Reactions of young children to the MRI scanner environment

Another Way to Perform a Pediatric MRI Avoiding Sedation After Hours When Anesthesia Is Less Accessible: The Skin-to-Skin Technique

This innovative system for conducting pediatric MRI describes a method of calming children by allowing them to rest on their accompanying adult's abdomen during the examination. This approach reduces their agitation, enabling the acquisition of diagnostic images when anesthesia is either unavailable or not advisable.

Consistency of children's hemodynamic responses during spontaneous speech

Significance: Hemodynamic responses (HRs) are typically averaged across experimental sessions based on the assumption that brain activation is consistent over multiple trials. This may not be a safe assumption, especially in pediatric populations, due to unaccounted effects of inattention, fatigue, or habituation. Aim: The purpose of this study was to quantify the consistency of the HR over speech and language brain regions during speech production in typically developing school-aged children. Approach: Brain activity over speech and language regions of interest (ROIs) was recorded with functional near-infrared spectroscopy during a picture description paradigm with 37 children (aged 7 to 12 years). We divided the 30 experimental trials, each 5 s long, into three segments of 10 trials each corresponding with early (trials 1 to 10), middle (trials 11 to 20), and late (trials 21 to 30) trials. We then compared oxygenated (HbO) and deoxygenated (HbR) hemoglobin concentrations averaged across each 10 trial segment to overall concentrations averaged across all 30 trials. We also compared differential hemoglobin (HbD) across ROIs. Results: HbO and HbR averaged across all experimental trials most strongly correlated with HbO and HbR from early trials. HbD values from channels over most speech and language regions did not appreciably change throughout the experimental session. The exception was HbD values from channels over the dorsal inferior frontal gyrus (dIFG). This region showed significantly higher activation over the left hemisphere during the first segment of the experiment. Conclusions: Our findings suggest that brain activity from speech and language ROIs was relatively consistent over the experimental session. The exception was increased activation of left dIFG during earlier experimental trials. We suggest that researchers critically evaluate the consistency of HRs from different brain regions to determine the reliability of HRs recorded during experimental sessions. This step is instrumental in ensuring that uncontrolled effects do not mask patterns of task-related activation.

Developmental Factors That Predict Head Movement During Resting-State Functional Magnetic Resonance Imaging in 3-7-Year-Old Stuttering and Non-stuttering Children

Early childhood marks a period of dynamic neurocognitive development. Preschool-age coincides with the onset of many childhood disorders and is a developmental period that is frequently studied to determine markers of neurodevelopmental disorders. Magnetic resonance imaging (MRI) is often used to explore typical brain development and the neural bases of neurodevelopmental disorders. However, acquiring high-quality MRI data in young children is challenging. The enclosed space and loud sounds can trigger unease and cause excessive head movement. A better understanding of potential factors that predict successful MRI acquisition would increase chances of collecting useable data in children with and without neurodevelopmental disorders. We investigated whether age, sex, stuttering status, and childhood temperament as measured using the Child Behavioral Questionnaire, could predict movement extent during resting-state functional MRI (rs-fMRI) in 76 children aged 3–7 years, including 42 children who stutter (CWS). We found that age, sex, and temperament factors could predict motion during rs-fMRI scans. The CWS were not found to differ significantly from controls in temperament or head movement during scanning. Sex and age were significant predictors of movement. However, age was no longer a significant predictor when temperament, specifically effortful control, was considered. Controlling for age, boys with higher effortful control scores moved less during rs-fMRI procedures. Additionally, boys who showed higher negative affectivity showed a trend for greater movement. Considering temperament factors in addition to age and sex may help predict the success of acquiring useable rs-fMRI (and likely general brain MRI) data in young children in MR neuroimaging.

An eye tracking based virtual reality system for use inside magnetic resonance imaging systems

Patients undergoing Magnetic Resonance Imaging (MRI) often experience anxiety and sometimes distress prior to and during scanning. Here a full MRI compatible virtual reality (VR) system is described and tested with the aim of creating a radically different experience. Potential benefits could accrue from the strong sense of immersion that can be created with VR, which could create sense experiences designed to avoid the perception of being enclosed and could also provide new modes of diversion and interaction that could make even lengthy MRI examinations much less challenging. Most current VR systems rely on head mounted displays combined with head motion tracking to achieve and maintain a visceral sense of a tangible virtual world, but this technology and approach encourages physical motion, which would be unacceptable and could be physically incompatible for MRI. The proposed VR system uses gaze tracking to control and interact with a virtual world. MRI compatible cameras are used to allow real time eye tracking and robust gaze tracking is achieved through an adaptive calibration strategy in which each successive VR interaction initiated by the subject updates the gaze estimation model. A dedicated VR framework has been developed including a rich virtual world and gaze-controlled game content. To aid in achieving immersive experiences physical sensations, including noise, vibration and proprioception associated with patient table movements, have been made congruent with the presented virtual scene. A live video link allows subject-carer interaction, projecting a supportive presence into the virtual world.

