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Figure 8 | EJNMMI Research

Figure 8

From: FDG kinetic modeling in small rodent brain PET: optimization of data acquisition and analysis

Figure 8

Loss of information by prolonging the infusion duration. (A) Simulated IFs, bolus 10 s (dark line) and infusions 300 (dotted line) and 900 s (grey line). (B) Zoom into TAC generated with a typical set of rate constants K 1 0.328 mL/min/cm3 , k 2 0.550 min−1, k 3 0.079 min−1, k 4 0 (dark line). An additional TAC was generated by increasing K 1 by 10% (1.1 × K 1). At the same time, k 2 was also increased to match the original TAC as close as possible. The respective factor for k 2 was 1.11 (1.11 × k 2). TACs with either increased K 1 or k 2 are shown in addition. The newly generated TAC with 1.1 × K 1 and 1.11 × k 2 deviates from the original TAC around the infusion stop, i.e., around the peak of the IF. This difference is indispensable to distinguish between the effects of K 1 and k 2 on the TAC and thus for kinetic modeling. (C) TACs generated with the same rate constants as in (B) for the 300-s infusion and (D) for the 900-s infusion. The difference between the two TACs (indicated by an arrow in C) reduces as infusion duration increases, explaining the improper fit parameters with the simulated 900-s infusion protocol at longer sampling intervals. Note that (B) to (D) zoom into the TAC region of interest and the activity scale, therefore starts at 600 Bq/cm3.

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