J. Saeckl, A. Ehlerding, K. Herrmann, T. Wendler, M. Schwaiger, M. Kiechle, H. Friess, A. K. Buck, A. Schnelzer, M. E. Martignoni Evaluation of feasibility of freehand SPECT in the operating room Proceedings of the International Conference on Sentinel Node Biopsy and Radioguided Head & Neck Surgery (SNB), Copenhagen, Denmark, May 2010 (bib)
	Aim Confirm feasibility of using innovative freehand SPECT (fhSPECT) for lymphatic mapping in the operating room (OR) in the simple setup of axillary sentinel lymph node (SLN) biopsy (SLNB) and define border conditions for large scale comparison studies with conventional, non-image guided procedures. Methods: To date, 10 patients undergoing SLNB (6x breast cancer - BC, 4x melanoma with drain to axilla - MDA) were recruited and scanned intraoperatively using fhSPECT (CSS300 of SurgicEye?) before excision of SLNs. Position of SLNs at fhSPECT was compared to the position detected using gamma probe. After excision, fhSPECT was used to control the success of SLN resection in the OR. Preoperative planar scintigraphy was done in all patients. Results: Preoperatively, 16 SLNs were mapped with conventional scintigraphy (8 SLNs in BC and 8 SLN in ME). Operation was performed 16.3h (SD, 6.7h) after injection resulting in a total activity of 13.2MBq at the time point of surgical incision (SD, 11.1MBq). In the pre-incision scan fhSPECT managed to map all but 1 SLN in the identical position as compared to node location at planar scintigrams (1 BC). Gamma probe failed to detect SLNs in 1 BC. 12 SLNs were resected and confirmed to be radioactive ex-vivo (5 in BC, 7 in MDA). fhSPECT detected 4 SLNs in 4 pts (3 BCs, 1 MDA) post-excision, which would have otherwise have not been extracted. In the remaining 6 pts no residual radioactivity was found. Pre-excision fhSPECT acquisitions took approx. 4.0min (SD, 1.4min) while post-excision scans took 3.5min (SD, 0.9min). The surgical procedure was extended by 15min (8min before incision and 7min after excision of SLNs). Conclusions: Preliminary experience indicates feasibility of intraoperative imaging with fhSPECT for lymphatic mapping. Alteration of the surgical workflow was considered minimal given potential clinical advantages, like assurance of complete resection, image-guided incision and in situ planning (using depths of the SLNs as given by the fhSPECT system). Due to the good correlation between fhSPECT images and SLNs detected with gamma probe, fhSPECT will be further evaluated in ongoing studies including SLNB for head and neck malignancies and melanoma with drain to groin. Acknowledgements: This research was partly funded by DFG’s SFB 824 and the SurgicEye? GmbH?.
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