Vascular Ultrasound Accurate, First-Line Imaging Test for Large Vessel Giant Cell Arteritis

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VASCULAR ULTRASOUND ACCURATE, FIRST-LINE IMAGING TEST FOR LARGE VESSEL GIANT CELL ARTERITIS

Newswise — CHICAGO – Vascular ultrasound is sensitive enough to use as a first-line imaging test in patients suspect to have giant cell arteritis, according to new research findings presented this week at the 2018 ACR/ARHP Annual Meeting (Abstract #2905).

Giant cell arteritis (GCA) is a type of vasculitis, which is a disease involving blood vessel inflammation. In GCA, the vessels most often involved are the arteries of the scalp and head, especially the arteries over the temples, which is why another term for GCA is “temporal arteritis.” Biopsy of the temporal artery is usually done to confirm GCA, although ultrasound and an erythrocyte sedimentation rate (ESR) blood test may also be used.

Vascular ultrasound is a cheap, readily available imaging test to diagnose suspected GCA. According to the study, there is a lower incidence of large vessel GCA in vascular ultrasound studies than in studies using positron emission tomography (PET), which may suggest that ultrasound has a lower diagnostic sensitivity.

“Cranial GCA patients present with cranial symptoms such as headache, jaw claudication and visual disturbances that are considered typical for GCA. However, large vessel GCA patients seldom present with these symptoms. They often present with constitutional symptoms mimicking infection or cancer,” said Berit Dalsgaard Nielsen, MD, a doctoral fellow at Aarhus University and the study’s presenting author.

A biopsy is often negative in these patients, and a biopsy of large vessels is typically not an option. To evaluate ultrasound’s sensitivity and specificity in diagnosing large vessel GCA, researchers at Aarhus University Hospital in Denmark conducted a prospective study of glucocorticoid-naïve patients suspected of having new-onset GCA and evaluated the diagnostic accuracy of axillary artery ultrasound using 18F-FDG PET/CT as a reference standard.

“Large vessel GCA diagnosis is frequently delayed for about eight months with patients going through extensive examinations,” Dr. Nielsen stated. She further noted that some “fast track” clinics use vascular ultrasound to diagnose GCA; however, its accuracy in large vessel GCA diagnosis is unknown. The study aimed to investigate the diagnostic accuracy of vascular ultrasound in large vessel GCA diagnosis using PET as the gold standard.

Patients suspected of having GCA were considered for study inclusion based on the following criteria: age 50 or older; C-reactive protein (CRP) of more than 15 mg/L or ESR of more than 40 mm; and either cranial symptoms, new-onset limb claudication, protracted constitutional symptoms or PMR symptoms. Researchers excluded patients with recent or ongoing glucocorticoid or disease-modifying antirheumatic drug (DMARD) treatment, a previous GCA or PMR diagnosis, and large vessel inflammation that mimicked large vessel GCA.

The researchers performed clinical evaluation and imaging before treatment was initiated. The reference diagnosis for large vessel GCA used in the study was a clinical diagnosis of GCA and an 18F-FDG PET/CT that revealed aortic and/or subclavian/axillary artery FDG uptake over liver uptake. Patients not diagnosed with GCA were considered controls.

Ultrasounds were performed by experienced sonographers who were blinded to PET results. They assessed the patients’ axillary arteries for the presence or absence of the “halo sign,” and measured intima media thickness (IMT). The researchers evaluated the sensitivity and specificity of the halo sign in patients’ axillary arteries, and performed a ROC curve analysis to estimate the axillary IMT cut-off.

The study’s results included 86 patients. Of these, 45 were diagnosed with large vessel GCA with or without concomitant cranial GCA, 10 were diagnosed with isolated cranial GCA, 21 were diagnosed with PMR and 10 were diagnosed with other diseases. None of the controls had a positive axillary ultrasound, but 36 out of 45 large vessel GCA patients were axillary ultrasound-positive, which shows the test has 100 percent specificity and 80 percent sensitivity.

Researchers believe the study’s findings show Vascular ultrasound of axillary arteries is highly sensitive and specific for the diagnosis of large vessel GCA.

“The high accuracy compared to PET and CT indicates that vascular ultrasound is a reasonable first-line imaging test not only in suspected cranial GCA patients, but in all GCA-suspected patients,” said Dr. Nielsen. “In GCA fast track clinics, the inclusion of axillary ultrasound may make additional large-vessel examination redundant, accelerating large vessel GCA diagnosis and sparing the patients unneeded examinations.”

