Comparison of early and delayed lymphoscintigraphy images of early breast cancer patients undergoing sentinel node mapping.

Objective: We compared early and delayed lymphoscintigraphy images using intradermal injection of (99m)Tc-antimony sulfide colloid, which has small particles.

Methods: Eighty patients with early-stage breast cancer were included into the study. Intradermal injection of (99m)Tc-antimony sulfide colloid was used for sentinel node mapping. After radiotracer injection, 30 min and 20 h later, lymphoscitigraphy images were obtained in lateral and anterior views. After the completion of each image sets, the location of the visible nodes in the axilla was marked on the skin. Two nuclear medicine specialists reviewed the images independently and the number and location of detected nodes were recorded.

Results: At least one hotspot was detected in the axillary region in 78 (97.5%) and 79 (98.75%) patients on the early and delayed images, respectively. No extra-axillary drainage was noted in the patients. The number and location of detected hot spots were the same in 77 patients on both image sets. In one patient the early image did not show any axillary hot spot despite its visualization on the delayed image set and in one patient no hot spot was noted on either images. In one patient an additional axillary hot spot was noted on the delayed image, which was not apparent on the early image.

Conclusion: Our study showed that a delay of up to 20 h in sentinel lymph node biopsy using intradermal injection of (99m)Tc-antimony sulfide colloid does not result in washout of the tracer from the true sentinel node or migration of the radiotracer into second-echelon nodes.