T1 and T2 mapping for identifying malignant lymph nodes in head and neck squamous cell carcinoma

Background: This study seeks to assess the utility of T1 and T2 mapping in distinguishing metastatic lymph nodes from reactive lymphadenopathy in patients with head and neck squamous cell carcinoma (HNSCC), using diffusion-weighted imaging (DWI) as a comparison. Methods: Between July 2017 and November 2019, 46 HNSCC patients underwent neck MRI inclusive of T1 and T2 mapping and DWI. Quantitative measurements derived from preoperative T1 and T2 mapping and DWI of metastatic and non-metastatic lymph nodes were compared using independent samples t-test or Mann–Whitney U test. Receiver operating characteristic curves and the DeLong test were employed to determine the most effective diagnostic methodology. Results: We examined a total of 122 lymph nodes, 45 (36.9%) of which were metastatic proven by pathology. Mean T2 values for metastatic lymph nodes were significantly lower than those for benign lymph nodes (p< 0.001). Conversely, metastatic lymph nodes exhibited significantly higher apparent diffusion coefficient (ADC) and standard deviation of T1 values (T1_SD) (p< 0.001). T2 generated a significantly higher area under the curve (AUC) of 0.890 (0.826–0.954) compared to T1_SD(0.711 [0.613–0.809]) and ADC (0.660 [0.562–0.758]) (p= 0.007 and p< 0.001). Combining T2, T1_SD, ADC, and lymph node size achieved an AUC of 0.929 (0.875–0.983), which did not significantly enhance diagnostic performance over using T2 alone (p= 0.089). Conclusions: The application of T1 and T2 mapping is feasible in differentiating metastatic from non-metastatic lymph nodes in HNSCC and can improve diagnostic efficacy compared to DWI.