99mTC-Nanocolloid SPECT/MRI fusion for the selective assessment of nonenlarged sentinel lymph nodes in patients with early-stage cervical cancer

Abstract

We aimed to explore the accuracy of 99mTc SPECT/MRI fusion for the selective assessment of nonenlarged sentinel lymph nodes (SLNs) for diagnosing metastases in early-stage cervical cancer patients. Methods: We consecutively included stage IA1–IIB1 cervical cancer patients who presented to our tertiary referral center between March 2011 and February 2015. Patients with enlarged lymph nodes (short axis $ 10 mm) on MRI were excluded. Patients underwent an SLN procedure with preoperative 99mTc-nanocolloid SPECT/CT-based SLN mapping. When fused datasets of the SPECT and MR images were created, SLNs could be identified on the MR image with accurate correlation to the histologic result of each individual SLN. An experienced radiologist, masked to histology, retrospectively reviewed all fused SPECT/MR images and scored morphologic SLN parameters on a standardized case report form. Logistic regression and receiver-operating curves were used to model the parameters against the SLN status. Results: In 75 cases, 136 SLNs were eligible for analysis, of which 13 (9.6%) contained metastases (8 cases). Three parameters—short-axis diameter, long-axis diameter, and absence of sharp demarcation—significantly predicted metastatic invasion of nonenlarged SLNs, with quality-adjusted odds ratios of 1.42 (95% confidence interval [CI], 1.01–1.99), 1.28 (95% CI, 1.03–1.57), and 7.55 (95% CI, 1.09–52.28), respectively. The area under the curve of the receiveroperating curves combining these parameters was 0.749 (95% CI, 0.569–0.930). Heterogeneous gadolinium enhancement, cortical thickness, round shape, or SLN size, compared with the nearest non-SLN, showed no association with metastases (P 5 0.055–0.795). Conclusion: In cervical cancer patients without enlarged lymph nodes, selective evaluation of only the SLNs—for size and absence of sharp demarcation— can be used to noninvasively assess the presence of metastases.