Isolated inflammatory involvement of the occipital artery in giant cell arteritis and polymyalgia rheumatica: findings from a retrospective analysis and the critical role of MRI in diagnosis.

Abstract

Background: Diagnosis of Giant Cell Arteritis (GCA) and Polymyalgia rheumatica (PMR) may be challenging as many patients present with non-specific symptoms. Superficial cranial arteries are predilection sites of inflammatory affection. Ultrasound is typically the diagnostic tool of first choice supplementary to clinical and laboratory examination. Inflammation of temporal arteries can be detected sonographically with high reliability. However, due to the vessel's course and location, occipital arteries evade sonographic detectability.

Objective: The aim of our study was to evaluate the infestation pattern of superficial cranial arteries in GCA and PMR patients with special focus on the occipital arteries.

Methods: 90 treatment-naïve patients with clinically and/or histologically proven GCA and/or PMR (51 GCA, 20 PMR, 10 GCA-PMR) were included in the study. All patients underwent contrast-enhanced, fat-suppressed, high-resolution black blood 2D T1-weighted spin echo imaging at 3T MRI. Images were read by three different readers independently. Temporal and occipital arteries were assessed regarding vasculitic affection. Circumferential mural hyperenhancement and thickening of the vessel wall ≥ 600 μm was considered positive for vasculitis.

Results: 9/90 (10%) of all patients revealed inflammatory changes of the occipital artery only. Prevalence of isolated inflammatory affection of occipital artery was even higher in the GCA subgroup with 7/51 (14%) patients.

Conclusion: 14% of GCA patients and 10% of GCA-PMR patients present with signs of inflammation of the occipital artery only. Since the occipital artery is not accessible to routine ultrasound examination, MRI renders incremental value in the diagnosis of GCA and PMR patients.