Comparison between colour duplex sonography findings and different histological patterns of temporal artery

Halo sign on temporal artery ultrasound versus temporal artery biopsy for giant cell arteritis

BACKGROUND

Giant cell arteritis (GCA) is a systemic, inflammatory vasculitis primarily affecting people over the age of 50 years. GCA is treated as a medical emergency due to the potential for sudden, irreversible visual loss. Temporal artery biopsy (TAB) is one of the five criteria of the American College of Rheumatology (ACR) 1990 classification, which is used to aid the diagnosis of GCA. TAB is an invasive test, and it can be slow to obtain a result due to delays in performing the procedure and the time taken for histopathologic assessment. Temporal artery ultrasonography (US) has been demonstrated to show findings in people with GCA such as the halo sign (a hypoechoic circumferential wall thickening due to oedema), stenosis or occlusion that can help to confirm a diagnosis more swiftly and less invasively, but requiring more subjective interpretation. This review will help to determine the role of these investigations in clinical practice.

OBJECTIVES

To evaluate the sensitivity and specificity of the halo sign on temporal artery US, using the ACR 1990 classification as a reference standard, to investigate whether US could be used as triage for TAB. To compare the accuracy of US with TAB in the subset of paired studies that have obtained both tests on the same patients, to investigate whether it could replace TAB as one of the criteria in the ACR 1990 classification.

SEARCH METHODS

We used standard Cochrane search methods for diagnostic accuracy. The date of the search was 13 September 2022.

SELECTION CRITERIA

We included all participants with clinically suspected GCA who were investigated for the presence of the halo sign on temporal artery US, using the ACR 1990 criteria as a reference standard. We included studies with participants with a prior diagnosis of polymyalgia rheumatica. We excluded studies if participants had had two or more weeks of steroid treatment prior to the investigations. We also included any comparative test accuracy studies of the halo sign on temporal artery US versus TAB, with use of the 1990 ACR diagnostic criteria as a reference standard. Although we have chosen to use this classification for the purpose of the meta-analysis, we accept that it incorporates unavoidable incorporation bias, as TAB is itself one of the five criteria. This increases the specificity of TAB, making it difficult to compare with US. We excluded case-control studies, as they overestimate accuracy, as well as case series in which all participants had a prior diagnosis of GCA, as they can only address sensitivity and not specificity.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion in the review. They extracted data using a standardised data collection form and employed the QUADAS-2 tool to assess methodological quality. As not enough studies reported data at our prespecified halo threshold of 0.3 mm, we fitted hierarchical summary receiver operating characteristic (ROC) models to estimate US sensitivity and also to compare US with TAB. We graded the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Temporal artery ultrasound was investigated in 15 studies (617 participants with GCA out of 1479, 41.7%), with sample sizes ranging from 20 to 381 participants (median 69). There was wide variation in sensitivity with a median value of 0.78 (interquartile range (IQR) 0.45 to 0.83; range 0.03 to 1.00), while specificity was fair to good in most studies with a median value of 0.91 (IQR 0.78 to 1.00; range 0.40 to 1.00) and four studies with a specificity of 1.00. The hierarchical summary receiver operating characteristic (HSROC) estimate of sensitivity (95% confidence interval (CI)) at the high specificity of 0.95 was 0.51 (0.21 to 0.81), and 0.84 (0.58 to 0.95) at 0.80 specificity. We considered the evidence on sensitivity and specificity as of very low certainty due to risk of bias (-1), imprecision (-1), and inconsistency (-1). Only four studies reported data at a halo cut-off > 0.3 mm, finding the following sensitivities and specificities (95% CI): 0.80 (0.56 to 0.94) and 0.94 (0.81 to 0.99) in 55 participants; 0.10 (0.00 to 0.45) and 1.00 (0.84 to 1.00) in 31 participants; 0.73 (0.54 to 0.88) and 1.00 (0.93 to 1.00) in 82 participants; 0.83 (0.63 to 0.95) and 0.72 (0.64 to 0.79) in 182 participants. Data on a direct comparison of temporal artery US with biopsy were obtained from 11 studies (808 participants; 460 with GCA, 56.9%). The sensitivity of US ranged between 0.03 and 1.00 with a median of 0.75, while that of TAB ranged between 0.33 and 0.92 with a median of 0.73. The specificity was 1.00 in four studies for US and in seven for TAB. At high specificity (0.95), the sensitivity of US and TAB were 0.50 (95% CI 0.24 to 0.76) versus 0.80 (95% CI 0.57 to 0.93), respectively, and at low specificity (0.80) they were 0.73 (95% CI 0.49 to 0.88) versus 0.92 (95% CI 0.69 to 0.98). We considered the comparative evidence on the sensitivity of US versus TAB to be of very low certainty because specificity was overestimated for TAB since it is one of the criteria used in the reference standard (-1), together with downgrade due to risk of bias (-1), imprecision (-1), and inconsistency (-1) for both sensitivity and specificity.

