TABLE 2

Tissue-to-Plasma and Tissue-to-Muscle Ratios Besides Selectivity Index (Tumor vs. Inflammation)

Parameter18F-FLT untreated (n = 3)18F-FLT + phosphorylase (n = 5)18F-FDG (n = 5)Effect of phosphorylase on 18F-FLT uptakeFLT + phosphorylase vs. 18F-FDG
Tumor-to-plasma ratio1.0 ± 0.43.8 ± 1.46.1 ± 2.7<0.05NS
Tumor-to-muscle ratio1.4 ± 0.43.8 ± 1.313.2 ± 3.00.050.001
Inflammation-to-plasma ratio0.9 ± 0.11.2 ± 0.32.1 ± 0.8NS<0.05
Inflammation-to-muscle ratio1.2 ± 0.01.3 ± 0.44.8 ± 1.2NS0.0002
Selectivity index*1.8 ± 1.7>10.6†3.5 ± 1.2

  • ↵* Defined as (tumor uptake − muscle uptake)/(inflammation uptake − muscle uptake), that is, tumor-to-inflammation ratio corrected for background activity.

  • ↵† SD cannot be given because, in some animals, tracer uptake in inflamed muscle equalled that in contralateral healthy muscle.