MANCHESTER, U.K. – An early halo sign on ultrasound is both diagnostic and prognostic according to the findings of a substudy of the ongoing TABUL trial.
In newly diagnosed giant cell arteritis (GCA), halo on ultrasound was seen in 46% of cases, and its presence correlated significantly with both ischemic symptoms and abnormal physical examination of the temporal arteries.
The finding “supports the early use of the halo as a diagnostic and potentially prognostic marker,” Dr. Raashid Luqmani, professor of rheumatology at the University of Oxford, England, said at the British Society for Rheumatology annual conference.
|Courtesy Dr. Raashid Luqmani
This is a longitudinal color Doppler scan of a temporal artery from a patient with GCA showing a halo (dark gray area surrounding the vessel), an irregular flow pattern with areas of stenosis and turbulent flow (colors are not uniform).
The halo sign is an abnormal shadow seen around the temporal arteries on ultrasound, Dr. Luqmani explained.
“The value of halo size change over time in individual patients is being investigated as a marker of response to treatment,” he added, noting that the size of the halo decreased rapidly with longer duration of early, high-dose steroid treatment.
The main TABUL (Temporal Artery Biopsy Versus Ultrasound for the Diagnosis of Giant Cell Arteritis) trial is looking at the overall diagnostic performance, accuracy, and cost-effectiveness of ultrasound versus biopsy in patients with newly suspected GCA. A total of 430 patients have been recruited and have undergone a single ultrasound scan of the temporal and axillary arteries followed by temporal artery biopsy within 7 days of commencing steroids.
Clinicians are blinded to the results of the ultrasound scan until 2 weeks after a treatment decision has been made and they intend to start rapid steroid withdrawal. Following this, patients are seen at a 6-month follow-up visit.
|Dr. Raashid Luqmani|
The aim of the substudy reported by Dr. Luqmani was to describe the features of the early halo sign in response to steroid therapy and whether it correlated to ischemic symptoms.
A cross-sectional analysis was performed on data from 312 patients to look at the extent of arterial involvement, the maximum thickness of the halo, the duration of steroid treatment when the ultrasound was performed, and what ischemic symptoms were present.
The mean age of the 220 women studied was 72.5 years, and that of the 92 men was 71.2 years.
Most patients had one (30.6%), two (22.2%), or three (13.9%) temporal arterial segments involved, with the remaining third having four or more. Bilateral halos were seen in 30% of patients, temporal or axillary artery halos in 13.5%, and isolated axillary halos in 2.6%.
The fact that 13.5% had both temporal and axillary artery involvement and 2.6% had only isolated axillary halos suggests a role for scanning both the axillary and temporal arteries, Dr. Luqmani suggested.
The likelihood of finding a halo diminished with the duration of steroid therapy, he reported. “Patients who received no steroid therapy had a much bigger halo and it got progressively smaller and significantly less by day 4,” he observed.
“Although there are still some patients who still have a halo at days 5 and 6 of steroid treatment, the likelihood of finding that halo is much, much less,” he added.
Looking at the presence of halo in relation to ischemic symptoms, there did appear to be an association but it was only significant (P < .004) for jaw claudication.
“If you have a patient with newly suspected GCA, you are likely to see a significant halo, but you need to be quick, you need to be seeing that halo within 4 days of starting steroids or evaluating patients who have not had any steroid treatment,” Dr. Luqmani said.
The TABUL study is funded by the U.K. Health Technology Assessment, a program of the National Institute for Health Research,and sponsored by the University of Oxford. Dr. Luqmani had received consulting fees from GlaxoSmithKline, Novartis, Roche, and Pfizer.