Ki-67 proliferation index (PI) is important for providing information on tumor behavior, treatment response, and prognosis. Integrated positron emission tomography/magnetic resonance (PET/MR) may have the potential to assess Ki-67 PI in patients with lung adenocarcinoma.To explore the value of simultaneousProspective.Seventy-eight patients with lung adenocarcinoma and with Ki-67 PI.3.0 T, simultaneous PET/MRI including diffusion-weighted imaging (DWI) andDWI-derived parameters, namely, apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo diffusion coefficient (D*), perfusion fraction (f), diffusion heterogeneity index (α), and distributed diffusion coefficient (DDC); and PET-derived parameters, namely, maximum standardized uptake value (SUVStudent's t-test, Mann-Whitney U test, chi-square test, and receiver operating characteristic (ROC) curves. A P-value0.05 was considered statistically significant.The SUVThe combination of D, SUV1 TECHNICAL EFFICACY: Stage 2.