CHICAGO – Vascular ultrasound showed high sensitivity and specificity for diagnosing large-vessel giant-cell arteritis (LV-GCA) in a prospective study of patients with suspected new-onset disease.
The findings highlight the value of vascular ultrasound – in the hands of experienced sonographers – as a first-line imaging test in this setting, Berit Dalsgaard Nielsen, MD, reported at the annual meeting of the American College of Rheumatology.
Of 41 control subjects without LV-GCA, none had a positive ultrasound, whereas 36 of 45 LV-GCA patients had a positive ultrasound, which gives the test a specificity of 100% and sensitivity of 80%, Dr. Nielsen of Aarhus (Denmark) University Hospital said during a press briefing at the meeting.
Ultrasound was performed on the carotid artery in the neck and axillary arteries under the arm, which are easily accessible by ultrasound.
“These patients also had temporal arteries evaluated, and if we included this evaluation in the diagnostic performance, it showed a sensitivity of 91%,” she noted, explaining that temporal artery ultrasound alone conferred 71% sensitivity. “So it actually helped us identify more GCA patients.”
The study subjects were adults with suspected GCA. Inclusion criteria included age of at least 50 years, C-reactive protein of more than 15 mg/L or erythrocyte sedimentation rate of more than 40 mm, and either cranial symptoms, new-onset limb claudication, protracted constitutional symptoms, or polymyalgia rheumatica (PMR) symptoms. Patients were excluded if they had recent or ongoing glucocorticoid or disease-modifying antirheumatic drug treatment, a previous GCA or PMR diagnosis, or a large vessel inflammation that mimicked LV-GCA.
Clinical evaluations and imaging tests were performed prior to treatment initiation. The reference diagnosis was a clinical diagnosis of GCA and a positive 18F-FDG PET/CT scan, Dr Nielsen said, adding that ultrasound examinations were performed by experienced sonographers who were blinded to the PET/CT results.
Of the 86 patients included, 45 had LV-GCA with or without concomitant cranial GCA, 10 had isolated cranial GCA, 21 had PMR, and 10 were diagnosed with other diseases. The patients found to not have LV-GCA were considered control subjects.
The findings are notable because, while PET is considered the gold standard, it is very expensive and not always readily available, Dr. Nielsen said.
Additionally, while cranial-GCA patients generally present with symptoms such as headache, jaw claudication, and visual disturbances that are considered typical for GCA, LV-GCA patients rarely present with these symptoms.
Rather, these LV-GCA patients tend to present with constitutional symptoms mimicking infection or cancer, and they undergo extensive examination programs before the diagnosis is established. For this reason, diagnosis is often delayed for several months in LV-GCA patients until late in the disease course.
“During this time they often experience a decline in physical ability,” she said. “So in this disease subset of patients with GCA, there’s an unmet need for earlier recognition and earlier diagnosis.”
New recommendations from the European League Against Rheumatism call for early diagnostic imaging in all cases of suspected GCA, she added, noting that, for cranial-GCA symptoms, temporal artery ultrasound is recommended first line, but for those who present without cranial symptoms, no particular imaging modality is recommended because of a lack of comparative and diagnostic accuracy data in LV-GCA.
Biopsy has traditionally been used in these cases, but now imaging can be substituted – and vascular ultrasound is an attractive first-line option given its affordability and availability.
Indeed, the current findings support its use in this setting, she said.
“We think that these results indicate that ultrasound should not only be the first-line imaging test in patients presenting with cranial symptoms, but also in patients suspected of GCA presenting with constitutional symptoms, and if this examination is included in the standard examinations in fast-track clinics, it may overcome the delay in diagnosis and the patients can be treated earlier. It may also spare the unneeded examinations performed in these patients,” she concluded.
Dr. Nielsen disclosed a relationship with Roche.
SOURCE: Nielsen B et al. Arthritis Rheumatol. 2018;70(Suppl 10): .