AUTHORS' CONCLUSIONS

There is limited published evidence on the accuracy of temporal artery US for detecting GCA. Ultrasound seems to be moderately sensitive when the specificity is good, but data were heterogeneous across studies and either did not use the same halo thickness threshold or did not report it. We can draw no conclusions from accuracy studies on whether US can replace TAB for diagnosing GCA given the very low certainty of the evidence. Future research could consider using the 2016 revision of the ACR criteria as a reference standard, which will limit incorporation bias of TAB into the reference standard.

Ultrasound intima media thickness cut-off values for cranial and extracranial arteries in patients with suspected giant cell arteritis

Objective

To determine the optimal ultrasound (US) cut-off values for cranial and extracranial arteries intima media thickness (IMT) to discriminate between patients with and without giant cell arteritis (GCA).

Methods

Retrospective observational study including patients referred to an US fast-track clinic. All patients underwent bilateral US examination of the cranial and extracranial arteries including the IMT measurement. Clinical confirmation of GCA after 6 months was considered the gold standard for diagnosis. A receiver operating characteristic (ROC) analysis was performed to select the cut-off values on the basis of the best tradeoff values between sensitivity and specificity.

Results

A total of 157 patients were included, 47 (29.9%) with clinical confirmation of GCA after 6 months. 41 (87.2%) of patients with GCA had positive US findings (61.7% had cranial and 44.7% extracranial involvement). The best threshold IMT values were 0.44 mm for the common temporal artery; 0.34 mm for the frontal branch; 0.36 mm for the parietal branch; 1.1 mm for the carotid artery and 1 mm for the subclavian and axillary arteries. The areas under the ROC curves were greater for axillary arteries 0.996 (95% CI 0.991-1), for parietal branch 0.991 (95% CI 0.980-1), for subclavian 0.990 (95% CI 0.979-1), for frontal branch 0.989 (95% CI 0.976-1), for common temporal artery 0.984 (95% CI 0.959-1) and for common carotid arteries 0.977 (95% CI 0.961-0.993).

Conclusion

IMT cut-off values have been identified for each artery. These proposed IMT cut-off values may help to improve the diagnostic accuracy of US in clinical practice.

Ultrasound centre frequency shifts as a novel approach for diagnosing giant cell arteritis

OBJECTIVE

Giant cell arteritis (GCA) is a treatable, but potentially sight- and life-threatening form of systemic vasculitis. Prompt and correct diagnosis is therefore important. Temporal artery biopsy (TAB) is the gold standard for diagnosing GCA, but is associated with risks. There is no reliable non-invasive technique for the diagnosis of GCA. Ultrasound centre frequency shift (CFS) is a novel technique that uses high-frequency ultrasound and the analysis of the centre frequency of the ultrasound pulse, which is dependent on the size of the microstructures in the tissue. This provides an objective measure of the scattering microstructures in the tissue, and thus has the potential to discriminate changes due to disease. The aim of this study was to assess ultrasound CFS as a means of discriminating arteries affected by GCA from healthy arteries.

METHOD

TAB specimens from 68 subjects, 53 female and 15 male, with a mean age of 73 (range 52-87) years, with suspected GCA were examined using ultrasound ex vivo and the CFS was analysed. The temporal arteries were then examined histopathologically.

RESULTS

Histopathological examination revealed that 25 of the 68 biopsies of the temporal artery showed inflammatory changes in the vessel wall compatible with GCA. The ultrasound CFS decreased less in TAB-positive than in TAB-negative temporal arteries (p < 0.05).

CONCLUSIONS

This proof-of-principle study indicates that ultrasound CFS has the potential to detect GCA in temporal arteries. Further technical development will be needed before in vivo examination can be performed and the clinical applicability can be assessed.

Role of the halo sign in the assessment of giant cell arteritis: a systematic review and meta-analysis

Objectives

This systematic review and meta-analysis aimed to evaluate the diagnostic value of the halo sign in the assessment of GCA.

Methods

A systematic literature review was performed using MEDLINE, EMBASE and Cochrane central register databases up to August 2020. Studies informing on the sensitivity and specificity of the US halo sign for GCA (index test) were selected. Studies with a minimum of five participants were included. Study articles using clinical criteria, imaging such as PET-CT and/or temporal artery biopsy (TAB) as the reference standards were selected. Meta-analysis was conducted with a bivariate model.

Results

The initial search yielded 4023 studies. Twenty-three studies (patients n = 2711) met the inclusion criteria. Prospective (11 studies) and retrospective (12 studies) studies in academic and non-academic centres were included. Using clinical diagnosis as the standard (18 studies) yielded a pooled sensitivity of 67% (95% CI: 51, 80) and a specificity of 95% (95% CI: 89, 98%). This gave a positive and negative likelihood ratio for the diagnosis of GCA of 14.2 (95% CI: 5.7, 35.5) and 0.375 (95% CI: 0.22, 0.54), respectively. Using TAB as the standard (15 studies) yielded a pooled sensitivity of 63% (95% CI: 50, 75) and a specificity of 90% (95% CI: 81, 95).

