The Clinical Application Of MR Diffusion-Weighted Imaging For Abdominal Lymph Node

Objective: To study the feasibility of MR diffusion-weighted imaging(DWI)for abdominal lymph node and its value of differentiation for benign and malignant lymph nodes.Materials and Methods: There were 53 patients in this study performed MRI examination with both conventional sequence (T1WI, T2WI, and dynamic contrast imaging) and MR diffusion-weighted imaging, using a b-value of 0 and 300s/mm2 . Of them 23 patients with both type B hepatitis confirmed by clinical examination and hepatic hilum lymph node enlargement finding on conventional MR images were served as Group hepatitis; and 30 patients with both hepatic carcinoma confirmed or suspected by clinical examination and abdominal lymph node metastasis on conventional MR images were served as Group carcinoma. The image analysis included: (1) the quality of the DW images was categorized as excellent,acceptable,poor three scale in the two groups to rank the quality of DWI for depicting lymph nodes; (2) images depicting enlarged lymph nodes were selected from conventional T2 weighted imaging and diffusion-weighted imaging to calculate the number of enlarged lymph nodes in the two groups, respectively; the ability of two sequence for predicting lymph nodes and the maximum long diameter of visible enlarged lymph nodes on two sequence was compared respectively; (3) the data of diffusion-weighted imaging in group hepatitis and group hepatic carcinoma were transported to AW 4.1 workstation, ADC imaging was reconstructed on workstation. The ADC values of lymph nodes were measured and compared in group hepatitis and group hepatic carcinoma.Results: In group hepatitis, lymph nodes were located in hepatic hilum; while in group hepatic carcinoma, lymph nodes were mainly located in hepatic hilum,port-cavity gap,celiac trunk,abdominal aorta peripheral region. In group hepatitis, the quality of DW images for depicting lymph nodes were rated as excellent 73.9% (17/23), acceptable 26.1% (6/23) and poor 0% (0/23), respectively; in group hepatic carcinoma, they were rated as excellent 70% (21/30), acceptable 23.3% (7/30) and poor 6.7% (2/30), respectively. In 23 patients of group hepatitis, all of 51 lymph nodes depicted were shown on both T2 weighted imaging and DWI imaging; the maximum long diameters were, respectively, 1.14±0.27cm (0.8～1.7cm) and 1.13±0.26cm (0.8～1.6cm) on T2 weighted imaging and DWI imaging (p>0.05). In the 30 patients of group hepatic carcinoma, all the 113 lymph nodes depicted was shown on both T2 weighted imaging and DWI imaging; the maximum long diameters were, respectively, 2.7±0.83cm (1.4～4.4cm) and 2.73±0.85cm (1.5～4.6cm) on T2 weighted imaging and DWI (p>0.05). The lymph nodes with their maximum long diameter more than 0.8cm depicted on T2WI can also be depicted on DWI. The ADC values of lymph nodes were, respectively, 3.92±0.28×10-3mm2/s in group hepatitis and 3.19±0.39×10-3mm2/s and group hepatic carcinoma (t=7.19, p<0.001).Conclusion: MR DWI has an ability to depict abdominal enlarged lymph nodes comparable to that of T2 weighted imaging, and can be an alterative method to differentiate benign from malignant lymph nodes.