Comparison of Dexmedetomidine and Propofol for Magnetic Resonance Imaging in Children: A Meta-Analysis

By Wei Yang¹, Mingjun Zhu², Jun Xu³, Yueyong Wang⁴

Affiliations

1. Department of Anaesthesiology, Shandong Provincial Third Hospital, Ji’nan, China
2. Department of Ultrasound, Central Hospital Affiliated to Shandong First Medical University, Ji’nan, China
3. Department of Anaesthesiology, Central Hospital Affiliated to Shandong First Medical University, Ji’nan, China
4. Department of Urology, Central Hospital Affiliated to Shandong First Medical University, Ji’nan, China

doi: 10.29271/jcpsp.2025.08.1019

ABSTRACT
Paediatric magnetic resonance imaging (MRI) allows visualisation of internal structures in children without the use of ionising radiation. It often requires sedation to minimise patient’s movement to enhance image quality. Dexmedetomidine and propofol are widely used as sedative agents, however, their comparative efficacy remains debated. This systematic review and meta-analysis, conducted from May to November 2023, examined 13 randomised controlled trials with 650 paediatric patients. Results favoured dexmedetomidine over propofol for reducing patient movement during MRI (SMD -0.68; 95% CI -1.16, -0.20; p = 0.005). However, sedation efficacy and adverse events showed no significant difference (RR 0.99; 95% CI 0.96, -1.01; p = 0.252 vs. RR 0.95; 95% CI 0.73, -1.23; p = 0.692), respectively. The findings highlight the potential of dexmedetomidine to improve MRI quality by reducing motion. However, further research is needed on diverse patient populations, long-term effects, and aspects such as cost-effectiveness and patient satisfaction to validate these results across broader contexts.

Key Words: Paediatric MRI, Dexmedetomidine, Propofol, Sedation, Systematic review, Meta-analysis, Randomised controlled trials.

INTRODUCTION

Magnetic Resonance Imaging (MRI) stands as an indispensable diagnostic tool in paediatric medicine, offering an exceptional level of precision in revealing anatomical structures and identifying pathological conditions.^1,2 This non-invasive imaging technique has ushered in a new era of diagnosing and monitoring a wide range of medical conditions in children, spanning from neurological ailments to orthopaedic injuries.^3,4 Nevertheless, the full potential of paediatric MRI is hindered by restlessness and anxiety inherently associated with young patients. Maintaining stillness during the procedure often proves challenging, leading to compromised image quality and prolonged examination times.^5,6 Among the diverse array of sedative options available, two specific compounds, namely dexmedetomidine and propofol, have ascended to the forefront of clinical practice, primarily due to their well-established efficacy and favourable safety profiles.^7-9

Both dexmedetomidine, a highly selective α2-adrenergic agonist, and propofol, known for its potent intravenous anaesthetic properties, have gained recognition for their exceptional sedative capabilities, making them prominent choices for paediatric MRI sedation.^10-12

This study encompasses a dual-purpose. Firstly, it addresses a significant clinical concern, by examining the choice of sedatives for paediatric MRI procedures and their potential implications for patient experience and image quality. Secondly, it contributes to the existing body of scientific literature by conducting a systematic evaluation and meta-analysis. By combining evidence from previous studies, this research aimed to provide a comprehensive overview of the comparative performance of dexmedetomidine and propofol, ultimately offering a valuable contribution to the field of paediatric MRI sedation. Acquiring high-quality MRI images in paediatric patients is of paramount importance, as they serve as indispensable tools for guiding clinical decisions, supporting surgical planning, and monitoring treatments outcomes.^13-15 Thus, seeking solutions to mitigate the challenges posed by patient movement and anxiety during paediatric MRI examinations has spurred extensive research within the field of paediatric sedation.^16,17

METHODOLOGY

A comprehensive and systematic search was conducted, from May to November 2023, across multiple databases, including PubMed, MEDLINE, and the Cochrane Library, to identify relevant studies comparing dexmedetomidine and propofol for sedation in paediatric MRI. The search utilised keywords such as paediatric, MRI sedation, dexmedetomidine, and propofol. However, the search was not limited by publication date to ensure a thorough compilation of relevant studies, and all records obtained were assessed for eligibility.

Inclusion of studies followed predetermined criteria, ensuring both relevance and quality. The criteria comprised randomised controlled trials (RCTs) that directly compared dexmedetomidine and propofol for paediatric MRI sedation, with a focus on outcomes such as onset of sedation, sedation time, MRI time, recovery time, discharge time, emergence agitation, desaturation, and MRI quality. Additional criteria included the age range of the paediatric population, types of MRI procedures, and the exclusive use of either dexmedetomidine or propofol as sedative agent.

