Study On The Application Of Fat-suppression T₂WI Combined With Diffusion-weighted Imaging In Target Delineation Of Lung Carcinoma

Objective: To discuss the clinical application value of3.0T MRI fat-suppressionT2WI combined with diffusion-weighted imaging (DWI) in target delineation of lungcarcinoma.Methods: From December2012to December2013,32consecutive untreatedpatients in our hospital with biopsy/cytology-proven lung cancer were enrolled inour study. Each patient was examined by enhanced CT and MRI for radiotherapysimulation, T2WI was fused with DWI (T2WI-DWI) by Pinnacle3radiotherapyplanning system. Tumors and lymph nodes detected by enhanced CT and T2WI-DWIwere staged according to AJCC (2009edition) TN staging criterion. Gross tumorvolume (GTV) was named separately according to two imaginary methods: ctGTVt,mGTVt for lung tumor target delineation and ctGTVt, mGTVt for lymph node targetdelineation. The difference of two methods in diagnosis for tumors and atelectasis,lymph nodes were valued by the Matching chi-square test. The influence factors of GTV were calculated by the Logistic method, The normality test followed byWilcoxon rank sum test was used in the analysis of GTVnd.Results: Compared with enhanced CT scanning, the borders of tumors could bedetermined more easier in16cases accompanied with atelectasis（χ2=4.9，P=0.021）,T-staging was elevated in2patients（6.25%）while downgraded in3patients（9.38%）. The Multivariate Logistic regression analysis was performed todescribe the association between the variables with the change between ctGTV andmGTV. Results showed that atelectasis was the only predictor of the change of GTVin two imagery methods （χ2=10.115，P=0.001）.Meanwhile, when lung tumorswere accompanied with atelectasis, the GTV was delineated by two imagerymethods varied greatly （36.61±27.27%）. When not, the GTV varied slightly（3.45±7.87%）.43lymph nodes were detected by CT images while52lymphnodes by T2WI-DWI.9extra lymph nodes close to pulmonary hilus or pulmonaryvessels were detected by T2WI-DWI and6lymph nodes（66.7%）were positiveaccording to T2WI-DWI criterion.43lymph nodes were discovered both by twomethods, According to different lymph node diagnostic criteria in two images,3lymph nodes (6.98%) were diagnosed as positive in enhanced CT, which werediagnosed as negative in T2WI-DWI;5lymph nodes（11.63%）were diagnosed asnegative in enhanced CT, which were diagnosed as positive in T2WI-DWI.Nosignificant difference was observed in the qualitative diagnosis of43lymph nodesdiscovered by two imagery methods （χ2=0.125，P=0.727）. Likewise, thectGTVnd and mGTVnd of32lymph nodes which were diagnosed as malignanciesrevealed no statistical significance（Z=-1.255，P=0.210）.Compared with enhancedCT,N-stating was elevated in3patients（9.38%）while downgraded in2patients（6.25%） in T2WI-DWI.Conclusions: The technical of fat-suppression T2WI combined with DWI can beapplied in gross tumor volume accurate delineation of lung carcinoma. Comparedwith enhanced CT, it is easier in distinguishing the border of tumor when the primarytumor accompanies with atelectasis or detected lymph node which is close topulmonary hilus or pulmonary vessels. Meanwhile, the technique of T2WI combinedwith DWI may has an influence on GTV delineation and TN stating of some lung carcinoma penitents.