Four-dimensional Multiphase Steady-State MRI with Ferumoxytol Enhancement: Early Multicenter Feasibility in Pediatric Congenital Heart Disease

Background The value of MRI in pediatric congenital heart disease (CHD) is well recognized; however, the requirement for expert oversight impedes its widespread use. Four-dimensional (4D) multiphase steady-state imaging with contrast enhancement (MUSIC) is a cardiovascular MRI technique that uses ferumoxytol and captures all anatomic features dynamically. Purpose To evaluate multicenter feasibility of 4D MUSIC MRI in pediatric CHD. Materials and Methods In this prospective study, participants with CHD underwent 4D MUSIC MRI at 3.0 T or 1.5 T between 2014 and 2020. From a pool of 460 total studies, an equal number of MRI studies from three sites (n = 60) was chosen for detailed analysis. With use of a five-point scale, the feasibility of 4D MUSIC was scored on the basis of artifacts, image quality, and diagnostic confidence for intracardiac and vascular connections (n = 780). Respiratory motion suppression was assessed by using the signal intensity profile. Bias between 4D MUSIC and two-dimensional (2D) cine imaging was evaluated by using Bland-Altman analysis; 4D MUSIC examination duration was compared with that of the local standard for CHD. Results A total of 206 participants with CHD underwent MRI at 3.0 T, and 254 participants underwent MRI at 1.5 T. Of the 60 MRI examinations chosen for analysis (20 per site; median participant age, 14.4 months [interquartile range, 2.3-49 months]; 33 female participants), 56 (93%) had good or excellent image quality scores across a spectrum of disease complexity (mean score ± standard deviation: 4.3 ± 0.6 for site 1, 4.9 ± 0.3 for site 2, and 4.6 ± 0.7 for site 3; P < .001). Artifact scores were inversely related to image quality (r = -0.88, P < .001) and respiratory motion suppression (P < .001, r = -0.45). Diagnostic confidence was high or definite in 730 of 780 (94%) intracardiac and vascular connections. The correlation between 4D MUSIC and 2D cine ventricular volumes and ejection fraction was high (range of r = 0.72-0.85; P < .001 for all). Compared with local standard MRI, 4D MUSIC reduced the image acquisition time (44 minutes ± 20 vs 12 minutes ± 3, respectively; P < .001). Conclusion Four-dimensional multiphase steady-state imaging with contrast enhancement MRI in pediatric congenital heart disease was feasible in a multicenter setting, shortened the examination time, and simplified the acquisition protocol, independently of disease complexity. Clinical trial registration no. NCT02752191 © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Roest and Lamb in this issue.

Fast acquisition abdominal MRI study for the investigation of suspected acute appendicitis in paediatric patients

Objectives

To assess the diagnostic accuracy of fast acquisition MRI in suspected cases of paediatric appendicitis presenting to a tertiary referral hospital.

Materials and methods

A prospective study was undertaken between May and October 2017 of 52 children who presented with suspected appendicitis and were referred for an abdominal ultrasound. All patients included in this study received both an abdominal ultrasound and five-sequence MRI consisting of axial and coronal gradient echo T2 scans, fat-saturated SSFSE and a diffusion-weighted scan. Participants were randomised into groups of MRI with breath-holds or MRI with free breathing. A patient satisfaction survey was also carried out. Histopathology findings, where available, were used as a gold standard for the purposes of data analysis. Statistical analysis was performed, and p values < 0.05 were considered statistically significant.

Results

Ultrasound had a sensitivity and specificity of 25% and 92.9%, respectively. MRI with breath-hold had a sensitivity and specificity of 81.8% and 66.7%, respectively, whilst MRI with free breathing was superior with sensitivity and specificity of 92.3% and 84.2%, respectively. MRI with free breathing was also more time efficient (p < 0.0001). Group statistics were comparable (p < 0.05).