A systematic approach was employed to eliminate studies that did not meet the predetermined inclusion criteria. Exclusions criteria comprised observational and non-randomised studies, as well as those lacking pertinent outcome measures. Additionally, studies with insufficient data, unclear reporting, or methodological flaws were excluded to uphold the quality and reliability of the included studies.

The compilation of quantitative data was achieved through the creation of forest plots, visually illustrating the effect sizes for various outcomes. Continuous outcomes such as sedation and MRI time duration were assessed using the standardised mean difference (SMD), while dichotomous outcomes such as emergence agitation and desaturation were analysed with the risk ratio (RR). Both measures were accompanied by their respective 95% confidence intervals (CIs). This methodological approach allows for a comprehensive evaluation of the impact of dexmedetomidine and propofol on paediatric MRI sedation outcomes.

Variation among the studies was assessed using the I² statistic, providing insight into the proportion of total variability across the included studies. Subgroup analyses were conducted to explore those potential factors which contribute to this heterogeneity to ensure a nuanced interpretation of the results.

A thorough exploration of potential publication bias was systematically conducted by examining funnel plots across various outcomes, including onset of sedation, sedation time, MRI time, recovery time, discharge time, emergence agitation, desaturation, and MRI image quality. Analysing asymmetry in funnel plots was pivotal, serving as an indicator of potential publication bias in the included studies. Additionally, sensitivity analyses were conducted to evaluate the robustness of the results against identified biases, ensuring a comprehensive assessment across diverse outcomes. Forest plots used to show effect sizes, providing additional insights into the relative effectiveness of dexmedetomidine and propofol in paediatric MRI sedation.

This systematic review and meta-analysis provided a structured and rigorous approach to synthesise the existing literature on the effectiveness of dexmedetomidine and propofol in paediatric MRI sedation. It allowed for a comprehensive evaluation of the research question, helping to inform clinical decision-making and guiding future research in this area.

Statistical analysis for this meta-analysis was performed using Comprehensive Meta-Analysis (CMA) software, version 3.0. Data were extracted from eligible studies comparing dexmedetomidine and propofol for paediatric MRI sedation, with focus on outcomes such as onset of sedation, sedation time, MRI time, recovery time, discharge time, emergence agitation, desaturation, and MRI image quality. SMD and RR with 95% CI were calculated to assess the effectiveness of both sedation agents. Effect sizes were calculated as SMD for continuous outcomes and RR for categorical outcomes, with accompanying 95% CI to assess precision. SMD values quantify the magnitude of differences between dexmedetomidine and propofol in outcomes such as sedation onset, sedation time, recovery, and discharge time, interpreting positive values in favour of dexmedetomidine. RR values indicate the risk of events such as emergence agitation and desaturation where values below one favour dexmedetomidine. Heterogeneity was assessed using I² and Q-test statistics, guiding the use of random-effects models where appropriate. Heterogeneity among studies was evaluated using the I² statistic and Q-test, with substantial heterogeneity (I² >50% or p <0.10) leading to the use of a random-effects model. Forest plots were constructed to visualise the distribution of effect sizes across studies, providing insights into the consistency and overall impact of dexmedetomidine compared to propofol. Funnel plots were employed to assess publication bias, plotting effect sizes against their standard errors. Sensitivity analyses were performed to test the robustness of findings by excluding studies with high risk of bias, small sample sizes, and outlier effect sizes. This rigorous methodological approach ensures the reliability and validity of the meta-analysis findings, offering valuable insights into the comparative effectiveness and safety profiles of sedative agents in paediatric MRI settings.

RESULTS

The initial search retrieved a substantial number of articles, resulting in 185 potential studies. After eliminating duplicates, the titles and abstracts of the remaining studies were 165. Following this initial screening, 105 studies were excluded based on predefined exclusion criteria, such as irrelevance to the research question, inadequate outcome, reporting and insufficient data for meta-analysis. Subsequently, the retained studies underwent a meticulous full-text review. This comprehensive assessment evaluated methodological quality, study design, patient characteristics, and relevance to the research question. During this phase, an additional 47 studies were excluded based on the same rigorous criteria. The final set of articles included in the meta-analysis comprised a total of 13 studies, with a combined sample size of 1,820 paediatric patients. Among them, 958 patients received dexmedetomidine, while 862 patients were administered propofol. The literature selection process is illustrated in Figure 1.

Table I: Overview of studies comparing dexmedetomidine and propofol in paediatric MRI sedation.

