The role of high frequency ultrasound in reconstructive microsurgery and lymphedema surgery

Introduction High-frequency ultrasound is a non-invasive and dynamic real-time imaging modality. The first objective of this study was to compare the use of ultra-high frequency ultrasound (UHFUS) with conventional high frequency ultrasound (CHFUS) in the detection of lymphatic vessels. The second objective was to evaluate the ability of UHFUS to identify functional lymphatic vessels in preoperative planning. The third objective is to determine whether high frequency ultrasound was as effective in perforator localization and flap planning for reconstructive procedures. Materials and methods Firstly, the upper limbs of healthy volunteers were evaluated at our Institution. Identification of the lymphatic vessels was performed using UHFUS and CHFUS. Secondly, patients presenting with unilateral lymphedema were evaluated with UHFUS. Patients undergoing a reconstructive procedure with pedicled or free flap which required the choice of a perforator were studied preoperatively with high-frequency ultrasound. Results Per subject, 6.64 ± 1.12 lymphatic vessels were found with UHFUS and 4.36 ± 0.67 lymphatic vessels were found with CHFUS (p<0.001). When analyzing the size of the lymphatic vessels, the difference was found to be statistically significant (p<0.001). The difference between the pathological vessels in the affected limbs and the vessels in healthy limbs was evaluated in terms of measurements for lumen, wall thickness, outer diameter and lumen to outer diameter ratio. The difference in measurement for wall thickness was found to be statistically significant at all levels (p < 0.001). In reconstructive surgery a perforator was always found at the location preoperatively marked with US. In 94.4% of cases that perforator was intraoperatively considered suitable for flap harvest. Conclusions With relation to lymphedema surgery, UHFUS was able to locate more lymphatic vessels compared to CHFUS and allowed the surgeon to evaluate the characteristics of the vessel. During flap planning HFUS allowed the surgeon to locate in a precise way a suitable perforator for flap harvesting.