[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(ADC(min))and mean ADC(ADC(mean)), 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, ADC(mean) and ADC(min) 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/mm(2)). 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, ADC(mean) and ADC(min) between two groups.The diagnostic performance of short-axis diameter, LSR, ADC(mean) and ADC(min) was analyzed by ROC curves.

Results

There were significant differences in short-axis diameter, ADC(mean), ADC(min) and LSR values between two groups (all P<0.01). The short-axis diameter and LSR of the metastatic group were higher than that in non-metastasis group, while ADC(mean) and ADC(min) in metastatic group were lower than that in non-metastasis group.The ROC curve analysis showed that ADC(mean), ADC(min) and LSR achieved excellent but comparable diagnostic performance with an AUC of 0.977, 0.972 and 0.941, respectively (P<0.05). While the short-axis diameter of lymph nodes demonstrated poor diagnosis performance with an AUC of 0.798 (P<0.05). The thresholds of short-axis diameter, ADC(mean), ADC(min) and LSR were 9.86 mm, 1.88×10(-3) mm(2)/s, 1.57×10(-3) mm(2)/s and 0.80, respectively.Sensitivity, specificity, positive predictive value, negative predictive value and accuracy for ADC(mean) were 96.6%, 90.3%, 94.9%, 93.3% and 94.4%, respectively, and those for ADC(min) were 98.3%, 90.3%, 95.0%, 96.6% and 94.4%, respectively, those for LSR were 91.4%, 90.3%, 94.6%, 84.8% and 89.9%, respectively, while those for short-axis diameter were 79.3%, 71.0%, 83.6%, 64.7% and 76.4%, respectively.There were significant differences in the area under the ROC curve between short-axis diameter and LSR, short-axis diameter and ADC(mean), short-axis diameter and ADC(min) (P<0.05). But there was no significant difference in the area under ROC curve between LSR and ADC(mean), LSR and ADC(min), ADC(mean) and ADC(min) (P>0.05).

Conclusion

LSR, ADC(min) and ADC(mean) are the reliable parameters for the differentiation of metastatic and non-metastatic lymph nodes in lung cancer patients, and have good performance.