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Abstract #10363 Published in IGR 6-1
A comparison of 10 MHz and 20 MHz ultrasound probes in imaging the eye and orbit
Hewick SA; Fairhead AC; Culy JC; Atta HRBritish Journal of Ophthalmology 2004; 88: 551-555
BACKGROUND/AIMS: B-scan ultrasonography is an invaluable, versatile, non-invasive tool in ophthalmology. Recently, a 'high frequency' contact 20 MHz probe has been introduced. B -scanning ultrasonography of orbital and ocular structures was performed with both a 10 MHz and the new 20 MHz probe, in order to evaluate what information was best obtained from each probe, and to provide recommendations for the use of each. METHODS: Patients were selected from routine ultrasound clinics at Aberdeen Royal Infirmary between January 1st, 2002 and August 1st, 2002. The vitreous, retina, choroid, sclera and, in the orbit, the extraocular muscles, optic nerve, and orbital fat were assessed with both the 10 MHz and 20 MHz probes. In the laboratory, using a 'point target', the characteristics of the ultrasound beam at different distances from the probe were also assessed. RESULTS: The point target showed that focus was deeper and that the lateral, and to a lesser degree the axial, resolution are sharper with the 20 MHz probe, compared with the 10 MHz probe. In patients' eyes, highly reflective structures are seen at higher resolution with the 20 MHz probe. Imaging of lower intensity reflectors such as the vitreous and particles within it are seen better with the 10 MHz probe. Increased tissue attenuation was evident with the 20 MHz probe. CONCLUSIONS: The 20 MHz probe has a superior resolution and can be used to better detect details at the posterior pole and in the orbit. The 10 MHz probe can be used to examine low intensity scatterers, such as the vitreous humor, that cannot be seen using a higher frequency probe.
Dr. S.A. Hewick, Department of Ophthalmology, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN, UK
Classification:
6.12 Ultrasonography and ultrasound biomicroscopy (Part of: 6 Clinical examination methods)
