Role of Diffusion Weighted MRI in Characterization of Abdomino-Pelvic Lymphadenopathy

Abstract

Background: Abdomino-pelvic lymphadenopathies, are classified either benign or malignant. The benign lymphadenopathies include infection and inflammation while the malignant group consists of two subtypes, primary as lymphoma and secondary as metastatic. Objective: The aim of the study was to determine if diffusion weighted magnetic resonance imaging could help in discrimination between benign and malignant abdomino-pelvic lymph nodes. Patients and Methods: Twenty-four patients with pelvic-abdominal lymphadenopathies were included in this study. The study was performed in Ain Shams university hospital, Air forces specialized hospital & Cairo specialized Hospital - Cleopatra Hospital Group (CHG) between December 2020 and June 2023. Full clinical history of all patients was taken and their laboratory Investigations, Histopathological data and previous imaging were reviewed. All patients underwent conventional MR imaging using a 1.5&3T machine (Achieva and Ingenia, Philips medical system, Eindhoven, Netherlands) using a phased array coil, for characterization and detection of the lymph nodes, including; Axial T1 WI, Axial T2 Wi, Axial T2 SPAIR fat suppression, diffusion and ADC map sequences. Results: We found a significant difference between ADC values of benign and malignant abdomino-pelvic lymph nodes, with a threshold ADC value equal to 1.1x 10-3 mm2 /sec. identified. This value could be used in the pre-treatment phase for better oncologic staging and assessment. The higher accuracy of DWI using high b Values (500&1000 sec/mm2 ),as compared with conventional MR imaging, was most beneficial in the detection of not only the enlarged but also the sub-centimetric metastatic lymph nodes. These findings suggest that DWI can be complementary to conventional MRI hence the related size and morphologic criteria lack sufficient reliability for better detection and characterization of nodal metastasis. A significant difference between the ADC value of lymphoma and metastatic lymph nodes was also detected in our study, with a threshold equal to 0.78 x 10-3mm2 / sec identified. Conclusion: DWI can be a considered supportive tool in differentiation between benign and malignant lymph nodes and can to a lesser extent differentiate between the types of malignant lymphadenopathies.