Conclusion

The US halo sign is a sensitive and specific approach for GCA assessment and plays a pivotal role in diagnosis of GCA in routine clinical practice.

Registration

PROSPERO 2020 CRD42020202179.

Diagnosing Giant Cell Arteritis: A Comprehensive Practical Guide for the Practicing Rheumatologist

Giant cell arteritis (GCA) is the most common large vessel vasculitis in the elderly population. In recent years, advanced imaging has changed the way GCA can be diagnosed in many locations. The GCA fast-track clinic (FTC) approach combined with ultrasound (US) examination allows prompt treatment and diagnosis with high certainty. FTCs have been shown to improve prognosis while being cost effective. However, all diagnostic modalities are highly operator dependent, and in many locations expertise in advanced imaging may not be available. In this paper, we review the current evidence on GCA diagnostics and propose a simple algorithm for diagnosing GCA for use by rheumatologists not working in specialist centres.

Ultrasonography in the diagnosis and follow-up of giant cell arteritis

Colour Doppler ultrasonography is the first measure to allow objective bedside assessment of GCA. This article discusses the evidence using the OMERACT filter. Consensus definitions for ultrasonographic changes were agreed upon by a Delphi process, with the 'halo' and 'compression' signs being characteristic. The halo is sensitive to change, disappearing within 2-4 weeks of starting glucocorticoids. Ultrasonography has moderate convergent validity with temporal artery biopsy in a pooled analysis of 12 studies including 965 participants [κ = 0.44 (95% CI 0.38, 0.50)]. The interobserver and intra-observer reliabilities are good (κ = 0.6 and κ = 0.76-0.78, respectively) in live exercises and excellent when assessing acquired images and videos (κ = 0.83-0.87 and κ = 0.88, respectively). Discriminant validity has been tested against stroke and diabetes mellitus (κ=-0.16 for diabetes). Machine familiarity and adequate examination time improves performance. Ultrasonography in follow-up is not yet adequately defined. Some patients have persistent changes in the larger arteries but these do not necessarily imply treatment failure or predict relapses.

Ultrasonographic Halo Score in giant cell arteritis: association with intimal hyperplasia and ischaemic sight loss

Objectives

We investigated the relationship between the ultrasonographic Halo Score and temporal artery biopsy (TAB) findings in GCA.

Methods

This is a prospective study including 90 patients suspected of having GCA. Ultrasonography of temporal/axillary arteries and a TAB were obtained in all patients at baseline. An experienced pathologist evaluated whether TAB findings were consistent with GCA, and whether transmural inflammation, giant cells and intimal hyperplasia were present. Ultrasonographic Halo Scores were determined. Receiver operating characteristic analysis was performed.

Results

Twenty-seven patients had a positive TAB, while 32 patients with a negative TAB received a clinical diagnosis of GCA after 6 months of follow-up. Patients with a positive TAB showed higher Halo Scores than patients with a negative TAB. The presence of intimal hyperplasia in the biopsy, rather than the presence of transmural inflammation or giant cells, was associated with elevated Halo Scores in patients with GCA. The Halo Score discriminated well between TAB-positive patients with and without intimal hyperplasia, as indicated by an area under the curve of 0.82 in the receiver operating characteristic analysis. Patients with a positive TAB and intimal hyperplasia more frequently presented with ocular ischaemia (40%) than the other patients with GCA (13–14%).

Conclusion

The ultrasonographic Halo Score may help to identify a subset of GCA patients with intimal hyperplasia, a TAB feature associated with ischaemic sight loss.

Clinicopathologic Associations in a Large International Cohort of Patients with Giant Cell Arteritis

OBJECTIVE

In addition to aiding in diagnosis, histopathologic findings from temporal artery biopsy (TAB) specimens in giant cell arteritis (GCA) may be valuable for their associations with clinical features of the disease. This study compared histopathologic findings on TAB with biopsy interpretation and demographic, clinical, and imaging features at time of diagnosis.

METHODS

Patients with a clinical diagnosis of GCA who had a TAB were selected from an international, multicenter observational cohort of vasculitis. Associations between demographic, clinical, radiographic, and histopathologic features were identified using bivariate testing and multivariate regression modeling.

