Quantification of Vascular Burden on Cranial Vessel Wall Magnetic Resonance Imaging and Ophthalmic Complications in Giant Cell Arteritis

OBJECTIVE: There is a need for measures of disease severity for giant cell arteritis (GCA), which may enable identification of high-risk subgroups (eg, ophthalmic complications) and individualized approaches to therapy. We derived a continuous score using data from cranial vessel wall magnetic resonance imaging (VW-MRI) to quantify vascular burden in GCA and assessed the score's association with ophthalmic manifestations. METHODS: Patients with suspected new or relapsing GCA underwent cranial VW-MRI plus dedicated orbital MRI. A radiologist assessed VW-MRI enhancement of seven cranial structures bilaterally. Using a generalized linear mixed-effects model, a continuous MRI-derived patient-level score (range 1-10) of disease extent was developed: the Cranial Artery MRI Score for GCA (CAMRIS-GCA). CAMRIS-GCA was compared between clinical diagnosis (ocular GCA, nonocular GCA, or non-GCA) and patients with versus without ocular inflammation on MRI (defined as ophthalmic artery or optic nerve sheath enhancement). RESULTS: Seventy-four patients (17 ocular GCA, 16 nonocular GCA, and 41 non-GCA) were included. CAMRIS-GCA increased linearly across clinically defined groups of non-GCA, nonocular GCA, and ocular GCA (CAMRIS-GCA median 0.6 [interquartile range (IQR) 0-1.7] vs median 2.5 [IQR 0.5-6.6] vs median 4.8 [IQR 2.1-8.5]; P < 0.01). Patients with orbital inflammation on MRI (with or without visual symptoms) had a higher median CAMRIS-GCA compared to patients with negative orbital MRI (median 6.7 [IQR 5.6-8.5] vs median 0.4 [IQR 0-1.6]; P < 0.01). CONCLUSION: This proof-of-concept study introduces a quantitative MRI-derived vascular burden score in GCA and demonstrates its association with ophthalmic involvement. These early findings suggest that cranial VW-MRI may offer a prognostic value in identifying patients at risk for vision-threatening disease.