Normative measurements of parotid lymph nodes on CT imaging

Purpose The goal of this study is to characterize the normal size of parotid lymph nodes among healthy adult patients on CT. Methods This was a single-center retrospective observational study of 543 patients who underwent maxillofacial CT scans between January 2019 and July 2019. The long and short axis diameters of the largest lymph nodes in the bilateral superficial parotid glands were measured. Results Among the 543 patients, 407 subjects with a mean age of 47.0 ± 18.4 years had a total of 719 detectable intraparotid lymph nodes. The mean patient age was 47.0 ± 18.4 years. Of all 719 measured intraparotid lymph nodes, the measured long and short axis diameter means were 4.4 ± 1.4 mm and 3.3 ± 1.1 mm, respectively. In our study, 96% (689/719) of all lymph nodes had a long axis diameter of 7 mm or less and 93% (671/719) of all lymph nodes had a short axis diameter of 5 mm or less. Younger patients had significantly larger lymph nodes than older patients in both long axis (4.5 vs 4.3 mm; P = 0.03) and short axis (3.4 vs 3.1 mm, P = 0.01) measurements. Conclusion Our findings suggest 5 mm as an upper limit of normal for the short axis diameter of superficial intraparotid lymph nodes.