[Application of ⁹⁹mTc-SPECT-CT and carbon nanoparticles suspension injection in sentinel lymph node mapping for rectal cancer].

Objective: To evaluate the accuracy of sentinel lymph node mapping(SLM) in patients with rectal cancer by single-photon emission computed tomography (SPECT-CT) lymphoscintigraphy and carbon nanoparticles suspension injection.

Methods: Twelve patients with clinical T(1-2)N(0)M(0) rectal cancer were selected and locally injected with technetium-(99m)sulfur-colloid and carbon nanoparticles suspension by endoscope one day before surgery, followed by SPECT-CT scanning 1, 3 and 5 hours later. Radioactive isotope(RI) uptake of each sentinel node(SN) basin with location preoperatively determined by SPECT-CT was postoperatively calculated using gamma probe. Nodes with the highest RI uptake, the number of which was also pre-determined by SPECT-CT, was defined as SNs. Immunohistochemical cytokeratin staining was performed for all the SNs and non-SNs.

Results: The rate of sentinel node detection was 91.7%(11/12) with at least one SN(1-3) per patient. Ten cases showed metastasis-negative in SNs as well as all the resected regional nodes by immunohistochemical cytokeratin staining. Only one patient had positive nodes in both SN and non-SNs. The accuracy of SLM was 100%.

Conclusion: SPECT-CT lymphoscintigraphy and carbon nanoparticles suspension injection can effectively detect the anatomic location and number of sentinel nodes, and improve the accuracy of SLM for rectal cancer.