TABLE 1

Computational Performance Summary

Model	Sensitivity equations	Frames	Without sensitivity equations		With sensitivity equations
Model	Sensitivity equations	Frames	ODEs	Time (s)	ODEs	Time (s)
Blood flow	K₁, k₂	18 × 5 s	3	0.426	9	0.627
				(0.010)		(0.005)
FDG	K₁, k₂, k₃, k₄	12 × 0.16, 10 × 0.5, 10 × 2, 10 × 5, 4 × 10 min	4	0.504	20	1.144
(0.012)	(0.010)
Receptor	K₁, k₂, k_on, k_off, B_max	240 × 0.25 min	6	3.904	66	13.629
				(0.071)		(0.258)

Times are mean (SD) of 10 runs. ODEs is number of ODEs solved and includes output, state, and, if indicated, sensitivity equations. These equations were automatically generated by COMKAT. For blood flow, plasma input function was specified as C_p(t) = 0.055(t/60)⁶e^−t/60/1.8 + 10(t/60)e^−t/60/22 + 0.7(t/60)e^−t/60/180, t ≥ 0, and blood radioactivity input function as C_a(t) = C_p(t)e^−2.033t, with t in minutes. For FDG, plasma input function was specified as C_p(t) = 650 e^−6.7t + 146e^−0.25t + 105e^−0.03t + 21e^−0.0001t, t ≥ 0, with t in minutes (26). For receptor, plasma input function was obtained by linearly interpolating input function data for protocol 4 from (8). For both FDG and receptor models, contribution from vascular radioactivity was not included, because these input functions were not available.