This study evaluates the effects of nanostructured photonic crystal coatings on the light extraction and timing performance of LYSO scintillators for time-of-flight positron emission tomography (TOF PET). A half-patterned LYSO crystal was used, with one side coated with TiO₂ nanostructures and the other left bare, enabling direct comparison under identical conditions. Results demonstrate a significant improvement in light extraction, with 70% of scintillation light escaping through the patterned face compared to 30% for the unpatterned face. However, timing effects were minimal, with a slight average delay of 17 ps observed for photons exiting through the patterned surface. While the timing delay is negligible for practical PET applications, the enhanced light extraction suggests promising implications for improving spatial resolution and overall detector efficiency in TOF PET systems.