Usefulness of 33 MHz Linear Probe in Lymphatic Ultrasound for Lymphedema Patients.

Lymphatic ultrasound has recently been reported useful in the treatment of lymphedema. However, no conclusions have been reached regarding the best probe for lymphatic ultrasound. This was a retrospective study. Fifteen limbs of 13 patients with lymphedema in whom we could not find dilated lymphatic vessels on lymphatic ultrasound with an 18 MHz probe but later could find them with 33 MHz probe were included. All patients were women, and the mean age was 59.5 years. We performed lymphatic ultrasound in four areas per limb by applying an index of D-CUPS, as we previously reported. We measured the depth and diameter of the lumen of the lymphatic vessels. We also diagnosed the degree of lymphatic degeneration based on the normal, ectasis, contraction, and sclerosis type (NECST) classification. We found lymphatic vessels in 22/24 (91.7%) areas in the upper limbs and 26/36 (72.2%) areas in the lower limbs. The mean depth and diameter of the lymphatic vessels were 5.2 ± 0.28 mm and 0.33 ± 0.029 mm, respectively. Based on the NECST classification, 68.2% of the upper limbs and 56.0% of the lower limbs were of the ectasis type. We found functional lymphatic vessels in 6/6 (100%) of the upper limbs and 5/7 (71.4%) of the lower limbs, which indicated lymphaticovenous anastomosis (LVA) in these 11 patients. Using 33 MHz probe, we could detect functional lymphatic vessels in most patients. Even if lymphatic vessels were not found with the 18 MHz probe, LVA could be performed using a higher frequency probe.