Table 2.

Image segmentation methods for PET data of 19 glioma patients acquired on a Biograph 64 PET/CT system.

Method	Threshold	Empirical factors F
Background intensity	${\mathrm{F}}_{\mathrm{B}\mathrm{G}}\bullet {\mathrm{I}}_{\mathrm{B}\mathrm{G}}$	1.4; 1.6; 1.8
Maximum intensity	${\mathrm{F}}_{\mathrm{m}\mathrm{a}\mathrm{x}}\bullet {\mathrm{I}}_{\mathrm{m}\mathrm{a}\mathrm{x}}$	0.4; 0.45; 0.5
Contrast	${\mathrm{F}}_{\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{t}}\bullet \left({\mathrm{I}}_{\mathrm{m}\mathrm{a}\mathrm{x}}-{\mathrm{I}}_{\mathrm{B}\mathrm{G}}\right)+{\mathrm{I}}_{\mathrm{B}\mathrm{G}}$	0.3; 0.35; 0.4