BACKGROUND: The exact median effective dose (ED50) of intranasal dexmedetomidine combined with oral midazolam sedation for magnetic resonance imaging (MRI) examination in children remains unknow and the aim of this study was to determine the ED50 of their combination.
METHODS: This is a prospective dose-finding study. A total of 53 children aged from 2 months to 6 years scheduled for MRI examination from February 2023 to April 2023 were randomly divided into group D (to determine the ED50 of intranasal dexmedetomidine) and group M (to determine the ED50 of oral midazolam). The dosage of dexmedetomidine and midazolam was adjusted according to the modified Dixon\'s up-and-down method, and the ED50 was calculated with a probit regression approach.
RESULTS: The ED50 of intranasal dexmedetomidine when combined with 0.5 mg∙kg- 1 oral midazolam was 0.39 µg∙kg- 1 [95% confidence interval (CI) 0.30 to 0.46 µg∙kg- 1] while the ED50 of oral midazolam was 0.17 mg∙kg- 1 (95% CI 0.01 to 0.29 mg∙kg- 1) when combined with 1 µg∙kg- 1 intranasal dexmedetomidine. The sedation onset time of children with successful sedation in group D was longer than in group M (30.0[25.0, 38.0]vs 19.5[15.0, 35.0] min, P < 0.05). No other adverse effects were observed in the day and 24 h after medication except one dysphoria.
CONCLUSIONS: This drug combination sedation regimen appears suitable for children scheduled for MRI examinations, offering a more precise approach to guide the clinical use of sedative drugs in children.
BACKGROUND: Chinese Clinical Trial Registry, identifier: ChiCTR2300068611(24/02/2023).

BACKGROUND: The success rate of sedation with triclofos sodium and midazolam for pediatric magnetic resonance imaging (MRI) has been reported. However, there are no reports of an association of adverse events and examination success rates with patient medical backgrounds using a combination of these sedatives. We performed this study to investigate these points.
METHODS: We investigated 191 pediatric patients who were sedated for MRI with triclofos sodium and midazolam at Matsudo City Hospital between November 2013 and October 2015. We surveyed the patients\' characteristics, including age, sex, body weight, allergies, medication, neuromuscular, gastrointestinal, respiratory, and cardiac disorders, airway obstruction factors, and developmental disorders. Outcomes were sedation success and adverse events, including oxygen desaturation. We reviewed the relationship between patient backgrounds and each adverse event or success rate of sedation.
RESULTS: Among all cases, the success rate was 92.7%. Older age (odds ratio [OR] = 0.984), developmental disorders (OR = 0.215), and respiratory disorders (OR = 0.353) were factors for lower success rates. Adding midazolam was associated with a higher success rate (OR = 5.971), but the higher total dose of midazolam was associated with sedation failure (OR = 0.003). The only adverse event was oxygen desaturation (11.5%). Older age affected oxygen desaturation with multiple analysis. However, by stepwise analysis, no patient medical background nor sedative dose was associated with oxygen desaturation.
CONCLUSIONS: Older age, developmental disorders, and respiratory disorders were associated with sedation failure. Increasing midazolam did not increase the success rate, and there might be an optimal dose of midazolam.

OBJECTIVE: To investigate the prevalence and nature of adverse events in magnetic resonance imaging (MRI) of pediatric cochlear implant (CI) patients.
METHODS: Retrospective chart review at a tertiary pediatric hospital. CI patients who underwent MRI from 2004 through 2019 were identified via our internal radiology database. Comorbidities, CI model, age at MRI, number of MRIs, type of MRIs, indication for MRIs, precautions taken for MRIs, quality of MRIs, anesthesia during MRIs, patient language abilities, and adverse events were recorded from the electronic medical record. The literature was reviewed, and our results were compared to those of previous similar series.
RESULTS: From 2004 to 2019, 12 pediatric patients (17 ears) with CIs underwent 22 MRIs. 12 MRIs were performed in CI patients with retained internal magnet. 4/22 MRIs resulted in morbidity; 2 patients experienced pain requiring MRI abortion, 1 experienced magnet rotation requiring surgical replacement, and 1 underwent operative removal of the magnet prior to the scan with surgical replacement thereafter. 19/22 MRIs were performed to evaluate the brain; 17/22 of the radiologic reports noted limitation of evaluation due to artifact. 18/22 MRIs required the administration of anesthesia. 9 of the 22 MRI events involved 2 patients whose CIs had been without internal magnet in anticipation of future MRI requirement.
CONCLUSIONS: Adverse events affecting pediatric patients with CI can occur as a result of MRI, despite appropriate precautions. Safety requires consideration of factors unique to a pediatric hearing-impaired population. Clinicians must remain informed on best practices and manufacturer recommendations.

Manual segmentation of anatomy in brain MRI data taken to be the closest to the \"gold standard\" in quality is often used in automated registration-based segmentation paradigms for transfer of template labels onto the unlabeled MRI images. This study presents a library of template data with 16 subcortical structures in the central brain area which were manually labeled for MRI data from 22 children (8 male, [Formula: see text]). The lateral ventricle, thalamus, caudate, putamen, hippocampus, cerebellum, third vevntricle, fourth ventricle, brainstem, and corpuscallosum were segmented by two expert raters. Cross-validation experiments with randomized template subset selection were conducted to test for their ability to accurately segment MRI data under an automated segmentation pipeline. A high value of the dice similarity coefficient ([Formula: see text], [Formula: see text], [Formula: see text]) and small Hausdorff distance ([Formula: see text], [Formula: see text], [Formula: see text]) of the automated segmentation against the manual labels was obtained on this template library data. Additionally, comparison with segmentation obtained from adult templates showed significant improvement in accuracy with the use of an age-matched library in this cohort. A manually delineated pediatric template library such as the one described here could provide a useful benchmark for testing segmentation algorithms.