A positron emission tomography (PET) detector assembly is provided. The PET detector assembly includes a plate having a first side and an opposite second side, the plate being fabricated from a thermally conductive material. The PET detector assembly also includes multiple PET detector units coupled to the first side of the plate. The PET detector assembly further includes a readout electronics section coupled to the second side of the plate, wherein, during operation, the readout electronics section generates heat that is transferred to the plate. The plate comprises a heat pipe disposed within the plate and configured to extract the heat from the plate and to transfer the heat away from the plate.