PURPOSE: To explore the pattern of metastasis to level II nodes and its relationship with tumor range in nasopharyngeal carcinoma (NPC) patients by using magnetic resonance imaging. METHODS AND MATERIALS: Magnetic resonance images of 618 NPC patients were reviewed. Nodes were classified as metastatic based on size criteria, the presence of nodal necrosis, and extracapsular spread. RESULTS: Patients (87.9%, 543) had lymphadenopathy, 470 (86.5%) in level IIb and 326 (60.0%) in level IIa, respectively. Incidence of RLN involvement was less than that of level IIb node involvement (72.2% vs. 86.5%) in 543 patients with lymphadenopathy. Cranial boundaries (71.1%) of level IIb nodes was below the caudal border of C1, and 5.1% was below the skull base, while all the cranial boundaries of level IIa nodes were below the caudal edge of C1. Incidence of level IIb and/or level IIa node metastasis had no correlation with primary tumor extension. Incidence of level IIb metastasis did not differ significantly among T1, 2, 3, and 4 disease, nor did that of level IIa node. CONCLUSIONS: Cervical level IIb nodes were the most commonly involved nodes in NPC. Metastasis to level IIb and level IIa nodes had no correlation with primary tumor extension, or with T stage. Setting the cranial border of level IIb node at the skull base should be considered when delineating nodal target volume.
PURPOSE: To explore the pattern of metastasis to level II nodes and its relationship with tumor range in nasopharyngeal carcinoma (NPC) patients by using magnetic resonance imaging. METHODS AND MATERIALS: Magnetic resonance images of 618 NPCpatients were reviewed. Nodes were classified as metastatic based on size criteria, the presence of nodal necrosis, and extracapsular spread. RESULTS:Patients (87.9%, 543) had lymphadenopathy, 470 (86.5%) in level IIb and 326 (60.0%) in level IIa, respectively. Incidence of RLN involvement was less than that of level IIb node involvement (72.2% vs. 86.5%) in 543 patients with lymphadenopathy. Cranial boundaries (71.1%) of level IIb nodes was below the caudal border of C1, and 5.1% was below the skull base, while all the cranial boundaries of level IIa nodes were below the caudal edge of C1. Incidence of level IIb and/or level IIa node metastasis had no correlation with primary tumor extension. Incidence of level IIb metastasis did not differ significantly among T1, 2, 3, and 4 disease, nor did that of level IIa node. CONCLUSIONS: Cervical level IIb nodes were the most commonly involved nodes in NPC. Metastasis to level IIb and level IIa nodes had no correlation with primary tumor extension, or with T stage. Setting the cranial border of level IIb node at the skull base should be considered when delineating nodal target volume.