We present an implantable single-photon shank-based imager, monolithically integrated onto a single CMOSIC. The imager comprises of 512 single-photon avalanchediodes distributed along two shanks, with a 6-bit depth in-pixelmemory and an on-chip digital-to-time converter. To scale downthe system to a minimally invasive form factor, we substituteoptical filtering and focusing elements with a time-gated,angle-sensitive detection system. The imager computationallyreconstructs the position of fluorescent sources within a 3-Dvolume of 3.4 mm×600μm×400μm.