Table 1.

Current clinical application of lymphatic resolution

Technique	Typical Tracers	Depth	Resolution	Advantages	Limitations	Applications	References
X-ray lymphography	Lipiodol	No limit	~ 1 mm	Deep tissue penetration	Invasiveness, Time consuming Radiation exposure	Central and collecting lymphatic imaging	[25, 30–33]
Lymphoscintigraphy/SPECT	99mTc-coupled radioactive probes	No limit	1–1.5 cm	Deep tissue penetration, high sensitively	Exposure to ionizing radiation Planar image Poor spatiotemporal resolution	Visualization of collecting lymphatic vessels and dermal backflow, Quantitative assessment of lymphatic function, SLN mapping	[26, 34–38]
MR lymphography	Gd-based tracers or SPIO	No limit	0.5–2 mm	High imaging depth, 3D imaging can be realized without radiation	Low lymphatic specificity of clinically approved contrast, Venous signal interference, High cost	Collecting lymphangiography, Functional (dynamic contrast-enhanced MRL) and morphological evaluation of lymphatic vessels, SLN mapping	[27, 39–43]
Fluorescence imaging	Mainly ICG	1.5–2.0 cm	In the μm range (Depending on the instrument and depth)	Simple operation, no ionizing radiation, high temporal and spatial resolution, low costs	Limited depth of imaging, serious self-aggregation, lack of better clinically-approved tracers	Precise imaging of peripheral lymphatic vessels, Visualization of dermal backflow and quantitative assessment of lymphatic function, SLN mapping	[28, 29, 44–47]