Is Diffusion-Weighted MRI Useful for Differentiation of Small Non-Necrotic Cervical Lymph Nodes in Patients with Head and Neck Malignancies?

Abstract

Objective: To evaluate the usefulness of measuring the apparent diffusion coefficient (ADC) in diffusion-weighted magnetic resonance imaging to distinguish benign from small, non-necrotic metastatic cervical Lymph nodes in patients with head and neck cancers. Materials and Methods: Twenty-six consecutive patients with head and neck cancer underwent diffusion-weighted imaging (b value, 0 and 800 s/mm(2)) preoperatively between January 2009 and December 2010. Two readers independently measured the ADC values of each cervical lymph node with a minimum-axial diameter of 5 mm but < 11 mm using manually drawn regions of interest. Necrotic lymph nodes were excluded. Mean ADC values were compared between benign and metastatic Lymph nodes after correlating the pathology. Results: A total of 116 lymph nodes (91 benign and 25 metastatic) from 25 patients were included. Metastatic lymph nodes (mean +/- standard deviation [SD], 7.4 +/- 1.6 mm) were larger than benign lymph nodes (mean +/- SD, 6.6 +/- 1.4 mm) (p = 0.018). Mean ADC values for reader 1 were 1.17 +/- 0.31 x 10(-3) mm(2)/s for benign and 1.25 +/- 0.76 x 10(-3) mm(2)/s for metastatic lymph nodes. Mean ADC values for reader 2 were 1.21 +/- 0.46 x 10(-3) mm(2)/s for benign and 1.14 +/- 0.34 x 10(-3) mm(2)/s for metastatic lymph nodes. Mean ADC values between benign and metastatic Lymph nodes were not significantly different (p = 0.594 for reader 1, 0.463 for reader 2). Conclusion: Measuring mean ADC does not allow differentiating benign from metastatic cervical lymph nodes in patients with head and neck cancer and non-necrotic, small lymph nodes.