Effectiveness of vascularized lymph node transfer for extremity lymphedema using volumetric and circumferential differences

Background: Circumferential difference of lymphedematous limbs at designated anatomic distances has been the primary mode for measuring lymphedematous extremities. Computed tomography (CT) imaging produces accurate, consistent, hygienic volume measurements and a direct limb representation. This study compares these 2 main modalities and assesses their correlation. Methods: CT and circumferential difference measurements, costs, and correlation of patient limbs that received vascularized lymph node transfer were compared. Results: Mean circumferential difference by tape measurement pre- and postoperatively was 31.4% ± 19.1% and 17.4% ± 8.8% for upper limbs and 43.2% ± 16.1% and 22.4% ± 12% for the lower limbs, respectively. Mean CT volumetric difference pre- and postoperatively were 36.1 ± 4.1% and 27.2 ± 2.8% for the upper limb and 46.2 ± 3.2% and 33.2 ± 2.1% for the lower limbs, respectively. CT volume measurements significantly correlated with their respective circumferential difference with Pearson correlation coefficient of r = +0.7, which was statistically significant (P = 0.03), indicating a strong positive correlation between circumferential difference and actual limb volume changes as determined by CT imaging. Circumferential differences are more cost effective than CT volume assessments in the domains of measurement frequency (P = 0.03), fee (P < 0.01), time (P = 0.03), total cost per year (P < 0.01), and cost/minute (P = 0.03). Conclusions: Standardized circumferential differences that are currently used are comparable to unbiased CT volumetric measurements and can be used as a reliable, reproducible, minimally invasive, low cost, and accurate method of measuring the lymphedematous limbs.