Objectives: Indocyanine Green Lymphography (ICGL) has emerged as a potentially powerful tool for the study of the superficial lymphatic system and to support the diagnosis of lymphoedema. However, detailed descriptions of ICGL findings in healthy individuals are limited. In this study, we imaged a series of healthy participants using ICGL, attempting to establish what represents normal presentation. Methods: Sixteen healthy individuals aged 20-55 years were recruited to undergo lower limb ICGL. Diluted 0.1mL injections of ICG were administered intradermally to five sites: 1st and 4th web spaces, lateral midfoot and lateral and medial rear-foot (heel); locations considered optimal for lymphatic vessel access. Outcome measures included: i) the drainage routes of contractile lymphatic collectors observed, ii) the number of lymphatic vessels crossing the anterior ankle and iii) the pumping frequency within a single vessel. Abnormal features, such as highly tortuous or vessels with retrograde lymph flow, were noted. Results: Contraction of lymphatic vessels propelling ICG could be seen in all individuals, with drainage via the anteromedial and anterolateral drainage pathways predominating (observed in 31/32 and 25/32 limbs respectively). The number of lymphatic vessels crossing the anterior ankle was 3.4 +- 1.1 with an average rate of 1 propulsion every 66 seconds (i.e. 0.9 min-1) in the vessels investigated. Isolated cases of highly tortuous and refluxing vessels were observed. Conclusions: ICGL is a reliable method for imaging superficial lymphatic vessels in vivo and in real time, helping to establish normal anatomy, vessel numbers and flow characteristics, and so better detect pathological abnormalities.
Mills et al. (2025) studied this question.