The Application Research Of Diffusion-weighted And Conventional MRI Image Fusion For Cervical Lymphadenopathy

Image fusion means to transform imaging data obtained from the same or different imaging modalities and create a new image including source images information.The purpose of image fusion is to merge complementary information from multimodalities data for clinical diagnosis.We tried using the open source image processing software,OsiriX,to combine function image with anatomy image in order to provide more helpful information for the clinical management.Objective:To study the feasibility of image fusion between diffusion-weighted image and conventional MRI in neck by adjusting the scanning parameters and to evaluate the usefulness of clinical application for cervical lymphadenopathy.Objects and Methods:â‘ Parameter Optimization:Axial and coronal conventional MRI and DWI scans with three different b values(300s/mm²,500s/mm²,1000s/mm²)were performed in 18 normal volunteers who ranged in age from 21 to 35 years old(10 male,8 female,mean age 29 years).MR scanning were performed on Marconi Eclipse 1.5T scanner with cervical phased array coil and DWI was performed with single shot echo planar imaging technique and short time inversion recovery sequence.Image quality with different b values and section were compared and image data were processed with software packages.â‘¡Clinical Evaluation:Conventional MRI and DWI scans were performed in 32 patients who had pathology and follow-up proven malignant tumors(22)and benign lesions(10) by using Marconi Eclipse 1.5T scanner with cervical phased array coil.DWI images and T₁WI images with the same field of vision,thickness and interval were fused by using image processing software.The ability of detection of DWI/T₁ WI,DWI and T₂WI images and the diagnostic accuracy of T₂WI and DWI/T₁WI in showing lesions were compared.The difference of ADC values between two kinds of lymph nodes was also analyzed.Results:â‘ The image quality of coronal scan is better than axial scan,there was significant difference between the two scan planes(P=0.000).Statistically significant difference(P＜0.05)was found in SNR values with different b values(300s/mm², 500s/mm² and 1000S/mm²).The study also suggested the ADC values with diffrent b values had significant statistical difference.We fused coronal DWI(b values= 500s/mm²)and conventional MRI image data and obtained satisfactory fusional image.â‘¡DWI and DWI/T₁WI could more sensitively show lymph nodes than that of conventional MR(T₂ WI).The ability of detection for DWI/T₁ WI was better than DWI and significant statistical difference was found(P＜0.01).The area under the curve(AUC)of the composite receiver operating characteristic(ROC)curve of DWI/T₁WI(0.943)was significantly higher than those of T₂WI(0.793;P＜0.01). Kappa values were 0.872(high)for DWI/T₁WI and 0.643(moderate)for T₂WI.Mean ADC values of malignant lymph nodes was(0.948±0.167)×10^-3mm²/s,mean ADC values of benign lymph nodes was(1.459±0.141)×10³mm²/s,there was significant difference in two kinds of lymph nodes(P＜0.05).Conclusion:By adjusting the scanning parameters,image fusion between diffusion-weighted image and conventional MRI in neck is feasible.Fusion image of diffusion-weighted image with conventional MRI can obviously improve spatial resolution of DWI,and may improve accuracy of imaging diagnosis.