Outlining the body contours with scattered photons in lymphoscintigraphy for sentinel nodes

Although lymphoscintigraphy is a useful method of detecting the sentinel no des of malignancy, conventional lymphoscintigraphy images only the sentinel nodes without revealing their anatomical location. We, therefore, used sca ttered photons to attempt to outline the body contours of patients with eit her breast or esophageal cancer. Lymphoscintigraphy was performed 3 to 4 ho urs after the injection of 111 MBq of Tc-99m tin colloid into the peritumor al region. Images were obtained with dual-energy windows of 130 to 150 keV for the primary photons and 70 to 110 keV for the scattered photons. The im ages constructed from the scattered photons clearly showed the contours of the body, and the fusion images constructed from the primary and scattered photons allowed for easy identification of the location of the sentinel nod es. The results of this study confirm that images obtained from scattered p hotons on lymphoscintigraphy are helpful in identifying the anatomical loca tion of sentinel nodes.