Abstract: Objective To establish MRI evaluation mode of the tumor (preoperative grouping)in the therapy with interstitial implantation of 125I seeds for central bronchial carcinoma before operation, and to estimate its clinical value. Methods 44 cases central bronchial carcinoma were randomly selected since 2005, which are treated with the particl e 125I therapy. All cases were performed by MRI. On the basis of the clinical requirment of selection of the implantation plan, orientation of the mass target, and the avoidance of the puncture risk, to summarize and analyse the mass signal, mass complications, bronchus abnormal features, metabasis of the hilar and mediastinal lymph nodes, mediastinal invasion, cardiac and vascular invasion, as well as chest wall involved. Results Most of them show oval or irregular shape, equal signal on T1WI, equal or high signal on T2WI. some of them, blood and necrosis in tumor can be found. Adjacent structures can be involved. Conclusion Preoperative grouping of the therapy with interstitial implantation of 125I seeds for central bronchial carcinoma is very valuable for the orientation of the mass target, localization of the puncuture, confirmation of the modus operandi, as well as making sure of the risk in the operation.

Key words: central bronchial carcinoma, MR, Radioactive Nuclide, 125I seeds