A. K. Buck, A. Ehlerding, J. Saeckl, K. Herrmann, T. Wendler, M. E. Martignoni, A. Schnelzer, M. Schwaiger Evaluation of feasibility of freehand SPECT in the operating room Proceedings of EANM 2010, Vienna, Austria, October 2010 (bib)
	Aim: Confirm feasibility of using innovative freehand SPECT (fhSPECT) for lymphatic mapping in the operating room and define border conditions for large scale comparison studies with conventional, non-image guided procedures. Methods: To date, 21 patients (30-73y) undergoing sentinel lymph node (SLN) biopsy were recruited and scanned intraoperatively using fhSPECT (CSS300 by SurgicEye GmbH) before excision of SLNs (13x breast cancer BC, 5x melanoma axilla MA, 3x melanoma groin MG). Position of SLNs at fhSPECT was compared to the position of SLNs detected using gamma probe. After excision, fhSPECT was used to control the success of SLN resection in the OR. Preoperative planar scintigraphy acquired the day before surgery was available for planning of the surgical procedure. Results: Preoperatively, 33 primary and 7 secondary SLNs were mapped with conventional scintigraphy. Operation was performed approx. 18.5h (SD, 5.7h) after injection resulting in a total activity of 10.4MBq at the time point of surgical incision (SD, 8.3MBq). In the pre-incision scan fhSPECT managed to map all but 2 SLNs (2x BC) in the identical position as compared to node location at planar scintigrams, as well as 1 further SLN in 1 MG (39/40). Gamma probe failed to detect any SLNs in 2 BCs and mapped in total 31 of 40 nodes. 31 SLNs were resected and confirmed to be radioactive ex-vivo. fhSPECT detected 11 SLNs in 11 patients post-excision. In 3 BCs additionally detected nodes were resected and confirmed to be radioactive, while in 4 BCs, 1 MA and 2 MDs harvesting of the additionally detected node was discarded as higher uptake SLNs had been removed already (8 nodes). In the remaining 10 pts no residual radioactivity was found in the region of interest. Pre-excision fhSPECT acquisitions took approx. 3.3min (SD, 1.2min) while post-excision scans took 3.0min (SD, 0.8min). The surgical procedure was extended by 12min (6min before incision and 6min after excision of SLNs). Conclusions: Preliminary experience indicates that intraoperative imaging with fhSPECT for lymphatic mapping is feasible. Alteration of the surgical workflow was considered minimal given potential clinical advantages, like assurance of complete resection and minimized invasivity. Due to the good correlation between fhSPECT images and SLNs detected by gamma probe, fhSPECT will be further evaluated in ongoing studies. Acknowledgements: This research was partly funded by the German Research Society (DFG's project SFB-824) and SurgicEye GmbH.
	This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each authors copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.