Preoperative sentinel node mapping with ^99mTc-nanocolloid SPECT-CT significantly reduces the intraoperative sentinel node retrieval time in robot assisted laparoscopic cervical cancer surgery

Objective: To compare preoperative sentinel node (SN) mapping with planar lymphoscintigraphy (LSG) to single photon emission computed tomography with computed tomography (SPECT-CT) for differences in intraoperative SN retrieval time in surgically treated cervical cancer patients. Methods: In cervical cancer patients planned for radical surgery, one day preoperatively, 220-290 MBq technetium-99m-nanocolloid was injected intracervically in four quadrants. Subsequent SN mapping was performed by either LSG (09.2009-03.2011) or SPECT-CT (03.2011-10.2012). The SN resection, by four armed robot assisted laparoscopy, was based on blue dye and technetium-99m and followed by pelvic lymph node dissection. Timing of perioperative care, including SN procedure times, was prospectively registered. Results: Out of the 62 subjects included, 33 (53.2%) underwent LSG and 29 (46.8%) SPECT-CT. No significant differences in baseline characteristics were observed. Bi- and unilateral SN visualization rates were 75.8% and 15.2% for LSG versus 86.2% and 6.9% for SPECT-CT (p = 0.299 and p = 0.305, respectively). Intraoperative bi/unilateral SN detection occurred in 84.8% and 9.1% of LSG subjects versus 89.7% and 3.4% for SPECT-CT (p = 0.573 and p = 0.616). Correlation in SN location between mapping and surgery was low for LSG (Spearman ρ = 0.098; p = 0.449) but high for SPECT-CT (ρ = 0.798; p < 0.001). Bilateral intraoperative SN retrieval times for LSG and SPECT-CT were 75.4 ± 33.5 and 50.1 ± 15.6 min, resulting in an average difference of 25.4 min (p = 0.003). Conclusion SPECT-CT significantly reduces intraoperative SN retrieval with a clinically relevant time compared to LSG. The trend towards better bilateral visualization rates and significantly higher anatomical concordance may partly explain the observed difference in SN retrieval time.