Magnetic resonance lymphangiography: Correlation with indocyanine green lymphangiography in lower limb lymphedema

Indocyanine green (ICG) lymphography is considered the gold standard method for real-time imaging of the lymphatic vessels. Despite extensive literature on the effectiveness of different imaging modalities, research comparing the reliability of ICG lymphography and magnetic resonance lymphangiography (MRL) is limited. We retrospectively analyzed and compared the capability of MRL and ICG lymphangiography to detect lower limb lymphoedema abnormalities.

This monocentric cohort study included patients who had examinations and surgeries between September 2021 and December 2023. The assessment comprised scoring the severity levels of the drainage pattern, lymphatic vessel conspicuity, anatomic level of lymphatic vessel enhancement, contrast medium deposition in the foot, and the anatomic coverage of dermal backflow. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRL and ICG lymphangiography were calculated.

A total of 89 patients with clinically proven moderate to severe lymphoedema (stages II-III) affecting 92 lower limbs were enrolled. Good to excellent agreement was determined between MRL and ICG lymphography in drainage pattern (k=0.710), contrast medium deposition in the foot (k=0.933), and anatomic coverage of dermal backflow (k=0.653). Anatomical level of lymphatic vessel enhancement was in moderate correlation (k=0.524), and the visualization of lymphatic vessels was correlated (k=0.330) between the two modalities. MRL demonstrated lower NPV (50% vs 100%) in lymphatic vessel conspicuity but better sensitivity (100% vs 98%) and NPV (100% vs 97.6%) of contrast medium deposition in the foot as compared to ICG lymphography.

MRL demonstrated better performance on the lymphatic vessel conspicuity when dermal backflow is obvious. For normal lymphatic vessels, ICG lymphography provided a better description.