RESULTS

Out of 705 patients with GCA who underwent TAB, 69% had histopathological evidence of definite vasculitis. Specific histopathological findings included the presence of giant cells (51%), fragmentation of the internal elastic lamina (41%), intimal thickening (33%), and predominantly mononuclear leukocyte infiltration (32%). Histopathologic interpretation of definite vasculitis was independently associated with giant cells (odds ratios (OR) 151.8, 95% confidence interval (CI): 60.2-551.6), predominantly mononuclear leukocyte infiltration (OR 11.8, CI 5.9-24.9), and fragmentation of the internal elastic lamina (OR 3.7, CI 1.9-7.4). A halo sign on temporal artery ultrasound and luminal damage of large arteries on angiography were significantly associated with presence of giant cells (OR 2.6, CI 1.1-6.5 and OR 2.4, CI 1.1-5.2, respectively). Specific histopathologic findings were associated with older age but no associations were identified with vision loss or other clinical features.

CONCLUSION

Histopathologic findings in GCA are strongly associated with the clinical diagnosis of GCA but have a limited role in identifying patterns of disease.

Significance of inflammation restricted to adventitial/periadventitial tissue on temporal artery biopsy

OBJECTIVE

To evaluate the characteristics and significance of inflammation restricted (RI) to the adventitial and/or periadventitial tissue on temporal artery biopsy (TAB).

METHODS

We studied a retrospective cohort of 80 patients with RI, extending our earlier series of 39 patients. For comparison purposes, we collected the same data from 254 patients with transmural inflammation (TMI) and 81 TAB-negative patients. A review of the literature was also performed.

RESULTS

A final diagnosis of giant cells arteritis (GCA) and/or polymyalgia rheumatica (PMR) was observed in 86% of patients with RI. Compared to TMI, GCA diagnosis was significantly less frequently observed in patients with RI and in those TAB-negative (p < 0.0001), while cranial manifestations were significantly less frequent (p = 0.001) and ESR and CRP values at diagnosis significantly reduced (p < 0.0001). PMR, permanent visual loss, and large vessel involvement at diagnosis were equally present in the 3 subgroups. The median duration of prednisone therapy, the cumulative prednisone dosages, and the relapse and long-term remission rates were similar between patients with GCA-RI and those with TMI. The positive likelihood ratios (LRs) of pathological evidence of RI at TAB for GCA or GCA/PMR diagnoses were 0.88 (CI, 0.61-1.27) and 1.15 (CI, 0.67-1.99), while that of inflammation limited to adventitia was 1.37 (CI, 0.59-3.19) and 3.77 (CI, 0.53-26.72). In the literature review, the positive LR of RI for GCA diagnosis was 0.92 (CI, 0.68-1.25).

CONCLUSION

A large part of the patients with RI have GCA/PMR, however, the diagnostic value of RI for GCA diagnosis is not relevant.

Diagnosis of giant cell arteritis

GCA is the most common form of primary systemic vasculitis affecting older people. It is considered a clinical emergency because it can lead to irreversible blindness in around 20% of untreated cases. High doses of glucocorticoids should be initiated promptly to prevent disease-related complications; however, glucocorticoids therapy usually results in significant toxicity. Therefore, correct diagnosis is crucial. For many years, temporal artery biopsy has been considered the diagnostic ‘gold standard’ for GCA, but it has many limitations (including low sensitivity). US has proven to be effective for diagnosing GCA and can reliably replace temporal artery biopsy in particular clinical settings. In cases of suspected GCA with large-vessel involvement, other imaging modalities can be used for diagnosis (e.g. CT and PET). Here we review the current evidence for each diagnostic modality and propose an algorithm to diagnose cranial-GCA in a setting with rapid access to high quality US.

The role of vascular ultrasound in managing giant cell arteritis in ophthalmology

Giant cell arteritis is the most common systemic vasculitis in the elderly and is a potentially life-threatening ophthalmic emergency that can result in irreversible blindness. Blindness is most commonly associated with acute onset, irreversible arteritic ischemic optic neuropathy. Without treatment, second eye involvement may occur, resulting in bilateral blindness. Patients with established visual loss are treated with high-dose steroids and generally undergo a temporal artery biopsy to confirm their diagnosis. A significant number of patients are, however, referred for urgent ophthalmology assessment from concerns about "incipient" arteritic ischemic optic neuropathy. Before visual loss, patients may experience a range of ocular symptoms related to ischemia. This generally leads to treatment with high-dose systemic steroid and an urgent request for a temporal artery biopsy. Temporal artery biopsy is considered as the standard investigation for confirmatory diagnosis. It is generally arranged as soon as possible, although it is often not carried out for several days, and there may also be delays in histopathological reporting. It is often perceived that the patient is "safe" while on corticosteroids, in that they are being treated to avoid visual loss. What is not acknowledged, however, is that, if patients do not have giant cell arteritis and are being treated "just in case," they will often require a tapering of oral steroids over several weeks, exposing them to unnecessary and significant side effects. In the rheumatology setting, vascular ultrasound has emerged as a safe and reliable alternative to temporal artery biopsy as a point of care diagnostic tool in the management of giant cell arteritis. Given an experienced sonographer and optimal equipment, a rapid diagnosis can be established in a fast-track clinic setting, taking into consideration clinical assessment, scoring, and ultrasound findings. A huge advantage of ultrasound is that it provides immediate information that can be used to inform treatment decisions. We explore the evidence that supports the incorporation of vascular ultrasound into the ophthalmology repertoire to make a more efficient diagnosis that is cost-effective and associated with better patient outcomes, including a potential reduction in loss of sight and avoidance of unnecessary long-term steroid treatment by early exclusion of mimics.

