Imaging of the normal pontine cisternal segment of the abducens nerve, using three-dimensional constructive interference in the steady state MRI

Our objective was to determine the visibility of the cisternal segment of t he normal abducens nerve using a three-dimensional Fourier-Transform constr uctive interference in the steady state (3DFT-CISS) sequence. Its visibilit y was rated in 150 patients without clinical evidence of abducens nerve dis turbance. Axial 1-mm 3DFT-CISS images were obtained (TRITE 17/7 ms, flip an gle 50 degrees, field of view 160 mm, matrix 256 x 256). The cisternal segm ent was seen in 79 % of cases, bilaterally in 73 % and unilaterally in 11 % of cases; neither cisternal segment was seen in 16% of cases. Identificati on of Dorello's canal was often of help in detecting the point lateral to t he dorsum sellae at which the nerve pierces the dura mater. Flow artifacts and vascular loops in the pontine cistern sometimes caused problems in inte rpretation. 3DFT-CISS MRI with 1-mm-thick sections can however be considere d a reasonably reliable technique for showing the cisternal segment of the abducens nerve.