Liliequist membrane: three-dimensional constructive interference in steady state MR imaging.

PURPOSE To evaluate the Liliequist membrane in healthy volunteers by using three-dimensional (3D) Fourier transformation constructive interference in steady state (CISS) magnetic resonance (MR) imaging. MATERIALS AND METHODS In 31 volunteers, the authors performed 3D CISS MR imaging. They divided the membrane into three segments: the sellar, diencephalic, and mesencephalic segments. MR images were evaluated to identify the segments, superior and inferior attachments, lateral border, and thickness of the Liliequist membrane. RESULTS Three-dimensional CISS MR imaging depicted the sellar, diencephalic, and mesencephalic segments of the Liliequist membrane in the sagittal plane in 25 (81%), 16 (52%), and five (16%) of the 31 subjects, respectively. Transverse MR imaging depicted these segments in 24 (77%), 10 (32%), and two (6%) subjects, respectively, and coronal MR imaging depicted them in 24 (77%), 12 (39%), and two (6%) subjects, respectively. Clear attachment of the membrane to the dorsum sellae was observed in 22 (88%) of 25 subjects in whom the sellar segment was identified. Clear attachment to the mamillary body was identified in eight (50%) of 16 subjects in whom the diencephalic segment was identified. The Liliequist membrane was attached to the oculomotor nerve on seven (14%) of 50 sides of the lateral border and to the arachnoid membrane around the oculomotor nerve on 28 (56%) sides. In the sagittal plane, the thickness of the membrane was less than one-half the thickness of the third ventricle floor in 22 (88%) of 25 subjects. CONCLUSION The Liliequist membrane can be visualized by using 3D CISS MR sequences.