Investigating the Lymphatic System by Dual-Color Elemental Mass Spectrometry Imaging.

Secondary lymphedema accompanied with strong restrictions in quality of life is still major side effects in cancer therapy. Therefore, dedicated diagnostic tools and further investigation of the lymphatic system are crucial to improve lymphedema therapy. In this pilot study, a method for quantitative analysis of the lymphatic system in a rat model by laser ablation (LA) with inductively coupled plasma mass spectrometry imaging (ICP-MSI) is presented. As a possible lymph marker, thulium(III)(1R, 4R, 7R, 10R)-alpha,alpha',alpha ",alpha "'-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (Tm-DOTMA) is introduced and compared to the clinically used magnetic resonance imaging contrast agent gadolinium(III) 2,2',2 "-(10-((2R, 3S)-1,3,4-trihydroxybutan-2-yl)1,4,7,10- tetraazacyclododecane-1,4,7-triyl) triacetate (Gd-DO3A-butrol). Gadobutrol functioned as standard contrast media in MRI lymphangiography to detect lymphatic flow qualitatively. Thus, Tm-DOTMA was investigated as lymphatic marker to detect lymphatic flow quantitatively. Both contrast agents were successfully used to visualize the lymphatic flow in successive lymph nodes in LA-ICP-MS due to lower limits of detection compared to MRI. Furthermore, the distribution of contrast agents by multicolored imaging showed accumulation in specific areas (sectors) of the lymph nodes after application of contrast agents in different areas.