Background/Purpose: Imaging techniques such as magnetic resonance imaging (MRI) are a cornerstone for the diagnosis of giant cell arteritis (GCA). In the further course of the disease, strict control of inflammatory activity is required to prevent complications such as relapse or aneurysms. To date, the role of imaging in follow-up (FU) has not been well defined and current recommendations suggest an individualized approach based on patient-specific factors [1]. As MRI is well suited to visualize vascular inflammation in GCA, the question arises whether regular MRI examinations could have a positive impact on further disease management.

Methods: Patients with confirmed GCA were prospectively monitored by MRI. All patients underwent at least one regularly scheduled MRI within one year of diagnosis. In case of suspected relapse, an unscheduled emergency MRI was performed. By high-resolution contrast-enhanced 3 Tesla MRI of the superficial temporal, occipital, carotid, vertebral, subclavian and axillary arteries as well as the thoracic aorta and suprarenal abdominal aorta were examined. In addition to clinical information and inflammatory blood values, the treating rheumatologist had all the information on the MRI, including inflammation and anatomical vascular changes (“pathological findings”), i.e. stenosis or aneurysm. It was then investigated whether the regular MRI appointments led to a change in clinical management.

Results: N=61 patients with confirmed GCA had at least one FU-MRI (median time to baseline 203 days). In total, N=134 FU-MRI were performed. Of those, N=110 were scheduled regularly and N=24 were performed due to suspected relapse. 28/134 (20.9%) showed inflammation in MRI, general judgement as active disease by the treating rheumatologist was seen in 13/28 (46.3%) patients. Of those with suspected relapse, 8/24 (33.3%) showed active disease in MRI. Regularly scheduled FU-MRI showed pathological findings in 22/110 (20%) and led to changes in management in 17/110 (15.4%).

Conclusion: FU MRIs in asymptomatic GCA patients led to an increase in immunosuppression in 15.4% with a false positive rate of 4.6%, whereas in symptomatic patients event-triggered MRI showed a positivity in 46.3%. Considering cost and expense of MRIs, regular FU MRIs in asymptomatic GCA patients cannot be recommended.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/magnetic-resonance-imaging-for-therapy-monitoring-in-giant-cell-arteritis-impact-on-disease-management/