Microcomputed Tomography Is a Precise Method That Allows for Topographical Characterization of Lymph Nodes and Lymphatic Vessels.

Abstract

Background: Surgical excision and/or radiation targeting of regional lymph nodes are an essential component in the clinical management of cancer. Importantly, a more accurate understanding of lymphatic anatomy could enable refinement of present treatment strategies. Given the spatial resolution limitations of contemporary imaging methods, our group sought to utilize noncontrast-enhanced microcomputed tomography (μCT) imaging to clarify regional lymphatic anatomy. Methods and Results: This study was conducted with embalmed en bloc lymphatic tissue packets from six donors (three females and three males: medianage of death = 78 years). All specimens were investigated with noncontrast-enhanced μCT imaging using a conebeam-CT imaging system. Adipose and lymphatic tissues were segmented by radiodensity based on sampling regions of interest. To confirm the observations from μCT, lymph nodes from each packet were exposed to hematoxylin and eosin staining and anti-D240 immunostaining. Following μCT imaging, mean peak radiodensities of -203.14 ± 19.35 Hounsfield units (HU) and 37.25 ± 31.95 HU were revealed for adipose and lymphatic tissues, respectively (p < 0.01). By analyzing histograms of the radiodensity distributions, we determined a threshold of -82.42 HU to differentiate adipose and lymphatic tissue, to generate three-dimensional renderings, and to calculate quantitative metrics. On average, adipose tissue comprised 9.62 ± 3.60 cm3 (73.6%) of the total packet volume, whereas lymphatic tissue comprised 3.47 ± 2.71 cm3 (26.4%). Moreover, each en bloc packet contained four small lymph nodes (1-5 mm) and three to four large lymph nodes (>5 mm). Histology corroborated the observations from μCT. Conclusions: Altogether, a precise understanding of regional lymphatic anatomy elucidated by the present imaging modality may help refine clinical cancer treatment strategies.