Diagnostic performance of ¹⁸F-fluorodeoxyglucose positron emission tomography in giant cell arteritis: a systematic review and meta-analysis

Imaging modalities in the management of aortitis

Aortitis is a pathological term that refers to the inflammation of one or more layers of the aortic wall. It is associated with a wide spectrum of inflammatory diseases of infectious and non-infectious origins, and often present with vague clinical findings and non-specific laboratory results that can model other entities. As a result, aortitis may not form part of the initial workup and appropriate treatment can be delayed or missed. Therefore, imaging modalities are required to assess for inflammation and structural changes in the aorta to support or exclude the diagnosis of aortitis. This review presents current literature on the imaging modalities utilized in the diagnosis and management of aortitis, which surgeons and physicians should be familiar with for providing optimal patient care.

Comparative effectiveness of 18F-FDG PET-CT and contrast-enhanced CT in the diagnosis of suspected large-vessel vasculitis

OBJECTIVE

Large-vessel vasculitis (LVV) is a serious illness with potentially life-threatening consequences. (¹⁸Fluorine) fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) has emerged as a valuable diagnostic tool in suspected LVV, combining the strengths of functional and structural imaging. This study aimed to compare the accuracy of FDG PET-CT and contrast-enhanced CT (CECT) in the evaluation of patients with LVV.

METHODS

A retrospective database review for LVV patients undergoing CECT and PET-CT between 2011 to 2016 yielded demographics, scan interval and vasculitis type. Qualitative and quantitative PET-CT analyses included aorta:liver FDG uptake, bespoke FDG uptake distribution scores and vascular maximum standardised uptake values (SUV_max). Quantitative CECT data were assessed for wall thickness and mural-lumen ratio. Receiver operating characteristics (ROC) curves were constructed to evaluate comparative diagnostic accuracy and a correlational analysis was conducted between SUV_max and wall thickness.

RESULTS

36 adults (17 LVV, 19 controls) with a mean age (range) 63 (38-89) years, of which 17 (47%) were males were included. Time interval between CT and PET was mean [standard deviation (SD)] 1.9 (1.2) months. Both SUV_max and wall thickness demonstrated a significant difference between LVV and controls, with a mean difference [95%confidence interval (CI)] for SUV_max 1.6 (1.1, 2.0) and wall thickness 1.25 (0.68, 1.83) mm, respectively. These two parameters were significantly correlated (p < 0.0001, R = 0.62). The area under the curve (AUC) (95% CI) for SUV_max was 0.95 (0.88-1.00), and for mural thickening was 0.83 (0.66-0.99).

CONCLUSION

FDG PET-CT demonstrated excellent accuracy whilst CECT mural thickening showed good accuracy in the diagnosis of LVV. Both parameters showed a highly significant correlation. In hospitals without access to FDG PET-CT or in patients unsuitable for PET-CT (e.g. uncontrolled diabetes) CECT offers a viable alternative for the assessment of LVV. Advances in knowledge: FDG PET-CT is a highly accurate test for the diagnosis of LVV. Aorta:liver SUV_max ratio is the most specific parameter for LVV. In hospitals without PET-CT or in unsuitable patients e.g. diabetics, CECT is a viable alternative.

Concomitant Polymyalgia Rheumatica and Large-Vessel Vasculitis Visualized on 18F-FDG PET/CT

Polymyalgia rheumatica (PMR) and large-vessel vasculitis (LVV) are related rheumatic diseases which are occasionally present concomitantly. PMR is characterized by synovitis and bursitis. In LVV, inflammation of the blood vessel wall is seen. Both disorders can be difficult to diagnose since patients often present non-specific symptoms and results of blood tests. The non-specific symptoms cannot always be distinguished from symptoms indicating an occult malignancy. We present a case of PMR and LVV in a Scandinavian man visualized on [¹⁸F]-2-deoxy-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) with the presentation of typically affected sites of joints and arteries and with the same imaging modality ruling out occult malignancy.

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.

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.

Stroke as an atypical initial presentation of giant cell arteritis

Background

Giant cell arteritis (GCA) is an immune mediated inflammatory disease of medium and large arteries which afflicts older people. The classical presentation features include: headache, visual disturbances, and jaw claudication. Patients diagnosed with GCA have also been observed to be at higher risk for the subsequent development of strokes.