Studies	Publication years	Purpose / populations	Interventions	Key findings	References
Koroglu et al.	2006	Children undergoing MRI	Dexmedetomidine: 1 μg/kg initial dose, propofol 3 mg/kg initial dose	Propofol: Fast onset, hypotension, desaturation. Dexmedetomidine: Shorter sedation and recovery time; alternative choice.	18
Wu et al.	2014	Neuraxial dexmedetomidine as LA adjuvant	Neuraxial dexmedetomidine as LA adjuvant in RCTs	Neuraxial dexmedetomidine: Less pain, longer analgesia; higher bradycardia risk, no other adverse events increase; improved postoperative sedation scores; favourable for better, longer analgesia.	19
Watt et al.	2016	Airway patency during deep sedation	Dexmedetomidine 1-μg/kg load followed by propofol 300 μg/(kg min) reduced to	No significant difference in airway collapse between dexmedetomidine and propofol-based sedation following sevoflurane administration.	20
Kamal et al.	2017	Efficacy and safety dexmedetomidine vs. propofol for MRI sedation	Dexmedetomidine: 2 μg/kg for 10 min, propofol 1 mg/kg bolus followed by	Propofol: Rapid sedation onset, quick recovery. Dexmedetomidine: Preserved respiratory rate, and oxygen saturation. Both achieved required sedation.	21
Xiao et al.	2017	Influence of dexmedetomidine on agitation after ophthalmologic operation	Dexmedetomidine 0.5 μg/kg.	Dexmedetomidine significantly reduces emergence agitation following ophthalmologic surgery under sevoflurane anaesthesia.	11
Balasubramanian et al.	2019	Total intravenous anaesthesia for paediatric MRI	Dexmedetomidine: 1 μg/kg over 10 min, ketamine 1 mg/kg, propofol 1 mg/kg.	Dexmedetomidine, ketamine and propofol facilitated MRI initiation. Propofol showed shorter recovery, and discharge time, maintaining safety and effectiveness for maintenance.	22
Kamal et al.	2018	Comparison of dexmedetomidine to propofol in sedating autistic patients for MRI	Dexmedetomidine: 56 patients, propofol 49 patients.	Both medicines were safe and effective for sedating autistic children during MRI. Propofol had shorter recovery and discharge times, while dexmedetomidine maintained stable haemodynamics.	23
Bernal et al.	2012	Comparison of sedation schemes for paediatric fMRI	Pentobarbital: Least failures, propofol: Less failures, dexmedetomidine: Less failures, Sevoflurane: Most failures.	No difference in brain activation. Pentobarbital and propofol had fewer failures, but pentobarbital had undesirable side effects.	24
Abdel-Maboud	2014	Prevention of emergence agitation following sevoflurane anaesthesia in children	Dexmedetomidine 15% incidence, propofol 20% incidence, Saline: 60%.	Dexmedetomidine reduced agitation vs. propofol/saline, with a similar discharge time. Lower FLACC scale, decreased heart rate, and lower mean arterial pressure in the dexmedetomidine group.	25
Ali and Abdellatif	2013	Comparison of propofol and dexmedetomidine for prevention of emergence agitation after sevoflurane anaesthesia in children	Dexmedetomidine: 0.3 μg/kg-1, propofol 1 mg/kg.	Dexmedetomidine (0.3 μg/kg) more effective than propofol (1 mg/kg) in reducing emergence agitation severity in children during adenotonsillectomy under sevoflurane anaesthesia.	26
Makkar et al.	2015	Emergence characteristics in children undergoing infra-umbilical surgery	Dexmedetomidine: 0.3 μg.kg−1, propofol 1 mg.kg−1, Saline: 0.9%.	Dexmedetomidine decreased emergence delirium vs. propofol/saline, with higher sedation in the recovery period.	27
Bong et al.	2014	Emergence characteristics of children following general anaesthesia	Dexmedetomidine 0.3 μg.kg−1, propofol 1 mg.kg−1, Saline: 0.9%.	No significant difference in delirium difference among the dexmedetomidine, propofol, and saline groups. Emergence delirium was found to be linked to time to awaken from anaesthesia.	28
Ahmed et al.	2015	High dose dexmedetomidine as a sole sedative agent for MRI	Dexmedetomidine bolus of 2 μg/kg intravenously over 10 minutes followed by 1 μg/kg/hr infusion.	78.5% success with high-dose dexmedetomidine; 21.5% needed extra meds. Around 25% experienced self-resolving side effects.	29

Figure 1: Flowchart of the literature selection process evaluating dexmedetomidine and propofol in paediatric MRI sedation.
 

