Practice Preferences: Temporal Artery Biopsy versus Doppler Ultrasound in the Work-Up of Giant Cell Arteritis

Temporal artery biopsy: A technical guide and review of its importance and indications

Temporal artery biopsy (TAB) is a surgical procedure that enables the histological diagnosis of giant cell arteritis (GCA). Performing a TAB requires expertise and a precise approach. Nevertheless, available data supports the value of tissue diagnosis in managing GCA. The current therapeutic recommendation for GCA is long-term glucocorticoid therapy, with an increasing emphasis on the addition of immunosuppressants/biotherapies. Though effective, immunosuppressants and other such biotherapies may put the patient at more risk. Optimizing the diagnosis through tissue evaluation is therefore important in weighing the risks and benefits of initiating therapeutic intervention. We evaluate the evidence supporting the importance of TAB and its indications. We also describe what technical approaches should be used to maximize sensitivity and to avoid possible complications during the procedure.

Evolution of ultrasound in giant cell arteritis

Ultrasound (US) is being increasingly used to diagnose Giant Cell Arteritis (GCA). The traditional diagnostic Gold Standard has been temporal artery biopsy (TAB), but this is expensive, invasive, has a false-negative rate as high as 60% and has little impact on clinical decision-making. A non-compressible halo with a thickened intima-media complex (IMC) is the sonographic hallmark of GCA. The superficial temporal arteries (STA) and axillary arteries (AA) are the most consistently inflamed arteries sonographically and imaging protocols for evaluating suspected GCA should include at least these two arterial territories. Studies evaluating temporal artery ultrasound (TAUS) have varied considerably in size and methodology with results showing wide discrepancies in sensitivity (9–100%), specificity (66–100%), positive predictive value (36–100%) and negative predictive value (33–100%). Bilateral halos increase sensitivity as does the incorporation of pre-test probability, while prior corticosteroid use decreases sensitivity. Quantifying sonographic vasculitis using Halo Counts and Halo Scores can predict disease extent/severity, risk of specific complications and likelihood of treatment response. Regression of the Halo sign has been observed from as little as 2 days to as late as 7 months after initiation of immunosuppressive treatment and occurs at different rates in STAs than AAs. US is more sensitive than TAB and has comparable sensitivity to MRI and PET/CT. It is time-efficient, cost-effective and allows for the implementation of fast-track GCA clinics which substantially mitigate the risk of irreversible blindness. Algorithms incorporating combinations of imaging modalities can achieve a 100% sensitivity and specificity for a diagnosis of GCA. US should be a standard first line investigation in routine clinical care of patients with suspected GCA with TAB reserved only for those having had a normal US in the context of a high pre-test probability.

The Utility of the Bilateral Temporal Artery Biopsy for Diagnosis of Giant Cell Arteritis

OBJECTIVE

A surgical temporal artery biopsy (TAB) is the gold standard for diagnosis of giant cell arteritis (GCA). The necessity of performing a bilateral biopsy remains under debate. The primary objective of this study was to assess the rate of discordance between pathology results in patients who underwent bilateral temporal artery biopsy for suspected GCA.

METHODS

We performed a retrospective review of patients who underwent bilateral temporal artery biopsy for diagnosis of GCA between 2011 and 2020. The primary endpoint was the rate of discordance between specimens for patients with pathology positive GCA. Secondary endpoints included assessments of the sensitivity of pre-operative temporal artery duplex and the effects of specimen length and specialty of referring provider on the diagnostic yield of the biopsy.

RESULTS

During the study period, 310 patients underwent bilateral temporal artery biopsy for diagnosis of giant cell arteritis. These patients were primarily female (73.9%), elderly (mean age 70.8 years), and Caucasian (95.8%). Pre-operative symptoms for patients were typically bilateral (59%) and included headache (81%), vision changes (45.2%), and temporal tenderness (32.6%). Most patients (85.2%) were on pre-operative steroid therapy at the time of surgical biopsy with a mean pre-operative duration of steroid therapy of 15.1 days. Overall, 91 patients (29.4%) had a positive pathologic diagnosis after bilateral temporal artery biopsy. Of these patients, 11 had a positive pathology result in only a single specimen, resulting in a discordance rate of 12.1%. Pre-operative temporal artery duplex demonstrated low sensitivity (27.3%) for identifying patients with pathologic positive disease. There were no significant differences between the pathology positive and negative patients in terms of mean surgical specimen length (1.67 vs 1.64 cm; p = 0.67) or specialty of referring provider (p = 0.73).

CONCLUSIONS

At our institution, we observed a 12.1% discordance rate between pathology results in patients who underwent bilateral temporal artery biopsy for diagnosis of GCA. A pre-operative temporal artery duplex provided little value in identifying patients with biopsy-proven GCA.