Conclusions

The use of fast acquisition MRI protocols, particularly free breathing sequences, for patients admitted with suspected appendicitis can result in faster diagnosis, treatment and discharge. It also has a statistically significant diagnostic advantage over ultrasound. Additionally, the higher specificity of MR can reduce the number of negative appendectomies performed in tertiary centres.

Application of Color Transformation Techniques in Pediatric Spinal Cord MR Images: Typically Developing and Spinal Cord Injury Population

The purpose of this study was to evaluate an improved and reliable visualization method for pediatric spinal cord MR images in healthy subjects and patients with spinal cord injury (SCI). A total of 15 pediatric volunteers (10 healthy subjects and 5 subjects with cervical SCI) with a mean age of 11.41 years (range 8-16 years) were recruited and scanned using a 3.0T Siemens Verio MR scanner. T2-weighted axial images were acquired covering entire cervical spinal cord level C1 to C7. These gray-scale images were then converted to color images by using five different techniques including hue-saturation-value (HSV), rainbow, red-green-blue (RGB), and two enhanced RGB techniques using automated contrast stretching and intensity inhomogeneity correction. Performance of these techniques was scored visually by two neuroradiologists within three selected cervical spinal cord intervertebral disk levels (C2-C3, C4-C5, and C6-C7) and quantified using signal to noise ratio (SNR) and contrast to noise ratio (CNR). Qualitative and quantitative evaluation of the color images shows consistent improvement across all the healthy and SCI subjects over conventional gray-scale T2-weighted gradient echo (GRE) images. Inter-observer reliability test showed moderate to strong intra-class correlation (ICC) coefficients in the proposed techniques (ICC > 0.73). The results suggest that the color images could be used for quantification and enhanced visualization of the spinal cord structures in addition to the conventional gray-scale images. This would immensely help towards improved delineation of the gray/white and CSF structures and further aid towards accurate manual or automatic drawings of region of interests (ROIs).

Assessing the use of the anatomical method for the estimation of sub-adult stature in Black South Africans

Stature estimation is rarely attempted in sub-adults due to the general lack of available standards as a result of the dearth of sufficiently large sub-adult skeletal collections with known demographic information. To overcome this problem sub-adult research mainly relies on modern imaging modalities. In the current study Magnetic Resonance Imaging (MRI) scans were used to assess the use of the anatomical method for stature estimation in sub-adults. A total of 53 Black South African sub-adult males (n=24) and females (n=29) aged between 10 and 17 years participated in the study by voluntarily completing a full-body MRI scan. A stadiometer was used to measure living stature prior to all MRI scans. Skeletal elements that contribute directly to stature were measured from the MRI scans using OsiriX and summed to compute the total skeletal height. Total skeletal height was calculated using the diaphyseal, maximum and physiological long bone lengths and correlated to living stature using Pearson's correlations. Subsequently least squares regression equations were generated for the estimation of sub-adult stature. Results indicated strong, statistically significant positive correlations between living stature and total skeletal heights in sub-adult males, females and a combined sex sample. The regression equations were characterized by small standard error of estimates which are comparable to that reported for Black South African adults. Based on these results the anatomical method can be used to accurately describe living stature in Black South African sub-adults. This method is therefore encouraged as it will add valuable information when dealing with unknown sub-adult skeletal remains.

Diffusion tensor imaging of the cervical spinal cord in children

PURPOSE

Obtaining fast, reliable, high-resolution diffusion tensor imaging (DTI) of the pediatric cervical spinal cord (CSC) is challenging, given the multitude of technical limitations involved. Overcoming these limitations may further potentiate DTI as a valuable quantitative tool in evaluating the pediatric CSC.

METHODS

Sixteen patients (9 girls and 7 boys) with hypoxic brain injury, craniocervical junction malformations, and head trauma were included in this retrospective study. Region of interests were placed from C1-C2 through C7-T1 consecutively at the cervical intervertebral disc levels. DTI metrics were compared with a pediatric DTI database of healthy controls. Clinical background and outcomes were tabulated.

RESULTS

Patients with hypoxic brain injury, Chiari I and II malformations, and head trauma demonstrated lower fractional anisotropy values than that of healthy controls at certain cervical intervertebral disc levels.

CONCLUSIONS

DTI may be a promising modality for providing additional information beyond that of conventional magnetic resonance imaging in pediatric central nervous system disorders.

