Duplex ultrasound evaluation in lymphedema: Pictorial essay

Introduction Lymphedema is a chronic and progressive condition resulting from impaired lymphatic drainage, leading to protein-rich fluid accumulation, tissue remodeling, and fibrosis. It represents a relevant public health issue worldwide, with substantial functional and psychosocial impact. This pictorial essay aims to illustrate the role of ultrasound in the assessment of lymphedema and to describe sonographic features that assist in distinguishing early from advanced disease stages. Methods This exploratory pictorial essay is based on representative cases of upper- and lower-limb lymphedema examined in routine clinical practice. High-frequency ultrasound probes (18–21 MHz) were used with B-mode imaging, colour Doppler, power Doppler, micro-flow presets, elastosonography, and AI-assisted image optimisation. The examination focused on skin, subcutaneous tissue, lymphatic channels, and their dynamic behaviour during provocation manoeuvres. No quantitative measurements or statistical analyses were performed. Results Distinct patterns of oedema distribution were observed on ultrasound. Mild lymphedema was characterised by predominantly vertical diffusion of fluid from the dermis toward the superficial fascial plane, whereas moderate to severe forms showed horizontal expansion within the subcutaneous compartment, frequently associated with dilated lymphatic lacunae. Lymphatic channels were identifiable as thin-walled, non-compressible structures without inducible flow on colour or power Doppler, even after distal manual compression. Advanced high-frequency imaging enabled visualisation of isoechoic intraluminal material consistent with fibrin deposition in chronically obstructed lymphatic pathways. Elastosonography demonstrated increased stiffness of the deep dermal and subdermal layers in chronic disease. Conclusion Ultrasound provides a non-invasive and detailed visual assessment of lymphatic vessels and soft-tissue alterations in lymphedema. When combined with elastosonography and AI-assisted imaging, it facilitates recognition of disease stage and chronicity and supports its role as a valuable tool in the comprehensive evaluation of lymphedema.