Case presentation

We describe a case of an 84-year old right-handed man who presented to hospital with dysarthria, dysphagia, right-sided facial drop, a history of generalized weakness and multiple falls. He was admitted to geriatric medicine with the working diagnosis of a posterior circulation stroke syndrome. He was also started on antibiotic treatment for a possible community-acquired pneumonia because of the presence of a low-grade fever and a chest radiograph showing ill-defined left lower lobe airspace disease. Initial lab results were remarkable for an erythrocyte sedimentation rate (ESR) of 112 mm/h and a C-reactive protein (CRP) level of 110 mg/L consistent with an active inflammatory state. Neurovascular imaging showed mild atherosclerotic changes of the aortic arch and proximal great vessels without significant stenosis. The patient was started on daily high-dose prednisone because of the possibility of a cerebral vasculitis. Bilateral biopsy of temporal arteries showed giant cell arteritis. The patient’s neurologic status and inflammatory markers significantly improved (ESR 52 mm/h, CRP 7.0 mg/L) and he was eventually discharged to a seniors home with services.

Conclusion

The initial presentation of giant cell arteritis as a stroke syndrome, especially in the posterior circulation territory, is exceedingly rare. Other atypical presenting symptoms may include chronic cough and fever of unknown origin. The elevated ESR and CRP levels were clues to the diagnosis and clinical decision-making should be driven by a high index of suspicion since no single test (ESR, CRP, temporal artery biopsy) has perfect sensitivity. Elevated CRP may have a role in increasing stroke risk. This case report illustrates that in older people clinicians must consider atypical presentations of disease more often since timely diagnosis and initiation of treatment can result in optimal outcomes.

Giant Cell Arteritis: Practical Pearls and Updates

PURPOSE OF REVIEW

The purpose of this review is to summarize recent updates and distill practical points from the literature which can be applied to the care of patients with suspected and confirmed giant cell arteritis (GCA).

RECENT FINDINGS

Contemporary thinking implicates a fundamental failure of T regulatory cell function in GCA pathophysiology, representing opportunity for novel therapeutic avenues. Tocilizumab has become the first Food and Drug Administration-approved treatment for GCA following demonstration of efficacy and safety in a phase 3 clinical trial. There have been significant parallel advances in both our understanding of GCA pathophysiology and treatment. Tocilizumab, and other agents currently under investigation in phase 2 and 3 clinical trials, presents a new horizon of hope for both disease remission and avoidance of glucocorticoid-related complications.

Acute Brachial Radiculoplexopathy and Giant Cell Arteritis

INTRODUCTION

Giant cell arteritis (GCA), a vasculitis involving large-sized and medium-sized vessels (which most commonly involves temporal arteries), is easily recognized in older patients presenting with headache, scalp tenderness, and raised inflammatory markers. Neurological complications (either central or peripheral) are classically described in GCA.

CASE REPORT

We report the case of an 85-year-old woman with bilateral acute brachial radiculoplexopathy, a rare neurological complication of GCA. She also presented right oculomotor palsy (with ptosis) and raised inflammatory markers, but she did not complain of the other classic cranial symptoms of the disease. We compare this case with 16 similar cases reported in the medical literature.

CONCLUSIONS

In assessing a patient over 50 years of age with unexplained (unilateral or bilateral) brachial radiculoplexopathy (especially if C5-C6 nerve roots are affected) and elevated inflammatory markers, we would recommend specific enquiries with regard to the manifestations of GCA. The purpose is to reduce the risk of missing the wider spectrum of this condition and minimize the subsequent risk for disability of this treatable disease.

Repetitive 18F-FDG-PET/CT in patients with large-vessel giant-cell arteritis and controlled disease

OBJECTIVE

¹⁸F-FDG PET/CT can detect large-vessel involvement in giant-cell arteritis (GCA) with a good sensitivity. In patients with clinically and biologically controlled disease, we aimed to assess how vascular uptakes evolve on repetitive FDG-PET/CT.

PATIENTS AND METHODS

All included patients had to satisfy the 4 following criteria: 1) diagnosis of GCA was retained according to the criteria of the American College of Rheumatology or based on the satisfaction of 2 criteria associated with the demonstration of large-vessel involvement on FDG-PET/CT; 2) all patients had a positive PET/CT that was performed at diagnosis before treatment or within the first 10days of treatment; 3) another FDG-PET/CT was performed after at least 3months of controlled disease without any relapse; 4) patients were followed-up at least for 12months.

RESULTS

Twenty-five patients (17 [68%] women, median age: 69 [65-78]) with large-vessel inflammation on a baseline FDG-PET/CT and with repetitive imaging during the period with controlled disease were included and followed-up for 62 [25-95] months. Four repeated procedures revealed total extinction of vascular uptakes at 11.5 [8-12] months after the first FDG-PET/CT. Eight PET/CT revealed decreased numbers of vascular uptakes, and 10 procedures revealed no changes. The 3 remaining procedures indicated worsening of the numbers of vascular uptakes in the absence of relapse.

