Value of LSR and ADCs in differential diagnosis of hilar and mediastinal lymph nodes in lung cancer

Objective To evaluate the value of minimum ADC(ADCmin)and mean ADC(ADCmean), lesion to spinal cord signal intensity ratio (LSR) in diagnosis of metastatic hilar and mediastinal lymph nodes in patients with lung cancer. Methods A total of 34 patients (89 lymph nodes) pathologically diagnosed as lung cancer were enrolled into this study who were examined in the Second Affiliated Hospital of Nantong University from January 2016 to June 2017. All patients underwent MRI scan 1 week before surgery or endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). The short-axis diameter, ADCmean and ADCmin of lymph nodes were measured and recorded respectively by two radiologists.The signal intensity of lymph nodes and spinal cord was also measured on DWI images (b=800 s/mm2). According to pathological findings, all lymph nodes were divided into metastasis group (58 lymph nodes) and non-metastasis group(31 lymph nodes). An independent sample t-test was used to compare the differences between the two groups of short-axis diameter, LSR, ADCmean and ADCmin between two groups.The diagnostic performance of short-axis diameter, LSR, ADCmean and ADCmin was analyzed by ROC curves. Results There were significant differences in short-axis diameter, ADCmean, ADCmin and LSR values between two groups (all P 0.05). Conclusion LSR, ADCmin and ADCmean are the reliable parameters for the differentiation of metastatic and non-metastatic lymph nodes in lung cancer patients, and have good performance. Key words: Lung neoplasms; Lymph nodes; Diffusion magnetic resonance imaging; Lesion to spinal cord signal intensity ratio