Diagnosing vasculitis with ultrasound: findings and pitfalls

Rheumatologists are increasingly utilizing ultrasound for suspected giant cell arteritis (GCA) or Takayasu arteritis (TAK). This enables direct confirmation of a suspected diagnosis within the examination room without further referrals. Rheumatologists can ask additional questions and explain findings to their patients while performing ultrasound, preferably in fast-track clinics to prevent vision loss. Vascular ultrasound for suspected vasculitis was recently integrated into rheumatology training in Germany. New European Alliance of Associations for Rheumatology recommendations prioritize ultrasound as the first imaging tool for suspected GCA and recommend it as an imaging option for suspected TAK alongside magnetic resonance imaging, positron emission tomography and computed tomography. Ultrasound is integral to the new classification criteria for GCA and TAK. Diagnosis is based on consistent clinical and ultrasound findings. Inconclusive cases require histology or additional imaging tests. Robust evidence establishes high sensitivities and specificities for ultrasound. Reliability is good among experts. Ultrasound reveals a characteristic non-compressible 'halo sign' indicating intima-media thickening (IMT) and, in acute disease, artery wall oedema. Ultrasound can further identify stenoses, occlusions and aneurysms, and IMT can be measured. In suspected GCA, ultrasound should include at least the temporal and axillary arteries bilaterally. Nearly all other arteries are accessible except the descending thoracic aorta. TAK mostly involves the common carotid and subclavian arteries. Ultrasound detects subclinical GCA in over 20% of polymyalgia rheumatica (PMR) patients without GCA symptoms. Patients with silent GCA should be treated as GCA because they experience more relapses and require higher glucocorticoid doses than PMR patients without GCA. Scores based on intima-thickness (IMT) of temporal and axillary arteries aid follow-up of GCA, particularly in trials. The IMT decreases more rapidly in temporal than in axillary arteries. Ascending aorta ultrasound helps monitor patients with extracranial GCA for the development of aneurysms. Experienced sonologists can easily identify pitfalls, which will be addressed in this article.

[Imaging of large vessel vasculitis]

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are the most important primary large vessel vasculitides. A rapid and reliable confirmation of the diagnosis is necessary to prevent ischemic complications. Patients with extracranial GCA and TAK often present with unspecific symptoms. Since 2018 the EULAR has recommended imaging as an alternative to histology for confirming the diagnosis. Ultrasound is particularly recommended as the primary imaging modality for cranial GCA. Alternatively, MRI and PET can be used for the diagnostics of temporal arteritis. Ultrasound is also valuable for extracranial GCA, alternatively MRI, CT or PET-CT can be used. This review discusses the current status of imaging techniques in large vessel vasculitis as well as the advantages and disadvantages. The focus is on ultrasound, which is increasingly being used as the primary diagnostic modality due to its excellent diagnostic quality, wide availability, noninvasiveness, and patient friendliness. Technical aspects, prerequisites, and normal and pathological findings are also presented. Finally, an outlook is given on promising new developments, such as scores for evaluating disease progression and contrast-enhanced ultrasound.

Vascular ultrasound in rheumatology practice

Rheumatologists are increasingly using vascular ultrasound. Several guidelines now recommend ultrasound as the first diagnostic modality in giant cell arteritis (GCA). The German curriculum for rheumatology training has recently included ultrasound for the acute diagnosis of vasculitis. Recent studies have shown that ultrasound of temporal, axillary, subclavian, and vertebral arteries has sensitivities and specificities of >90%. Vascular ultrasound detects subclinical GCA in approximately 20% of patients with "pure" polymyalgia rheumatica. GCA fast-track clinics might regularly include these patients. A new score based on the intima-media thickness of the temporal and axillary arteries allows the monitoring of structural changes with treatment. The score decreases faster for the temporal arteries than it does for the axillary arteries. Measuring the diameter of the ascending aorta and the aortic arch might become a fast and cost-effective tool for the long-term monitoring of aortic aneurysms in extracranial GCA. Vascular ultrasound also has a role for Takayasu arteritis, thrombosis, Behçet's syndrome, and Raynaud's phenomenon.

