TABLE 1

Comparison of PETGTV and CTGTV

Mean ± SD
Tumors (n)SUVmaxCTGTV (cm3)PETGTV at 40% threshold (cm3)*Optimal threshold (%)†
All (20)12 ± 8198 ± 27744 ± 3024 ± 13
<3 cm (4)3.0 ± 0.413 ± 714 ± 1442 ± 2
3–5 cm (10)13 ± 990 ± 6938 ± 2224 ± 9
>5 cm (6)16 ± 5502 ± 34869 ± 2815 ± 6

  • ↵* GTV determined by PET with 40% SUVmax threshold.

  • ↵† Optimal threshold is percentage threshold that yields 1:1 volumetric match between PET- and CT-delineated tumors.