Assessing accuracy of resonances obtained with reassigned spectrograms from the "ground truth" of physical vocal tract models.

The reassigned spectrogram (RS) has emerged as the most accurate way to infer vocal tract resonances from the acoustic signal [Shadle, Nam, and Whalen (2016). "Comparing measurement errors for formants in synthetic and natural vowels," J. Acoust. Soc. Am. 139(2), 713-727]. To date, validating its accuracy has depended on formant synthesis for ground truth values of these resonances. Synthesis is easily controlled, but it has many intrinsic assumptions that do not necessarily accurately realize the acoustics in the way that physical resonances would. Here, we show that physical models of the vocal tract with derivable resonance values allow a separate approach to the ground truth, with a different range of limitations. Our three-dimensional printed vocal tract models were excited by white noise, allowing an accurate determination of the resonance frequencies. Then, sources with a range of fundamental frequencies were implemented, allowing a direct assessment of whether RS avoided the systematic bias towards the nearest strong harmonic to which other analysis techniques are prone. RS was indeed accurate at fundamental frequencies up to 300 Hz; above that, accuracy was somewhat reduced. Future directions include testing mechanical models with the dimensions of children's vocal tracts and making RS more broadly useful by automating the detection of resonances.

An acoustic study of Cantonese alaryngeal speech in different speaking conditions.

Esophageal (ES) speech, tracheoesophageal (TE) speech, and the electrolarynx (EL) are common methods of communication following the removal of the larynx. Our recent study demonstrated that intelligibility may increase for Cantonese alaryngeal speakers using clear speech (CS) compared to their everyday "habitual speech" (HS), but the reasoning is still unclear [Hui, Cox, Huang, Chen, and Ng (2022). Folia Phoniatr. Logop. 74, 103-111]. The purpose of this study was to assess the acoustic characteristics of vowels and tones produced by Cantonese alaryngeal speakers using HS and CS. Thirty-one alaryngeal speakers (9 EL, 10 ES, and 12 TE speakers) read The North Wind and the Sun passage in HS and CS. Vowel formants, vowel space area (VSA), speaking rate, pitch, and intensity were examined, and their relationship to intelligibility were evaluated. Statistical models suggest that larger VSAs significantly improved intelligibility, but slower speaking rate did not. Vowel and tonal contrasts did not differ between HS and CS for all three groups, but the amount of information encoded in fundamental frequency and intensity differences between high and low tones positively correlated with intelligibility for TE and ES groups, respectively. Continued research is needed to understand the effects of different speaking conditions toward improving acoustic and perceptual characteristics of Cantonese alaryngeal speech.

Refining and extending measures for fricative spectra, with special attention to the high-frequency rangea).

Fricatives have noise sources that are filtered by the vocal tract and that typically possess energy over a much broader range of frequencies than observed for vowels and sonorant consonants. This paper introduces and refines fricative measurements that were designed to reflect underlying articulatory and aerodynamic conditions These show differences in the pattern of high-frequency energy for sibilants vs non-sibilants, voiced vs voiceless fricatives, and non-sibilants differing in place of articulation. The results confirm the utility of a spectral peak measure (FM) and low-mid frequency amplitude difference (AmpD) for sibilants. Using a higher-frequency range for defining FM for female voices for alveolars is justified; a still higher range was considered and rejected. High-frequency maximum amplitude (Fh) and amplitude difference between low- and higher-frequency regions (AmpRange) capture /f-θ/ differences in English and the dynamic amplitude range over the entire spectrum. For this dataset, with spectral information up to 15 kHz, a new measure, HighLevelD, was more effective than previously used LevelD and Slope in showing changes over time within the frication. Finally, isolated words and connected speech differ. This work contributes improved measures of fricative spectra and demonstrates the necessity of including high-frequency energy in those measures.

Formants are easy to measure; resonances, not so much: Lessons from Klatt (1986).

