Predictors of Anesthetic Exposure in Pediatric MRI

Molecular Insights into Propofol's Neurotoxic Effects: Targeting the HTR1A/cAMP Signaling Pathway

Propofol, a commonly used anesthetic in clinical practice, is favored for its rapid onset and short duration of action. Despite its widespread use, the potential neurotoxic effects of propofol remain insufficiently understood. This study utilized high-throughput transcriptome sequencing and network pharmacology to investigate the mechanisms by which propofol induces neurotoxicity in rat hippocampal neural progenitor cells (NPCs), focusing on the HTR1A/cAMP signaling pathway. Our findings reveal that propofol significantly inhibits the HTR1A/cAMP pathway, leading to altered expression of key genes that affect neuronal activity, inflammatory responses, and apoptosis. In vivo experiments further demonstrate that propofol impairs spatial learning and memory in rats, an effect that is partially reversed by overexpression of HTR1A. These results not only elucidate the molecular mechanisms underlying propofol-induced neuronal damage but also provide critical insights into the safe application of propofol in clinical settings.

Innovative 4D FreeBreathing technique in pediatric abdominal MRI improves feasibility and image quality

OBJECTIVES

To compare the feasibility and imaging quality of a golden angle radial stack-of-stars dynamic three-dimensional free-breathing T1w turbo field echo acquisition (4D FreeBreathing) with a conventional dynamic cartesian breath-hold T1w sequence in young children undergoing abdominal magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Fifty consecutive pediatric patients (34 females; 3.4 ± 2.0 years) underwent abdominal MRI: 25 were examined with 4D FreeBreathing and 25 with conventional dynamic T1w sequence. The image quality was evaluated subjectively on a 5-point scale by two radiologists. Interobserver agreement, as well as signal-to-noise ratio for arterial (SNRart) and portal venous (SNRpv) phases, were evaluated separately. Additionally, the image quality of 4D FreeBreathing sequence was compared to a non-dynamic post-contrast radial stack-of-stars free-breathing T1w fast field echo acquisition (3D T1w Vane mDixon). Interobserver agreement of both assessors was calculated using quadratic weighted Cohen's kappa test (ϰ), while independent samples Student's t-test was employed to compare mean SNR values among the two groups.

RESULTS

Using 4D FreeBreathing, SNRart and SNRpv were significantly higher from 500 ± 170 and 550 ± 160 to 900 ± 210 and 820 ± 260 (p < 0.001); the diagnostic image quality increased from 77.6 to 89.6%; respiratory artifacts decreased from 22.4 to 10.4%, with an almost perfect interobserver agreement. Compared to 3D T1w Vane mDixon sequence, SNR and image quality were equal.

CONCLUSION

4D FreeBreathing pediatric abdominal MRI improves the feasibility and image quality compared to conventional dynamic exams while showing an image quality equivalent to post-contrast 3D T1w Vane mDixon.

KEY POINTS

Question During dynamic abdominal MRI in young children, it is important to conduct a brief yet robust examination without respiratory artifacts. Findings 4D FreeBreathing MRI technique for pediatric abdominal imaging enhances both image quality and feasibility when compared to conventional dynamic scans that require breath-holding. Clinical relevance Dynamic abdominal MRI using the 4D FreeBreathing sequence provides significant benefits for pediatric patients. The absence of breath-holding requirements improves patient cooperation, reduces the need for general anesthesia, and results in higher-quality diagnostic images.

Deep learning MR reconstruction in knees and ankles in children and young adults. Is it ready for clinical use?

OBJECTIVE

To evaluate the diagnostic performance and image quality of accelerated Turbo Spin Echo sequences using deep-learning (DL) reconstructions compared to conventional sequences in knee and ankle MRIs of children and young adults.

MATERIALS AND METHODS

IRB-approved prospective study consisting of 49 MRIs from 48 subjects (10 males, mean age 16.4 years, range 7-29 years), with each MRI consisting of both conventional and DL sequences. Sequences were evaluated blindly to determine predictive values, sensitivity, and specificity of DL sequences using conventional sequences and knee arthroscopy (if available) as references. Physeal patency and appearance were evaluated. Qualitative parameters were compared. Presence of undesired image alterations was assessed.

RESULTS

The prevalence of abnormal findings in the knees and ankles were 11.7% (75/640), and 11.5% (19/165), respectively. Using conventional sequences as reference, sensitivity and specificity of DL sequences in knees were 90.7% and 99.3%, and in ankles were 100.0% and 100.0%. Using arthroscopy as reference, sensitivity and specificity of DL sequences were 80.0% and 95.8%, and of conventional sequences were 80.0% and 97.9%. Agreement of physeal status was 100.0%. DL sequences were qualitatively "same-or-better" compared to conventional (p < 0.032), except for pixelation artifact for the PDFS sequence (p = 0.233). No discrete image alteration was identified in the knee DL sequences. In the ankle, we identified one DL artifact involving a tendon (0.8%, 1/125). DL sequences were faster than conventional sequences by a factor of 2 (p < 0.001).

