Evaluation of the Substantia Nigra in Patients with Parkinsonian Syndrome Accomplished Using Multishot Diffusion-Weighted MR Imaging

41-year-old male control subject.

A, Axial T2-weighted image (3540/105) of the midbrain barely depicts the substantia nigra (arrow). The red nucleus (arrowhead) is depicted as a round area of low intensity resulting from the accumulation of iron.

B, Diffusion-weighted image with a left-right direction diffusion-sensitizing gradient shows a distinct crescent of low signal intensity (arrow) between the cerebral peduncle and the tegmentum. Large arrowhead indicates substantia nigra; small arrowhead, mammillary body.

Thickness of the substantia nigra in the control subjects, the patients with Parkinson's disease, and the patients with secondary parkinsonism. The mean (± SD) thickness of the substantia nigra in the control group (n = 72) was 5.1 ± 0.89 mm, that in the group with Parkinson's disease (n = 47), 4.8 ± 0.75 mm; and that in the group with secondary parkinsonism (n = 10), 3.4 ± 0.53 mm. There was a significant difference between the group with Parkinson's disease and the group with secondary parkinsonism by unpaired Student's t-test (P < .01)

67-year-old man with Parkinson's disease (Hoehn and Yahr scale, 4).

A, On T2-weighted image (3540/105), the substantia nigra is difficult to identify. There are no abnormal signal changes in the midbrain.

B, On diffusion-weighted image, the substantia nigra (arrow) is depicted clearly as a crescent of low signal intensity. No atrophy of the substantia nigra is seen.

19-year-old man with secondary parkinsonism (carbon monoxide intoxication) 3 years after onset.

A, On T2-weighted axial image (3540/105), a hyperintense lesion (arrow) is observed in the globus pallidus; a result of carbon monoxide poisoning.

B, Diffusion-weighted axial image of the midbrain shows atrophy of both substantia nigra (arrow). The signal intensity is relatively higher than that in the control subjects.

75-year-old man with secondary parkinsonism after bilateral putaminal hemorrhage.

A, T2-weighted image shows a large hyperintense area in the left putamen and a slitlike hyperintensity in the right putamen. Multiple spotty areas of hyperintensity are also seen in both putamen. The margins of the large area of hyperintensity and of the slitlike hyperintensity are hypointense owing to susceptibility effects resulting from the accumulation of iron (hemosiderin).

B, On T2-weighted image (3540/105) of the midbrain, the substantia nigra is not distinguishable. There are no abnormal signal changes in the midbrain.

C, On diffusion-weighted image, both substantia nigra are reduced in size. This image shows hyperintensity in the substantia nigra, which might reflect neuronal degeneration and gliosis.