Intraoperative Resection Guidance with Photoacoustic and Fluorescence Molecular Imaging Using an Anti-B7-H3 Antibody-Indocyanine Green Dual Contrast Agent

Purpose: Breast cancer often requires surgical treatment including breast-conserving surgical resection. However, with current post-surgical histological margin analysis, one-quarter of breast cancer patients undergo re-excision to achieve negative margins corresponding to decreased local recurrence and better outcomes. Therefore, a method with high resolution and specificity for intraoperative margin assessment is needed. Experimental Design: First, quantitative immunofluorescence staining of B7-H3 expression was assessed in four pathological stages of breast cancer progression of the MMTV-PyMT transgenic murine model. Next, an antibody-dye contrast agent, B7-H3-ICG, was injected into mice prior to surgical resection of breast cancer. Anatomical ultrasound, spectroscopic photoacoustic (sPA), and fluorescence imaging were used to guide resection of mammary glands suspected of containing cancer. Resected tissues were processed for H&E staining and pathological assessment and compared to sPA and fluorescence imaging signals. Results: Tissue containing DCIS (46.0±4.8 a.u.) or invasive carcinoma (91.7±21.4 a.u.) showed significantly higher (P<0.05) B7-H3 expression than normal and hyperplastic tissues (1.3±0.8 a.u.). During image guided surgical resection, tissue pieces assessed as normal or hyperplastic (n=17) showed lower average sPA (3.17±0.48 a.u.) and fluorescence signal (6.83E07±2.00E06 (p/s)/(µW/cm²)) than DCIS and invasive carcinoma tissue (n=63) with an average sPA signal of 23.98±4.88 a.u. and an average fluorescence signal of 7.56E07±1.44E06 (p/s)/(µW/cm²) with AUCs of 0.93 (95% CI; 0.87, 0.99) and 0.71 (95% CI; 0.57, 0.85), respectively. Conclusions: It was demonstrated that sPA and fluorescence molecular imaging combined with B7-H3-ICG agent can assess the disease status of tissues with high diagnostic accuracy, intraoperatively, with high resolution, sensitivity, and specificity.

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