Detection of Sentinel Lymph Node in Endometrial Cancer Using 99mTc-Nanocolloid SPECT/CT: A Retrospective Cohort Study

<b>Background</b> Sentinel lymph node mapping (SLNM) using ^99m Tc-nanocolloid single photon emission tomography/computed tomography (SPECT/CT) is a minimally invasive technique for detecting lymphatic metastasis in early-stage endometrial cancer. This study aimed to evaluate the detection rate (DR) of sentinel lymph nodes (SLNs) using SPECT/CT and compare the findings with intraoperative gamma probe evaluation and histopathological results. <b>Methods</b> A retrospective cohort study was conducted at Dr. Hasan Sadikin General Hospital, Bandung, Indonesia, between December 2022 and January 2024. Twenty-six patients with FIGO (International Federation of Gynecology and Obstetrics) stage I endometrial cancer were included. ^99m Tc-nanocolloid was injected into four cervical quadrants, followed by SPECT/CT imaging and intraoperative gamma probe evaluation. Histopathological analysis was performed to confirm the presence of metastasis. <b>Results</b> SLNs were detected in 20 patients (76.9%) using SPECT/CT, with 100% concordance with gamma probe findings. Histopathological analysis identified metastasis in four patients (15.4%). Tumor size was significantly associated with SLN detection ( <i>p</i> < 0.001), with larger tumors (> 4 cm) more frequently associated with positive SLNs. However, no significant correlation was found between SPECT/CT maximum counts and histopathological metastasis ( <i>p</i> : 0.156). Among the six patients with negative SPECT/CT findings, all patients underwent lymphadenectomy, and no metastasis was detected in these cases. <b>Conclusion</b> SPECT/CT using ^99m Tc-nanocolloid is an effective tool for SLNM in early-stage endometrial cancer, demonstrating a high DR and perfect concordance with intraoperative gamma probe findings. Its superior anatomical accuracy enhances surgical planning. Tumor size significantly influences SLN detection, with larger tumors being more frequently associated with positive SLNs. However, SPECT/CT count intensity does not correlate with histopathological metastasis.