CONCLUSIONS

Our study revealed long-term persistent vascular uptake on repeated FDG-PET/CT in >80% of our GCA patients with large-vessel inflammation and clinical-biological controlled disease. Prospective studies are required to confirm these findings.

Usefulness of PET in recognizing and managing vasculitides

PURPOSE OF REVIEW

The aim of this article was to review the recent contributions to the scoring methods of PET in vasculitis as well as to its role in the diagnostic work-up.

RECENT FINDINGS

Both visual and semiquantitative scoring methods can be used to interpret PET scans. PET has been shown to be both sensitive and specific in the diagnosis of large-vessel vasculitis. In addition, it also has a role in predicting vascular complications.

SUMMARY

There is a need to better standardize the scoring methods used to interpret PET scans. In clinical practice, PET is useful to diagnose untreated individuals with suspected large-vessel vasculitis and contributes to identify patients at risk for vascular complications.

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.

Temporal artery biopsy in the diagnosis of giant cell arteritis: Does the end justify the means?

BACKGROUND

Early temporal artery biopsy is recommended in all patients with suspected cranial GCA (Giant Cell Arteritis) by the BSR (British Society of Rheumatology) and BHPR (British Health Professionals in Rheumatology) guidelines. This should be performed within one week ideally.

AIM

To assess ACR (American College of Rheumatology) score at presentation and whether temporal artery biopsy result affects clinical management of the clinically suspected GCA patient.

METHOD

Case records of all temporal artery biopsies performed within January 2012 until December 2014 were analysed for size and result of biopsy and this was correlated to clinical management following result.

RESULTS

129 temporal arteries were biopsied with a total of 17 positive biopsy results. 10 biopsy samples were insufficient to confirm or refute GCA. 8 patients within the biopsies negative for GCA had their prednisolone therapy stopped. 5 patients had unknown follow up, with the remainder (89, 87.3%) of the patients continued prednisolone management for treatment of GCA for at least 6 weeks.

CONCLUSION

Overall 13.2% of our biopsies were positive for GCA and 87.3% of biopsy negative patients continued prednisolone therapy on clinical grounds. In the face of new diagnostic tests (high resolution MRI (Magnetic Resonance Imaging), colour duplex USS (Ultra Sound Scan) and PET (Positive Emission Topography) can we justify invasive surgery to all patients on histological grounds when the results may not alter management? Further investigation is needed directly comparing newer imaging modalities to histology.

Diagnostic accuracy of 18F-FDG PET or PET/CT for large vessel vasculitis : A meta-analysis

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of 18F-fluorodeoxyglucose positron-emission tomography (18F-FDG PET) or positron-emission tomography/computed tomography (PET/CT) for patients with large vessel vasculitis.

METHODS

Based on a search in the PubMed, Embase, and Cochrane Library databases, a meta-analysis was performed on the diagnostic accuracy of 18F-FDG PET or PET/CT in patients with large vessel vasculitis.

RESULTS

A total of eight studies involving 400 subjects (170 vasculitis patients and 230 controls) were selected for meta-analysis. The pooled sensitivity and specificity of 18F-FDG PET or PET/CT were 75.9 % (95 % confidence interval, CI 68.7-82.1) and 93.0 % (95 % CI 88.9-96.0), respectively. The positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were 7.267 (95 % CI 3.707-14.24), 0.303 (95 % CI 0.229-0.400), and 32.04 (95 % CI 13.08-78.45), respectively. The area under the curve (AUC) was 0.863 and the Q^* index 0.794, indicating good diagnostic accuracy. There was no evidence of a threshold effect (Spearman's correlation coefficient = 0.120, p = 0.776). When the data were limited to giant cell arteritis (GCA), the pooled sensitivity and specificity of 18F-FDG PET or PET/CT were 83.3 % (95 % CI 72.1-91.4) and 89.6 % (95 % CI 79.7-95.7), respectively; AUC was 0.884, and the Q^* index 0.815, indicating modest accuracy with a small increase in diagnostic accuracy.

CONCLUSION

This meta-analysis of published studies demonstrates that 18F-FDG PET or PET/CT has good diagnostic accuracy for large vessel vasculitis and plays an important role in the diagnosis of this condition.

Other cerebrovascular occlusive disease

In this chapter we review the optimal imaging modalities for subacute and chronic stroke. We discuss the utility of computed tomography (CT) and multimodal CT imaging. Further, we analyze the importance of specific magnetic resonance imaging sequences, such as diffusion-weighted imaging for acute ischemic stroke, T2/fluid-attenuated inversion recovery for subacute and chronic stroke, and susceptibility imaging for detection of intracranial hemorrhages. Different ischemic stroke mechanisms are reviewed, and how these imaging modalities may aid in the determination of such. Further, we analyze how topographic patterns in ischemic stroke may provide important clues to the diagnosis, in addition to the temporal evolution of the stroke. Lastly, specific cerebrovascular occlusive diseases are reviewed, with emphasis on the optimal imaging modalities and their findings in each condition.