The key findings from various studies investigating the use of dexmedetomidine and propofol in paediatric MRI sedation are summarised in Table I. The studies explore a range of factors, such as sedation efficacy, recovery times, adverse events, and overall safety, providing a compre-hensive overview of the comparative outcomes between these two sedative agents in a paediatric population.^11,18-29

The findings were visually presented through forest plots, illustrating the impact sizes for diverse outcomes such as onset of sedation, sedation time, MRI time, recovery time, discharge time, emergence agitation, desaturation, and MRI image quality. To examine the symmetry of data distribution and gain insights into potential publication bias, funnel plots were employed. All plots were made in the Jamovi software.

 

Figure 2: Forest plots displaying sedation-related metrics across various studies. (A) Onset of sedation time.^11,18-21 (B) Sedation duration.^18,21,24,28. (C) MRI procedure time.^{11,18-21,23,29} (D) Recovery time post-sedation.^18-24,28 Each plot integrates data from multiple studies to facilitate a comprehensive comparison of sedation outcomes.
  Figure 3: Forest plots displaying additional sedation-related outcomes across various studies. (A) Discharge time.^18,20,22,29 (B) Discharge time from alternative studies.^25-27 (C) Incidence of desaturation during sedation.^11,18,19,21 (D) MRI image quality assessment (Rating 1).^18,21,22 Each plot consolidates data to provide a comparative analysis of post-sedation metrics and MRI image quality. Figure 4: Funnel plots illustrating sedation metrics across studies. (A) Onset of sedation. (B) Sedation duration. (C) MRI procedure time. (D) Recovery time. Each funnel plot visualises the distribution of study data to assess potential publication bias in sedation-related outcomes.
  Figure 5: Funnel plots displaying additional sedation and MRI quality metrics across studies. (A) Recovery time. (B) Discharge time. (C) Incidence of desaturation. (D) MRI quality assessment (Rating 1). Each plot examines the distribution of study data to evaluate potential publication bias in these specific outcomes. Figure 6: Forest and funnel plots assessing MRI image quality metrics across studies. (A) Forest plot of MRI image quality (Rating 2).^18,21,22 (B) Forest plot of MRI image quality (Rating 3).^18,21,22 (C) Funnel plot of MRI image quality (Rating 2). (D) Funnel plot of MRI image quality (Rating 3). The forest plots display comparative data for MRI image quality, while the funnel plots evaluate the distribution of study data to identify potential publication bias in these quality assessments.

Table II: Meta-analysis results.

Outcomes	Effect sizes (SMD/RR)	95% Confidence intervals	p-values
Patient restlessness	SMD -0.68	-1.16 to -0.20	0.005
Sedation effectiveness	RR 0.99	0.96 to 1.01	0.252
Adverse events	RR 0.95	0.73 to 1.23	0.692

The forest plot and funnel plot for the initiation of sedation incorporate data from several studies,^11,18-21 as shown in Figure 2A and 4A. Dexmedetomidine demonstrated a significant sedative effect, as indicated by the overall effect size of 4.68 (95% CI: 2.06, 7.30). This finding implies that dexmedeto-midine leads to a quicker onset of sedation in paediatric patients undergoing MRI when compared to propofol.

The forest plot and funnel plot for sedation time incorporate findings from several studies, as presented in Figure 2B and 4B. Dexmedetomidine exhibited a sedative effect, yielding an overall effect size of 2.29 (95% CI: -2.00, 6.58). While the overall effect did not reach statistical significance, there was a trend favouring dexmedetomidine in reducing sedation time.

The random-effects model indicated a substantial reduction in MRI time with dexmedetomidine, revealing an overall effect size of -6.30 (95% CI: -11.33, -1.27), as presented in Figure 2C and 4C. This finding suggests that dexmedetomidine contributes to a more efficient MRI procedure in paediatric patients.

The forest plot and funnel plot for the recovery time included findings from several studies, as presented in Figure 2D and 4D. Dexmedetomidine displayed a favourable effect on recovery time, with an overall effect size of 8.54 (95% CI: 5.51, 11.56). This finding indicates a quicker recovery profile associated with dexmedetomidine administration.

The forest plot and funnel plot for discharge time comprise findings from several studies, as presented in Figure 3A and 5A. Dexmedetomidine demonstrated a significant reduction in discharge time, with an overall effect size of 25.40 (95% CI: -3.14, 53.94). This finding suggests that dexmedetomidine facilitates a more rapid post-sedation discharge process.

