Imaging of the normal pontine cisternal segment of the abducens nerve, using three-dimensional constructive...

Our objective was to determine the visibility of the cisternal segment of the normal abducens nerve using a three-dimensional Fourier-Transform constructive interference in the steady state (3DFT-CISS) sequence. Its visibility was rated in 150 patients without clinical evidence of abducens nerve disturbance. Axial 1-mm 3DFT-CISS images were obtained (TR/TE 17/7 ms, flip angle 50 degrees, field of view 160 mm, matrix 256 x 256). The cisternal segment was seen in 79% of cases, bilaterally in 73% and unilaterally in 11% of cases; neither cisternal segment was seen in 16% of cases. Identification of Dorello's canal was often of help in detecting the point lateral to the dorsum sellae at which the nerve pierces the dura mater. Flow artifacts and vascular loops in the pontine cistern sometimes caused problems in interpretation. 3DFT-CISS MRI with 1-mm-thick sections can however be considered a reasonably reliable technique for showing the cisternal segment of the abducens nerve.