The Expanding Role of Imaging in Systemic Vasculitis

Various imaging modalities, including color duplex ultrasonography, CT angiography, magnetic resonance angiography, and PET, are emerging as important aids to the diagnosis, staging, evaluation of disease activity and response to treatment in systemic vasculitis. Although large-vessel vasculitis is the main target of imaging, refinement and increasing accuracy of imaging modalities are also providing useful information in the evaluation of medium-vessel and small-vessel vasculitis.

3D-black-blood 3T-MRI for the diagnosis of thoracic large vessel vasculitis: A feasibility study

OBJECTIVES

To evaluate the feasibility of T1w-3D black-blood turbo spin echo (TSE) sequence with variable flip angles for the diagnosis of thoracic large vessel vasculitis (LVV).

METHODS

Thirty-five patients with LVV, diagnosed according to the current standard of reference, and 35 controls were imaged at 3.0T using 1.2 × 1.3 × 2.0 mm³ fat-suppressed, T1w-3D, modified Volumetric Isotropic TSE Acquisition (mVISTA) pre- and post-contrast. Applying a navigator and peripheral pulse unit triggering (PPU), the total scan time was 10-12 min. Thoracic aorta and subclavian and pulmonary arteries were evaluated for image quality (IQ), flow artefact intensity, diagnostic confidence, concentric wall thickening and contrast enhancement (CWT, CCE) using a 4-point scale.

RESULTS

IQ was good in all examinations (3.25 ± 0.72) and good to excellent in 342 of 408 evaluated segments (83.8 %), while 84.1 % showed no or minor flow artefacts. The interobserver reproducibility for the identification of CCE and CWT was 0.969 and 0.971 (p < 0.001) with an average diagnostic confidence of 3.47 ± 0.64. CCE and CWT were strongly correlated (Cohen's k = 0.87; P < 0.001) and significantly more frequent in the LVV-group (52.8 % vs. 1.0 %; 59.8 % vs. 2.4 %; P < 0.001).

CONCLUSIONS

Navigated fat-suppressed T1w-3D black-blood MRI with PPU-triggering allows diagnosis of thoracic LVV.

KEY POINTS

• Cross-sectional imaging is frequently applied in the diagnosis of LVV. • Navigated, PPU-triggered, T1w-3D mVISTA pre- and post contrast takes 10-12 min. • In this prospective, single-centre study, T1w-3D mVISTA accurately depicted large thoracic vessels. • T1w-3D mVISTA visualized CWT/CCW as correlates of mural inflammation in LVV. • T1w-3D mVISTA might be an alternative diagnostic tool without ionizing radiation.

Positron emission tomography and computed tomography angiography for the diagnosis of giant cell arteritis: A real-life prospective study

The use of 18F-fluoro-deoxyglucose positron emission tomography scan (FDG-PET) and computed tomography angiography (CTA) to improve accuracy of diagnosis of giant cell arteritis (GCA) is a very important clinical need. We aimed to compare the diagnostic performance of FDG-PET and CTA in patients with GCA.FDG-PET and CTA were acquired in all consecutive patients suspected for GCA. Results of FDG-PET and CTA were compared with the final diagnosis based on clinical judgment, temporal artery biopsy (TAB) findings, and ACR criteria. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated for each method.Twenty-four patients suspected for GCA were included. Fifteen (62.5%) were ultimately diagnosed as having GCA. Among them, all fulfilled ACR criteria and 6 had biopsy-proven GCA. Strong FDG uptake in large vessels was found in 10 patients who all had GCA. Mean maximal standard uptake values (SUVmax) per patient measured at all the arterial territories were of 3.7 (range: 2.8-4.7). FDG uptake was negative in 14 patients including 9 and 5 patients without and with GCA, respectively. Mural thickening suggestive of aortitis or branch vessel arteritis was observed on CTA in 11 patients with and 2 patients without GCA. No mural thickening was observed in 11 patients including 7 patients without and 4 patients with GCA. Overall, sensitivity was 66.7% and 73.3%, specificity was 100% and 84.6%, NPV was 64.3% and 64.6%, and PPV was 100% and 84.6% of FDG-PET and CTA, respectively.Both FDG-PET and CTA have a strong diagnostic yield for the diagnosis of GCA. FDG-PET appeared to have a higher PPV as compared to CTA and may be the preferred noninvasive technique to explore patients with suspected GCA.

