Correlation of Inguinal Lymph Node Number and Volume with Lower Extremity Lymphedema Severity.

There are very limited studies on the relationship of inguinal lymph node number and volume correlated with lower extremity lymphedema severity. In this IRB-approved retrospective study, patients who obtained an MRI for lower extremity lymphedema and who did not have lymph node resection or biopsy were identified. The MRI images were used to determine the number and volume of inguinal lymph nodes for each limb in addition to fat and fluid-based scoring using a validated grading system. Wilcoxon signed-rank tests were used to compare the greater-affected limbs with the lesser-affected limbs. The spear-man-rank correlation was performed on a 'per limb' basis for MRI-based scoring and clinical parameters with ipsilateral lymph node number and volume and for differences between the limbs. A total of 32 patients were included. The greater-affected limb had higher MRI fluid scores (median (interquartile range) = 3 (3 - 3) vs. 0 (0 - 1), (p < 0.01) relative to the contra-lateral limb and had a median fat asymmetry score of 2 (1 - 3). On the per-limb analysis, lymph node number and volume inversely correlated with total MRI scores (ρ = -0.47, p < 0.01 for node number and volume). The difference of lymph node number and volume correlated with MRI score difference (node number: ρ = -0.66, p < 0.01; node volume: ρ = -0.64, p < 0.01) and perometer difference (node number: ρ = -0.58, p < 0.01; node volume: ρ = -0.59, p < 0.01). Inguinal lymph node number and volume inversely correlate with lower extremity edema presence and severity.