The relationship between pre-treatment 18F-FDG PET/CT and shear-wave elastography quantitative parameters in patients with breast cancer

Objective: This prospective study aimed to evaluate the relationship between quantitative parameters obtained from 18F-FDG PET/CT and Shear-Wave Elastography (SWE) in breast cancer patients and to assess their association with tumor biological behavior. Materials and Methods: A total of 111 histopathologically confirmed female breast cancer patients underwent pre-treatment 18F-FDG PET/CT and SWE. PET parameters (SUVmax, MTV, TLG, TBR) and SWE parameters (Vmean, Vmax, Vsd) were compared with tumor grade, molecular subtypes and Ki-67 proliferation index. Statistical analyses were performed using the Mann–Whitney U, Kruskal–Wallis, and Spearman correlation tests. Results: Patients with SUVmax ≥6.5 showed significantly higher tumor size, TLG, MTV, and TBR values (p=0.000). High SUVmax group demonstrated a significantly higher Ki-67 proliferation index, an increased rate of HER2 positivity, and a decreased proportion of the Luminal A subtype. When comparing Ki-67 <14 and ≥14 groups, no differences were found in Vmax, Vmean, or Vsd values, whereas at the Ki-67 ≥30 threshold, Vmax was found to be significantly higher (p=0.045). Conclusion: High SUVmax, TLG, and MTV values were found to be significantly associated with increased Ki-67 proliferation index and HER2 positivity, indicating that these parameters may reflect the metabolic activity and biological aggressiveness of the tumor. However, no significant correlation was observed between SWE parameters and PET parameters. These findings suggest that the two modalities may be sensitive to different aspects of tumor biology.