K. Herrmann, A. Schnelzer, M. E. Martignoni, T. Wendler, A. K. Buck Evaluation of feasibility of freehand SPECT in the operating room Proceedings of the Annual Meeting of the Society of Nuclear Medicine (SNM), Salt Lake City, Utah, USA, June 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, 10 patients undergoing sentinel lymph node (SLN) biopsy (6x breast cancer - BC, 4x melanoma with drain to axilla - MDA) were recruited and scanned intraoperatively using fhSPECT before excision of SLNs. Position of SLNs at fhSPECT was compared to the position of SLNs detected using gamma probe and blue dye. 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, 16 SLNs were mapped with conventional scintigraphy (8 SLNs in BC and 8 SLN in MDA). Operation was performed approx. 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 not been extracted. In the remaining 6 pts no residual radioactivity was found in the axilla. 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 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.
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