UTILITY OF DIFFUSION WEIGHTED IMAGING IN DIFFERENTIATING BENIGN AND MALIGNANT CERVICAL LYMPH NODES

Abstract

Abstract Background: Detection of cervical lymph nodes and their differentiation into benign or malignant is important especially in patients with head and neck cancer for staging, treatment planning and follow-up of cancer. This study aims to evaluate the role of DWI in differentiating benign and malignant cervical lymph nodes by evaluating the ADC values in different malignant histopathologies. Methods and Materials: A observational study was conducted in the department of Radiodiagnosis in a tertiary care hospital over a period of one and half year. 47 subjects with cervical lymphadenopathy were included in the study after fulfilling the inclusion and exclusion criteria. ADC maps were reconstructed for all patients and ADC values were calculated for each lymph node. DWI was performed using a single-shot echo-planar MRI sequence with b values of 0,500 and 1000s/mm2. Imaging results were correlated with histopathological diagnosis. Results: Cervical lymph node enlargement was secondary to metastases from squamous cell carcinomas, metastasis from small cell carcinoma of lung, metastasis from medullary carcinoma thyroid, NHL, HL, reactive lymphadenitis, tuberculosis and kikuchi lymphadenitis. The mean ADC values were 0.75+/-0.11 x10−3mm2/s for metastatic lymph nodes, 0.68±0.09 x10−3mm2/s for lymphomatous nodes and 1.11±0.15 x10−3mm2/s for benign cervical lymph nodes. ADC values of malignant lymph nodes were significantly lower than ADC values of benign lymph nodes. The ADC value of the metastatic lymph node varied according to degree of differentiation. Poorly differentiated metastatic lymph nodes showed lower ADC values than moderately differentiated lesions. Using a threshold ADC value of 0.95x10−3mm2/s 93.6% of lesions were correctly classified as benign or malignant. Conclusion: Evaluation of lymph nodes by MRI can help the radiologist to differentiate benign and malignant lymph nodes. However, histopathological diagnosis will remain mainstay in differentiating benign and malignant lymph nodes. DW-MRI with ADC mapping is a promising technique that can differentiate malignant from benign lymph nodes. DWI can be preferred as a non-invasive method for patients with enlarged cervical lymph nodes enabling earlier diagnosis and treatment planning.