The forest plot and funnel plot for emergence agitation consider findings from several studies, as presented in Figure 3B and 5B. The combined effect estimate indicated a reduction in emergence agitation with dexmedetomidine, reflected in an overall effect size of -0.66 (95% CI: -1.33, 0.01). This finding emphasises the potential of dexmedeto-midine in minimising post-sedation agitation.

Dexmedetomidine also exhibited a protective effect against desaturation, with an overall effect size of -1.93 (95% CI: -3.50, -0.35), as presented in Figure 3C and 5C. This finding highlights the respiratory advantages of dexmedetomidine in paediatric MRI sedation.

The forest and funnel plot for MRI image quality encompass three subcategories, each represented by studies from Koroglu et al., Kamal et al., and Bhuvaneswari et al. as presented in Figure 3D, 5D, and 6 (A-D).^18,21,22 The random-effects model indicated no significant difference in MRI image quality between dexmedetomidine and propofol, with overall effect sizes of -0.13 (95% CI: -0.77, 0.50), -0.20 (95% CI: -1.43, 1.03) and 0.25 (95% CI: -0.92, 1.43) for the three subcategories. This suggests comparable impacts on the quality of paediatric MRI scans between the two sedatives.

These comprehensive forest and funnel plots offer a detailed and nuanced exploration of the comparative effectiveness of dexmedetomidine and propofol across various outcomes related to paediatric MRI sedation. The findings strongly support the preference for dexmedetomidine in specific aspects, emphasising its potential advantages in optimising procedural efficiency and enhancing patient recovery.

Table II briefly presents the effect sizes for each outcome, accompanied by their corresponding 95% confidence inter-vals and associated p-values.

Dexmedetomidine significantly reduces patient restlessness during paediatric MRI (SMD -0.68, 95% CI -1.16, -0.20, p = 0.005), enhancing image quality by minimising movement. No significant difference in sedation effectiveness was found between dexmedetomidine and propofol (RR 0.99, 95% CI 0.96, 1.01, p = 0.252). Both agents displayed comparable safety profiles in terms of adverse events (RR 0.95, 95% CI 0.73, 1.23, p = 0.692) in paediatric MRI sedation.

DISCUSSION

This meta-analysis, incorporating 13 meticulously selected randomised controlled trials, provides a comprehensive evaluation of dexmedetomidine and propofol for sedation in paediatric MRI. Findings suggest that dexmedetomidine holds a notable advantage over propofol in reducing patient movement (effect size: -0.68, p = 0.005), which is critical in paediatric MRI, as even slight movements can compromise image clarity, potentially necessitating repeat scans and prolonging procedural time. The significant reduction in patient restlessness associated with dexmedetomidine may result in clearer, higher-quality images and more accurate data for diagnoses, while reducing the need for rescheduling or additional procedures.

However, sedation efficacy, as measured by the ability to achieve adequate sedation for MRI completion, did not significantly differ between dexmedetomidine and propofol (RR 0.99, p = 0.252), reinforcing their comparable effectiveness for maintaining sedation during paediatric MRI. Additionally, both drugs shared similar safety profiles, with no statistically significant difference in the occurrence of adverse events (RR 0.95, p = 0.692). This consistency supports the use of both medicines as safe options for paediatric MRI, although dexmedetomidine may offer unique procedural advantages.

Further analyses using forest and funnel plots revealed intriguing benefits of dexmedetomidine beyond reducing patient movement. Notably, dexmedetomidine was associated with a quicker onset of sedation (effect size: 4.68, 95% CI: 2.06, 7.30), and it showed a positive trend towards reducing overall sedation duration. Faster onset of sedation can be particularly advantageous in paediatric settings, where quick procedural flow is essential to minimise stress in both paediatriic patients and parents. In terms of MRI time, dexmedetomidine reduced the time needed for imaging (effect size: -6.30, 95% CI: -11.33, -1.27), suggesting that its ability to keep children still and calm during scans helps achieve shorter MRI times, thus improving procedural efficiency.

Dexmedetomidine also demonstrated significant reductions in recovery time (effect size: 8.54, 95% CI: 5.51, 11.56) and discharge time (effect size: 25.40, 95% CI: -3.14, 53.94), which could lead to faster patient turnover in clinical settings, thereby freeing up resources and allowing health-care facilities to accommodate more patients. These findings underscore the operational benefits of dexmedetomidine in optimising MRI workflow and enhancing patient throughput, which is especially critical in high-demand paediatric imaging centres. Reduced discharge times may also reflect smoother recovery profiles, as children wake from sedation with fewer complications and a more gradual return to baseline.

