Results from a Danish study indicate that ultrasound is potentially a companion test to temporal artery biopsy in diagnosing giant cell arteritis (GCA).
Study design
This was a prospective, cross-sectional study of 78 patients who were suspected of having GCA who underwent temporal artery biopsy and ultrasound. Positive ultrasound findings were increased vessel wall thickening (halo-sign) or noncompressible arteries due to vessel wall thickening (positive compression sign). Diagnosis of GCA was established by expert physicians in neuro-ophthalmology and rheumatology, based on symptoms, examination findings, medication, inflammatory markers, vascular imaging, and biopsy results.
Outcomes
Thirty-five of the 78 patients were eventually diagnosed with GCA. Biopsy was positive in 24 patients, all of whom were clinically diagnosed with GCA. Ultrasound was positive in 31 patients, 22 of whom were clinically diagnosed with GCA (9 false positives). Conversely, of 47 patients with negative ultrasound, 13 were eventually diagnosed with GCA. Biopsy and ultrasound had comparable sensitivities (69% and 63%, respectively), while specificity was higher in biopsy than in ultrasound (100% vs 79%, respectively). Compression sign had the best diagnostic performance.
Limitations
The exact criteria for the diagnosis of GCA were not clearly stated in the study. Although the use of experts to determine the diagnosis seems reasonable, there could be room for subjective assessment, which may lead to misdiagnosis and affect the data.
Clinical significance
Temporal artery biopsy has long been considered the gold standard for diagnosis of GCA. Although it is considered to be a minor invasive procedure, it is a procedure nonetheless. The concept of being able to do temporal artery ultrasound is intriguing, and ultrasound is slowly gaining acceptance as a valid test, as it is noninvasive, fast, and cost-efficient. In addition, ultrasound can assess the entire length of the artery. Although ultrasound does not appear to be able to replace temporal artery biopsy at this point, it appears to be an additional useful test. Its utility is dependent on experienced ultrasonographers, but as additional data and experience are accumulated with this technique, it is possible that temporal artery biopsies may no longer be performed in the future.
Financial Disclosures: Dr. Richard Allen discloses no financial relationships.