The correlation between 18F-FDG and Ki67 was particularly pronounced in head and neck tumors (Figs. 5 and 6) and hematological malignancies (Figs. 7, 8 and 9), consistent with findings by Minn et al. [15] in head and neck tumors and aligning with the highly aggressive, glycolytically active biology of lymphomas with minimal stromal interference [16]. The gene discussed is MKI67; the disease is lymphoma.