Formants in speech signals are easily identified, largely because formants are defined to be local maxima in the wideband sound spectrum. Sadly, this is not what is of most interest in analyzing speech; instead, resonances of the vocal tract are of interest, and they are much harder to measure. Klatt [(1986). in Proceedings of the Montreal Satellite Symposium on Speech Recognition, 12th International Congress on Acoustics, edited by P. Mermelstein (Canadian Acoustical Society, Montreal), pp. 5-7] showed that estimates of resonances are biased by harmonics while the human ear is not. Several analysis techniques placed the formant closer to a strong harmonic than to the center of the resonance. This "harmonic attraction" can persist with newer algorithms and in hand measurements, and systematic errors can persist even in large corpora. Research has shown that the reassigned spectrogram is less subject to these errors than linear predictive coding and similar measures, but it has not been satisfactorily automated, making its wider use unrealistic. Pending better techniques, the recommendations are (1) acknowledge limitations of current analyses regarding influence of F0 and limits on granularity, (2) report settings more fully, (3) justify settings chosen, and (4) examine the pattern of F0 vs F1 for possible harmonic bias.

The Effect of Clear Speech on Cantonese Alaryngeal Speakers' Intelligibility.

BACKGROUND/AIM: The purpose of this study was to provide preliminary data concerning the effect of clear speech (CS) on Cantonese alaryngeal speakers' intelligibility. METHODS: Voice recordings of 11 sentences randomly selected from the Cantonese Sentence Intelligibility Test (CSIT) were obtained from 31 alaryngeal speakers (9 electrolarynx [EL] users, 10 esophageal speakers and 12 tracheoesophageal [TE] speakers) in habitual speech (HS) and CS. Two naïve listeners orthographically transcribed a total of 1,364 sentences. RESULTS: Significant effects of speaking condition on speaking rate and CSIT scores were observed, but no significant effect of alaryngeal communication methods was noted. CS was significantly slower than HS by 0.78 syllables/s. Esophageal speakers demonstrated the slowest speech rate when using CS, while EL users demonstrated the largest decrease in speaking rate when using CS compared to HS. TE speakers had the highest CSIT scores in HS (listener 1 = 81.4%; listener 2 = 81.3%), and esophageal speakers had the highest CSIT scores in CS (listener 1 = 87.5%; listener 2 = 89.7%). EL users experienced the largest increase in intelligibility while using CS compared to HS (9.1%) followed by esophageal speakers (8.9%) and TE speakers (1.4%). CONCLUSION: Preliminary data indicate that CS may significantly affect Cantonese alaryngeal speakers' speaking rate and intelligibility. However, intelligibility appeared to vary considerably across speakers. Further research involving larger, heterogeneous groups of speakers and listeners alongside longer and more refined CS training protocols should be conducted to confirm that CS can improve Cantonese alaryngeal speakers' intelligibility.

Comparison of auto-contouring and hand-contouring of ultrasound images of the tongue surface.

Contours traced by trained phoneticians have been considered to be the most accurate way to identify the midsagittal tongue surface from ultrasound video frames. In this study, inter-measurer reliability was evaluated using measures that quantified both how closely human-placed contours approximated each other as well as how consistent measurers were in defining the start and end points of contours. High reliability across three measurers was found for all measures, consistent with treating contours placed by trained phoneticians as the 'gold standard.' However, due to the labour-intensive nature of hand-placing contours, automatic algorithms that detect the tongue surface are increasingly being used to extract tongue-surface data from ultrasound videos. Contours placed by six automatic algorithms (SLURP, EdgeTrak, EPCS, and three different configurations of the algorithm provided in Articulate Assistant Advanced) were compared to human-placed contours, with the same measures used to evaluate the consistency of the trained phoneticians. We found that contours defined by SLURP, EdgeTrak, and two of the AAA configurations closely matched the hand-placed contours along sections of the image where the algorithms and humans agreed that there was a discernible contour. All of the algorithms were much less reliable than humans in determining the anterior (tongue-tip) edge of tongue contours. Overall, the contours produced by SLURP, EdgeTrak, and AAA should be useable in a variety of clinical applications, subject to spot-checking. Additional practical considerations of these algorithms are also discussed.

