What is the role of ultrasonography in the diagnosis of giant cell arteritis (GCA) (temporal arteritis)?

Updated: Sep 03, 2020
  • Author: Mythili Seetharaman, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Color duplex ultrasonography of the temporal artery has emerged as a promising alternative or complement to TAB. [91, 92, 93, 94, 95, 96] Its specificity is 80%-100% when a dark halo (classic halo sign) is seen about the vessel. [93] This key diagnostic feature is believed to represent vessel wall edema. Its sensitivity is limited, however; in particular, early inflammatory changes that can be seen on TAB specimens do not produce the characteristic halo effect.

Color duplex ultrasonography is user dependent. However, experienced sonographers with proper training and equipment have been shown to provide reliable diagnosis of GCA. [97]

The prospective Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL) study, which included an ultrasound training program for diagnosing GCA, analyzed 381 patients who underwent both ultrasound and TAB within 10 days of starting treatment for suspected GCA, and found that the sensitivity of TAB was 39% (95% confidence interval (CI) 33% to 46%), which was significantly lower than previously reported and inferior to that of ultrasound (54%; 95% CI 48% to 60%). However, TAB had 100% specificity (95% CI 97% to 100%), versus 81% (95% CI 73% to 88%) for ultrasound. [98]

The TABUL authors noted that performing ultrasound scans in all patients with suspected GCA and performing biopsies only on negative cases would increase the sensitivity of ultrasound to 65% while maintaining specificity at 81%, reducing the need for biopsies by 43%. Furthermore, strategies that combined clinical judgement with testing showed sensitivity and specificity of 91% for TAB and 81% for ultrasound, and specificity of 93% and 77%, respectively. Cost-effectiveness favored ultrasound, with both cost savings and a small health gain. [98]

At the very least, however, the use of ultrasonography to “map” the path of the artery is a very useful adjunct to the evaluation of a patient with suspected GCA, making considerably more straightforward the choice of incision site and the biopsy target segment. [99]


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