Table 1.
Scan parameters used to acquire the 2D-neuromelanin-sensitive MRI and each quantitative map (T1, T2, and T2*).
Fig 1.
Neuromelanin-sensitive MRI of the lower midbrain.
(a) 2D-neuromelanin-sensitive MRI. The SNc appears as the high SI area. The SCP is the small low SI area below the SNc. The CP is above the SNc. The MT is located in the middle of the lower midbrain. (b) The ROIs for measuring the SI were traced manually at the following locations on a single slice: SNc (ROIs 1 and 2), SCP (ROIs 3 and 4), CP (ROIs 5 and 6), and MT (ROI 7).
Fig 2.
Typical quantitative T1, T2, and T2* maps of the lower midbrain.
(a) Typical T1 map. The gray scale represents the T1 values from 0 to 3000 ms. (b) Enlarged T1 map. (c) Typical T2 map. The gray scale represents the T2 values from 0 to 300 ms. (d) Enlarged T2 map. (e) Typical T2* map. The gray scale represents the T2* values from 0 to 200 ms. (f) Enlarged T2* map. The location of the single slices of the T1, T2, and T2* maps was the same as the location of the neuromelanin-sensitive MRI slice.
Fig 3.
Measurements of CR of the lower midbrain.
The box plot represents the minimum, first quartile, median, third quartile, and maximum of the CR. *** p < 0.001, vs. the CR in the SNc; $ $ p < 0.01, vs. the CR in the SCP.
Fig 4.
Measurements of quantitative T1, T2, and T2* relaxation times of the lower midbrain.
(a) T1 relaxation times. (b) T2 relaxation times. (c) T2* relaxation times. The box plot represents the minimum, first quartile, median, third quartile, and maximum of each relaxation time in the four regions. ** p < 0.01 and *** p < 0.001, vs. the relaxation times in the SNc; $ $ p < 0.01 and $ $ $ p < 0.001, vs. the relaxation times in the SCP; ### p < 0.001, vs. the relaxation times in the MT.
Fig 5.
Correlations between the CR and quantitative T1, T2, and T2* relaxation times.
(a, d, g) Correlation between each relaxation time and the CR in the SNc. (b, e, h) Correlation between each relaxation time and the CR in the SCP. (c, f, i) Correlation between each relaxation time and the CR in the CP. The average values of the CRs and relaxation times in the left and right side of each region were used.