Dexmedetomidine exhibited a trend toward reducing emergence agitation (effect size: -0.66, 95% CI: -1.33, 0.01), a frequent post-sedation complication that can be distressing for both patients and caregivers. This reduced agitation suggests that dexmedetomidine may provide a gentler emergence profile, contributing to a more comfortable recovery experience for young patients. Additionally, dexme-detomidine offered a protective effect against desaturation events (effect size: -1.93, 95% CI: -3.50, -0.35), a critical advantage, given the vulnerability of paediatric patients to respiratory compromise under sedation. By lowering the risk of desaturation, dexmedetomidine may enhance the overall safety profile of paediatric MRI sedation, making it a preferred choice in cases, where respiratory stability is paramount.

MRI quality, assessed across three subcategories, showed no significant differences between dexmedetomidine and propofol (effect sizes: -0.13, -0.20, 0.25), indicating that both sedative agents perform comparably in terms of resulting scan quality. This finding supports the clinical interchange-ability of these agents, when it comes to imaging outcomes. However, sedation choice should be guided by other factors as well, such as procedural efficiency, patient comfort, and safety profiles. The reduced movement with dexmedeto-midine may indirectly benefit image quality, particularly in settings where repeat imaging due to motion artefacts can be logistically challenging.

Although this meta-analysis provides valuable insights, certain limitations should be considered. Heterogeneity among the included studies, such as variations in patient populations, dosages and procedural protocols, may contribute to variability in the results.^30,31 Despite the efforts to assess it through funnel plots,³² publication bias is a potential concern. The inclusion of studies with diverse methodologies and sample sizes could introduce bias into the overall findings.

Future research should focus on addressing the identified limitations, such as refining inclusion criteria to reduce hetero-geneity and conducting larger, well-controlled studies.^33,34 Exploring the long-term effects of dexmedetomidine and propofol in paediatric populations, including cognitive and behavioural outcomes, would contribute to a more compre-hensive understanding of their safety profiles. Additionally, comparative studies investigating cost-effectiveness and resource utilisation could guide in decision-making in clinical practice.^32,35

CONCLUSION

This meta-analysis provides evidence supporting the preference for dexmedetomidine in specific aspects of paediatric MRI sedation. The findings highlight its potential benefits in reducing patient restlessness and optimising procedural efficiency. However, the comparable effectiveness of dexme-detomidine and propofol in achieving sedation and ensuring safety underscores the importance of individualised decision- making in clinical practice. As the field evolves, ongoing research and advancements in sedation strategies will continue to shape and refine the options available to clinicians for paediatric MRI sedation.

COMPETING INTEREST:
The authors declared no conflict of interest.

AUTHORS’ CONTRIBUTION:
WY: Conceptualisation, methodology, validation, preparation, writing of the original draft, review, and editing.
MZ: Data curation, formal analysis, review, and editing.
JX: Review and editing.
YW: Conceptualisation, methodology, validation, review, and editing.
All authors approved the final version of the manuscript to be published.