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Abstract #: 2905

Ultrasound Diagnosis of Large Vessel Inflammation in New-Onset Treatment-Naïve GCA Patients Using Fluorine-18-Fluorodeoxyglucose PET/CT As the Reference Standard – a Prospective Study of 86 Patients Suspected of GCA

Berit Dalsgaard Nielsen¹, Ib Tønder Hansen¹, Kresten Krarup Keller², Philip Therkildsen³, Lars Christian Gormsen⁴ and Ellen-Margrethe Hauge⁵, ¹Department of Clinical Medicine, Aarhus University Hospital, Århus N, Denmark, ²Department of Rheumatology, Aarhus University Hospital, Aarhus, Aarhus, Denmark, ³Department of Rheumatology, Aarhus University Hospital, Aarhus C, Denmark, ⁴Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Århus C, Denmark, ⁵Department of Rheumatology, Aarhus University Hospital, Department of Clinical Medicine, Aarhus, Denmark

Background/Purpose: EULAR recommendations suggest diagnostic imaging in all GCA suspects. Vascular ultrasound (US) is cheap, readily available and the recommended first line examination in cranial GCA (c-GCA). Hence, US is an attractive first line examination also in large vessel GCA (LV-GCA). However, lower incidence of LV involvement is reported in US studies than in PET studies indicating a lower diagnostic sensitivity of US. In a prospective study of glucocorticoid-naïve patients suspected of new-onset GCA, we evaluated the diagnostic accuracy of axillary artery US in the diagnosis of LV-GCA using 18F-FDG PET/CT as reference standard.

Methods: Patients suspected of GCA were consecutively considered for inclusion. Inclusion criteria were: 1) age ≥50 years; 2) CRP>15 mg/L or ESR>40 mm/h; 3) either a) cranial symptoms, b) new-onset claudication c) protracted constitutional symptoms d) polymyalgia rheumatica (PMR) symptoms. Main exclusion criteria were: 1) recent or ongoing glucocorticoid or DMARD treatment; 5) previous diagnosis of GCA or PMR ; 6) large vessel inflammation mimicking LV-GCA. Clinical evaluation and imaging was performed before treatment initiation. The reference diagnosis for LV-GCA was a clinical diagnosis of GCA and a 18F-FDG PET/CT revealing aortic and/or subclavian/axillary artery FDG uptake > liver uptake. Patients not diagnosed with GCA were considered controls. US was performed by experienced sonographers, blinded to PET results. Axillary arteries were assessed for the presence or absence of the ‘halo sign’ and intima media thickness (IMT) was measured. Sensitivity and specificity of the halo sign in axillary arteries was evaluated. ROC curve analysis was performed to estimate axillary IMT cut off.

Results: 86 patients were included (97 screened). 45 were diagnosed with LV-GCA (with or without concomitant c-GCA), 10 with isolated c-GCA, 21 with PMR and 10 with other diseases. Baseline characteristics of LV-GCA and controls are shown in table 1.

None of the controls had a positive axillary US, whereas 36/45 LV-GCA patients were axillary US positive yielding a specificity of 100% (95%CI: 89-100%) and a sensitivity of 80% (95%CI: 65-90%)). Of the 73 PET positive axillary arteries in LV-GCA patients, 53 were axillary US positive (sensitivity 72% (95%CI: 61-83%)). Four PET negative axillary arteries were US positive (specificity 95% (95%CI: 87-99%)). An AUC of 0.86 (95%CI: 0.79-0.92) was obtained by ROC curve analysis of axillary IMT with axillary PET diagnosis as a reference. An IMT cut off value of 0.9mm revealed a sensitivity of 74% and a specificity of 92%.

Conclusion: In the hands of experienced sonographers, axillary arteries US shows high sensitivity and specificity for the diagnosis of LV-GCA which clearly suggests US as a first line imaging test in LV-GCA suspected patients. Suggested IMT cut off confirms findings of previous studies using different reference standards.

Disclosures: B. D. Nielsen, Roche, 9 I. Tønder Hansen, None K. K. Keller, Pfizer, Inc., 9 P. Therkildsen, None L. C. Gormsen, None E. M. Hauge, Roche and Novartis, 2, MSD, AbbVie, UCB and Sobi, 9