Treated surgically in 103 Military Hospital and Cho Ray Hospitals from August 2014 to January 2017. All patients had undergone surgery to remove thymus, thymoma, and had pathology reports. All of them had not received any neoadjuvant chemo-radiotherapeutic treatment. MRI examination was obtained using a 1.5 T MRI unit (Intera, Philips Healthcare, the Netherlands) from the thoracic inlet to the cardiophrenic angle. Comparison of the chemical shift ratio(CSR) between two groups was processed by the T-Student test. Logistic multivariate regression was performed to estimate the probability that patients had thymoma by both predictive qualitative and quantitative variables. A p value of <0.05 was considered indicative a statistically significant differencefor all statistical analyses.