In time-of-flight (TOF) positron emission tomography (PET), the coincidence resolving time (CRT) has a strong influence on the overall performance. Multichannel digital silicon photomultipliers (MD-SiPMs) are able to obtain several timestamps for gamma photon timemark estimation. Using this feature, the CRT is improved and the system robustness is significantly increased by utilizing multiple photoelectron timestamps. In addition, the PET instrumentation chain is simplified because of the intrinsic digitization and integrated functionality of the MD-SiPM. The main objective of this work is to demonstrate the possibility of building a complete highly-miniaturized PET detector module for endoscopic applications. In addition, we show that it's possible to operate simultaneously several MD-SiPM array chips in order to build a small-animal PET detector modules. We present the implementation of two PET detector modules that are based on MD-SiPMs: a small animal and an endoscopic PET detector modules. The small animal PET detector module consists of 2×4 monolithic MD-SiPM array chips. In addition, this module includes a low-cost field programmable gate array (FPGA), a temperature controlling system and data transfer interfaces. The endoscopic PET detector module comprises a single monolithic array of 9×18 MD-SiPM and a small form-factor FPGA. In this module, a remarkable level of compactness is achieved. Eventually, a thermal characterization and a preliminary radiation measurement are presented.