Predictive value of positive temporal artery biopsies in patients with clinically suspected giant cell arteritis considering temporal artery ultrasound findings

PURPOSE

To investigate the impact of ocular symptom, non-ocular symptom, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and temporal artery ultrasound (TAU) findings on the predictive value of a positive temporal artery biopsy (TAB) in patients with clinically suspected giant cell arteritis (GCA).

METHODS

In a retrospective, interventional study, data from 68 patients with clinically suspected GCA who underwent TAB between 2015 and 2017 were analysed. Analysis included five parameters: ocular symptom, non-ocular symptom, ESR, CRP level and TAU findings. Using a contingency table, each parameter was separately analysed for the predictive value of a positive TAB, and a discriminant analysis was applied to check for the predictive value of a positive TAB under consideration of all five parameters and of the three strongest predictive parameters.

RESULTS

A positive TAB was significantly associated with a positive TAU in 15 of 15 patients (p < 0.001), an increased ESR in 37 of 53 patients (p < 0.001), an increased CRP level in 35 of 56 patients (p = 0.004) and non-ocular symptoms in 27 of 40 patients (p = 0.01). A positive TAB was not significantly associated with the presence of ocular symptoms (25 of 46 patients, p = 0.988). Using a discriminant analysis, the combined parameters TAU, ESR and CRP were able to predict a positive TAB in 97.3% of all patients. The positive predictive value was 78.3%, and the negative predictive value was 95.4%.

CONCLUSION

Temporal artery biopsy to confirm the diagnosis of GCA may not be mandatory in patients who show an elevated ESR and CRP level and a positive TAU.

Diagnostic performance and utility of very high-resolution ultrasonography in diagnosing giant cell arteritis of the temporal artery

OBJECTIVE

Very-high resolution US (VHRU; 55 MHz) provides improved resolution and could provide non-invasive diagnostic information in GCA of the temporal artery. The objective of this study was to assess the diagnostic utility of VHRU-derived intima thickness (VHRU-IT) in comparison to high-resolution US halo-to-Doppler ratio (HRU-HDR) in patients referred for temporal artery biopsy.

METHODS

VHRU and HRU of the temporal artery were performed before a biopsy procedure in 78 prospectively recruited consecutive patients who had received glucocorticoid treatment for a median of 8 days (interquartile range 0-13 days) before imaging. Based on the final diagnosis and biopsy findings, the study population was divided into the following four groups: non GCA (n = 40); clinical GCA with no inflammation on biopsy (n = 15); clinical GCA with inflammation limited to adventitia (n = 9); and clinical GCA with transmural inflammation (TMI; n = 11).

RESULTS

Both VHRU and HRU were useful for identifying subjects with TMI, with VHRU outperforming HRU (area under curve: VHRU-IT 0.99, 95% CI 0.97, 1.00; HRU-HDR 0.74, 95% CI 0.52, 0.96; P=0.026). The diagnostic utility for diagnosing clinical GCA (negative biopsy) or inflammation limited to the adventitia was poor for both VHRU and HRU-HDR. From 5 days after initiation of glucocorticoid treatment, VHRU-IT was increased in eight of nine patients, whereas HRU-HDR was positive in three of seven patients. Both methods showed excellent inter-observer agreement (Cohen's κ: VHRU-IT 0.873; HRU-HDR 0.811).

CONCLUSION

In suspected GCA, VHRU allows non-invasive real-time imaging of TMI manifestations of the temporal artery wall. VHRU-derived intimal thickness measurement seems to be more sensitive than the halo sign and HRU-HDR in detecting TMI in patients with prolonged glucocorticoid treatment.

Ultrasound in the diagnosis and management of giant cell arteritis

US has become an important diagnostic tool for musculoskeletal diseases. Because of its wide availability in rheumatology practice, US has also been applied in other rheumatic diseases such as GCA. In acute GCA, US displays a non-compressible, hypoechoic, most commonly concentric arterial wall thickening. Temporal and axillary arteries should be examined in patients with suspected GCA and PMR. Additionally, almost all other large arteries, with the exception of the thoracic aorta, can be easily delineated by US. Many studies and several meta-analyses have been conducted to evaluate the diagnostic performance of US. US is more sensitive than temporal artery biopsy (TAB) because TAB evaluates only a limited anatomical region in a systemic disease. Most US studies arrive at specificities between 90 and 100% compared with the final clinical diagnosis. Reliability for reading US images and videos is excellent and comparable to reliability for reading TAB specimens. The advantage of US over other imaging techniques in GCA is its availability, safety and tolerability and its high resolution of 0.1 mm. Rheumatology departments are increasingly establishing fast-track clinics. Physicians can refer patients with suspected GCA within 24 h. Patients receive clinical and US examination by experienced specialists, establishing a clear diagnosis either before TAB or without the need for TAB. The introduction of fast-track clinics has led to a significant reduction of permanent vision loss. Furthermore, a process that primarily includes US is significantly more cost-effective than TAB.

