Use of Ultrasound in the Diagnosis and Management of the Vasculitides

Color Doppler Eye Ultrasonography in giant cell arteritis: differential diagnosis between arteritic and non-arteritic sudden blindness

PURPOSE

Temporal (TA) and axillary (AXA) arteries Color Doppler Ultrasonography (CDUS) is the most reliable diagnostic technique for the diagnosis of giant cell arteritis (GCA), displaying high sensitivity and specificity. Nevertheless, CDUS is still poorly performed in the common clinical practice, being employed only by rheumatologists with a relevant expertise in this field. Color Doppler Eye Ultrasound (CDEUS) is a procedure variously employed in ophthalmology and preliminary findings have displayed a possible role also in the diagnostic work-up of GCA. Aim of this study was to assess whether CDEUS may play a role in the differential diagnosis between arteritic and non-arteritic blindness.

METHODS

We prospectively included all patients evaluated since September 2021 to May 2022 by our Ophthalmology Unit for sudden blindness and referred to our Vasculitis Clinic in the suspicion of GCA. All patients underwent complete ophthalmological evaluation, routine blood tests, AxA and TA CDUS and CDEUS. According to the definite diagnosis, patients were divided in the following subgroups: (A) patients suffering from arteritic central retinal artery occlusion (CRAO), (B) patients suffering from non-arteritic CRAO, (C) patients suffering from arteritic anterior ischemic optic neuropathy (AION), (D) patients suffering from non-arteritic AION.

RESULTS

During the observational period, we included a total of 25 patients suffering from sudden blindness and referred to Vasculitis Clinic for ruling out GCA. Patients belonging to group A showed no flow or reduced flow within the territory of central retinal artery (CRA), no "spot sign" and positive TA CDUS; on the other hand, patients from group B presented normal TA CDUS, no flow or reduced flow within the territory of CRA and the presence of "spot sign". Conversely, no relevant difference was evidenced at CDEUS in patients with and without arteritic AION.

CONCLUSION

Our preliminary data displayed a good reliability of CDEUS in distinguishing between arteritic and non-arteritic CRAO, while no difference was assessed between arteritic and non-arteritic AION. Since AION represents the most common presentation of cranial GCA, CDEUS does not seem a reliable procedure in the diagnostic work-up of GCA and should be restricted only to the exclusion of thrombo-embolic occlusions within the territory of central retinal artery.

Structural and Functional Imaging of the Retina in Central Retinal Artery Occlusion - Current Approaches and Future Directions

Central retinal artery occlusion (CRAO) is a form of acute ischemic stroke which affects the retina. Intravenous thrombolysis is emerging as a compelling therapeutic approach. However, it is not known which patients may benefit from this therapy because there are no imaging modalities that adequately distinguish viable retina from irreversibly infarcted retina. The inner retina receives arterial supply from the central retinal artery and there is robust collateralization between this circulation and the outer retinal circulation, provided by the posterior ciliary circulation. Fundus photography can show canonical changes associated with CRAO including a cherry-red spot, arteriolar boxcarring and retinal pallor. Fluorescein angiography provides 2-dimensional imaging of the retinal circulation and can distinguish a complete from a partial CRAO as well as central versus peripheral retinal non-perfusion. Transorbital ultrasonography may assay flow through the central retinal artery and is useful in the exclusion of other orbital pathology that can mimic CRAO. Optical coherence tomography provides structural information on the different layers of the retina and exploratory work has described its utility in determining the time since onset of ischemia. Two experimental techniques are discussed. 1) Retinal functional imaging permits generation of capillary perfusion maps and can assay retinal oxygenation and blood flow velocity. 2) Photoacoustic imaging combines the principles of optical excitation and ultrasonic detection and - in animal studies - has been used to determine the retinal oxygen metabolic rate. Future techniques to determine retinal viability in clinical practice will require rapid, easily used, and reproducible methods that can be deployed in the emergency setting.