The Pilot Study of Spectral CT for the Diagnosis of Mediastinal Lymph Node Metastasis in Primary Lung Cancer

Objective: To investigate the application value of spectral CT for the diagnosis of mediastinal lymph node metastasis in primary lung cancer. Materials and Methods: 32 patients who had primary lung cancer with 90 enlarged mediastinal lymph nodes underwent spectral CT by using gemstone spectral imaging (GSI) mode. The spectral curves of regions of interest (ROI) in primary lung cancer and mediastinal lymph nodes were measured with GSI post-processing software. The spectral curve slope between 40 and 140 keV was calculated and compared between them for the diagnosis of mediastinal lymph node metastasis. The data were divided into metastatic group (group A) and non-metastatic group (group B) according to the pathologic findings. SPSS17.0 software with paired sample t test was used for statistical analysis and P < 0.05 was considered statistically significant difference. Results: The spectral curve slopes in primary lung cancer and mediastinal lymph node in group B were 0.96 +/- 0.13 and 1.32 +/- 0.17. There was significant difference between them (t = -2.68, P < 0.05). While there was no significant difference between them in group A (t = -1.62, P > 0.05) with the values of 1.06 +/- 0.09 and 1.09 +/- 0.12. The accuracy, sensitivity and specificity of diagnosing mediastinal lymph node metastasis were 84.21%, 86.67% and 82.77%, respectively in line with spectral curve. Conclusions: Spectral CT, as a new and non-invasive method, has valuable effect for the diagnosis of mediastinal lymph node metastasis in pre-operative staging of lung cancer.