Giant cell arteritis

Giant cell arteritis (GCA) is the most common vasculitis of the elderly. The diagnosis can be challenging at times because of the limitation of the American Rheumatology Association (ARA) classification criteria and the significant proportion of biopsy-negative patients with GCA. We discuss the role of advanced imaging techniques, including positron emission tomography (PET) scanning, in establishing diagnosis and improved histopathology techniques to improve the sensitivity of temporal artery biopsy. There have been significant advances in the understanding of the pathogenesis of GCA, particularly the role of cytokine pathways such as the interleukins, IL-6-IL-17 axis, and the IL-12-interferon-γ axis and their implication for new therapies. We highlight that glucocorticoids remain the primary treatment for GCA, but recognize the risk of steroid-induced side effects. A number of pharmacotherapies to enable glucocorticoid dose reduction and prevent relapse have been studied. Early diagnosis and fast-track pathways have improved outcomes by encouraging adherence to evidence-based practice.

Giant-cell arteritis without cranial manifestations: Working diagnosis of a distinct disease pattern

Diagnosis of giant-cell arteritis (GCA) is challenging in the absence of cardinal cranial symptoms/signs. We aimed to describe the clinical presentation, diagnostic process, and disease course of GCA patients without cranial symptoms, and to compare them to those of patients with typical cranial presentation. In this retrospective multicenter study, we enrolled patients with GCA who satisfied at least 3 of the 5 American College of Rheumatology criteria for GCA, or 2 criteria associated with contributory vascular biopsy other than temporal artery biopsy or with demonstration of large-vessel involvement; underwent iconographic evaluation of large arterial vessels (aortic CT scan or a positron emission tomography with F-fluorodeoxyglucose combined with computed tomography (FDG-PET/CT) scan or cardiac echography combined with a large-vessel Doppler) at diagnosis. We divided the cohort into 2 groups, distinguishing between patients without cranial symptoms/signs (i.e., headaches, clinical temporal artery anomaly, jaw claudication, ophthalmologic symptoms) and those with cranial symptoms/signs. In the entire cohort of 143 patients, all of whom underwent vascular biopsy and vascular imaging, we detected 31 (22%) patients with no cranial symptoms/signs. In the latter, diagnosis was biopsy proven in an arterial sample in 23 cases (74% of patients, on a temporal site in 20 cases and on an extratemporal site in 3). One-third of these 31 patients displayed extracranial symptoms/signs whereas the remaining two-thirds presented only with constitutional symptoms and/or inflammatory laboratory test results. Compared to the 112 patients with cardinal cranial clinical symptoms/signs, patients without cranial manifestations displayed lower levels of inflammatory laboratory parameters (C-reactive level: 68 [9-250] mg/L vs 120 [3-120] mg/L; P < 0.01), highest rate of aorta and aortic branch involvement identified (19/31 (61%) vs 42/112 (38%); P = 0.02) and also a lower rate of disease relapse (12/31 (39%) vs 67/112 (60%); P = 0.04). Our results suggest that patients without cranial symptoms/signs are prone to lower inflammatory laboratory parameters, fewer relapses, and more large-vessel involvement than those displaying cardinal cranial manifestations. Further studies are therefore required in order to determine whether these 2 subgroups of patients have a different prognosis, and therefore warrant different therapeutic and monitoring regimens.

18F-fluorodeoxyglucose positron emission tomography and the risk of subsequent aortic complications in giant-cell arteritis: A multicenter cohort of 130 patients

Previous studies reported a 2- to 17-fold higher risk of aortic complications (dilation or dissection) in patients with giant-cell arteritis (GCA). We aimed to determine whether or not GCA patients with large-vessel involvement demonstrated by positron emission tomography with F-fluorodeoxyglucose combined with computed tomography (FDG-PET/CT) have a higher risk of aortic complications. We conducted a retrospective multicenter study between 1995 and 2014. Patients were included if they fulfilled at least 3 American College of Rheumatology criteria for GCA, or 2 criteria associated with extratemporal biopsy-proven giant-cell vasculitis; they underwent at least 1 FDG-PET/CT scan at diagnosis or during follow-up; and the morphology of the aorta was assessed by medical imaging at diagnosis. Patients with an aortic complication at the time of diagnosis were excluded. Of the 130 patients included [85 women (65%), median age 70 (50-86)], GCA was biopsy proven in 77 (59%). FDG-PET/CT was performed at diagnosis in 63 (48%) patients and during the follow-up period in the 67 (52%) remaining patients. FDG-PET/CT was positive in 38/63 (60%) patients at diagnosis and in 31/67 (46%) patients when performed during follow-up (P = NS). One hundred four patients (80%) underwent at least 1 morphological assessment of the aorta during follow-up. Nine (9%) patients developed aortic complications (dilation in all and dissection in 1) at a median time of 33 (6-129) months after diagnosis. All of them displayed large-vessel inflammation on previous FDG-PET/CT. A positive FDG-PET/CT was significantly associated with a higher risk of aortic complications (P = 0.004).In our study, a positive FDG-PET/CT was associated with an increased risk of aortic complications at 5 years.

