Apparent diffusion coefficient for discriminating metastatic lymph nodes in patients with squamous cell carcinoma of the head and neck

Abstract

PURPOSE We aimed to evaluate the apparent diffusion coefficient (ADC) values of metastatic lymph nodes in patients with squamous cell carcinoma (SCC) of the head and neck.METHODSPatients with metastatic lymph nodes underwent 1.5 Tesla diffusion-weighted magnetic reso-nance imaging (MRI). The ADC values of the histologically proven metastases were evaluated retro-spectively and mean ADC values were compared using one-way analysis of variance test. Receiver operating characteristic analysis was performed to identify ADC threshold values.RESULTSWe included 33 patients (27 males, 6 females; mean age, 60.7 years) with 53 metastatic lymph nodes in the study. Mean ADC values for nodal metastases of nasopharyngeal carcinoma (NPC) (n=7), oro-pharyngeal (n=12), laryngeal (n=27), and hypopharyngeal (n=7) carcinoma were (0.810±0.158)×10-3mm2/s, (0.985±0.099)×10-3 mm2/s, (1.037±0.150)×10-3 mm2/s, and (0.948±0.081)×10-3 mm2/s, respec-tively. The mean ADC values of nodal metastases of NPC were significantly lower than ADC values of laryngeal carcinoma (LSCC) (P = 0.002). An ADC value less than 0.890×10-3 mm2/s was found to facilitate differentiation of NPC from LSCC with a sensitivity of 71% and specificity of 85% (area under the curve, 0.852).CONCLUSIONThe mean ADC values showed significant differences between nodal metastases of NPC and LSCC. Considering SCCs as a single group may affect the accuracy of ADC-based differentiation. Location of the primary tumor should be taken into account and cutoff values should be determined sepa-rately for each anatomical location.