PHASED-ARRAY SURFACE COIL MR OF THE ORBITS AND OPTIC NERVES

PURPOSE: To devise a practical technique for high-resolution evaluatio n of the anterior optic apparatus using a phased-array surface coil sy stem, and to evaluate this system in patients with suspected optic pat hway abnormalities. METHODS: A four-element phased-array coil pair was placed on each side of the head, and signal-to-noise measurements wer e obtained using a head phantom. Comparison between the phased-array c oil, the quadrature coil, and a single-turn 12.7-cm (5-in) surface coi l was done. T1 spin-echo and T2 fast spin-echo sequences were obtained in the oblique axial and oblique sagittal planes, to approximate the long axis of the optic nerves and the nonoblique coronal plane, RESULT S: The phantom signal-to-noise measurements at simulated locations of the optic nerve head, optic canal, and optic chiasm revealed an improv ement of at least 30% using the phased-array system. Of 24 imaged case s, 9 had trauma, 5 had suspected neoplasms, and 2 had optic neuritis. In 3 patients, an unexpected diagnosis of optic pathway contusion or i nfarction was made. The remaining 8 patients had various suspected vis ual pathway lesions. CONCLUSION: Phased-array surface coils allow rapi d, thin-section imaging of the entire anterior optic pathway, with imp roved signal-to-noise ratio. This may improve evaluation of optic path way lesions over conventional techniques.