For patients with giant cell arteritis (GCA) undergoing aortic monitoring, the use of ultrasound and computed tomography (CT) provided comparable results when measuring the ascending aorta’s diameter, according to a study published in Arthritis Care & Research. That study also found the development of new ascending aortic aneurysms common in patients with GCA, especially in those with large-vessel involvement, underscoring the need for regular aortic screening in these patients.1
“It is well established that patients with GCA have an increased long-term risk of developing ascending aortic aneurysms. However, there is currently no consensus on how to effectively and safely monitor for these complications—nor agreement on the optimal imaging modality or surveillance interval,” explains corresponding author Anne C. Bull Haaversen, MD, a rheumatologist at Martina Hansens Hospital in Baerum, and a PhD candidate at the University of Oslo, both in Norway. “CT is widely considered the gold standard for aortic imaging, but it involves radiation exposure, often requires contrast and may be less readily available.”
Dr. Anne Bull Haaversen
Dr. Bull Haaversen notes, “Our study is the first to demonstrate a strong correlation and agreement between transthoracic ultrasound and CT in measuring the ascending aorta in patients with GCA. The finding is important because it identifies ultrasound as a safe, accessible and cost-effective alternative for longitudinal aortic surveillance. Moreover, we found that nearly one in five patients without baseline aneurysms developed new ascending aortic aneurysms during a 4.5-year follow-up. Together, these results underscore both the need for long-term vascular monitoring in GCA and a practical approach for implementing it.”
Ultrasound vs. CT Study
To compare diameter measurements provided by the two imaging modalities, the researchers performed a cross-sectional trial including 140 patients with CGA who were followed at the Department of Rheumatology in Martina Hansens Hospital. Patients had undergone imaging of the ascending aorta via ultrasound and CT within six months of each other, providing a total of 169 scans. The patients’ mean age was 71 years, 63% were female and the mean disease duration stood at 47.8 months. Of the patients, 46.4% had mixed GCA, 34.3% had cranial GCA and 19.3% had large-vessel GCA.
To assess the development of new ascending aortic aneurysms, the researchers performed a prospective trial that included 40 of the patients with aortic imaging at GCA diagnosis and follow-up, between September 2017 and June 2024. This provided a longitudinal assessment of aortic diameter changes, with aneurysms in the ascending and descending aorta defined with a cutoff value of 40 mm or greater. At diagnosis, 32 patients had undergone a CT scan and 21 had an ultrasound. At follow-up, all 40 patients underwent an ultrasound, and 35 also had a CT scan.
Results from the crossover part of the study suggested that measurements from the two modalities showed a strong alignment and similar values. The median diameter of the ascending aorta via ultrasound and CT was 34 mm and 36 mm, respectively. Of 140 patients, six had an aneurysm in the descending aorta, and five of these patients had a simultaneous aneurysm in the ascending aorta. The “findings confirm that thoracic aneurysms mainly occur in the ascending part of the aorta,” the authors write.
Of the 40 patients in the prospective part of the study, 17.5% developed aneurysms in the ascending aorta at a mean of 54 months follow-up. The aneurysms only developed in patients with large-vessel involvement, specifically large-vessel GCA or mixed GCA. Male sex represented a “strong independent predictor for the development of ascending aortic aneurysm in patients with GCA, with males exhibiting more than fourfold increased odds,” the authors write. Of the 35 patients with a follow-up CT, none developed an aneurysm in the descending aorta.
Limitations of the study included measurement variability between the ultrasound operators. The CT data was subject to differences in measurement technique, scan quality, acquisition phase and contrast use. Potential bias may have occurred in the ultrasound measurements because one ultrasonographer was not blinded to a small number of CT scans completed before performing ultrasound imaging. Other limitations included the small patient number in the prospective part of the study, the lack of predetermined imaging intervals and the varied imaging modalities. The authors add that using “a 40 mm cutoff for defining aortic aneurysms may be debated [because] aortic diameter may be influenced by individual factors, such as age, sex and body surface area.”
Implications for Rheumatologists
According to Dr. Bull Haaversen, “Surveillance practices for aortic complications in GCA vary widely, and most patients are not routinely monitored for this complication. Our findings suggest a new approach using transthoracic ultrasound as a first-line tool for aortic surveillance during routine clinical follow-up.”
“By integrating ultrasound into standard follow-up visits, annually or biannually, clinicians can monitor aortic dimensions safely and efficiently. This approach is particularly relevant for patients with large-vessel involvement, as they were the only ones in our prospective cohort to develop aneurysms,” Dr. Bull Haaversen explains. “In this way, ultrasound could be seamlessly incorporated into standard care, improving early detection and long-term outcomes.”
For rheumatologists in academia, “this study expands the role of vascular ultrasound in GCA beyond initial diagnosis, supporting its use in longitudinal monitoring. It also raises important questions for future research, including optimal imaging intervals, predictive models of aneurysm development and cost-effectiveness analyses,” says Dr. Bull Haaversen. For rheumatologists in private practice, those “with access to basic ultrasound equipment and training can integrate ascending aorta assessment into their regular follow-up routines.
“Our study reflects real-world conditions [because] all imaging data were collected under standard clinical settings,” notes Dr. Bull Haaversen. “This strengthens the generalizability of our findings and supports the feasibility of integrating ultrasound into everyday practice.”
For researchers, “these findings pave the way for larger, multicenter prospective studies comparing ultrasound- and CT-based surveillance strategies, particularly in patients with large-vessel GCA,” she adds. “They also highlight the need for updated international guidelines to reflect the expanding utility of ultrasound in this context.”
Current Guidelines
Dr. Mehrdad Maz
Computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) are standard modalities for baseline imaging and longitudinal monitoring in large-vessel vasculitis, says Mehrdad Maz, MD, an author of the 2021 ACR/Vasculitis Foundation guideline for GCA.2 Dr. Maz is a professor of medicine and chief of the Division of Allergy, Clinical Immunology and Rheumatology at the University of Kansas Medical Center, Kansas City.
“Current ACR and EULAR guidelines collectively recommend imaging of extracranial vessels (US [ultrasound], CT, MRI or PET [positron emission tomography]) at diagnosis and follow-up or disease relapse,” Dr. Maz notes.3 “Findings from this study suggest that vascular ultrasound may serve as an alternative for routine surveillance of the ascending aorta in patients with GCA, offering reduced radiation exposure and lower healthcare costs without compromising diagnostic accuracy.
“CTA or MRA remain indispensable for comprehensive evaluation, including confirmation of aneurysm progression, surgical decision making and assessment of the descending aorta or other vascular territories not adequately visualized by ultrasound.”
Katie Robinson is a medical writer in New York.
References
- Bull Haaversen AC, Brekke LK, Kermani TA, et al. Ultrasound compared to computed tomography in identifying thoracic aortic aneurysms in patients with giant cell arteritis. Arthritis Care Res. 2025. Accepted Author Manuscript. First published September 30. doi: 10.1002/acr.25657.
- Maz M, Chung SA, Abril A, et al. 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of giant cell arteritis and Takayasu arteritis. Arthritis Care Res (Hoboken). 2021 Aug;73(8):1071–1087.
- Dejaco C, Ramiro S, Bond M, et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice: 2023 update. Ann Rheum Dis. 2024 May;83(6):741–751.
