DWI And Dynamic Contrast-enhanced MRI In Differential Diagnosis Of Lymph Node Lesions

PURPOSE: To evaluate the role of diffusion-weighted imaging(DWI), apparent diffusion coefficient(ADC) , and dynamic contrast-enhanced MR imaging(DCE-MRI) in the differential diagnosis of lymph node lesions.METHODS: Conventional MR imaging(spin echo T1WI,T2WI and STIR) was used to scan 46 patients with histologically proven malignant tumors(26) and benign lesions(20) on a GE 1.5T scanner using cervical phased array coil. Six B values(46 cases) were acquired with diffusion gradients applied in all three orthogonal directions using body coil. Images were acquired independently in each of the gradient directions(X,Y and Z). Diffusion scan time was 40⁵2 seconds. ADC values were measured in the lymph node lesions. And all the lesions were evaluated by dynamic contrast-enhanced MR imaging. The lesion detectability of T1WI, T2WI, and contrast series, the signal intensity character, enhancement pattern, morphology manifestation of the lesions were observed.RESULTS: All benign and malignant lymph nodes were visible in DWI and showed significant hyperintensity signal. The differences in mean ADC of Group malignant lymph nodes[(0.834±0.192)×10^-3mm²/s] and Group benign lymph nodes[(1.687±0.252)×10^-3mm²/s] were statistically significant(P<0.05). There were not significant difference between benign and malignant lymph nodes on enhancement homogenity, morphology and margin characteristics(P>0.05).The benign and malignant characteristics of intermediate and late periods of post-contrast which described by the SI-Time curves were as follows: Typeâ… most appeared in cases of benign lymph nodes, Typeâ…¡could be found both in benign and malignant lesions, whereas the SI-Time curves of malignant lymph nodes were a majority of Typeâ…¢(P<0.05) .CONCLUSION: Diffusion weighted imaging is a rapid and feasible method in detecting cervical lymph node lesions and shows a potential for distinguishing between benign and malignant lymph nodes. Dynamic contrast-enhanced MR imaging has certain value in differential diagnosis of benign and malignant lymph node lesions.