Fig 6.

Lacunar infarcts of the SNr. Due to the small size of the cell clusters that form the SNr (near or below the lower limit of MR imaging resolution), detection of these infarcts can be difficult. A, Tiny bilateral infarcts of the SNr are seen on a bFFE image. The resolution of this image is 0.6 × 0.6 × 1.0 mm per voxel. The infarcts measure approximately 1 mm. Both are found in the anterior location. B, Slightly larger bilateral infarcts of the SNr are seen on an MPRAGE image with a resolution of 0.9 × 0.9 × 1.0 mm per voxel. These infarcts are in the middle location. C, Bilateral infarcts at 2 sites (anterior and posterior) in the SNr are seen on an MPRAGE image. SNr infarcts were found in only 3 distinct locations, which we are designating by their relative positions; the anterior location was the most common (20 infarcts), followed by the posterior location (9 infarcts). The middle location was the least common (5 infarcts).