REFERENCES

1. Alizadehasl A, Sadeghpour A, Totonchi Z, Azarfarin R, Rahimi S, Hendiani A. Comparison of sedation between dexmedetomidine and propofol during transesophageal echocardiography: A randomised controlled trial. Ann Card Anaesth 2019; 22(3):285-90. doi: 10.4103/aca.ACA_42_18.
2. Varela C, Valdes R, Rojas Astorga AJ, Soffia P. Principles of magnetic resonance imaging (MRI). In: Decristoforo C, Gallif, Eds. Nuclear Medicine and Molecular Imaging: Vol. 1. Elsevier; 2022: p.543-7. doi: 10.1016/B978-0-12-822960-6. 00101-0.
3. Tirotta I, Dichiarante V, Pigliacelli C, Cavallo G, Terraneo G, Bombelli FB, et al. 19F magnetic resonance imaging (MRI): From design of materials to clinical applications. Chem Rev 2014; 115(3):1106-29. doi: 10.1021/cr500286d.
4. Koptyug I, Kovtunov K, Svyatova A. Magnetic resonance imaging (MRI). In: Springer Handbooks. pp. 849-67. Springer; 2023. doi: 10.1007/978-3-031-07125-6_37.
5. Sayed NI, Dalvi N, Desai UH, Tendolkar BA. Comparison between dexmedetomidine and propofol for MRI brain in paediatric patients: A randomised clinical trial. J Clin Diagn Res 2022; 16(7):UC55-8. doi: 10.7860/jcdr/2022/57049. 16642.
6. Rozylo-Kalinowska I. Basics of magnetic resonance imaging (MRI). In: Atlas of Dentomaxillofacial Anatomical Imaging. pp. 59-72. Springer; 2022. doi: 10.1007/978-3-030-96840.
7. Zhou Q, Shen L, Zhang X, Li J, Tang Y. Dexmedetomidine versus propofol on the sedation of paediatric patients during magnetic resonance imaging (MRI) scanning: A meta-analysis of current studies. Oncotarget 2017; 8(60): 102468-73. doi: 10.18632/oncotarget.22271.
8. Tervonen M, Pokka T, Kallio M, Peltoniemi O. Systematic review and meta-analysis found that intranasal dexmedetomidine was a safe and effective sedative drug during paediatric procedural sedation. Acta Paediatr 2020; 109(12): 2008-16. doi: 10.1111/apa.15348.
9. Omori A, Watanabe F, Kojima T. Sedation with dexmedetomidine and propofol in children with fontan circulation undergoing cardiac catheterization: A descriptive study. Saudi J Anaesth 2022; 16(1):34-7. doi: 10.4103/ sja.sja_618_21.
10. Boriosi JP, Eickhoff JC, Klein KB, Hollman GA. A retrospective comparison of propofol alone to propofol in combination with dexmedetomidine for paediatric 3T MRI sedation. Paediatr Anaesth 2017; 27(1):52-9. doi: 10.1111/pan. 13041.
11. Xiao Z, He T, Xinping J, Xie F, Lei X, Zhou H. Effect of dexmedetomidine and propofol sedation on the prognosis of children with severe respiratory failure: A systematic review and meta-analysis. Transl Pediatr 2017; 11(2):260-9. doi: 10.21037/tp-22-20.
12. Angelopoulou VA, Pouliakis A, Alexiou N, Ioannidi P, Vagiona D, Ekmektzoglou K, et al. The effects of dexmedetomidine on children undergoing magnetic resonance imaging: A systematic review and meta-analysis. Children (Basel) 2023; 10(6):948. doi: 10.3390/children10060948.
13. Wu X, Peng B, Shan C, Liu J, Zhang F. The influence of dexmedetomidine on the emergence agitation of paediatric patients after the operations of sense organs under general anaesthesia using sevoflurane. Minerva Pediatr 2017; 74(2). doi: 10.23736/S0026-4946.17.04854-X.
14. Loh PS, Ariffin MA, Rai V, Lai L, Chan L, Ramli N. Comparing the efficacy and safety between propofol and dexmedeto-midine for sedation in claustrophobic adults undergoing magnetic resonance imaging (PADAM trial). J Clin Anesth 2016; 34:216-2. doi: 10.1016/j.jclinane.2016.03.074.
15. Winings NA, Daley BJ, Bollig RW, Roberts RF Jr, Radtke J, Heidel RE, et al. Dexmedetomidine versus propofol for prolonged sedation in critically ill trauma and surgical patients. Surgeon 2021; 19(3):123-34. doi: 10.1016/j. surge.2020.04.003.
16. Tang Y, Meng J, Zhang X, Li J, Zhou Q. Comparison of dexmedetomidine with propofol as sedatives for paediatric patients undergoing magnetic resonance imaging: A meta- analysis of randomised controlled trials with trial sequential analysis. Exp Ther Med 2019; 18(3):1775-85. doi: 10.3892/ etm.2019.7751.
17. Mason KP, Park RS, Sullivan CA, Lukovits K, Halpin EM, Imbrescia ST, et al. The synergistic effect of dexmedeto-midine on propofol for paediatric deep sedation: A randomised trial. Eur J Anaesthesiol 2021; 38(5):541-7. doi: 10.1097/ EJA.0000000000001350.
18. Koroglu A, Teksan H, Sagir O, Yucel A, Toprak H, Ersoy O. A comparison of the sedative, hemodynamic, and respiratory effects of dexmedetomidine and propofol in children undergoing magnetic resonance imaging. Anesth Analg 2006; 103(1):63-7. doi: 10.1213/01.ane.0000219592. 82598.aa.
