Ultra-High frequency ultrasound imaging of lymphatic channels correlates with their histological features: A step forward in lymphatic surgery

Background: Indocyanine green (ICG) lymphography gained widespread acceptance as a gold standard in lymphatic surgery, although this imaging modality has several limitations. Ultrasound is progressively emerging as a powerful tool in LVA preoperative planning, as it expands the available knowledge for both lymphatic channels and recipient venules. The purpose of this study is to evaluate the accuracy of ultrahigh frequency ultrasound (UHFUS) in detecting the lymphatic vessels and in evaluating their degeneration status, including wall and lumen characteristics, compared with direct histology observation. Patients and Methods: From May 2018 to November 2018, 26 consecutive patients affected by extremities lymphedema who underwent LVA were prospectively assessed. For each patient, we evaluated the lymphatic vessels suitable for LVA by UHFUS preoperatively, intraoperatively, and by histology. Qualitative and quantitative data of lymphatic channels were analyzed for each evaluation including lymphatic outer diameter, inner diameter, and wall thickness. Quantitative outcome analysis after LVA was also performed. Results: On a total of 26 patients, 14 were upper limb lymphedema (ULL) and 12 lower limb lymphedema (LLL). All cases were secondary lymphedema. The qualitative and the quantitative analysis showed significant correlation and agreement between ultrasound and histological measurements. Conclusions: UHFUS preoperative and intraoperative analysis of lymphatic channel strongly correlates with their histology. By coupling this high detailed information on lymphatic channels with the ability to dynamically study preoperative recipient venules, UHFUS represents the quintessence in lymphatic surgery, and it should be considered as the new gold standard in the preoperative planning of LVA. Level of Evidence II (diagnostic).