Dexmedetomidine post-treatment attenuates cardiac ischaemia/reperfusion injury by inhibiting apoptosis through HIF-1α signalling.

Hypoxia-inducible factor 1α (HIF-1α) plays a critical role in the apoptotic process during cardiac ischaemia/reperfusion (I/R) injury. This study aimed to investigate whether post-treatment with dexmedetomidine (DEX) could protect against I/R-induced cardiac apoptosis in vivo and in vitro via regulating HIF-1α signalling pathway. Rat myocardial I/R was induced by occluding the left anterior descending artery for 30 minutes followed by 6-hours reperfusion, and cardiomyocyte hypoxia/reoxygenation (H/R) was induced by oxygen-glucose deprivation for 6 hours followed by 3-hours reoxygenation. Dexmedetomidine administration at the beginning of reperfusion or reoxygenation attenuated I/R-induced myocardial injury or H/R-induced cell death, alleviated mitochondrial dysfunction, reduced the number of apoptotic cardiomyocytes, inhibited the activation of HIF-1α and modulated the expressions of apoptosis-related proteins including BCL-2, BAX, BNIP3, cleaved caspase-3 and cleaved PARP. Conversely, the HIF-1α prolyl hydroxylase-2 inhibitor IOX2 partly blocked DEX-mediated cardioprotection both in vivo and in vitro. Mechanistically, DEX down-regulated HIF-1α expression at the post-transcriptional level and inhibited the transcriptional activation of the target gene BNIP3. Post-treatment with DEX protects against cardiac I/R injury in vivo and H/R injury in vitro. These effects are, at least in part, mediated via the inhibition of cell apoptosis by targeting HIF-1α signalling.

F0-induced formant measurement errors result in biased variabilities.

Many developmental studies attribute reduction of acoustic variability to increasing motor control. However, linear prediction-based formant measurements are known to be biased toward the nearest harmonic of F0, especially at high F0s. Thus, the amount of reported formant variability generated by changes in F0 is unknown. Here, 470 000 vowels were synthesized, mimicking statistics reported in four developmental studies, to estimate the proportion of formant variability that can be attributed to F0 bias, as well as other formant measurement errors. Results showed that the F0-induced formant measurements errors are large and systematic, and cannot be eliminated by a large sample size.

Three-dimensional printable ultrasound transducer stabilization system.

When using ultrasound imaging of the tongue for speech recording/research, submental transducer stabilization is required to prevent the ultrasound transducer from translating or rotating in relation to the tongue. An iterative prototype of a lightweight three-dimensional-printable wearable ultrasound transducer stabilization system that allows flexible jaw motion and free head movement is presented. The system is completely non-metallic, eliminating interference with co-recorded signals, thus permitting co-collection and co-registration with articulometry systems. A motion study of the final version demonstrates that transducer rotation is limited to 1.25° and translation to 2.5 mm-well within accepted tolerances.

Vowel coarticulation: Landmark statistics measure vowel aggression.

Regression analysis and mutual information have been used to measure the degree of dependence between a consonant and a vowel, and this has been used to identify the invariance of consonant place and to quantify the coarticulatory resistance of consonants [e.g., Fowler (1994). Percept. Psychophys. 55, 597-610]. This paper presents the first application of this approach to measure coarticulatory properties of vowels, using regression analysis and mutual information on articulatory data of CV syllables produced by seven Taiwan Mandarin speakers. The results show that vowel /i/ shares the most information with the preceding consonant among vowels for the tongue body, whereas vowels /a/ and /u/ are not significantly different from each other in that respect. For the lip articulator, the degree of information sharing for vowels is in the progression: /u/ > /i/ > /a/. Based on the CV model theory of gestural coordination (C-V in-phase relation) and the present results, this study proposes that landmark statistics for vowels reflect the degree of vowel aggression and that V-to-C effect is dominant over C-to-V effect in C-V coarticulation.