18F-FDG uptake in main arterial branches of patients with large vessel vasculitis: visual and semiquantitative analysis

OBJECTIVE

Over the last decade, the contribution of (18)F-FDG (FDG) PET/CT imaging to the diagnosis of large vessel vasculitis has been widely investigated. The aim of this study was to evaluate a more extensive role for PET/CT in grading vascular inflammation in patients with different clinical stages of disease.

METHODS

The images of 66 PET/CT studies of 34 patients, performed at diagnosis and/or during follow-up were reviewed. FDG uptake in different regions of aorta and in its major branches was visually (regional Score: rS) and semiquantitatively (regional SUVmean: rSUV) assessed. The global vascular uptake was also evaluated for each study by summing all rSs (summed Score; sS) and averaging rSUVs (averaged SUV; aSUV). FDG uptake in 15 PET/CT studies of control age-matched subjects without signs or symptoms of vasculitis was also analyzed.

RESULTS

Higher levels of regional and global FDG uptake were found at diagnosis in comparison with follow-up studies of 12 patients with complete longitudinal observation (p value range 0.0552-0.0026). In the latter group high values were generally observed when disease relapse or incomplete response to therapy (active disease) occurred, whereas lower uptake was found in studies of remitted patients (p = <0.01), whose FDG levels were similar to those of control subjects. At ROC analysis performed on all image dataset, optimal cut-off levels of regional and global FDG vascular uptake provided a good discrimination between 25 patients at diagnosis and 15 control subjects (aSUV greater than 0.697; PPV = 92.3; NPV = 92.9). Major overlap was observed among FDG levels of 21 patients with active disease and in remission (aSUV greater than 0.653; PPV = 58.3; NPV = 94.1). Similar performances of visual and semiquantitative analyses were found when areas under curves (AUCs) were compared.

CONCLUSIONS

(18)F-FDG PET/CT has a promising role in grading inflammation in patients with large arteries vasculitis. Nevertheless, a cut-off based analysis of FDG vascular uptake is not sufficient to separate patients with active and inactive disease during follow-up.

Imaging in Giant Cell Arteritis

Much progress has been made in the use of imaging as a diagnostic tool in giant cell arteritis (GCA), which assists in the management of patients where the initial diagnosis is unclear. This includes patients with atypical cranial symptoms, or with predominantly systemic, constitutional or limb symptoms. Ultrasound and magnetic resonance imaging are capable of visualising both the cranial and extracranial large vessel circulation, with vessel wall thickening and stenotic lesions being visualised. Computed tomographic angiography is helpful in visualising the aorta for aneurysm complicating GCA but can also detect vessel wall thickening in established large vessel vasculitis. PET-CT is a very sensitive test for early vascular inflammation in extracranial large vessel vasculitis, before aneurysmal or stenotic lesions have developed, of use in the patient with unexplained constitutional symptoms. The place of imaging in the follow-up of GCA is being investigated, and repeated imaging may be useful in select cases. Generally, vascular abnormalities become less defined once glucocorticoid treatment has been started, and therefore, imaging studies must be conducted early as part of a GCA fast-track assessment.

[Therapeutic endovascular procedures in aortitis]

Aortitis is an inflammation of the aortic wall with an infectious or non-infectious origin, which often progresses to vascular complications. The open surgical approach is a high-risk procedure for these pathologies. Endovascular interventions have improved the prognosis of patients with aortitis complications. This manuscript describes the pathophysiology responsible for vascular complications and the role of endovascular approach for their treatment.

Exploring the nature of atheroma and cardiovascular inflammation in vivo using positron emission tomography (PET)

Positron emission tomography (PET) has become widely established in oncology. Subsequently, a whole new “toolbox” of tracers have become available to look at different aspects of cancer cell function and dysfunction, including cell protein production, DNA synthesis, hypoxia and angiogenesis. In the past 5 years, these tools have been used increasingly to look at the other great killer of the developed world: cardiovascular disease. For example, inflammation of the unstable plaque can be imaged with 18-fludeoxyglucose (18F-FDG), and this uptake can be quantified to show the effect that statins have in reducing inflammation and explains how these drugs can reduce the risk of stroke. 18F-FDG has also become established in diagnosing and monitoring large-vessel vasculitis and has now entered routine practice. Other agents such as gallium-68 (68Ga) octreotide have been shown to identify vascular inflammation possibly more specifically than 18FFDG.Hypoxia within the plaque can be imaged with 18F-fluoromisonidazole and resulting angiogenesis with 18F-RGD peptides. Active calcification such as that found in unstable atheromatous plaques can be imaged with 18F-NaF. PET imaging enables us to understand the mechanisms by which cardiovascular disease, including atheroma, leads tomorbidity and death and thus increases the chance of finding new and effective treatments.

