Mid Brain Measurement in PSP.

Measuring the anterior-posterior distance of the pons and midbrain

(A) Midsagittal T1 image on conventional MRI. (B) Elliptical regions of interest were placed over the pons and the midbrain in the midsagittal slice. Two lines were drawn to define the major axes of the ellipses, corresponding to oblique superior-inferior axes (thin white lines). The maximal measurement perpendicular to the major axis was taken (thick white lines). In all cases, the posterior border of the pons was clearly identifiable and did not include the pontine tegmentum; the midbrain measurement did not include the collicular plate and was chosen to maximize the chance of detecting atrophy of this region in progressive supranuclear palsy as exhibited by the concave appearance in the midsagittal plane.7

Measurement                                                      PSP                                   Non PSP

Mid Brain:                                                         < 9.35 mm.                          > 9.35 mm.

Pons:                                                                   Insignificant.                       Insignificant.  

Mid Brain / Pons Ratio:                                     < 0.52.                                   > 0.52.