Utility of ADC Measurements in the Discrimination between Benign and Lymphomatous Abdomino-Pelvic Lymph Nodes

Background: Contrast-enhanced Computed Tomography (CT) has been the most commonly used imaging technique for staging of lymphoma as well as its follow-up for a long time. However, it does not provide metabolic or functional information and this may compromise the identification of the disease in non enlarged lymph nodes. 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) has been recently considered as the functional imaging method of choice for lymphoma as it depends on the identification of elevated glucose metabolism in lymphomatous lesions. However, not many institutions have this facility; it is expensive and carries the risk of exposure to radioactive material and ionizing radiation. It has been proposed recently that diffusion-weighted magnetic resonance imaging (DWI) may be a possible radiation-free alternative to FDG-PET/CT for the staging of lymphoma. It is a functional MRI technique that depends on the restriction of water movement in highly cellular tumors due to narrowing of the extracellular space.Aim of the Work: The purpose of this study is to investigate whether Apparent Diffusion Coefficient (ADC) measurements can help in the discrimination between lymphomatous and benign abdomino-pelvic lymph nodes with comparison to PET-CT.Patients and Methods: Thirty participants were included in this study. 18 cases of lymphoma (11 males and 7 females) and the other 12 participants (8 males and 4 females) were free from lymphoma or other malignancies. Their ages ranged from 30 to 75 (average age is 52). The study was performed in the period from June 2013, till January 2015. Full clinical history was taken from all patients as well as their histopathological data, laboratory investigations, and previous imaging. Conventional and diffusion weighted MRI and PET-CT studies were done for lymph nodes assessment.Results: The ADC values of lymphomatous lymph nodes (mean ADC value is 0.66±0.11 X 10^–³mm²/sec) were significantly lower than those of benign lymph nodes (mean ADC value is 1.27±0.15mm²/sec) with p-value 0.0001. There was a statistically significant inverse relation between the SUV max values and the ADC values of the examined lymph nodes (p-value 0.0001) suggesting that the ADC value measurements can provide pathophysiological information similar to PET CT.