CONCLUSION

In knee and ankle MRIs, DL sequences provided similar diagnostic performance and "same-or-better" image quality than conventional sequences at half the acquisition time.

Improving pediatric magnetic resonance imaging safety by enhanced non-technical skills and team collaboration

BACKGROUND

Safe pediatric magnetic resonance imaging (MRI) ideally relies on non-sedative techniques, as avoiding risky sedation is inherently safer. However, in practice, sedation often becomes unavoidable, particularly for younger children or those with anxiety, to ensure motion-free, high-quality imaging. This narrative review explores the current practices and proposes strategies to enhance safety in pediatric MRI examinations.

METHODS

We identified and analyzed 247 studies addressing various aspects of pediatric MRI safety, including sedation protocols, patient monitoring, and team-based management approaches.

RESULTS

Safe sedation requires careful drug selection tailored to individual needs, continuous monitoring, and robust emergency preparedness. While efforts are underway to minimize sedation, safer drug protocols and improved monitoring technologies remain essential. Assembling dedicated MRI teams trained in both technical and non-technical skills-such as situational awareness, communication, and teamwork-supports these strategies. Structured team briefings covering monitoring procedures, emergency scenarios, response protocols, and specific resuscitation roles are also critical. Developing a strong organizational culture that promotes patient safety and continuous learning from incident reports helps ensure ongoing improvements.

CONCLUSIONS

Achieving safe pediatric MRI examinations requires balancing the need for sedation with the goal of minimizing its use. Strengthening collaboration, refining sedation protocols, and implementing advanced safety monitoring systems are essential steps. Further advancements in imaging technologies are also necessary to reliably obtain high-quality scans without sedation, reducing risks and improving patient outcomes.

Hypotensive Events in Pediatric Patients Receiving Dexmedetomidine for MRI

PURPOSE

Dexmedetomidine, the preferred pediatric sedating agent for magnetic resonance imaging (MRI), has the side effect of hypotension. Newer recommendations for reporting adverse events in pediatric procedural sedation include using a two-pronged definition. Our aim was to describe the incidence of hypotension in patients undergoing sedated MRI and to identify demographic and clinical factors associated with hypotension, applying a two-pronged definition, where a numerical threshold/clinical criterion must be met as well as at least one clinical intervention performed.

DESIGN

An observational cohort study.

METHODS

Medical record data were extracted for outpatients less than 18 years of age sedated primarily with dexmedetomidine for MRI in a single center for over a seven-year period. Patients who received propofol as an adjunct were also included. Hypotension was defined using a two-pronged approach, as a 20% reduction in systolic blood pressure from baseline lasting ≥10 minutes, coupled with a fluid bolus. Analysis included descriptive statistics, t tests and logistic regression using discrete-time survival analysis.

FINDINGS

Of the 1,590 patient encounters, 90 (5.7%) experienced hypotension. Males were significantly more likely to have hypotension. Patients with hypotension had overall longer appointment times, including longer sedation times and recovery time. Greater blood pressure (BP) variability in the preceding 20 minutes also increased the risk of hypotension.

CONCLUSIONS

Our lower incidence of hypotension is likely related to the two-pronged intervention-based definition used, as it likely more accurately reflects clinically meaningful hypotension. To our knowledge, this is the first study using this approach with this population. Research further examining the relationship between prolonged sedation, blood pressure variability, gender, hypotension, and recovery time is needed. Understanding these relationships will help interdisciplinary teams, including nurses in pediatric procedural areas, to reduce the incidence of hypotension, potentially maximize patient safety, and optimize throughput.

Trends in Anesthesia/Sedation for Computed Tomography and Magnetic Resonance Imaging Encounters in Pediatric Emergency Departments, 2012-2022

This cross-sectional study assesses trends over time in sedation/anesthesia use for computed tomography (CT) and magnetic resonance imaging (MRI) across pediatric emergency departments (EDs).

Neonatal body magnetic resonance imaging: preparation, performance and optimization

Performing and optimizing MRI of the chest, abdomen and pelvis in neonates and young infants can be challenging. This is a result of several factors, including patient size, desire to avoid or minimize sedation/general anesthesia, and the relative rarity of these examinations. However, with proper preparation and protocol optimization, high-quality diagnostic images can be acquired that can aid in diagnosis and patient management. In addition, numerous special considerations arise when performing body MRI in neonates compared to older pediatric patients. This review article provides an update on the performance and optimization of MRI of the body in neonates and infants. Furthermore, the authors present common indications for neonatal body MRI and discuss the use of intravenous gadolinium-based contrast agents in this vulnerable patient population.

Strategies to perform magnetic resonance imaging in infants and young children without sedation

Given the increasing use of MRI in the pediatric population, the need for sedation in MRI performed in young children is a topic of growing importance. Although sedation is generally tolerated well by children, the financial and operational impacts of anesthesia on MRI workflow, as well as potential adverse effects of anesthetic medications, highlight the need to perform MRI in children without sedation whenever possible. This review focuses on current techniques to facilitate non-sedation MRI in children, including exam preparation with MRI simulation; asleep but not sedated techniques; awake and relaxed techniques using certified child life specialists, animal-assisted therapy, a child-friendly environment and in-scan entertainment; and non-sedated MRI protocol modifications such as shorter scan time, prioritizing sequences, reducing motion artifact, noise reduction, limiting use of gadolinium, employing an open MRI and modifying protocols.

