Figure 2.

Parameter maps from fits with different compartment models in an exemplary patient with grade IV glioma. Pharmacokinetic analysis was performed within an isocontour of 70%, which was delineated based on the endpoint static summation image, as illustrated in (a). SUV_max and SUR were extracted, where SUR is the ratio between SUV_max and mean background SUV. Both the standard 1TCM and a simplified 1TCM were fitted voxelwise to the time-activity curves (TACs), yielding estimates for exchange rates K₁ and k₂ (b). Furthermore, TACs were fitted with the more complex 2TCM, which yields metabolic exchange rates K₁, k₂, k₃ and k₄ (d). The general definitions of the 1TCM and 2TCM yield estimates on the blood volume V_B, which is displayed in (c). In the simplified 1TCM (s1TCM), the blood volume is assumed to be zero V_B = 0. Parameter maps of tracer kinetic analysis show enhanced detail on tumor substructure, however, stability is decreased for the 2TCM. Both 1TCM and 2TCM yield similar distributions of V_B, indicating that the parameter is not negligible.