Different Scoring Methods of FDG PET/CT in Giant Cell Arteritis: Need for Standardization

Giant cell arteritis (GCA) is the most frequent form of vasculitis in persons older than 50 years. Cranial and systemic large vessels can be involved. [¹⁸F] fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is increasingly used to diagnose inflammation of the large arteries in GCA. Unfortunately, no consensus exists on the preferred scoring method. In the present study, we aim to define the optimal FDG PET/CT scoring method for GCA diagnosis using temporal artery biopsy and clinical diagnosis as the reference method. FDG PET/CT scans of GCA patients (12 glucocorticoid-naive, 6 on glucocorticoid treatment) and 3 control groups (inflammatory, atherosclerotic, and normal controls) were evaluated. We compared 2 qualitative visual methods (i.e. (1a) first impression and (1b) vascular uptake versus liver uptake) and 4 semiquantitative methods ((2a) SUVmax aorta, (2b) SUVmax aorta-to-liver ratio, (2c) SUVmax aorta-to-superior-caval-vein ratio, and (2d) SUVmax aorta-to-inferior-caval-vein ratio). FDG uptake pattern (diffuse or focal) and presence of arterial calcifications were also scored. Diagnostic accuracy of the visual method vascular versus liver uptake (1b) was highest when the cut-off point "vascular uptake higher than liver uptake" (sensitivity 83%, specificity 91%) was used. Sensitivity increased to 92% when patients on glucocorticoids were excluded from the analysis. Regarding the semiquantitative methods, the aorta-to-liver ratio (2b) with a cutoff of 1.03 had the highest diagnostic accuracy, with a sensitivity and specificity of 69% and 92%, respectively. Sensitivity increased to 90% when patients on glucocorticoids were excluded. The number of vascular segments with diffuse FDG uptake pattern was significantly higher in GCA patients without glucocorticoid use compared with all control patient groups. CRP was not significantly different between positive and negative FDG PET scans in the GCA group. Visual vascular uptake higher than liver uptake resulted in the highest diagnostic accuracy for the detection of GCA, especially in combination with a diffuse FDG uptake pattern. Of the semiquantitative methods, the aorta-to-liver SUVmax ratio (cutoff point = 1.03) had the highest diagnostic accuracy. The diagnostic accuracy increased when patients using glucocorticoids were excluded from the analyses.

Imaging in systemic vasculitis

PURPOSE OF REVIEW

Imaging is becoming a relevant tool for the assessment of patients with systemic vasculitis. This review focuses on recently generated data with potential clinical impact in the diagnosis, evaluation of disease extent and management of systemic vasculitis.

RECENT FINDINGS

Temporal artery examination by color duplex ultrasonography (CDUS) is a valuable approach to the diagnosis of giant-cell arteritis. Evaluation of additional arteries may increase its diagnostic performance. However, CDUS-specific findings may not be detected in arteries with early inflammation and CDUS-guidance of temporal artery biopsy does not seem to significantly increase its diagnostic yield. Large-vessel involvement detected by computed tomography angiography occurs in two out of three of patients with giant-cell arteritis at diagnosis. Furthermore, significant ascending aortic dilatation can be observed in one out of three of patients after long-term follow-up. Objective cut-offs for detecting large-vessel inflammation by positron emission tomography (PET) are trying to be established through prospective studies. PET may also contribute to the assessment of disease extent in patients with ANCA-associated vasculitis or Behçet's disease.

SUMMARY

Data generated by existing and emerging imaging techniques are expected to have a major impact in the diagnosis, appraisal of disease extent, evaluation of disease activity and response to treatment in patients with systemic vasculitis.

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.

Advances in the diagnosis of large vessel vasculitis

The diagnosis of large-vessel vasculitis has experienced substantial improvement in recent years. While Takayasu arteritis diagnosis relies on imaging, the involvement of epicranial arteries by giant-cell arteritis facilitates histopathological confirmation. When appropriately performed temporal artery biopsy has high sensitivity and specificity. However, an optimal biopsy is not always achievable and, occasionally, the superficial temporal artery may not be involved. Imaging in its various modalities including colour-duplex ultrasonography, computed tomography angiography, magnetic resonance angiography and positron emission tomography, are emerging as important procedures for the diagnosis and assessment of disease extent in large-vessel vasculitis. Recent contributions to the better performance and interpretation of temporal artery biopsies as well as advances in imaging are the focus of the present review.

