FIG 5. Sagittal MR images through the red nucleus.

A, Sagittal T2-weighted image obtained in a control subject, a 55-year-old woman. Hypointense areas are visible at the red nucleus and at the anterior margin of the midbrain (arrow). The boundary of the hyperintense band is unclear at the level of lower midbrain.

B, Proton density-weighted image in the same section as in A. The SN is identified as a tilted gray matter structure (n) anteroinferior to the red nucleus (r).

C, T1-weighted image in the same section as in A. The SN is not identified.

D, Fast STIR image at the same section. The SN is identified as a bandlike structure with gray matter signal intensity (n) that is mainly located anteroinferior to the red nucleus (r).

E, Video-reversed fast STIR image onto which the hypointense regions of a T2-weighted image are superimposed (shaded areas). The low-signal-intensity area on the T2-weighted image includes the crural fibers and only the anterosuperior end of the SN.

F, Sagittal gross specimen of the human brain slightly lateral to the MR images. The SN (n) is identified as a tilted band-shaped area.