Impact of cardiovascular risk on the diagnostic accuracy of the ultrasound Halo Score for giant cell arteritis

OBJECTIVE

To evaluate the impact of cardiovascular risk (CVR) on the diagnostic accuracy of the ultrasonographic (US) Halo Score in patients with suspected giant cell arteritis (GCA).

METHODS

Retrospective observational study of patients referred to our US fast track clinic with suspected GCA for a 2-year period. The intima-media thickness (IMT) of cranial and extra-cranial arteries and the Halo Score was determined to assess the extent of vascular inflammation. The European Society of Cardiology Guidelines on CV Disease Prevention were used to define different categories of CVR and patients were classified according to the Systemic Coronary Risk Evaluation (SCORE). The gold standard for GCA diagnosis was clinical confirmation after a 6-month follow-up.

RESULTS

Of the 157 patients included, 47 (29.9%) had GCA after a 6-month follow-up. Extra-cranial artery IMT was significantly higher in patients with high/very high CVR than in those with low/moderate CVR, but only among patients without GCA. Non-GCA patients with high/very high CVR had also a significantly higher Halo Score in contrast with low/moderate CVR [9.38 (5.93) vs 6.16 (5.22); p = 0.007]. The area under the ROC curve of the Halo Score to identify GCA was 0.835 (95% CI 0.756-0.914), slightly greater in patients with low/moderate CVR (0.965 [95% CI 0.911-1]) versus patients with high/very high CVR (0.798 [95% CI 0.702-0.895]). A statistically weak positive correlation was found between the Halo Score and the SCORE (r 0.245; c = 0.002).

CONCLUSIONS

Elevated CVR may influence the diagnostic accuracy of the US Halo Score for GCA. Thus, CVR should be taken into consideration in the US screening for GCA.

The Diagnostic Performance of an Extended Ultrasound Protocol in Patients With Clinically Suspected Giant Cell Arteritis

Objective

To evaluate the diagnostic performance of an extended ultrasound protocol in patients referred under the suspicion of giant cell arteritis (GCA).

Methods

Consecutive patients with suspected GCA were examined with an extended color duplex ultrasound (CDU) protocol during a period of 2 years. The extended CDU protocol included temporal, axillary, subclavian, brachiocephalic, and carotid arteries. The reference was clinically diagnosed GCA, confirmed after ≥6-month follow-up. Hypo- or medium-echogenic, circumferential, homogenous wall thickening, and/or a positive compression sign in temporal arteries, were regarded as typical signs of arteritis.

Results

Of the eligible 201 patients, 83 (41%) received a clinical GCA diagnosis at follow-up ≥6 months post CDU examination. Among these cases, 48 (58%) demonstrated inflammation solely in temporal arteries, 8 (10%) showed abnormalities restricted to extra-cranial vessels, and 23 (28%) patients displayed inflammatory changes in both temporal and extra-cranial arteries. Color duplex ultrasound of temporal arteries yielded a diagnostic sensitivity and specificity [95% confidence intervals (CI)] of 86% (76–92%) and 99% (95–99%), respectively. By adding axillary artery examination, the sensitivity increased to 92% (83–97%) while the specificity remained unchanged. Further, inclusion of subclavian artery marginally increased the sensitivity by 1%. Finally, by also including brachiocephalic and common carotid arteries resulted in a sensitivity of 95% (88–99%) and a specificity of 98% (94–99%).

Conclusions

Color duplex ultrasound examination demonstrated a high accuracy in diagnosing patients both with cranial and extra-cranial GCA. Further examination of brachiocephalic and common carotid arteries can increase the sensitivity without affecting the specificity when temporal and axillary findings are indecisive. Finally, the extended CDU protocol allows measurement of the general burden of inflammation, which could be relevant for future monitoring purposes.

