Figure 6. Therapeutic response monitoring with 18F-FDG-PET imaging and immunohistochemical staining.

(a) Glucose metabolic activity was measured by ¹⁸F-FDG-PET imaging in SNU-1066 xenograft model. ¹⁸F-FDG-PET images were obtained before treatment and at 1, 2, and 4 weeks after treatment with saline, cetuximab, or ¹⁷⁷Lu-PCTA-cetuximab. PET images represented as SUV and SNU-1066 tumors are indicated by yellow arrows. (b) ¹⁸F-FDG uptake in tumors was quantified from small animal PET images (n = 3). ¹⁷⁷Lu-PCTA-cetuximab treatment group showed a marked reduction in FDG uptake compared with other groups. ^*; P < 0.05. (c, d and e) In TUNEL staining in SNU-1066 tumors, there were statistically significant differences in apoptosis level among ¹⁷⁷Lu-PCTA-cetuximab, saline and cetuximab treatment groups. Ki-67 positive cells in SNU-1066 tumors were markedly reduced in ¹⁷⁷Lu-PCTA-cetuximab treatment group, in comparison with the saline and cetuximab treatment groups. ^**, P < 0.01. ×400 magnification.