Objective To investigate the value of magnetic resonance image-diffusion weighted imaging(MRI-DMI)combined with attenuation imaging(ATI)in the diagnosis of focal nodular lesions<2 cm in the back-ground of fatty liver.Methods The clinical data of 68 patients with fatty liver complicated with focal nodular lesions<2 cm were retrospectively analyzed from June 2022 to June 2023 in Huaihe Hospital of Henan University.All patients underwent MRI,pathology and ATI examination.According to the degree of fatty liver disease,68 patients were divided into severe group(n=24),moderate group(n=27)and mild group(n=17).The apparent diffusion coefficient(ADC)and acoustic attenuation coefficient(AC)values of patients with different focal lesions were compared with clinical data,and the ADC values and AC values of patients with different fatty liver lesions were compared with clinical data,and the correlation was analyzed by Pearson.To analyze the value of MRI-DWI combined with AC value in the diagnosis of malignant fatty liver disease with focal nodular disease<2 cm.Results Pathological diagnosis showed that 41 of the 68 patients were benign and 27 were malignant.There were no significant differences in low density lipoprotein cholesterol(LDL-C),age,triglyceride(TG),sex,total cholesterol(TC)and high density lipoprotein cholesterol(HDL-C)between benign nodule group and malignant nodule group(P>0.05).There was no difference in TG,age,HDL-C,sex,TC and LDL-C among mild,moderate and severe groups(P>0.05).The ADC value of malignant nodule group was lower than benign nodule group under different b values(P<0.05),and the AC value of malignant nodule group was higher than that of benign nodule group(P<0.05).ADC value under different b values in the severe group was lower than mild and moderate groups(P<0.05),ADC value under different b values in the moderate group was lower than mild group(P<0.05),AC value in the severe group was higher than mild and moderate groups(P<0.05),and AC value in the moderate group was higher than mild group(P<0.05).ADC values at different b values were negatively correlated with the degree of fatty liver disease(P<0.05),but not with TG,HDL-C,TC and LDL-C(P>0.05).AC was positively correlated with the degree of fatty liver disease(P<0.05),negatively correlated with HDL-C(P<0.05),but not with TG,TC and LDL-C(P>0.05).The area under the curve(AUC)values of MRI-DWI,AC and their combi-nation in the diagnosis of fatty liver complicated with focal nodule disease<2 cm into malignancy were 0.775,0.773 and 0.909,respectively(P<0.05),and the AUC value of the combination was higher(P<0.05).Conclusion MRI-DWI and ATI have important value in the differential diagnosis of benign and malignant lesions of focal nodular lesions<2 cm in the background of fatty liver,and the combination of MRI-DWI and ATI has higher diagnostic value.