Abstract
Significance: Imaging needles consist of highly miniaturized focusing optics encased within a hypodermic needle. The needles may be inserted tens of millimeters into tissue and have the potential to visualize diseased cells well beyond the penetration depth of optical techniques applied externally. Multimodal imaging needles acquire multiple types of optical signals to differentiate cell types. However, their use has not previously been demonstrated with live cells. Aim: We demonstrate the ability of a multimodal imaging needle to differentiate cell types through simultaneous optical coherence tomography (OCT) and fluorescence imaging. Approach: We characterize the performance of a multimodal imaging needle. This is paired with a fluorescent analog of the therapeutic drug, tamoxifen, which enables cell-specific fluorescent labeling of estrogen receptor-positive (ER+) breast cancer cells. We perform simultaneous OCT and fluorescence in situ imaging on MCF-7 ER+ breast cancer cells and MDA-MB-231 ER− cells. Images are compared against unlabeled control samples and correlated with standard confocal microscopy images. Results: We establish the feasibility of imaging live cells with these miniaturized imaging probes by showing clear differentiation between cancerous cells.