Differences of Various Region-of-Interest Methods for Measuring Dopamine Transporter Availability Using ^𝟗𝟗𝐦𝐓𝐜-TRODAT-1 SPECT

Table 4

Striatal DAT availabilities, declines per decade of DAT availabilities, and striatum sizes in the regions: (1) inside both the threshold ROIs and the atlas-defined ROIs, (2) inside the threshold ROIs but outside the atlas-defined ROIs, and (3) outside the threshold ROIs but inside the atlas-defined ROIs.

Thresholds	Inside threshold, inside atlas			Inside threshold, outside atlas			Outside threshold, inside atlas
	Average****	Decline***	Size**	Average****	Decline***	Size**	Average****	Decline***	Size**
90%	2.71, 2.68*	5.04%, 5.93%	33.8, 41.1	2.65, 2.62	6.00%, 6.10%	15.8, 8.5	1.28, 1.40	9.43%, 7.59%	646.8, 596.2
85%	2.55, 2.56	6.13%, 6.06%	69.4, 82.2	2.50, 2.48	6.11%, 6.23%	42.0, 29.1	1.22, 1.33	9.54%, 7.97%	611.3, 555.1
80%	2.43, 2.43	6.28%, 6.08%	113.4, 130.8	2.36, 2.33	6.17%, 6.43%	84.6, 67.2	1.14, 1.24	9.77%, 8.28%	567.2, 506.6
75%	2.31, 2.32	6.40%, 6.17%	162.2, 184.1	2.21, 2.19	6.27%, 6.47%	150.4, 128.5	1.06, 1.15	10.03%, 8.75%	518.4, 453.3
70%	2.19, 2.20	6.54%, 6.21%	215.9, 242.0	2.07, 2.04	6.46%, 6.68%	246.6, 220.5	0.96, 1.05	10.51%, 9.30%	464.7, 395.4
65%	2.08, 2.10	6.68%, 6.25%	270.0, 298.8	1.92, 1.89	6.64%, 6.84%	377.0, 348.2	0.87, 0.95	11.02%, 9.99%	410.6, 338.5
60%	1.97, 2.00	6.82%, 6.29%	325.4, 354.7	1.77, 1.75	6.90%, 7.07%	550.6, 521.3	0.78, 0.85	11.70%, 10.79%	355.2, 282.6

∗In each pair of data, the left is for MRI-normalization, while the right is for SPECT-normalization.
∗∗Size: each voxel is of 2.897 mm × 2.897 mm × 2.897 mm.
∗∗∗Decline per decade.
∗∗∗∗For comparisons, the same OC averages from the threshold-ROI methods were used in the calculation of (ST-OC)/OC.