Rationale and objectives: The capability of an indirect computed tomographic lymphography (CT-LG) using a nonionic monometric contrast medium iopamidol for visualizing breast lymphatic pathways was preliminarily tested.
Materials and methods: In 10 female dogs, a total of 0.5 and 1 mL of undiluted iopamidol was injected subcutaneously into the skin areas overlying the both caudal mammary glands. Contiguous 2-mm-thick multidetector raw helical CT images were obtained through the upper thorax and axilla before and during 60 minutes after gentle massage at the injection sites, with reconstruction into three-dimensional (3D) postcontrast CT images. The first lymph node (1st LN) directly draining from the injection sites was marked under CT guidance, followed by pre- and postmortem examinations. This CT-LG with 2-mL iopamidol was also attempted in five human female volunteers.
Results: Even with 0.5-mL iopamidol, the CT-LG clearly visualized the direct connection of the 1st LN and lymphatic vessels draining from the injection sites throughout the examination time in all the animals, with the maximum CT attenuation of 269 Hounsfield units (HU) +/- 137 in the 1st LN on the first postcontrast images. The topographic 3D images provided comprehensive anatomic outlines of these lymphatic pathways. Of the total of 20 opacified 1st LN and 110 distant nodes, all the 1st LN (100%) and 92 (83.6%) distant nodes could be resected at pre- or postmortem, with a good correlation with the CT images. The CT-LG also effectively localized the 1st LN with the maximum attenuation of 223 HU +/- 63 in the human volunteers, without any significant late adverse effects.
Conclusion: Indirect CT-LG with iopamidol may have excellent potential for visualizing breast lymphatic drainage and for preoperative localization of breast sentinel lymph nodes.