Use of Noninvasive Imaging in Giant Cell Arteritis

Giant cell arteritis (GCA) requires a prompt diagnosis to avoid significant morbidity among the elderly. An accurate diagnosis is also paramount given the side effect profile of long-term corticosteroid treatment. Temporal artery biopsy (TAB) has long remained the gold standard for the diagnosis of GCA but requires an invasive procedure that is not without risk. This article discusses the argument for and against the use of noninvasive imaging including ultrasound, magnetic resonance imaging, and positron emission tomography scanning for the diagnosis of GCA. It also provides a suggested diagnostic algorithm for when to consider noninvasive imaging versus TAB.

The use of ultrasound to assess giant cell arteritis: review of the current evidence and practical guide for the rheumatologist

Colour duplex sonography (CDS) of temporal arteries and large vessels is an emerging diagnostic tool for GCA. CDS can detect wall oedema, known as a halo, throughout the length of the vessel and shows higher sensitivity compared with biopsy. Specificity reaches 100% in case of bilateral halos. A positive compression sign has been demonstrated to be a robust marker with excellent inter-observer agreement. The assessment of other large vessels, particularly the axillary arteries, is recognized to further increase the sensitivity and to reliably represent extra-cranial involvement in other areas. Nevertheless, CDS use is still not widespread in routine clinical practice and requires skilled sonographers. Moreover, its role in the follow-up of patients still needs to be defined. The aim of this review is to provide the current evidence and technical parameters to support the rheumatologist in the CDS evaluation of patients with suspected GCA.

Definitions and reliability assessment of elementary ultrasound lesions in giant cell arteritis: a study from the OMERACT Large Vessel Vasculitis Ultrasound Working Group

Objectives

To define the elementary ultrasound (US) lesions in giant cell arteritis (GCA) and to evaluate the reliability of the assessment of US lesions according to these definitions in a web-based reliability exercise.

Methods

Potential definitions of normal and abnormal US findings of temporal and extracranial large arteries were retrieved by a systematic literature review. As a subsequent step, a structured Delphi exercise was conducted involving an expert panel of the Outcome Measures in Rheumatology (OMERACT) US Large Vessel Vasculitis Group to agree definitions of normal US appearance and key elementary US lesions of vasculitis of temporal and extracranial large arteries. The reliability of these definitions on normal and abnormal blood vessels was tested on 150 still images and videos in a web-based reliability exercise.

Results

Twenty-four experts participated in both Delphi rounds. From originally 25 statements, nine definitions were obtained for normal appearance, vasculitis and arteriosclerosis of cranial and extracranial vessels. The ‘halo’ and ‘compression’ signs were the key US lesions in GCA. The reliability of the definitions for normal temporal and axillary arteries, the ‘halo’ sign and the ‘compression’ sign was excellent with inter-rater agreements of 91–99% and mean kappa values of 0.83–0.98 for both inter-rater and intra-rater reliabilities of all 25 experts.

Conclusions

The ‘halo’ and the ‘compression’ signs are regarded as the most important US abnormalities for GCA. The inter-rater and intra-rater agreement of the new OMERACT definitions for US lesions in GCA was excellent.

Ultrasound cut-off values for intima-media thickness of temporal, facial and axillary arteries in giant cell arteritis

Objective

To evaluate the intima-media thickness (IMT) of arteries involved in GCA for determining cut-off values.

Methods

Forty newly diagnosed GCA patients in a fast-track GCA clinic and 40 age- and sex-matched controls were included. IMT measurement was performed at or within 24 h after diagnosis. The common superficial temporal arteries with their frontal and parietal branches and the facial arteries were bilaterally examined with a 10-22 MHz probe and the axillary artery with a 6-18 MHz probe. Receiver operating characteristics analysis was performed for estimating cut-off values.

