Utility of 18F-FDG PET/CT for detecting neck metastasis in patients with salivary gland carcinomas: preoperative planning for necessity and extent of neck dissection.

BACKGROUND: The precise diagnosis of cervical lymph node metastasis (CLNM) of salivary gland cancer is important to determine the surgical extent and adjuvant therapy. This study assessed the clinical utility of (18)F-FDG PET in identifying CLNM in such patients.

METHODS: Fifty-four patients with intermediate or high-grade salivary gland cancer were preoperatively evaluated with (18)F-FDG PET/CT and CT/MRI. Histopathologic analysis of neck dissection tissues was used as the gold standard for assessing imaging techniques. Tumor and nodal maximum standardized uptake values (SUVmax) were measured for each patient. Univariate and multivariate analyses were used to identify CLNM predictive factors.

RESULTS: Of the 54 patients, 24 patients (44%) had CLNM. On a per-patient basis, the sensitivity and specificity of (18)F-FDG PET/CT and CT/MRI were not significantly different (92 vs. 83%, P = 0.625 and 93 vs. 97%, P = 1.000, respectively). On a per-level basis, (18)F-FDG PET/CT was significantly more sensitive and accurate than CT/MRI in the ipsilateral neck (96 vs. 54%, P < 0.001 and 92 vs. 83%, P < 0.001, respectively). The mean nodal SUVmax values of patients with and without nodal metastasis were 4.9 and 2.1, respectively (P = 0.008). Histologic grade was a significant predictor of CLNM (P = 0.014, odds ratio 14.46, 95% confidence interval 1.73-120.79).

CONCLUSIONS: (18)F-FDG PET/CT imaging and histologic grade are useful for detecting CLNM in patients with salivary gland carcinoma. This finding may guide preoperative planning for the necessity and extent of neck dissection in these patients.