Paraaortic sentinel lymph nodes: toward optimal detection and intraoperative localization using SPECT/CT and intraoperative real-time imaging

Abstract

Paraaortic sentinel node biopsy may be a challenging procedure because the sentinel nodes are located retroperitoneally in close proximity to vital structures. The purpose of this study was to describe and evaluate the value of preoperative SPECT/CT for lymphatic mapping, and a portable gamma-camera for intraoperative radioguidance, in patients with paraaortic sentinel nodes.

Methods: We evaluated our practice in 18 patients, who were treated at The Netherlands Cancer Institute with sentinel lymphadenectomy for different urologic malignancies and showed paraaortic drainage on preoperative images. After intratumoral injection of (99m)Tc-nanocolloid, the patients underwent sequential planar lymphoscintigraphy, hybrid SPECT/CT, and sentinel lymphadenectomy. Intraoperative node detection and localization were guided by a laparoscopic gamma-probe and a portable gamma-camera. This gamma-camera was set to display both the (99m)Tc signal and the (125)I-seed signal. This (125)I seed was placed on top of the gamma-probe, functioning as a pointer on screen, thus enabling real-time sentinel node localization with the gamma-camera.

Results: In 16 patients with midabdominal drainage on planar images and in 2 patients with nonvisualization on planar images, SPECT/CT showed clear localization of paraaortic sentinel nodes in relation to the abdominal vessels. Five patients underwent open surgery, and 13 patients underwent laparoscopy. The paraaortic sentinel nodes were successfully localized and removed in 15 patients with the help of the portable gamma-camera and gamma-probe and in 3 patients with the gamma-probe only. In 1 patient, the paraaortic sentinel node showed a metastasis.

Conclusion: If retroperitoneal drainage is expected, SPECT/CT provides good detection and clear localization of sentinel nodes in relation to anatomic structures. Detection and removal of paraaortic sentinel nodes by means of a laparoscopic gamma-probe and real-time imaging with a portable gamma-camera is a successful method with high intraoperative detection rates.