scans over a mean follow-up period of 97.5 months. Physician-determined PET/CT grading was able to distinguish between clinically active and inactive LVV with a sensitivity of 60% (95% CI 50.9, 68.7) and specificity of 80.1% (95% CI 75.5, 84.1); the area under the curve (AUC )was 0.70 (95% CI 0.65, 0.75). PETVAS was associated with disease activity, with an age and sex-adjusted odds ratio for active disease of 1.15 (95% CI 1.11, 1.19). A PETVAS ≥10 provided 60.8% sensitivity and 80.6% specificity in differentiating between clinically active and inactive LVV; the AUC was 0.73 (95% CI 0.68, 0.79). PETVAS was not associated with subsequent relapses, with an age and sex-adjusted hazard ratio of 1.04 (95% CI 0.97, 1.11).

CONCLUSIONS

The visual PET/CT grading scale and PETVAS had moderate accuracy to distinguish active LVV from remission. PETVAS did not predict disease relapses.

An Updated Review of Cardiovascular Events in Giant Cell Arteritis

Giant cell arteritis (GCA) is a systemic vasculitis with a direct and indirect increased risk of acute and chronic vascular events, affecting large and medium vessels, and responsible for most of the morbidity and mortality of this disease. We aimed in this review to provide an updated synthesis of knowledge regarding cardiovascular events observed in GCA. By definition, GCA patients are over 50 and often over 70 years old, and subsequently also present age-related cardiovascular risk factors. In addition, the systemic and vascular inflammation as well as glucocorticoids (GC) probably contribute to an accelerated atherosclerosis and to vascular changes leading to arterial stenoses and aortic dilations and/or dissections. GCA-related ischemic complications, especially ophthalmologic events, stroke or myocardial infarcts are mostly observed within the first months after the diagnosis, being mainly linked to the vasculitic process. Conversely, aortic complications, including dilations or dissections, generally occur several months or years after the diagnosis, mainly in patients with large-vessel vasculitis. In these patients, other factors such as atherosclerosis, GC-related endothelial damage and vascular wall remodeling/healing probably contribute to the vascular events. GCA management includes the detection and treatment of these previous and newly induced cardiovascular risk factors. Hence, the use of cardiovascular treatments (e.g., aspirin, anticoagulation, statins, anti-hypertensive treatments) should be evaluated individually. Aortic structural changes require regular morphologic evaluations, especially in patients with previous aortitis. The initial or secondary addition of immunosuppressants, especially tocilizumab, an anti-IL-6 receptor antibody, is discussed in patients with GCA-related cardiovascular complications and, more consensually, to limit GC-mediated comorbidities.

Need and value of targeted immunosuppressive therapy in giant cell arteritis

Despite the heterogeneity of the giant cell arteritis (GCA) at the level of clinical manifestations and the cellular and molecular players involved in its pathogenesis, GCA is still treated with standardised regimens largely based on glucocorticoids (GC). Long-term use of high dosages of GC as required in GCA are associated with many clinically relevant side effects. In the recent years, the interleukin-6 receptor blocker tocilizumab has become available as the only registered targeted immunosuppressive agent in GCA. However, immunological heterogeneity may require different pathways to be targeted in order to achieve a clinical, immunological and vascular remission in GCA. The advances in the targeted blockade of various molecular pathways involved in other inflammatory and autoimmune diseases have catalyzed the research on targeted therapy in GCA. This article gives an overview of the studies with targeted immunosuppressive treatments in GCA, with a focus on their clinical value, including their effects at the level of vascular inflammation.

Vessel inflammation and morphological changes in patients with large vessel vasculitis: a retrospective study

OBJECTIVE

The aim was to identify any association between imaging signs of vessel wall inflammation (positron emission tomography-CT (PET-CT) score and CT/MR wall thickening) and synchronous and subsequent vascular damage (stenoses/dilations) in patients with large vessel vasculitis (LVV).

METHODS

Consecutive patients with LVV referred to a tertiary centre in 2007-2020 with baseline PET-CT and morphological imaging (CT/MR angiography) performed within 3 months were included. All available PET-CT and CT/MR scans were reviewed to assess PET-CT uptake (4-point semi-quantitative score), wall thickening, stenoses and dilations for 15 vascular segments. The associations of baseline PET score and CT/MR wall thickening with synchronous and incident stenoses/dilations at CT/MR performed 6-30 months from baseline were evaluated in per-segment and per-patient analyses. Respective areas under the receiver operating characteristic curve (AUC) were calculated.

RESULTS

We included 100 patients with LVV (median age: 48 years, 22% males). Baseline PET score and wall thickening were strongly associated (Cuzick non-parametric test for trend across order groups (NPtrend) <0.001). The association with synchronous stenoses/dilations was weak for PET score (NPtrend=0.01) and strong for wall thickening (p<0.001). In per-patient analyses, sensitivity/specificity for ≥1 synchronous stenoses/dilations were 44%/67% for PET score ≥2 and 66.7%/60.5% for wall thickening. Subsequent CTs/MRs were available in 28 patients, with seven incident stenoses/dilations. Baseline PET score was strongly associated with incident stenoses/dilations (p=0.001), while baseline wall thickening was not (p=0.708), with AUCs for incident stenoses/dilations of 0.80 for PET score and 0.52 for wall thickening.

CONCLUSION

PET score and wall thickening are strongly associated, but only baseline PET score is a good predictor of incident vessel wall damage in LVV.

Large-vessel vasculitis

Large-vessel vasculitis (LVV) manifests as inflammation of the aorta and its major branches and is the most common primary vasculitis in adults. LVV comprises two distinct conditions, giant cell arteritis and Takayasu arteritis, although the phenotypic spectrum of primary LVV is complex. Non-specific symptoms often predominate and so patients with LVV present to a range of health-care providers and settings. Rapid diagnosis, specialist referral and early treatment are key to good patient outcomes. Unfortunately, disease relapse remains common and chronic vascular complications are a source of considerable morbidity. Although accurate monitoring of disease activity is challenging, progress in vascular imaging techniques and the measurement of laboratory biomarkers may facilitate better matching of treatment intensity with disease activity. Further, advances in our understanding of disease pathophysiology have paved the way for novel biologic treatments that target important mediators of disease in both giant cell arteritis and Takayasu arteritis. This work has highlighted the substantial heterogeneity present within LVV and the importance of an individualized therapeutic approach. Future work will focus on understanding the mechanisms of persisting vascular inflammation, which will inform the development of increasingly sophisticated imaging technologies. Together, these will enable better disease prognostication, limit treatment-associated adverse effects, and facilitate targeted development and use of novel therapies.

Functionally Heterogenous Macrophage Subsets in the Pathogenesis of Giant Cell Arteritis: Novel Targets for Disease Monitoring and Treatment

Giant cell arteritis (GCA) is a granulomatous large-vessel vasculitis that affects adults above 50 years of age. In GCA, circulating monocytes are recruited to the inflamed arteries. With cues from the vascular microenvironment, they differentiate into macrophages and play important roles in the pathogenesis of GCA via pro-inflammatory cytokine production and vascular remodeling. However, a deeper understanding of macrophage heterogeneity in GCA pathogenesis is needed to assist the development of novel diagnostic tools and targeted therapies. Here, we review the current knowledge on macrophage heterogeneity and diverse functions of macrophage subsets in the pathogenesis of GCA. We next discuss the possibility to exploit their heterogeneity as a source of novel biomarkers and as targets for nuclear imaging. Finally, we discuss novel macrophage-targeted therapies and future directions for targeting these cells in GCA.