Results

The mean age was 72 years (s.d. 9) and 68% were females. In the control group, IMT was 0.23 mm (s.d. 0.04), 0.19 mm (s.d. 0.03), 0.20 mm (s.d. 0.03), 0.24 mm (s.d. 0.05) and 0.59 mm (s.d. 0.10) for the common superficial temporal arteries, the frontal and parietal branches, the facial arteries and the axillary arteries, respectively. In vasculitic segments of GCA patients, IMT was 0.65 mm (s.d. 0.18), 0.54 mm (s.d. 0.18), 0.50 mm (s.d. 0.17), 0.53 mm (s.d. 0.16) and 1.7 mm (s.d. 0.41), respectively. Cut-off values are 0.42, 0.34, 0.29, 0.37 and 1.0 mm, respectively, with 100% sensitivities and specificities for common superficial temporal arteries, for frontal branches and for axillary arteries and sensitivities of 97.2 and 87.5% and specificities of 98.7 and 98.8% for parietal branches and facial arteries, respectively. The intraclass correlation coefficient was between 0.87 and 0.98.

Conclusion

IMT measurement can correctly distinguish vasculitic from normal arteries in suspected GCA.

The value of ultrasound in diagnosing extracranial large-vessel vasculitis compared to FDG-PET/CT: A retrospective study

Large-vessel vasculitis (LVV) is a group of diseases mainly comprised of giant-cell arteritis (GCA), Takayasu arteritis, and a series of rare diseases like Behçet's disease, IgG4-related disease, infectious aortitis, and other unfrequent entities. Besides clinical and laboratory features, Doppler sonography (DS) can assist in establishing the diagnosis. Its diagnostic sensitivity has been evaluated in various studies, most of them, however, in temporal arteritis (TA) respectively in LVV with involvement of the temporal artery. Little is known in extracranial LVV. We retrospectively evaluated the diagnostic accuracy of DS in 30 patients with extracranial, non-temporal LVV using the highly sensitive PET/CT as method of reference in comparison to 20 controls who were found to have no LVV. We investigated ten arterial sites and documented the presence of the sonographic halo sign. Sensitivities of DS for LVV were highest in the subclavian and axillary arteries (71.4%/72.2%) and low in the abdominal aorta (26.1%) and the common femoral artery (16.7%). DS detected 24 out of 30 cases of LVV (overall sensitivity 80.0%). The LVV cases where DS was completely negative did not significantly differ in leukocyte count, C-reactive protein, or erythrocyte sedimentation rate from LVV cases with positive DS. DS is a potent method in diagnosing extracranial LVV especially in the axillary and the subclavian arteries. Aortic, intraabdominal, and lower extremity artery manifestations, however, are often missed by DS. A second imaging modality (e.g., PET/CT) is therefore required.

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.

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.

Correlations between histopathological findings and clinical manifestations in biopsy-proven giant cell arteritis

OBJECTIVE

To correlate histopathological features of positive temporal artery biopsy (TAB) and clinical manifestations of the disease in a large single-center population-based cohort of patients with biopsy-proven giant cell arteritis (GCA).

METHODS

A pathologist with expertise in vasculitis and blinded to clinical data and final diagnosis reviewed all TABs performed for suspected GCA at our hospital between January 1986 and December 2013. Histopathologic features evaluated were: the severity of inflammation and intimal hyperplasia, both graded on a semiquantitative scale (mild = 1, moderate = 2, severe = 3), the presence of intraluminal acute thrombosis, calcifications, giant cells, fibrinoid necrosis and laminar necrosis.

RESULTS

274 patients had a final diagnosis of biopsy-proven GCA and were included in the study. Cranial ischemic events (CIEs) were observed in 161 (58.8%), visual manifestations in 79 (28.8%) and permanent (partial or complete) visual loss in 51 (18.6%) patients. Predictors for the development of CIEs were older age (OR = 1.057, 95% CI 1.019-1.097, p = 0.003), lower ESR values (OR = 0.990, 95% CI 0.981-0.999, p = 0.026) as well as the presence of giant cells (OR = 1.848, 95% CI 1.045-3.269, p = 0.035) and laminar necrosis at TAB (OR = 2.334, 95% CI 1.187-4.587, p = 0.014). Predictors for the development of permanent visual loss were lower CRP values (OR = 0.906, 95% CI 0.827-0.992, p = 0.033) and the presence of calcifications at TAB (OR = 3.672, 95% CI 1.479-9.121, p = 0.005). Fibrinoid necrosis was not observed in any of the TABs evaluated.

CONCLUSION

Pathological features of TAB may predict some manifestations of GCA. These findings may have implications for patients' management.

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.

