LIVERPOOL, ENGLAND – Invasive temporal arterial biopsy could be replaced by cranial Doppler ultrasound for the diagnosis of giant cell arteritis, according to research presented at the British Society for Rheumatology annual conference.
Cranial Doppler ultrasound (CDUS) more accurately diagnosed giant cell arteritis (GCA) compared with a clinical diagnosis at 3 months, with 81% sensitivity and 98% specificity. Temporal arterial biopsy was associated with a sensitivity of 53%, although it was 100% specific.
The noninvasive test also had high positive and negative predictive values of 97% and 88%, respectively, compared with 100% and just 47% for temporary artery biopsy.
GCA is one of the most common types of vasculitis and is characterized by inflammation of the medium and large arteries, usually in the head and neck. Permanent vision loss and ischemic stroke are some of the more serious symptoms of GCA, which is also linked to the development of polymyalgia rheumatica in around 50% of cases. The latter can manifest around the same time as those of GCA or develop shortly after.
"The inflammation in the temporal artery, or indeed in any large vessel affected by GCA is segmental in nature," said researcher Adam Croft, MRCP, Ph.D., of the Queen Elizabeth Hospital, Birmingham, England.
"So of course that means that if you stick a biopsy needle in randomly, as happens in temporal artery biopsy, then there is a good chance that you’ll end up with normal histology even in an affected artery." Furthermore, it is important to bear in mind that some of the characteristics of the inflammation seen in GCA have been observed in other vasculitic conditions, the researcher said.
Catching the inflammation early and treating with high-dose steroids can be "sight saving," but until now it has been difficult to determine if all patients with suspected GCA really need such treatment, and there is a high chance of over diagnosis and treatment.
Dr. Croft and colleagues conducted a retrospective study of 87 individuals with suspected GCA who underwent CDUS between January 2005 and July 2013. The aim was to see if CDUS could improve upon temporal arterial biopsy when compared with the standard of a clinical diagnosis at 3 months defined using American College of Rheumatology (ACR) criteria for GCA.
At the 3-month follow-up, 36 patients had a clinical diagnosis of GCA and 51 did not. All patients had undergone CDUS and of these, 30 (34%) had a halo sign present. The halo sign is a characteristic imaging feature used to detect GCA on ultrasound, but may be present in healthy individuals and in those with other inflammatory vascular disorders.
Temporal artery biopsy was performed in just over a quarter of all study subjects, 13 (43%) of whom had a halo sign present and 11 (19%) who did not. Biopsies were positive in 7 (54%) of individuals with a halo sign present and in one (9%) of those without the sign.
Dr. Croft observed that CDUS was the strongest predictor for a diagnosis of GCA at 3 months, whereas clinical symptoms using the ACR criteria were insufficiently specific to accurately rule in or rule out a diagnosis.
CDUS may be particularly useful in patients at either end of the clinical spectrum, he added; that is where the pretest clinical probability is very high or very low, and perhaps biopsy can be avoided in these patients.
Data on the discontinuation of steroids following a negative CDUS result in the study were compared with historical findings on steroid withdrawal in patients who had a negative biopsy. Significantly more (87% vs. 22%, P less than .01) patients with a negative ultrasound than biopsy stopped this treatment as a result, "suggesting that the clinician confidence in a negative ultrasound result is much greater, and they were more actively discontinuing steroids in these patients," said Dr. Croft.
For ultrasound to take the place of biopsy, however, he noted that an experienced ultrasonographer would be needed be able to identify the often subtle GCA changes, and that there was a short time frame when ultrasound would be accurate.
"The sensitivity rapidly falls after 4-5 days," the researcher noted, due to the use of steroids. "So you have to have the infrastructure to get these scans done early."
Dr. Croft had no conflicts of interest.