1. A multispectral medical imaging device comprising: a plurality of illumination devices arranged to illuminate a target tissue, the plurality of illumination devices configured to emit light of different near-infrared wavelength bands; an objective lens; a near-infrared image sensor positioned to capture image frames reflected from the target tissue through the objective lens; a visible-light image sensor positioned to capture image frames reflected from the target tissue through the objective lens; a processor connected to the near-infrared image sensor, the visible-light image sensor, and the plurality of illumination devices, the processor configured to modulate near-infrared light output of the plurality of illumination devices to illuminate the target tissue, the processor further configured to determine reflectance intensities from the image frames captured by the near-infrared image sensor and to generate a dynamic tissue oxygen saturation map of the target tissue using the reflectance intensities; and an output device connected to the processor for displaying the dynamic tissue oxygen saturation map.