Description and Validation of Histological Patterns and Proposal of a Dynamic Model of Inflammatory Infiltration in Giant-cell Arteritis

The extent of inflammatory infiltrates in arteries from patients with giant-cell arteritis (GCA) have been described using different terms and definitions. Studies investigating the relationship between GCA histological features and clinical manifestations have produced controversial results. The aims of this study were to characterize and validate histological patterns in temporal artery biopsies (TABs) from GCA patients, to explore additional histological features, including the coexistence of different patterns, and also to investigate the relationship of the inflammatory patterns with clinical and laboratory features.We performed histological examination of TAB from patients with GCA consecutively diagnosed between 1992 and 2012. Patterns of inflammation were defined according to the extent and distribution of inflammatory infiltrates within the artery. Clinical and laboratory variables were recorded. Two external investigators underwent a focused, one-day training session and then independently scored 77 cases. Quadratic-weighted kappa was calculated.TAB from 285 patients (200 female/85 male) were evaluated. Four histological inflammatory patterns were distinguished: 1 - adventitial (n = 16); 2 - adventitial invasive: adventitial involvement with some extension to the muscular layer (n = 21); 3 - concentric bilayer: adventitial and intimal involvement with media layer preservation (n = 52); and 4 - panarteritic (n = 196). Skip lesions were observed in 10% and coexistence of various patterns in 43%. Raw agreement of each external scorer with the gold-standard was 82% and 77% (55% and 46% agreement expected from chance); kappa = 0.82 (95% confidence interval [CI] 0.70-0.95) and 0.79 (95% CI 0.68-0.91). Although abnormalities on temporal artery palpation and the presence of jaw claudication and scalp tenderness tended to occur more frequently in patients with arteries depicting more extensive inflammation, no statistically significant correlations were found between histological patterns and clinical features or laboratory findings.In conclusion, we have described and validated 4 histological patterns. The presence of different coexisting patterns likely reflects sequential steps in the progression of inflammation and injury. No clear relationship was found between these patterns and clinical or laboratory findings. However, several cranial manifestations tended to occur more often in patients with temporal arteries exhibiting panarteritic inflammation. This validated score system may be useful to standardize stratification of histological severity for immunopathology biomarker studies or correlation with imaging.

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.

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.

Giant cell arteritis: diagnosis and treatment

Giant cell arteritis is the most common primary systemic vasculitis in adults. The condition is granulomatous arteritis of large and medium vessels, which occurs almost exclusively in patients aged 50 years or more. This article reviews the diagnosis and treatment of the disease.

Inflamed temporal artery: histologic findings in 354 biopsies, with clinical correlations

We reviewed 888 temporal artery biopsies (TAB) performed in 871 patients in a single institution from January 1986 to December 2013. Forty-four biopsies (4.9%) were inadequate, 490 (55.2%) were devoid of inflammation and were considered negative, and 354 (39.9%) showed inflammation and were considered positive. On the basis of the localization of the inflammation, positive TABs were further classified into 4 categories: small vessel vasculitis (SVV), in which inflammation was limited to small periadventitial vessels devoid of muscular coat, with sparing of the temporal artery (32 cases, 9% of the positive biopsies); vasa vasorum vasculitis (VVV), in which inflammation was limited to the adventitial vasa vasorum (23 cases, 6.5% of the positive biopsies); inflammation limited to adventitia (ILA), in which inflammation extended from a strictly perivascular localization to the surrounding adventitia, without medial involvement (25 cases, 7% of the positive biopsies); and transmural inflammation (TMI), in which inflammation crossed the external elastic lamina and extended to the media (274 cases, 77.5% of the positive biopsies). In TMI, inflammation was generally more prominent between media and adventitia and mostly consisted of T lymphocytes and macrophages, with occasionally a significant number of plasma cells. Numerous eosinophils or neutrophils (with or without leucocytoclasia and suppurative necrosis), fibrinoid necrosis (limited to small branches of the temporal artery), and acute thrombosis were unusual, being present in 8%, 1.8%, 0.7%, and 9.5% of our biopsies with TMI, respectively. Giant cells, laminar necrosis, and calcifications prevailed along the internal elastic lamina and were present in 74.8%, 25.2%, and 20% of the biopsies with TMI, respectively. Among the 322 patients with positive TAB on whom we obtained clinical information, 317 had giant cell arteritis and 5 had a different disease: 3 (with SVV at histology) had ANCA-associated vasculitis, 1 (with SVV with amyloid deposits) had primary systemic amyloidosis, and 1 (with TMI limited to a small branch) had polyarteritis nodosa. In none of these cases the biopsy showed fibrinoid necrosis or significant numbers of eosinophils or neutrophils. Considering the 317 patients with giant cell arteritis, those with SVV and VVV compared with those with TMI had a significantly lower frequency of cranial manifestation (including headache, jaw claudication, and abnormalities of temporal arteries), lower serum levels of acute-phase reactants, and a reduced frequency of prednisone therapy at the time of TAB, of the "halo sign" at color duplex sonography of temporal arteries, and of systemic symptoms (for VVV). Polymyalgia rheumatica and blindness were equally represented in all patients groups, whereas there was a higher frequency of male sex and peripheral arthritis in patients with SVV. Patients with ILA were more similar to those with TMI, having a lower frequency of headache, of abnormalities of temporal arteries, and of a positive "halo sign" at color duplex sonography of temporal arteries. In conclusion, the histologic spectrum of inflammatory lesions that can be found in TAB is broad, and the differences have clinical implications.