This review highlights the fundamental differences between pediatric and adult PET/MR imaging, emphasizing patient preparation, age-appropriate techniques, weight-based radiopharmaceutical dosing, and protocol customization. Unique physiologic uptake patterns in children are examined, along with common pitfalls in interpretation. Differences in clinical indications and disease prevalence between pediatric and adult populations further influence PET/MR imaging application. Understanding these distinctions at every step—from preparation to image interpretation—is essential to ensure diagnostic accuracy and to minimize false-positive and false-negative findings specific to pediatric imaging.