Time-lapse quantitative computed tomography lymphography: assessing lymphatic function in vivo.

RATIONALE AND OBJECTIVES: Immobility and massage produce different local limb lymph flow rates. We studied their influence on accumulation of radiopaque nanoparticulates in regional lymph nodes of normal rabbits. METHODS: Quantitative lymphography at 10-min intervals was used to follow the transport of subcutaneous (s.c.) nanoparticulates produced from insoluble esters of diatrizoic acid. In one design, both hindpaws received 0.5 ml of nanoparticulate s.c., and one hindpaw was massaged. In a second design, one hindpaw was injected and massaged while imaging the popliteal, presacral, and paraaortic nodes every 10 min. RESULTS: Gentle massage rapidly increased popliteal node accumulation in comparison with the immobile limb. On the massaged side, mean Hounsfield (HU) units, maximum Hounsfield units, and calculated iodine were significantly greater at 10 min and all subsequent times. In the node transfer experiments, it took 12, 30, and 45 min, respectively, to obtain 100-HU mean attenuation; 200-HU maximum attenuation thresholds were achieved at 20, 47, and 69 min, respectively. CONCLUSION: Quantitative computed tomography lymphography reflects local lymph physiology. Gentle massage of the s.c. injection site is a powerful lymphotropic stimulus.