Fever of unknown origin

More than 50 years after the first definition of fever of unknown origin (FUO), it still remains a diagnostic challenge. Evaluation starts with the identification of potential diagnostic clues (PDCs), which should guide further investigations. In the absence of PDCs a standardised diagnostic protocol should be followed with PET-CT as the imaging technique of first choice. Even with a standardised protocol, in a large proportion of patients from western countries the cause for FUO cannot be identified. The treatment of FUO is guided by the final diagnosis, but when no cause is found, antipyretic drugs can be prescribed. Corticosteroids should be avoided in the absence of a diagnosis, especially at an early stage. The prognosis of FUO is determined by the underlying cause. The majority of patients with unexplained FUO will eventually show spontaneous remission of fever. We describe the definition, diagnostic workup, causes and treatment of FUO.

FDG PET/CT in infection and inflammation--current and emerging clinical applications

Integrated positron emission tomography/computed tomography (PET/CT) with the glucose analogue, 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG), is an evolving hybrid imaging technique in the evaluation of an important and diverse group of pathological conditions, which are characterised by infection and aseptic inflammation. With a rapidly expanding body of evidence, it is being increasingly recognised that, in addition to its established role in oncological imaging, FDG PET/CT also has clinical utility in suspected infection and inflammation. The technique can identify the source of infection or inflammation in a timely fashion ahead of morphological changes on conventional anatomical imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), map the extent and severity of disease, identify sites for tissue sampling, and assess therapy response. FDG PET/CT exhibits distinct advantages over traditional radionuclide imaging techniques in terms of shorter duration of examination, higher spatial resolution, non-invasive nature of acquisition, ability to perform quantitative analyses, and the provision of a synergistic combination of functional and anatomical imaging. With the use of illustrative clinico-radiological cases, this article discusses the current and emerging evidence for the use of FDG PET/CT in a broad spectrum of disorders, such as fever of unknown origin, sarcoidosis, large vessel vasculitis, musculoskeletal infections, joint prosthesis or implant-related complications, human immunodeficiency virus (HIV)-related infections, and miscellaneous indications, such as IgG4-related systemic disease. It will also briefly summarise the role of more novel tracers such as FDG-labelled leukocytes and gallium-68 PET tracers in this arena.

Management of large-vessel vasculitis with FDG-PET: a systematic literature review and meta-analysis

We aimed to clarify the role of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the management of large-vessel vasculitis (LVV), focusing on 3 issues which are as follows: describe and determine the different FDG-PET criteria for the diagnosis of vascular inflammation, the performance of FDG-PET for the diagnosis of large-vessel inflammation in giant cell arteritis (GCA) patients, and the performance of FDG-PET to evaluate the disease inflammatory activity in Takayasu arteritis (TA) patients. MEDLINE, Cochrane Library, and EMBASE database were searched for articles that evaluated the value of FDG-PET in LVV, from January 2000 to December 2013. Inclusion criteria were American College of Rheumatology criteria for GCA or TA, definition PET positivity threshold, and >4 cases included. Sensitivity (Se) and specificity (Sp) of FDG-PET for the diagnosis of large-vessel inflammation were calculated from each included individual study, and then pooled for meta-analysis with a random-effects model. Twenty-one studies (413 patients, 299 controls) were included in the systematic review. FDG-PET showed FDG vascular uptake in 70% (288/413) of patients and 7% (22/299) of controls. Only vascular uptake equal to or higher than the liver uptake was significantly different between GCA/TA patients and controls (P < 0.001). The meta-analysis of GCA patients (4 studies, 57 patients) shows that FDG-PET has high Se and Sp for the diagnosis of large-vessel inflammation in GCA patients in comparison to controls, with a pooled Se at 90% (95% confidence interval [CI], 79%-93%) and a pooled Sp at 98% (95% CI, 94%-99%). The meta-analysis of TA patients (7 studies, 191 patients) shows that FDG-PET has a pooled Se at 87% (95% CI, 78%-93%) and Sp at 73% (95% CI, 63%-81%) for the assessment of disease activity in TA, with up to 84% Sp, with studies using National Institutes of Health criteria as the disease activity assessment scale. FDG-PET showed good performances in the diagnosis of large-vessel inflammation, with higher accuracy in GCA patients than in TA patients. Although a vascular uptake equal to or higher than the liver uptake appears to be a good criterion for the diagnosis of vascular inflammation, further studies are needed to define the threshold of significance as well as the clinical significance of the vascular uptake.