Reproducibility of a Standardized Quantitative Analysis Using Fixed Regions of Interest to Differentiate Movement Disorders on 123I-FP-CIT SPECT

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FIGURE 1.
Correlation between results obtained from ¹²³I-FP-CIT studies by 2 technologists (observers 1 and 2). Intra- and intertechnologist variabilities were 0.14 ± 0.13 (confidence value, 2.4%) and 0.19 ± 0.18 (confidence value, 3.1%), respectively. Cau le = left caudate nucleus; cau ri = right caudate nucleus; put le = left putamen; put ri = right putamen.
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FIGURE 2.
Absolute difference between 2 technologists plotted against mean ratio of both, confirming good reproducibility of method used in current study. Intraclass correlation coefficients, defined as measure of consistency or agreement of values within cases, of 1 technologist was equal to 0.99. This value for 2 independent technologists was equal to 0.98. Cau le = left caudate nucleus; cau ri = right caudate nucleus; operA = technologist 1; operB = technologist 2; put le = left putamen; put ri = right putamen.
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FIGURE 3.
Uptake values as obtained using automatic semiquantitative method of analysis. (A) Normal uptake in putamen and caudate nucleus of patient with essential tremor. (B) Patient with diminished uptake in caudate nucleus, suggesting early-onset PD; 2-y follow-up confirmed hypothesis. (C) Patient with diminished uptake in whole striatum, corresponding to PD.

TABLE 1

Uptake Ratios on ¹²³I-FP-CIT Studies Based on Standardized Analysis Method

Disease	No. of patients	CR	CL	PR	PL
PD	21	5.48 (1.52)	5.39 (1.54)	3.55 (1.35)	3.62 (1.43)
Hypokinetic rigid syndrome	19	7.00 (0.92)	7.00 (1.04)	6.00 (1.29)	6.08 (1.07)
Dystonia	8	7.39 (1.02)	7.14 (1.27)	5.65 (2.49)	6.59 (0.96)
Essential tremor	4	7.63 (1.16)	7.64 (0.69)	5.90 (0.46)	6.20 (0.74)
Normalized reference values
<40 y old		8.2 (±2.4)	8.2 (±2.4)	7.8 (±3.5)	7.8 (±3.5)
>40 y old		9.2 (±3.7)	9.2 (±3.7)	8.3 (±3.7)	8.3 (±3.7)

CR = right caudate nucleus; CL = left caudate nucleus; PR = right putamen; PL = left putamen.
Values in parentheses are SDs.

TABLE 2

Difference Between Mean Values Obtained with Fixed ROIs and Manually Drawn ROIs in Analysis of ¹²³I-FP-CIT Studies

		Standardized method		Manual method		P
Site	Normalized value	T1	T2	T1	T2	Standardized T1 vs. standardized T2	Manual T1 vs. manual T2	Manual vs. standardized
CR	9.2 (3.7)	6.6 (1.1)	6.7 (1.2)	5.1 (1.0)	5.1 (1.0)	0.810	0.892	<0.001
CL	9.2 (3.7)	6.4 (1.2)	6.6 (1.1)	5.0 (1.0)	4.9 (1.0)	0.665	0.703	<0.001
PR	8.3 (3.7)	5.7 (1.6)	5.7 (1.6)	4.4 (1.3)	4.1 (1.3)	0.982	0.002	<0.001
PL	8.3 (3.7)	5.8 (1.5)	5.8 (1.7)	4.3 (1.3)	4.0 (1.3)	0.835	0.014	<0.001

T1 = technologist 1; T2 = technologist 2; CR = right caudate nucleus; CL = left caudate nucleus; PR = right putamen; PL = left putamen.
Values in parentheses are SDs.