Application Of MRI In The Therapy With Interstitial Implantation Of ～(125)Ⅰ Seeds For Central Bronchial Carcinoma

Objective: To establish MRI evaluation mode of the tumor (preoperative staging )in the therapy with interstitial implantation of ¹²⁵I seeds for central bronchial carcinoma before operation, and to evaluate the role of MRI in target orientation in the therapy with interstitial implantation of ¹²⁵I seeds for central bronchial carcinoma with atelectasis.Methods: The central bronchial carcinoma were randomly selected, which were treated in the radioactive particle ¹²⁵I therapy center of the Tianjin Medical University 2nd hospital in the period of 2005.5～2007.3. Forty four cases were imaged by MRI, of them 34 cases it was difficult to show the mass in the area of obstructive atelectasis by CT. In order to satisfy the clinical requirements of selection of the implantation plan, orientation of the mass target, and the avoidance of the puncture risk to classify the lesion of the central bronchial carcinoma before the interstitial implantation of ¹²⁵I Seeds based on the TNM, 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. Both the CT images and MR images of the central bronchial carcinoma with obstructive atelectasis are inputed to the TPS system. TPS will show the equal dosage curve, the radioactive particle distribution picture, as well as the way of the implantation, then we compare the difference between the CT and MRI based on the results of the TPS. Of the 44 cases with central bronchial carcinoma, 38 cases received interstitial implantation of ¹²⁵I seeds guided by CT, in the mean time, of the 38 cases, 9 cases received interstitial implantation of ¹²⁵I seeds by the monitor of the bronchoscope. Of the 44 cases, 6 cases received exairesis and interstitial implantation of ¹²⁵I seeds in tumor bed. Scan the tumor again after 6 months, and follow up visits were within 12-30 months.Results: The central bronchial carcinoma were classified in five grades on MRI before the implantation operation. There were 3 cases in Grade I (Ia 1, Ib 2), 7 cases in Gradeâ…¡, 9 cases in Gradeâ…¢, 14 cases in Gradeâ…£and 11 cases in Gradeâ…¤. The masses in the atelectasis area on CT were not demonstrated in 34 cases, of the 34 cases, the masses in the atelectasis area on MRI were demonstrated in 29 cases, were demonstrated faintly in 3 cases, were also not demonstrated in 2 cases. Both the MR images which demonstrated the tumor from the atlectasis area in 29 cases and CT images on which the tumor was not shown were inputed to the TPS. The results showed that the average volume of mass target area was 50.97 cm³, the computed number of the seeds was 46 seeds in MRI group, and the average volume of mass target area was 60.34 cm³, the computed number of the seeds was 54 seeds in CT group. The average volume on MRI reduced by 15.53% than that of CT. Statistic results showed that there was significant difference between MRI group and CT group (P＜0.05). Follow-up CT 6 months later showed that the results accorded with the documents with CR(7 cases), PR(20 cases), NC(2 cases), and CR+PR(93.1%).Conclusion: MRI plays an important role in the lesion classification and mass target orientation before operation. It can assure the safety and efficiency of the therapy with interstitial implantation of ¹²⁵I seeds, and make the dose more precise, and decrease the damage of peripheral normal pulmonary tissue.