A 120 dB, Asynchronous, Time-Domain, Multispectral Imager for Near-Infrared Fluorescence Image-Guided Surgery

As surgery has become the standard-of-care for cancer, surgeons have been left underequipped to identify tumors in the operating room, causing many operations to end in positive margins and necessitating secondary treatments to remove remaining tumor tissue. Near-infrared fluorescence image-guided surgery utilizes near-infrared fluorescent markers and near-infrared sensitive cameras to highlight cancerous tissues. Unfortunately, state-of-the-art imaging systems are unable to handle the high dynamic range between strong surgical lighting and weak fluorescent emission and suffer from temperature-dependent co-registration error. To provide a cost-effective and space-efficient imaging system with sufficient dynamic range and no co-registration error, we have developed a single-chip snapshot multispectral imaging system that provides four channels across the visible and near-infrared spectra. By monolithically integrating an asynchronous time-domain image sensor and pixelated interference filters, we have achieved a dynamic range of 120 dB without co-registration error. The imager can detect less than 100 nM of the FDA-approved fluorescent dye indocyanine green under surgical lighting conditions, making it a promising candidate for image-guided surgery clinical trials.