[Diagnostic value of enhanced CT/MRI for thyroid cartilage invasion by malignant tumor]

Objective: To evaluate the values of enhanced CT and MRI for the diagnosis of thyroid cartilage invasion by laryngeal and hypopharyngeal cancer. Methods: One hundred and ninety-seven patients with primary laryngeal or hypopharyngeal cancer treated with surgery between January 2013 and December 2014 were included in this study. All patients underwent enhanced CT and MRI before surgery. With MRI using the techniques of fast recovery fast spin echo (FRFSE), spin echo echo planar imaging (SE-EPI) and diffusion weighted imaging (DWI), thyroid cartilage invasion was evaluated and the results of postoperative histopathological examination was used as a gold standard for the determination of thyroid cartilage invasion. The sensitivity, specificity, positive predictive value and negative predictive value of enhanced CT or MRI in detecting thyroid cartilage invasion by laryngeal and hypopharyngeal cancer were evaluated. Data were analyzed with SPSS17.0 software. Results: Among 197 patients, there were 35 cases with supraglottic laryngeal cancer, 92 cases with glottic laryngeal cancer, 9 cases with subglottic laryngeal cancer, and 61 cases with hypopharyngeal cancer. Postoperative pathologycal examinations showed that 63 (32.0%) of 197 patients had thyroid cartilage invasion by tumor. Based on TNM classification of AJCC (American Joint Commission for Cancer, 2010), there were 36 cases at T2 stage, 109 cases at T3 and 52 cases at T4; 117 cases with N0, 46 cases with N1 and 34 cases with N2. The sensitivity, specificity, positive predictive value and negative predictive value of CT for the detection of thyroid cartilage invasion were respectively 57%, 86%, 65% and 81%, and those of MRI were respectively 94%, 87%, 78% and 97%. Kappa values were 0.45 for CT and 0.77 for MRI in diagnosis of thyroid cartilage invasion, with statistically significant difference (χ(2)=6.78, P<0.05). Conclusion: MRI (FRFSE and SE-EPI DWI) has more advantages than CT in the diagnosis of thyroid cartilage invasion by laryngeal or hypopharyngeal cancer.