Screening Lymphatic Ultrasound to Detect Lymphatic Dysfunction

Background: We currently perform noncontrast lymphatic ultrasound, which has a higher resolution and is less invasive than contrast lymphatic ultrasound. This study aimed to clarify the usefulness of screening lymphatic ultrasound (SLUS) to evaluate lymphatic function. Methods: A retrospective study was conducted on 22 patients with leg lymphedema. We performed SLUS by dividing the leg into four areas (thigh and calf, lateral and medial) and the dorsum of the foot. Lymphatic findings were recorded according to NECST (Normal, Ectasis, Contraction, and Sclerosis type) classification. If no lymphatics were found, we recorded them as "not found." To differentiate between lymphatic vessels and veins, we referred to D-CUPS (Doppler, Crossing, Uncollapsible, Parallel, and Superficial fascia). The time required for SLUS was recorded. Indocyanine green (ICG) lymphography was also performed in 10 patients. Results: The mean age of the 22 patients was 63.9 years (range 50-86 years). The average time required for SLUS was 6 minutes 45 seconds for both legs. The identification rate of the lymphatic vessels was 95.5% for the medial thigh and medial calf, but decreased in the lateral calf and dorsum of the foot. When examining the distribution of the NECST classification, the ectasis type tended to be more common on the medial side than on the lateral side. Combined with the ICG lymphographic findings, dermal backflow (DB)-positive areas had significantly more ectasis type, and DB-negative areas had significantly more normal type and were not found (p < 0.01). Conclusion: SLUS should be useful for screening lymphatic vessel function.