Diagnosis of lymph node metastases of head and neck cancer and evaluation of effects of chemoradiotherapy using ultrasonography

Ultrasonographic diagnostic criteria were established to detect cervical metastatic lymph nodes including those up to 10 mm in thickness. Ultrasonography can diagnose not only cervical metastatic lymph nodes but can also be used to evaluate treatment-induced changes in lymph node metastases, one by one or degeneration of metastatic lesion in remaining lymph nodes after chemoradiotherapy. A high-frequency probe of 7.5 MHz or higher was used in the ultrasonographic diagnosis of cervical lymph node metastases, using B-mode, Doppler blood flow imaging, and tissue elasticity imaging. Cervical lymph node metastases of head and neck squamous cell carcinoma were diagnosed according to ultrasonographic lymph node metastasis criteria. These criteria consist of the thickness of a lymph node (more than 6 mm or not), and existence of intra-lymph nodal occupying lesions suspected as a metastatic focus or not. Furthermore, metastatic lymph nodes remaining without regression after chemoradiotherapy were also evaluated according to therapeutic effect, using ultrasonography, and we examined the efficacy of ultrasonography to predict clinical outcomes. These diagnostic criteria enabled the accurate diagnosis of metastatic lymph nodes that were up to 10-mm-thick; such nodes are difficult to diagnose by computed tomography (CT) or magnetic resonance imaging (MRI). Moreover, examination of therapeutic effects such as decreased blood flow into a metastatic focus, and softening of a lymph node, by evaluating B-mode dynamic images or employing tissue elasticity imaging, was also useful to determine the effectiveness of chemoradiotherapy and a favorable outcome. Ultrasonographic diagnostic criteria for cervical metastatic lymph nodes enabled accurate diagnosis. Ultrasonographic evaluation of therapeutic effects on cervical lymph node metastases revealed not only the control of metastasis in the cervical region but also the clinical course and control of the primary site.