Abstract
This study evaluates quantitative combined single photon emission tomography/computed x-ray tomography (SPECT/CT) to assess the influence of radiotracer concentration on detection of sentinel lymph nodes (SLN) in endometrial cancer (EC). Eighty EC patients underwent pericervical 99m-Tc-nanocolloid injection followed by SPECT/CT. The subgroup of patients with failed SLN detection in SPECT/CT (n = 20) was compared to match-paired patients showing at least two SLNs. Results of intraoperative gamma probe measurements and quantitative SPECT/CT were used for comparison. In patients with detection failure, the percentage of injected dose, absolute activity, and volume of the injection site were significantly lower (30 ± 24% vs. 55 ± 19%; p = 0.01, 43 ± 36 MBq vs. 73 ± 33 MBq; p = 0.04, and 183 ± 164 mL vs. 266 ± 164 mL; p = 0.03) while mean activity concentration in liver, spleen, and bone marrow was significantly higher (p = 0.02). Activity concentration (>33 KBq/mL) and absolute activity (>73 MBq) of injection areas correlated with successful intraoperative SLN detection. In a subgroup of 19 SLNs, a correlation between SPECT/CT-derived uptake and intraoperative count rate was found (R2 = 0.8; p < 0.001). SLN detection in EC patients depended on high radiotracer activity at the cervical injection site. Quantitative SPECT/CT could predict successful intraoperative SLN detection and may help to optimize injection technique.
Highlights
Endometrial cancer (EC) is the third most frequent cancer in women in the USA and the fourth in Europe [1,2,3]; its incidence is continuously increasing [3]
This technique was selected on the basis of previous results, as it was associated with a favorable sentinel lymph node (SLN) detection rate [17]
In 20/80 patients (25%) no SLN could be visualized on SPECT/CT images
Summary
Endometrial cancer (EC) is the third most frequent cancer in women in the USA and the fourth in Europe [1,2,3]; its incidence is continuously increasing [3]. In the early stage of gynecological cancers, the use of sentinel lymph node (SLN) mapping can potentially provide prognostic information, detect micro-metastases, and avoid systematic lymphadenectomy. SLN mapping was included into the US American guidelines for EC treatment [4]. It remains to be considered as an experimental approach according to the European guidelines due to the lack of large prospective studies. In case of intermediate/high EC recurrence risk according to the FIGO tumor classification, a bilateral pelvic and para-aortic lymphadenectomy would be preferred [6,7]. Complete lymphadenectomy has potential post-operative adverse effects such as lymphocele and lower-extremity lymphedema [8,9]
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