Super-imposing maxillary and palatal locations for electroarticulometry: A SIMPLE method.

This study proposes a method of superimposing a physical palatal profile, extracted from a speaker's maxillary impression, onto real-time mid-sagittal articulatory data. A palatal/dental profile is first obtained by three-dimensional-scanning the maxillary impression of the speaker. Then a high resolution mid-sagittal palatal line, extracted from the profile, is sub-divided into articulatory zones and superimposed, by Iterative Closest Point algorithm, onto reconstructed palatal traces in electromagnetic articulometric (EMA) data. Evaluations were carried out by comparing consonant targets elicited by EMA with the proposed method and by static palatography. The proposed method yields accurate results, as supported by palatography.

[Clinical research of anterior chamber inflammation after phacoemulsification surgery in patients with complicated cataract secondary to uveitis].

OBJECTIVE: To investigate anterior chamber inflammation after phacoemulsification with intraocular lens (IOL) implantation in patients with Vogt-Koyanagi-Harada (VKH) syndrome or Behçet's disease (BD). METHODS: Cohort study. Seventeen patients (20 eyes) with complicated cataracts and VKH syndrome or BD who underwent phacoemulsification with IOL implantation at Zhongshan Ophthalmic Center, Sun Yat-Sen University (SYSU) between January 2010 and June 2011 were included as the experimental group in this study. Cataract surgery was performed on these patients only when uveitis had been under control for more than three months. Thirty patients (40 eyes) with age-related cataracts who underwent phacoemulsification with IOL implantation in the same period were included as the control group. Quantitative measurements of anterior chamber aqueous flare and inflammatory cells were conducted preoperatively and postoperatively using a Laser Flare Cell Meter (LFCM). Independent t-test was used to compare patients' ages, and the energy and time of phacoemulsification between the two groups. The Student's t-test was used to assess the differences between paired data preoperatively and postoperatively. Independent t-test was also used to assess the quantitative data between groups. RESULTS: The study recruited 20 eyes in the experimental group and 40 eyes in the control group, including 11 eyes from 9 VKH patients and 9 eyes from 8 BD patients. The preoperative and postoperative flare values in the experimental group were (19.86 ± 6.47), (44.28 ± 18.47), (35.60 ± 12.65), (23.85 ± 8.41), and (13.86 ± 4.27) pc/ms, respectively, which were statistically higher than that of the control group preoperatively, and on days 1, 7, 30, and 90 after surgery (tpre = 4.643, Ppre < 0.01; t1 = 6.035, P1 < 0.01; t7 = 3.595, P7 = 0.001; t30 = 4.658, P30 < 0.01; t90 = 3.308, P90 = 0.002). Aqueous flare in Group A and Group B declined to preoperative levels on day 30 (t = 0.320, P = 0.753) and day 7 (t = 0.454, P = 0.653). For the experimental group, the inflammatory cell count on day 1 and 7 was (83.46 ± 27.08) and (27.56 ± 8.32) cells/0.5 mm(3), respectively, which was significantly higher than the preoperative level [(6.47 ± 3.56)cells/ 0.5 mm(3), t1 = 5.261, P1 < 0.01; t7 = 2.766, P7 = 0.012]. On days 30 and 90, the inflammatory cell count was (11.43 ± 4.81) and (4.82 ± 2.29) cells/0.5 mm(3), respectively, and there was no statistically significant difference in the inflammatory cell count compared with the preoperative level (t30 = 2.348, P30 = 0.042; t90 = 1.376, P90 = 0.186). For the control group, inflammatory cell count reduced to pre-operative level on day 7 (t7 = 2.464, P7 = 0.018). CONCLUSIONS: Anterior chamber inflammation reaches peak levels one week postoperatively in VKH and BD patients who receive phacoemulsification with IOL implantation. It takes three months for the inflammation to recede, and might take longer for complete restoration of the blood-aqueous barrier.

"Capsule drape wrap"-a new technology for iridoschisis management during phacoemulsification.

