Elena Vinogradov, Abstract Co-Author: Nothing to Disclose

David Brian Hackney MD, Presenter: Nothing to Disclose

Stephan E. Maier MD, Abstract Co-Author: Nothing to Disclose

Robert E. Lenkinski PhD, Abstract Co-Author: Nothing to Disclose

Alexandra Degenhardt, Abstract Co-Author: Nothing to Disclose

Derek Smith, Abstract Co-Author: Nothing to Disclose

Robert Marquis, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Evaluation of techniques for anatomical and physiological imaging of the intracranial optic nerve(ON), Optic Chiasm(OC), and optic tract(OT) at 3T, aimed at visualization of OC damage in Multiple Sclerosis.

Imaging was performed on the 3T scanner (Signa LX, GEMS, Waukesha, WI). All images were obtained employing a custom designed head coil, consisting of a coil array (25 cm diameter) and containing four 30x30cm squared coils. Oblique axial FSE images (1.5mm, FOV20x15cm, TR/TE=4000-5000/99-100ms, NEX=3, 512x384) and Magnetization Transfer (MT) enhanced oblique 3D GRE images (1.5mm, FOV20x15cm, TR/TE=200/2.5ms, NEX=1, 256x256) were acquired. Line Scan Diffusion Images (LSDI) were obtained (2mm, FOV20x5cm TR/TE=97/74ms, NEX=4, 256x256, two b-factors: 5 s/mm2 and 1000 s/mm2, bw=3.9kHz). Full Diffusion tensor analysis was performed leading to Apparent Diffusion Coefficient (ADC), Fractional Anisotropy (FA) and fiber direction maps.

The use of a multi four-channel coil and 3T allows obtaining high resolution FSE anatomic images, with the in-plane resolution as low as 390x520µ², enabling clear and detailed demonstration of OC in a relatively short scan time of 3min. The in-plane resolution of MT and LSDI images is 780x780µ². MT ratio of the OC is approximately 26%. LSDI produced high resolution diffusion images almost free of bulk motion artifacts and with limited susceptibility effects adjacent to the ONs within the optic canals. The OC, intracranial ON and OT are seen on these images and on ADC and FA maps. DTI-based tractography displays the dominant fiber orientations in the OC, and may be a helpful method to display loss of anisotropy in the setting of demyelinating lesions.

We have shown that the use of 3T and multi-coil allows acquisition of anatomic and physiological images of OC with high spatial resolution within SAR guidelines. Pilot results presented here pave the way for anterior visual pathway MR imaging in MS.

Vinogradov, E, Hackney, D, Maier, S, Lenkinski, R, Degenhardt, A, Smith, D, Marquis, R, et al, , High-Resolution Anatomic and Physiological Imaging of the Optic Chiasm at 3T.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4414426.html