The "morning glory sign" should be evaluated using thinly sliced axial images.

Fig. 2. A 20-year-old woman (healthy volunteer). ``Fig. A'' and ``Fig. B'' were re-formed to slices of 3-mm thickness using 3-dimensional fast imaging employing steady-state acquisition (FIESTA) sequence. Figure A is an axial image parallel to the line running through the nasion and pontomedullary junction. Figure B is an axial image parallel to the line running through the anterior commissure and posterior commissure. Both slices show concave aspects of the tegmentum of the midbrain (arrows). Magn Reson Med Sci, Vol. 6, No. 1, pp. 59–60, 2007