Figure 1.

Findings on conventional MRI and DTI in Parkinson's disease. On T2-weighted sequences and susceptibility-weighted imaging, the normal substantia nigra presents as a band of hypointensity between the cerebral peduncle and the mesencephalic tegmentum. In a 66-year-old patient without Parkinson's disease (A), an axial slice of the midbrain on susceptibility-weighted imaging shows a well-delineated substantia nigra (black circle), of normal thickness, showing well-defined cleavage with the red nucleus (white circle). In a 68-year-old patient with Parkinson's disease (B), an axial slice of the midbrain on susceptibility-weighted imaging shows a poorly delineated, thin substantia nigra and poorly defined cleavage of the substantia nigra with the red nucleus. The reduced volume of the substantia nigra in the patient with Parkinson's disease is attributable to iron deposition. The regions of interest in the substantia nigra in patients A and B (black circles) were copied and pasted onto the FA map (C and D, respectively), which shows that the FA value was lower in the patient with Parkinson's disease than in the patient without (0.425 vs. 0.581), indicating a loss of neuronal integrity. The contralateral findings were comparable between the two patients (images not shown).