The Interrater Reliability of the Scoring of the Lymphatic Architecture and Transport Through Near-InfraRed Fluorescence Lymphatic Imaging in Patients with Breast Cancer-Related Lymphedema

Background: Of the 1.38 million women who are diagnosed every year with breast cancer worldwide, 21% will develop arm lymphedema. Near-infrared fluorescence lymphatic imaging (NIRFLI) is an effective method for real-time evaluation of the lymphatic system. Reliability studies of the scoring of this NIRFLI are lacking. The aim of this study is to investigate if evaluation of the superficial lymphatic architecture and transport in patients with breast cancer-related lymphedema through NIRFLI can be performed in a reliable way. Methods and Results: The outcome parameters used to assess agreement were the presence of lymphatic transport from the injection sites, of dermal backflow patterns, of efferent lymphatic vessels, and of lymph nodes. The NIRFLI evaluations were scored before and after a break separately by two assessors. Twenty patients with lymphedema of the arm and/or hand were included. After the injection, there was weak to very strong agreement regarding the presence of transport from the injection sites ( K  = 0.459-1.000). The interpretation of the type of dermal backflow pattern varied from weak (WK = 0.452) to very strong agreement (WK = 1.000) between the two assessors. Agreement in the visualization of efferent lymphatic vessels was weak before and after the break ( K  = 0.490 and K  = 0.571) and agreement regarding the presence of lymph nodes was very strong ( K  = 1.000). Conclusion: Overall, there was moderate to strong agreement between the assessors when evaluating the lymphatic architecture and transport through NIRFLI. The study has been registered at clinicaltrials.gov (NCT02609724).