Improved support vector machine algorithm based on the influence of Gestational Diabetes Mellitus on the outcome of perinatal outcome by ultrasound imaging

Objectives:

In order to understand the incidence and epidemiological characteristics of gestational diabetes mellitus, the ultrasound imaging of support vector machine processing algorithm was used to clarify the outcome of maternal and neonatal gestational diabetes mellitus.

Methods:

This study selected clinical data of 12,190 pregnant women who were hospitalized for delivery, and were divided into diabetic group (1268 cases) and control group (10922 cases) according to the diagnosis of gestational diabetes. The study was conducted from January 1, 2012 to December 31, 2019. Colour Doppler ultrasound was performed to record fatal umbilical artery and brain the middle arteries and uterine arteries which are effective indicators of measuring fatal intrauterine conditions. Chi-square test was used to compare the rates between groups, and multivariate logistic regression was used for labour outcomes.

Results:

The incidence of diabetes during pregnancy is about 10.4% (1268/12190). Senior citizens and women suffering from obesity increase the risk of gestational diabetes, maternal hypertension disorders in pregnancy, premature rupture of membranes, oligohydramnios, fatal distress, multiple births, malpresentation risk increased significantly (P <0.05) than the control group. In gestational diabetes caesarean section rate was significantly higher (61.0% vs46.4%). Caesarean new born 5-minute Apgar score was significantly lower than the control group (P <0.05).

Conclusion:

In maternal gestational diabetes in high risk pregnancies, complications of pregnancy significantly increase the importance of enhancing weight management and blood glucose monitoring to reduce complications.

Recommendations for rheumatology ultrasound training and practice in the UK

OBJECTIVE

The aim of this paper is to present a UK-based consensus of principles and recommendations to guide rheumatology US training and practice.

METHOD

A Delphi process was conducted involving 19 US experts representing each of the 14 regions of the UK. A working group of experienced British Society for Rheumatology Ultrasound Special Interest Group (BSRUSSIG) members made seven proposals that were presented to the whole group for further discussion. This resulted in minor modifications and seven preliminary recommendations. Members were then asked to anonymously agree or disagree with each recommendation using an electronic ballot. A threshold of 75% was used to determine consensus agreement. Results were collated by an independent chairperson and presented to the BSRUSSIG in a face to face meeting where agreement for each recommendation was ratified and an action plan agreed for dissemination of the results and future development work.

RESULTS

Using a validated process, experts in rheumatology US have worked through an iterative process and have unanimously agreed seven recommendations for rheumatology training and practice. These cover a hierarchy of practice indications, education and training, including the need for practitioners to demonstrate lifelong learning, as well as a commitment to support mentors and trainers through the BSRUSSIG.

CONCLUSION

These are the first specific education and practice recommendations for rheumatology US in the UK and have been developed and endorsed by the BSRUSSIG. We intend that these proposals will help to support and validate rheumatology US practice and inform the development of future rheumatology training curricula and education programmes.

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.

Is the intima-media thickness of temporal and axillary arteries influenced by cardiovascular risk?

Objectives

To measure with US the intima-media thickness (IMT) of temporal (superficial, parietal and frontal branches) and axillary arteries in subjects without a diagnosis of GCA and/or PMR with different cardiovascular (CV) risk; and to assess the performance of previously proposed cut-off values for normal IMT.

Methods

Subjects ≥ 50 years without a diagnosis of GCA or PMR were included. Bilateral US of the temporal arteries, including the frontal and parietal branches, and axillary arteries was performed by two sonographers using a 10–22 MHz and 6–18 MHz probe. The following previously proposed cut-offs were considered: superficial temporal artery: 0.42 mm; frontal branch: 0.34 mm; parietal branch: 0.29 mm; axillary artery: 1.0 mm.

