Fig. 6

The mutant type-associated activation areas of the TS_TL in three EGFR-mutant lesions before and after TKI treatment. Case 1 (stage IV): A female non-smoker in the 60–65 age range presented with a solid mass in the left lower lung (41.1 × 29.7 mm) with an EGFR mutation in exon 20 and received oral poziotinib treatment; through PET/CT re-examination after 21 months, the original lesion shrunk (30.2 × 24.6 mm) and its metabolism was lower than before (SUVmax from 14.8 to 10.2). Poziotinib is a novel targeted drug for rare insertion mutations in exon 20 of EGFR and HER2. Case 2 (stage IV): A male smoker in the 65–70 age range presented with a solid mass in the left upper lung (40.9 × 26.7 mm) harboring an exon 21 EGFR mutation. The patient received oral Osimertinib treatment, and after 6 months, a follow-up PET/CT examination revealed a significant reduction in the size of the original lesion, which became subsolid (20.7 × 15.9 mm), and a decrease in metabolism (SUVmax from 11.8 to 3.9). Case 3 (stage IV): A male non-smoker in the 80–85 age range presented with a subsolid mass in the right upper lung (35.5 × 30.5 mm) carrying an exon 19 EGFR mutation. The patient received oral Icotinib hydrochloride treatment, and after 46 months, a follow-up PET/CT examination revealed a slight reduction in the size of the original lesion (28.5 × 27.9 mm) and a decrease in metabolism (SUVmax from 3.1 to 1.9)