Giant cell arteritis (GCA) is an inflammation of the blood vessels. A dangerous complication is sudden vision loss due to insufficient blood supply to the optic nerve. However, it is often difficult to distinguish acute vision loss due to GCA from a similar condition of insufficient blood supply to the optic nerve, called NAION. Quick treatment with anti-inflammatory medication is needed in case of GCA to prevent vision loss on the eye and other serious complications. Patients with NAION have no benefit of the medication, but can have serious side effects, why it is very important to differentiate between these conditions.
In this project, the investigators will use FDG PET/MRI with Black Blood (BB) sequences and OCT-imaging to study patients with GCA and/or ischemic optic nerve disease. The investigators will look for signs of inflammation in and around the small vessels of the orbit using PET/MRI and study subtle retinal changes using OCT images.
The investigators want to answer the following research questions:
Do patients with ischemic optic nerve disease and GCA show signs of inflammation in the orbital vessel wall on PET/MRI-scans, that are not present in patients with NAION?
Do GCA patients without vision loss, but with signs of orbital vessel wall inflammation on PET/MRI-scans, have a higher risk of later vision loss than GCA patients without?
Can subtle changes in the retina, detectable through OCT, help distinguish between GCA-related vision loss and NAION?
This will, to our knowledge, be the first study to systematically use FDG PET/MRI BB-scans to illuminate vascular changes in the orbit of patients with GCA and/or ischemic optic nerve disease. The results may improve diagnosis and treatment of GCA and NAION in the future. The investigators hope that this will help prevent blindness and other serious complications in patients with GCA, while also avoiding unnecessary treatments for patients with NAION.
Clinical suspicion of newly onset ischemic optic neuropathy (A-AION or NA-AION), defined by ipsilateral findings of: Papilledema; Relevant visual impairment measured by visual acuity and/or visual field; Relative afferent pupillary defect (RAPD), except if mydriatic agents have been administered or if bilateral optic neuropathy is present.
Age ≥ 50 years
Clinically- and ultrasound-confirmed, newly diagnosed GCA
Absence of visual changes related to GCA in one or both eyes, including: Transient vision loss; permanent vision loss; transient double vision; permanent double vision
Ferromagnetic implants
Severe renal impairment with eGFR < 30 mL/min/1.73m²
Allergy to MRI contrast agents
Severe claustrophobia
Patients seen at the Ophthalmological and/or Rheumatological Department at Rigshospitalet, Copenhagen, Denmark
Cohort
Prospective
Positron Emission Tomography / Magnetic Resonance Imaging
Diagnostic testFDG PET/MRI with Black Blood sequences of the head and neck area.
Orbital vascular inflammation on PET/MRI
To investigate whether there is increased FDG uptake, increased endothelial permeability, and thickening of the vessel wall in the direct vascular supply to the eye and optic nerve, as signs of orbital vascular inflammation, among patients with ischemic optic neuropathy.
Risk of vision loss in GCA
To investigate whether GCA patients without visual symptoms, but with signs of orbital vascular inflammation, have a higher incidence of GCA-related eye disease after 6 months compared to GCA patients without signs of orbital vascular inflammation (and possibly again after 2 years).
Retinal biomarkers in AION
To characterize the occurrence of subtle retinal changes, with a focus on paracentral acute middle maculopathy (PAMM; band-like hyperreflective changes in the middle retinal layers) and intra- and subretinal fluid (IRF/SRF; fluid in or beneath the retina) among patients with ischemic optic neuropathy.
Correlation with final clinical diagnosis
To correlate signs of orbital vascular inflammation with the final clinical diagnosis of GCA / A-AION or NAION.
Occurence of orbital vascular inflammation in GCA without vision loss
To assess the frequency and extent of orbital vascular inflammation among GCA patients without visual symptoms.
Eye examination biomarkers of orbital vascular inflammation
To investigate whether structural or functional eye changes can be detected by neuro-ophthalmological examination (including visual acuity, perimetry, fundus photography, and OCT) in GCA patients without visual symptoms but with orbital vascular inflammation.
Vascular inflammation outside of the orbit
To characterize the occurrence of increased FDG uptake, increased endothelial permeability, and vessel wall thickening, as signs of vascular inflammation, in the walls of other cranial blood vessels among patients with GCA.
Pathophysiology behind different retinal biomarkers in AION
To investigate the relationship between the type and degree of retinal changes and the presence of inflammatory and vascular changes in the orbit in patients with A-AION and NAION.
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