EGFR and non-small cell lung carcinoma: In gefitinib-sensitive NSCLC cell lines with EGFR mutations, the uptake of 18F-FDG was also decreased significantly as early as 2 h after treatment, whereas no measurable changes in 18F-FDG uptake were observed in gefitinib-resistant cells, representing treatment response of gefitinib that could be closely reflected by glucose metabolic activity (34).