AIM: To introduce a new technique for iridoschisis management during phacoemulsification: "capsule drape wrap". METHODS: "Capsule drape wrap" technique was used for an 80-year-old man with idiopathic iridoschisis in the right eye during phacoemulsification. The inserted flexible nylon iris hooks to hold anterior capsule in place, the margin of the anterior capsule could act as drape wrap, tracking the fibrillary iris strands firmly from free floating and stabilizing the capsular bags simultaneously. RESULTS: The eye with iridoschisis was successfully treated. Iris fibrils remained immobile during the procedure, and despite the severity of iridoschisis, there were no intraoperative complications such as tear of the iris, hyphema, iris prolapse, loss of mydriasis, or rupture of the posterior lens capsule during phacoemulsification. The best-corrected visual acuity was increased by 0.1 (logMAR) 6mo after the surgery. CONCLUSION: "Capsule drape wrap" for iridoschisis is easily manageable, prevents further disruption to the loose iris fibers and ensures the stability of capsule-iris complex simultaneously, consequently minimizing the risk of surgical complications in phacoemulsification.

Transient vacuolar changes of the crystalline lens in patients using a dispersive ophthalmic viscosurgical device.

AIM: To report the clinical prognosis and pathological findings of accidental lens vacuolar changes in eyes with intraoperative exposure to a dispersive ophthalmic viscosurgical device (OVD). METHODS: Two patients who developed transient lens vacuolar changes during uneventful persistent pupillary membrane (PPM) removal surgery were presented and followed up. This event was speculated to be associated with an intraoperative dispersive OVD DisCoVisc (hyaluronic acid 1.6%-chondroitin sulfate 4.0%) exposure. Then, to provide the pathological basis for our speculation, another four cataract patients were randomly exposed to different OVDs, and their anterior lens capsules were investigated with transmission electron microscopy (TEM). RESULTS: After months, the subcapsular vacuoles in both PPM cases were gradually disappeared without visual deterioration. For the cataract patients, similar lens changes were observed intraoperatively in those exposed to a dispersive DisCoVisc but not a cohesive OVD IVIZ (sodium hyaluronate gel 1.0%). In addition, marked ultrastructural changes, including chromatin condensation, extensive cytoplasmic vacuoles, and obvious intercellular space between lens epithelial cells in the anterior lens capsules of all eyes exposed to DisCoVisc, were observed by TEM. CONCLUSION: The lens vacuolar changes may be associated with a dispersive OVD exposure. Therefore, it is not preferable to use dispersive OVDs in patients with transparent lenses or without the intention of lens extraction. In addition, close follow-ups instead of immediate lens extraction are recommended for the occurrence of similar lens lesions.

Extreme stop allophony in Mixtec spontaneous speech: data, word prosody, and modelling.

Word-level prosody plays an important role in processes of consonant lenition. Typically, consonants in word-initial position are strengthened while those in word-medial position are lenited (Keating et al., 2003). In this paper we examine the relationship between wordprosodic position and obstruent lenition in a spontaneous speech corpus of Yoloxóchitl Mixtec, an endangered Mixtecan language spoken in Mexico. The language exhibits a surprising amount of lenition in the realization of otherwise voiceless unaspirated stops and voiceless fricatives in careful speech. In Experiment 1, we examine the relationships between word position, consonant duration, and passive voicing and find that word-medial pre-tonic position is the locus of both consonant lengthening and less passive voicing. Non-pre-tonic consonants are produced with more voicing and shorter duration. We also find that the functional status of the morpheme plays a role in voicing lenition. In Experiment 2, we examine manner lenition and find a similar pattern - word-medial pre-tonic stops are more often realized with complete closure relative to non-pre-tonic stops, which are more often realized with incomplete closure. In Experiment 3, we model these lenition patterns using a series of deep neural networks and find that, even with limited training data, we can achieve reasonably high accuracy in the automatic categorization of lenition patterns. The results of this research both complement recent work on the phonetics of lenition in the world's languages (Katz and Fricke, 2018; White et al., 2020) and provide computational tools for modeling and predicting patterns of extreme lenition.

