A gamma-distribution convolution model of 99mTc-MIBI thyroid time-activity curves

EJNMMI Physics

Table 1 Parameters for the GDC fit model

Pt thyroid^a	t _A (min)	a	b (min⁻¹)	α	β (min⁻¹)	S (10⁶ cts)^b	Fit err %^c	Noise %	1 − R² (%)^d
1L	0.195	0.846	0.909	0.8577	0.001849	3.529	1.713	1.174	0.534
1R	0.334	3.733	5.211	0.8661	0.004081	2.319	1.914	1.094	0.350
1T	0.277	1.631	2.060	0.8645	0.003106	5.222	1.421	0.800	0.271
2L	0.340	1.351	1.692	0.9408	0.004445	2.027	1.690	1.183	0.630
2R	0.282	0.995	0.928	0.8668	0.001240	6.510	1.353	1.022	0.395
2T	0.307	1.127	1.203	0.8998	0.002652	6.625	1.019	0.773	0.239
3L	0.306	7.878	11.644	0.8918	0.002029	3.201	1.801	1.225	0.818
3R	0.425	3.082	4.520	0.8942	0.002863	3.296	1.026	1.060	0.189
3T	0.374	6.470	9.842	0.8947	0.002554	6.287	0.988	0.801	0.224

^aPatient numbers 1,2,3 plus L left thyroid lobe, R right thyroid lobe, T total thyroid TACs, e.g., 1L, 2L
^b S is the scale factor used to equate AUC_TAC = S AUC_GDC. The AUC of the GDC is one, as it is for all density functions. The AUC of a TAC is the total counts collected in the ROI from time is zero to infinity
^cThe fit error was increased to offset for the effect of using 6 fit parameters in the GDC model—see Eq. (10)
^dFrom correlation of the TAC with the GDC model for the 89 one-minute sample times