Magnetic resonance imaging features of primary lower extremity lymphedema: A retrospective analysis of 228 patients

The value of magnetic resonance imaging (MRI) presentation of primary lower extremity lymphedema in assessing the severity of lower extremity lymphedema is uncertain. The purpose of this study was to assess the role of MRI presentation in staging primary lower extremity lymphedema. We enrolled 228 patients with clinically diagnosed primary lower limb lymphoedema from January 2018 to December 2019 in our hospital retrospectively. Patients were divided into stages I, II, and III based on the 2020 International Society of Lymphology clinical staging standards. Two radiologists assessed the following characteristics of the short-term inversion recovery sequence: the extent of edema (longitudinally and transversely); the frequency of MRI manifestations, including the presence of dermal thickening; and the morphology of edema (grid, honeycomb, parallel lines, banded, crescent, and lymphatic lake). The kappa test was used to assess interobserver agreement. The χ2 test was used to compare the frequency differences of MRI manifestations between different clinical stages. The Spearman test evaluated the correlation between edema extent and clinical stage. The extent of edema was correlated positively with clinical stage, both longitudinally and transversely. When comparing stages, the incidence of dermal thickening in stages II and III was significantly higher than in stage I. The incidence of parallel lines in stage I was significantly higher than that in stages II and III. The grid and banded sign incidence in stages I and II were significantly higher than in stage III. The incidence of honeycomb in stages II and III was significantly higher than in stage I. The incidence of lymphatic lake and crescent in stage III was significantly higher than in stages I and II (P < .001). Short-term inversion recovery can sensitively diagnose lymphedema and assist in clinical staging. MRI manifestations of primary lower extremity lymphedema in different stages have specific MRI features.