Circular RNA circ_0006089 promotes the progression of gastric cancer by regulating the miR-143-3p/PTBP3 axis and PI3K/AKT signaling pathway.

OBJECTIVES: Circular RNAs (circRNAs) play pivotal roles in malignancies including gastric cancer (GC). We aimed to investigate the biological function and regulatory mechanism of circ_0006089 in GC. METHODS: Circ_0006089, microRNA (miR)-143-3p, and polypyrimidine tract-binding protein 3 (PTBP3) expressions were measured via quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) in GC cell lines. Cell proliferative capacity was determined by colony formation and CCK-8 assays. Flow cytometry was employed for measuring cell apoptosis. Cell invasion and migration were measured via transwell and wound-healing assays. Western blot analysis was utilized for detecting protein expressions of E-cadherin, N-cadherin, vimentin, PTBP3, PI3K, p-PI3K, AKT, and p-AKT. Dual-reporter luciferase analysis was conducted to confirm the association between miR-143-3p and circ_0006089 or PTBP3. The role of circ_0006089 in vivo was detected via establishing a mice xenograft model. RESULTS: Circ_0006089 expression was increased in GC. Circ_0006089 downregulation suppressed the proliferation and metastasis and induced apoptosis of GC cells, which was counteracted by miR-143-3p inhibition or PTBP3 overexpression. In addition, circ_0006089 overexpression could promote GC progression. MiR-143-3p specially bound to circ_0006089 and PTBP3 was targeted by miR-143-3p. Moreover, circ_0006089 could regulate PTBP3 expression and the PI3K/AKT pathway by sponging miR-143-3p. Circ_0006089 knockdown also suppressed tumor growth. CONCLUSION: Circ_0006089 regulated miR-143-3p/PTBP3/PI3K/AKT pathway to facilitate GC progression.

Bifunctional covalent bromine: an advanced redox mediator for rechargeable lithium-oxygen batteries.

In this work, we introduce trimethylbromosilane (C3H9SiBr), which can protect lithium metal anodes via an in situ formed SEI layer while catalyzing the decomposition of Li2O2. As a result, lithium-oxygen batteries with C3H9SiBr offer a long cycle life of 110 cycles with a significantly reduced charging/discharging overpotential.

Effectiveness of surgical management of malignant glaucoma in phakic eyes.

AIM: To assess the effectiveness of core vitrectomy-phacoemulsification-intraocular lens (IOL) implantation-capsulo-hyaloidotomy in treating phakic eye at least 1mo after the onset of malignant glaucoma. METHODS: A retrospective analysis were performed on malignant glaucoma patients treated in Zhongshan Ophthalmic Center between 2016 and 2018. Demographic and clinical data were described. The preoperative and postoperative visual acuity (VA), intraocular pressure (IOP), number of IOP-lowering medications used, and anterior chamber depth (ACD) of the case series were compared by Wilcoxon signed-rank test. RESULTS: Thirteen phakic eyes with long time intervals between onset and surgery were identified in this case series. Core vitrectomy-phacoemulsification-IOL implantation-capsulo-hyaloidotomy reduced the IOP (P=0.046) and the number of IOP-lowering medications used (P=0.004), deepened the ACD (P=0.005). Complete success was achieved in 38.5% of the eyes, and anatomical success was achieved in 100% of the eyes without any recurrence. The only postoperative complication observed is corneal endothelial decompensation. It occurred in two cases. CONCLUSION: Core vitrectomy-phacoemulsification-IOL implantation-capsulo-hyaloidotomy is safe and effective for treatment of long onset phakic malignant glaucoma.

Ocular development in children with unilateral congenital cataract and persistent fetal vasculature.

