Qualifications and Limitations
While over half of patients ultimately diagnosed with GCA were diagnosed using ultrasound, that percentage was “a bit lower than expected,” said Mark Matza, MD, MBA, the co-clinical director of rheumatology at Massachusetts General Hospital in Boston. By comparison, one systematic review calculated ultrasound’s pooled sensitivity at 88% and pooled specificity at 96% for the diagnosis of GCA.
“In this [current] study, 30% of patients who had negative ultrasound were then found to have positive biopsy, indicating that ultrasound missed a substantial portion of patients who were ultimately diagnosed with GCA,” he continued.
Ultrasound is “very operator dependent,” he added, and there has been “variability in test performance of ultrasound.”
The authors acknowledged that techniques for ultrasound of the temporal arteries have also evolved over the study period, and thus, findings may not have been consistent.
However, about one in four patients with GCA were diagnosed after having both negative ultrasound and TAB results.
“One of the things that this paper shows is that even the gold standard of temporal artery biopsy isn’t 100% either,” noted Minna Kohler, MD, who directs the rheumatology musculoskeletal ultrasound program at Massachusetts General Hospital. “That’s why clinically, there is an increasing emphasis on using multimodality imaging to assist in the diagnosis of GCA along with a physician’s clinical intuition,” she said.
Massachusetts General Hospital/Harvard Medical School
Dr. Minna Kohler
While ultrasound can visualize axillary, subclavian, and carotid arteries, other imaging modalities such as CTA, MRA, and PET/CT are better to fully assess supra-aortic and aortic vessels, she continued. However, “this imaging is more expensive and takes more time to coordinate, schedule, whereas ultrasound of temporal and axillary arteries can easily be done within the clinic with an immediate answer.”
This study was supported by a grant from “Recherche CH-CHU Poitou-Charentes 2014.” Dr. Denis disclosed relationships with Leo Pharma, Janssen, Novartis, Takeda, and Sanofi. Dr. Matza reported honoraria from the Ultrasound School of North American Rheumatologists. Kohler had no relevant disclosures.
A version of this article appeared on Medscape.com.