Determination of the normal conus medullaris level in term infants: the role of MRI in early infancy

OBJECTIVE

This study aimed to explore the migration process of the conus medullaris (CM) in early infancy using infant MRI and to evaluate the application of MRI for locating the infant CM level.

METHODS

The authors retrospectively analyzed the CM level on the lumbosacral MR images of 26 term infants aged < 3 months who were classified into three groups according to age. The authors numbered the CM level in each patient and analyzed the range and average of the CM level of the cohort. The authors studied the linear correlation between CM level and postnatal days with linear regression analysis, 1-way ANOVA, and the least significant difference test.

RESULTS

The CM level ranged from the superior border of the L1 vertebra to the top third of the L3 vertebra. About 96.2% of infants had CM higher than the superior border of the L3 vertebra. On average, CM was located between the L1-2 intervertebral disc and the inferior border of the L2 vertebra (mean ± SD score 1.64 ± 1.14). The three groups had no significant statistical difference in CM level (F = 1.071 and p = 0.359; groups 1 and 2, p = 0.408; groups 1 and 3, p = 0.170; groups 2 and 3, p = 0.755). CM level had no linear regression correlation with postnatal days within the first month (r2 = 0.061, F = 0.654, p = 0.438) or within the first 3 months (r2 = 0.002, F = 0.056, p = 0.816).

CONCLUSIONS

The CM level reaches the normal adult level by birth in term infants and does not ascend during childhood. On average, the CM was between the L1-2 intervertebral disc and the inferior border of the L2 vertebra in term infants. Considering the possibility of physiologically low-lying CM, the authors agree that normal CM is located above the L3 level in term infants and CM at the L3 level could be equivocal and should be investigated with other clinical data. The study data suggest that MRI is an accurate and valuable method for determining the CM level in term infants.

Free-breathing radial stack-of-stars three-dimensional Dixon gradient echo sequence in abdominal magnetic resonance imaging in sedated pediatric patients

BACKGROUND

There is a strong need for improvements in motion robust T1-weighted abdominal imaging sequences in children to enable high-quality, free-breathing imaging.

OBJECTIVE

To compare imaging time and quality of a radial stack-of-stars, free-breathing T1-weighted gradient echo acquisition (volumetric interpolated breath-hold examination [VIBE]) three-dimensional (3-D) Dixon sequence in sedated pediatric patients undergoing abdominal magnetic resonance imaging (MRI) against conventional Cartesian T1-weighed sequences.

MATERIALS AND METHODS

This study was approved by the institutional review board with informed consent obtained from all subjects. Study subjects included 31 pediatric patients (19 male, 12 female; median age: 5 years; interquartile range: 5 years) undergoing abdominal MRI at 3 tesla with a free-breathing T1-weighted radial stack-of-stars 3-D VIBE Dixon prototype sequence, StarVIBE Dixon (radial technique), between October 2018 and June 2019 with previous abdominal MR imaging using conventional Cartesian T1-weighed imaging (traditional technique). MRI component times were recorded as well as the total number of non-contrast T1-weighted sequences. Two radiologists independently rated images for quality using a scale from 1 to 5 according to the following metrics: overall image quality, hepatic edge sharpness, hepatic vessel clarity and respiratory motion robustness. Scores were compared between the groups.

RESULTS

Mean T1-weighted imaging times for all subjects were 3.63 min for radial exams and 8.01 min for traditional exams (P<0.001), and total non-contrast imaging time was 32.7 min vs. 43.9 min (P=0.002). Adjusted mean total MRI time for all subjects was 60.2 min for radial exams and 65.7 min for traditional exams (P=0.387). The mean number of non-contrast T1-weighted sequences performed in radial MRI exams was 1.0 compared to 1.9 (range: 0-6) in traditional exams (P<0.001). StarVIBE Dixon outperformed Cartesian methods in all quality metrics. The mean overall image quality (scale 1-5) was 3.95 for radial exams and 3.31 for traditional exams (P<0.001).

CONCLUSION

Radial stack-of-stars 3-D VIBE Dixon during free-breathing abdominal MRI in pediatric patients offers improved image quality compared to Cartesian T1-weighted imaging techniques with decreased T1-weighted and total non-contrast imaging time. This has important implications for children undergoing sedation for imaging.

Safety challenges related to the use of sedation and general anesthesia in pediatric patients undergoing magnetic resonance imaging examinations

The use of sedation and general anesthesia has facilitated the significant growth of MRI use among children over the last years. While sedation and general anesthesia are considered to be relatively safe, their use poses potential risks in the short term and in the long term. This manuscript reviews the reasons why MRI examinations require sedation and general anesthesia more commonly in the pediatric population, summarizes the safety profile of sedation and general anesthesia, and discusses an amalgam of strategies that can be implemented and can ultimately lead to the optimization of sedation and general anesthesia care within pediatric radiology departments.