ABSTRACT: Quantitative relaxometry is a promising method for quantifying brain changes with early development and brain tissue differences as a function of genetics, environment or pathology. Relaxometry may be useful for assessing abnormal white matter damage in infants at risk for cerebral palsy, which is the leading movement disorder in children. Head motion is a significant challenge for MRI studies in young children, resulting in image artifacts and errors in quantitative imaging measures. Long and loud scans also adversely affect imaging compliance in young children. Consequently, there is a critical need to develop imaging methods that are robust to motion, faster, and quieter. This project will develop, optimize and evaluate novel 3D radial imaging technologies for multimodal structural imaging and quantitative relaxometry for studies in sleeping infants and toddlers. The outcome will be a fast, ultra-quiet imaging technique capable of providing imaging maps of quantitative relaxation times that are robust to nearly all motions. These optimized, motion-corrected, quantitative relaxometry technologies will be applied to a cohort of infants and toddlers without sedation to generate developmental relaxometry templates for normative studies from 0 to 2 years of age. The normative relaxometry framework will be applied to lesions and abnormal brain development of infants at risk for or diagnosed with cerebral palsy, The normative framework will also be used to investigate individual differences in brain and sensorimotor development in both typical development and cerebral palsy. Ultimately, this project will provide a set of robust, reliable and accurate image acquisition methods, software tools, and strategies for investigating healthy and abnormal brain development in both clinical and research pediatric populations without sedation.