AIM: To investigate the ocular development of patients who had unilateral congenital cataract (CC) combined with persistent fetal vasculature (PFV). METHODS: This cross-sectional, observational study included patients who had unilateral CC and PFV and those with isolated unilateral CC. Axial length (AL), keratometry, anterior chamber depth (ACD), lens thickness, and vitreous length were obtained. The ocular biometric parameters of the affected eyes of patients with CC and PFV were compared with the fellow eyes and with the affected eyes of patients with isolated CC. RESULTS: A total of 110 patients were included and divided into 4 groups: group 1 (18 patients with CC and PFV, <24mo), group 2 (22 patients with CC and PFV, ≥24mo), group 3 (35 patients with CC, <24mo), and group 4 (35 patients with CC, ≥24mo). The ALs of the affected eyes were shorter than those of the fellow eyes in group 1 (20.02±1.06 vs 20.66±0.63 mm, P=0.025). While the ALs of the affected eyes were longer than those of the fellow eyes in group 2 (23.18±2.00 vs 22.31±1.06 mm, P=0.044) and group 4 (22.64±1.80 vs 22.02±1.01 mm, P=0.033). The keratometries of the affected eyes were steeper than those of the fellow eyes in group 2 (44.78±1.66 vs 43.83±1.38 D, P=0.041) and group 4 (43.76±1.91 vs 43.34±1.46 D, P=0.043). No difference of ACDs between two eyes was found in all groups (all P>0.05). CONCLUSION: Compared with the fellow eyes, the ALs of the eyes with unilateral CC and PFV are shorter in patients younger than 24mo and longer in those older than 24mo; the keratometries of the eyes with unilateral CC and PFV are steeper in patients older than 24mo and similar with those younger than 24mo. These findings provide further understanding of ocular development in patients with both CC and PFV.

Effect of esketamine vs dexmedetomidine adjunct to propofol sedation for pediatric 3Tesla magnetic resonance imaging: a randomized, double-blind, controlled trial.

BACKGROUND: Adequate sedation is essential for pediatric patients undergoing 3Tesla (T) magnetic resonance imaging (MRI). Using propofol alone is associated with patient arousing and adverse airway events. This study aimed to assess esketamine vs dexmedetomidine adjunct to propofol sedation for pediatric 3 T MRI. METHODS: In this randomized, double-blind, controlled trial, 114 pediatric patients aged between 6 months and 8 years were randomly assigned, in a 1:1 ratio, to the esketamine-propofol group or the dexmedetomidine-propofol group. Sedation was provided with esketamine or dexmedetomidine in combination with propofol titration. The primary outcome was the total dose of propofol. Secondary outcomes included propofol infusion dose, adverse events, time to emergence from sedation, and time to discharge from recovery room. RESULTS: A total of 111 patients completed this study (56 in the esketamine-propofol group and 55 in the dexmedetomidine-propofol group). All MRI procedures were successfully performed under sedation. The total median (IQR) dose of propofol was significantly lower in the esketamine-propofol group (159.8 [121.7, 245.2] µg/kg/min) than that in the dexmedetomidine-propofol group (219.3 [188.6, 314.8] µg/kg/min) (difference in medians [95% CI] = - 66.9 [- 87.8 to - 43.0] µg/kg/min, P < 0.0001). The use of esketamine resulted in a lower dose of propofol for titration (difference in medians [95% CI] = - 64.3 [- 75.9 to - 51.9] µg/kg/min), a shorter time to emergence (difference in means [95% CI] = - 9.4 [- 11.4 to - 7.4] min), and a reduced time to recovery room discharge (difference in means [95% CI] = - 10.1 [- 12.1 to - 8.2] min). In the dexmedetomidine-propofol group, 2 patients experienced upper airway obstruction and 6 patients had bradycardia. No episodes of oxygen desaturation or other adverse events were observed. CONCLUSIONS: Although both regimens provided effective sedation for pediatric 3 T MRI, the esketamine-propofol sedation reduced propofol requirement and facilitated recovery, without detection of increased adverse effects in the studied population. Trial registration Chinese Clinical Trial Registry (identifier: ChiCTR2100048477).