X Chen

Map optogenetically driven hippocampal activity with simultaneous fMRI and GCaMP-mediated calcium recording

BODY: Abstract Body: Background: Breast cancer is the most commonly diagnosed cancer in women worldwide (1). In early breast cancer, the primary treatment option is breast-conserving surgery (BCS). There is a clear need for more accurate techniques to assess resection margins intra-operatively, as up to 40% of patients require further surgery to achieve clear margins (2). CLI combines optical and molecular imaging properties by detecting visible light emitted by 18F-FDG accumulating in cancer cells. Its high-resolution and portable equipment make it attractive for intraoperative use (3). Methods: The purpose of this study was to investigate the feasibility of CLI for the intraoperative assessment of tumor margins in breast-conserving surgery. Following informed consent, 23 BCS patients received 5 MBq/kg of 18F-FDG pre-operatively. An increased technetium-99m dose was used to ensure SLN detection. Following excision, specimens were inked for orientation, incised, and imaged using an investigational CLI imager (Lightpoint Medical Ltd, UK). The first 10 patients constituted a run-in dataset that was used to optimize the imaging protocol; the following thirteen patients were included in the analysis dataset. Images were analysed by calculating mean radiance ± std (photons/s/cm2/sr) and tumour-to-background ratios (TBRs). Tumour size and margin status (as informed by CLI images) were independently estimated by two surgeons. CLI results were correlated with histopathology. A onesample Wilcoxon test and Bland-Altman analysis were used to determine the degree of agreement on tumour size between CLI and histopathology. Agreement between surgeons was evaluated using an intraclass correlation coefficient (ICC) analysis. Radiation doses to staff were measured using body dosimeters. Results: Elevated radiance was identified in 10/13 patients. Mean radiance and TBR were 560 ± 160 photons/s/cm2/sr and 2.41 ± 0.54. In total, fifteen margins were assessed. Complete concordance between CLI and histopathology was observed with regards to identification of clear margins of excision. A non-significant underestimation of invasive tumour size on CLI was found (p = NS). Whole tumour size was significantly smaller on CLI (p ≤ 0.026). Agreement between surgeons was excellent (ICC = 0.97). SLNs were successfully detected in all patients. Radiation dose to staff was low; operating surgeons received the highest dose at 33 ± 15 μSv. Conclusions: Intraoperative 18F-FDG CLI is a feasible and low risk procedure that shows promise in the intraoperative assessment of resection margins in breast-conserving surgery. CLI imaging of WLE specimens provides high-resolution functional information that allows surgeons to accurately assess margin status with good correlation to gold-standard histopathological examination. This technology also has potential application during surgical resection of other solid cancers. DOI: 10.1007/s11307-01 0 Mol Imaging Biol (201 ) 1 (Suppl ): 1 S 6 8 6 S 2 Y 1279 696 1 30 1