BACKGROUNDHead magnetic resonance imaging (MRI) is of critical importance in the diagnosis and management of neurodevelopmental disorders. However, the use of sedation in affected children can present a significant challenge.AIMSTo identify the factors associated with sedation and MRI failure in children with neurodevelopmental disorders undergoing head MRI with oral triclofos sodium or rectal chloral hydrate.METHODSThis retrospective study analyzed 215 MRI sessions of children with neurodevelopmental disorders from January 2020 to December 2021. Sedation was administered via oral triclofos sodium or rectal chloral hydrate. Multivariate logistic regression was used to determine the factors associated with sedation failure and MRI failure.RESULTSThe sedation failure rate was 38.1 % (82/215). Factors significantly associated with sedation failure were older age (odds ratio [OR] 1.59, 95 % confidence interval [CI] 1.30-1.95, p < 0.001) and stranger anxiety (OR 4.07, 95 % CI 1.95-8.49, p < 0.001). The age cut-off for increased sedation failure risk was 4.0 years (p < 0.01). The MRI failure rate was 21.9 % (47/215), associated with autism spectrum disorder (ASD) diagnosis (OR 19.00, 95 % CI 2.43-149.00, p < 0.01), stranger anxiety (OR 3.66, 95 % CI 1.62-8.24, p < 0.01), and place anxiety (OR 3.18, 95 % CI 1.33-7.57, p < 0.01).CONCLUSIONSOlder age and stranger anxiety are significant risk factors for sedation failure, while ASD diagnosis, stranger anxiety, and place anxiety increase MRI failure risk in children with neurodevelopmental disorders undergoing head MRI.