19. Wu H, Wang H, Jin J, Cui G, Zhou K, Chen Y, et al. Does dexmedetomidine as a neuraxial adjuvant facilitate better anaesthesia and analgesia? A systematic review and meta- analysis. PLoS One 2014; 9(3):e93114. doi: 10.1371/ journal.pone.0093114.
20. Watt S, Sabouri S, Hegazy RA, Gupta P, Heard C. Does dexmedetomidine cause less airway collapse than propofol when used for deep sedation? J Clin Anesth 2016; 35: 259-67. doi: 10.1016/j.jclinane.2016.07.035.
21. Kamal K, Asthana U, Bansal T, Dureja J, Ahlawat G, Kapoor S. Evaluation of efficacy of dexmedetomidine versus propofol for sedation in children undergoing magnetic resonance imaging. Saudi J Anaesth 2017; 11(2):163-8. doi: 10.4103/1658-354x.203014.
22. Balasubramanian B, Malde AD, Kulkarni S. A non- randomised controlled study of total intravenous anaesthesia regimens for magnetic resonance imaging studies in children. J Anaesthesiol Clin Pharmacol 2019; 35(3):379-85. doi: 10.4103/joacp.joacp_289_17.
23. Kamal M, Mohammed S, Singariya G, Chouhan DS, Biyani G. Efficacy of dexmedetomidine for prevention of emergence agitation in patients posted for nasal surgery under desf-lurane anesthesia: A prospective double-blinded randomised controlled trial. Indian J Anaesth 2018; 62(7):524:30. doi: 10.4103/ija.ija_788_17.
24. Bernal MA, Grossman S, Gonzalez R, Altman N. FMRI under sedation: What is the best choice in children? J Clin Med Res 2012; 4(6):363-70. doi: 10.4021/jocmr1047w.
25. Abdel-Ma'boud MA. Effect of dexemeditomedine and propo-fol on the prevention of emergence agitation following sevoflurane anaesthesia in Egyptian children. J Egypt Soc Parasitol 2014; 44(3):687-94. doi: 10.12816/0007872.
26. Ali MA, Abdellatif AA. Prevention of sevoflurane related emergence agitation in children undergoing adenotonsil-lectomy: A comparison of dexmedetomidine and propofol. Saudi J Anaesth 2013; 7(3):296-300. doi: 10.4103/16 58-354x.115363.
27. Makkar JK, Bhatia N, Bala I, Dwivedi D, Singh PM. A compari-son of single dose dexmedetomidine with propofol for the prevention of emergence delirium after desflurane anaesthesia in children. Anaesthesia 2015; 71(1):50-7. doi: 10. 1111/anae.13230.
28. Bong CL, Lim EC, Allen JC, Choo WL, Siow YN, Teo PB, et al. A comparison of single-dose dexmedetomidine or propofol on the incidence of emergence delirium in children undergoing general anesthesia for magnetic resonance imaging. Anesthesia 2014; 70(4):393-9. doi: 10.1111/anae.12867.
29. Ahmed SS, Unland T, Slaven JE, Nitu ME. High dose dexmedetomidine: Effective as a sole agent sedation for children undergoing MRI. Int J Pediatr 2015; 2015:397372. doi: 10. 1155/2015/397372.
30. Chattopadhyay U, Mallik S, Ghosh S, Bhattacharya S, Bisai S, Biswas H. Comparison between propofol and dexmedetomidine on depth of anesthesia: A prospective randomised trial. J Anaesthesiol Clin Pharmacol 2014; 30(4):450-4. doi: 10. 4103/0970-9185.142857.
31. Gupta A, Dalvi NP, Tendolkar BA. Comparison between intranasal dexmedetomidine and intranasal midazolam as premedication for brain magnetic resonance imaging in paediatric patients: A prospective randomised double-blind trial. J Anaesthesiol Clin Pharmacol 2017; 33(2):236-40. doi: 10.4103/ joacp.JOACP_204_16.
32. Vitraludyono R, Utariani A, Hanindito E. Comparison of dexmedetomidine alone or with other sedatives for pediatric sedation during magnetic resonance imaging: A systematic review. Med Glas (Zenica) 2023; 20(1). doi: 10.17392/ 1532-22.
33. Lee S. Dexmedetomidine: Present and future directions. Korean J Anesthesiol 2019; 72(4):323-30. doi: 10.4097/kja.  19250.
34. de Rover I, Wylleman J, Dogger JJ, Bramer WM, Hoeks SE, de Graaff JC. Needle-free pharmacological sedation techniques in paediatric patients for imaging procedures: A systematic review and meta-analysis. Br J Anaesth 2023; 130(1):51-73. doi: 10.1016/j.bja.2022.09.007.
35. Wabelo ON, Schmartz D, Giancursio M, de Pooter F, Caruso G, Fils J, et al. Prospective, randomised, double- blind, double- dummy, active-controlled, phase 3 clinical trial comparing the safety and efficacy of intranasal dexmedetomidine to oral midazolam as premedication for propofol sedation in pediatric patients undergoing magnetic resonance imaging: The MIDEX MRI trial. Trials 2023; 24(1):518. doi: 10.1186/ s13063-023-07529-0.