Vascularity index of laryngeal cancer derived from 3-D ultrasound: a predicting factor for the in vivo assessment of cervical lymph node status.

To demonstrate whether a calculated vascularity index (VI) can predict metastases of cervical lymph nodes, the VI values of the primary tumors were obtained by using 3-D sonography in 87 subjects with laryngeal cancer confirmed by laryngoscope and biopsy. N-staging of the subjects was determined by pathological nodal harvesting. The relationship between the VI and pathological N-staging was evaluated by correlation coefficient. To test the accuracy of the VI for predicting cervical lymph node involvement, a receiver operating characteristic (ROC) curve was constructed, and the best operating point was determined by Youden's index. For comparison, 2-D sonography was applied to detect metastatic cervical lymph nodes. The accuracy, sensitivity and specificity of the VI, 2-D sonography and a combination of the two methods for diagnosis of metastatic cervical lymph nodes were compared. There was a positive linear correlation between the VI and pN-staging (r=0.740, p<0.001). The area under the ROC curve for the VI was 0.919. The best operating point of the VI was 4.4565, which derived higher sensitivity than that of 2-D sonography (95% vs. 81%, p=0.031), but lower specificity (75% vs. 95%, p=0.012). The combination of the two methods yielded a higher accuracy (97% vs. 85% and 89%, p=0.002 and 0.016), a higher sensitivity to 2-D sonography (95% vs. 81%, p=0.031) and a higher specificity to VI (98% vs. 75%, p=0.002). The VI of laryngeal cancer can be a useful factor for predicting metastases of cervical lymph nodes.