Results

A total of 808 arteries in 101 subjects were evaluated; of these, 31 (30.7%) were classified as very high CV risk, seven (6.9%) as high, 34 (33.7%) as moderate and 29 (28.7%) as low risk. Subjects with very high or high risk showed higher IMT than those with moderate or low risk in the superficial temporal arteries [0.23 (s.d. 0.07) vs 0.20 (s.d. 0.04), P &lt; 0.01] and in the axillary arteries [0.54 (s.d. 0.17) vs 0.48 (s.d. 0.10), P = 0.002]. The IMT was higher than the reference cut-off in 13/808 (1.6%) arteries, in ≥1 artery in 10/101 subjects (10.1%). Of these 10 subjects, 8 (80%) were classified as having very high or high risk.

Conclusion

Our results suggest that CV risk might influence the US-determined IMT of the temporal and axillary arteries in subjects without GCA. Therefore, in patients with suspected GCA, particular attention should be paid when measuring the IMT in those patients with very high/high CV risk.

Diagnostic value of axillary artery ultrasound in patients with suspected giant cell arteritis

Objectives

To compare colour duplex ultrasonography (CDU) findings with axillary ¹⁸F-fluorodeoxyglucose (FDG) PET/CT findings and to compare the diagnostic performance of temporal and axillary artery CDU with temporal artery CDU alone.

Methods

Patients suspected of GCA were retrospectively included. Presence of a halo or occlusion was considered a positive CDU finding. FDG-PET/CT-assessed axillary artery involvement was defined as axillary artery FDG uptake higher than liver uptake. The reference was the clinical diagnosis after 6 months, which was based on symptomatology and additional diagnostic tests, with the exception of CDU.

Results

Of the 113 included patients, GCA was diagnosed in 41. Twenty-eight out of 41 GCA patients underwent a FDG-PET/CT. FDG-PET-assessed extra-cranial GCA was present in 20/41 patients, of which 13 showed axillary involvement on FDG-PET/CT. An axillary halo was found in eight of these 13 patients. Six out of the 20 patients with FDG-PET-assessed GCA showed no axillary involvement on CDU or FDG-PET/CT. Five of them had single artery involvement on FDG-PET/CT (two aorta; three vertebral artery). One patient had an axillary occlusion on CDU, consistent with FDG-PET/CT results. Overall, sensitivity and specificity of temporal artery CDU was 52% (95% CI: 35, 67) and 93% (95% CI: 84, 97), respectively. Adding axillary artery results improved sensitivity to 71% (95% CI: 55, 84), while specificity did not change.

Conclusion

Presence of an axillary halo or occlusion on CDU is consistent with axillary artery FDG-PET/CT results, but a negative CDU does not rule out axillary involvement. Adding axillary artery assessment to temporal artery assessment may substantially increase the diagnostic performance of CDU.

Imaging for Diagnosis, Monitoring, and Outcome Prediction of Large Vessel Vasculitides

Purpose of Review

To discuss and summarize the latest evidence on imaging techniques in giant cell arteritis (GCA) and Takayasu arteritis (TAK). This is a report on the performance of ultrasound (US), magnetic resonance imaging (MRI), computed tomography (CT), 18F-fluorodeoxyglucose positron emission tomography (18-FDG-PET), and other emerging imaging techniques in diagnosis, outcome prediction, and monitoring of disease activity.

Recent Findings

Imaging techniques have gained an important role for diagnosis of large vessel vasculitides (LVV). As signs of vasculitis, US, MRI, and CT show a homogeneous arterial wall thickening, which is mostly concentric. PET displays increased FDG uptake in inflamed artery walls. US is recommended as the initial imaging modality in GCA. MRI and PET/CT may also detect vasculitis of temporal arteries. For TAK, MRI is recommended as the first imaging modality as it provides a good overview without radiation. Extracranial LVV can be confirmed by all four modalities. In addition, MRI and PET/CT provide consistent examination of the aorta and its branches. New techniques such as contrast-enhanced ultrasound, PET/MRI, and auxiliary methods such as “computer-assisted quantitative analysis” have emerged and need to be further validated.

Summary

Imaging has partly replaced histology for confirming LVV. Provided experience and adequate training, US, MRI, CT, or PET provide excellent diagnostic accuracy. Imaging results need to complement history and clinical examination. Ongoing studies are evaluating the role of imaging for monitoring and outcome measurement.