Idle behaviors of the hippocampus reflect endogenous cortisol levels in youth

OBJECTIVE

Compelling evidence indicates that disruption in functional connectivity (FC) in brain networks underlies many psychiatric and developmental disorders. Current theory posits that biological (i.e., cortisol) and environmental (i.e., stress) experiences in early life are strong determinants in the development of functional brain systems and formative in the genesis of such disorders. The objective of this study was to examine the extent to which individual differences in cortisol concentrations during FC magnetic resonance imaging (MRI) would map onto variability in hippocampal to default mode network (DMN) connectivity in typically developing youth.

METHOD

Salivary cortisol and FC MRI data were collected concurrently in 33 scan-naive 7- to 15-year-old participants. Twenty-nine of these participants previously completed the Trier Social Stress Test. Hippocampal to DMN FC and endogenous cortisol variability during MRI were examined. A possible association between MRI cortisol and cortisol response to the Trier Social Stress Test during the preceding visit or a participant's ratings of anxiety during MRI was tested.

RESULTS

There were significant positive relations between MRI cortisol levels and measurements in the following 3 areas: hippocampal to DMN FC during the resting state, cortisol levels during the Trier Social Stress Test, and fear/anxiety ratings during MRI. Fear/anxiety ratings during MRI also related to self-reported anxiety on standardized measurements.

CONCLUSIONS

This study shows for the first time that FC of the hippocampus is altered with changing cortisol responsivity in youth. Altered FC during the resting state may represent altered alertness or monitoring resulting from variation in glucocorticoid function in youth, which carries implications for the effect of stress on response monitoring and decision making.

Diffusion tensor imaging in pediatric spinal cord injury: preliminary examination of reliability and clinical correlation

STUDY DESIGN

The design was a nonexperimental, repeated measures design.

OBJECTIVE

To examine the reliability of repeated diffusion tensor imaging (DTI) values of the pediatric cord and to compare DTI values with values obtained on the clinical examination and findings from conventional magnetic resonance imaging (MRI).

SUMMARY OF BACKGROUND DATA

DTI quantifies the diffusion of water molecules in directions parallel and transverse to the plane of neuronal axons. The unique characteristic architecture of the spinal cord allows DTI to examine the white matter and potentially separate white matter from gray matter and assess structural damage of the cord.

METHODS

Ten youths with cervical spinal cord injury (SCI) were evaluated using the International Standards for Neurological Classification of SCI (ISNCSCI) and had 2 scans using a 3.0T Siemens Verio MR scanner. The imaging protocol consisted of conventional sagittal fast spin echo T1- and T2-weighted scans, axial fast spin echo T2-weighted scans, and axial DTI acquisition. Intraclass correlation coefficient (ICC) and 95% confidence interval were calculated for mean, axial, and radial diffusivity (MD, AD, RD, respectively) and fractional anisotropy (FA). Relationships among DTI, MRI, and ISNCSCI were evaluated using Spearman correlation coefficients (rs) and differences were tested using Cohen's method.

RESULTS

There was moderate-to-strong reliability (ICC = 0.75-0.95) for MD, AD, and RD for all spinal levels. Reliability for FA for mid-C4 and between C5-C6 and C7-T1 was moderate (ICC = 0.75-0.80). Diffusivity values demonstrated moderate-to-good negative relationships (rs = -0.30 to -0.59), with 4 ISNCSCI values. FA values had a moderate-to-good (rs = 0.33-0.53) positive relationship, with 5 ISNCSCI values. Compared with MRI, DTI values had significantly stronger correlations (P ≤ 0.0001) with the majority of ISNCSCI values.

CONCLUSION

DTI values had good-to-strong reliability on repeated scans and moderate-to-good concurrent validity with clinical scores. When compared with conventional MRI, DTI values had statistically stronger correlations with the majority of values from the clinical examination.

Diffusion tensor imaging of the normal pediatric spinal cord using an inner field of view echo-planar imaging sequence

BACKGROUND AND PURPOSE

DTI in the brain has been well established, but its application in the spinal cord, especially in pediatrics, poses several challenges. The small cord size has inherent low SNR of the diffusion signal intensity, respiratory and cardiac movements induce artifacts, and EPI sequences used for obtaining diffusion indices cause eddy-current distortions. The purpose of this study was to 1) evaluate the accuracy of cervical spinal cord DTI in children using a newly developed iFOV sequence with spatially selective 2D-RF excitations, and 2) examine reproducibility of the DTI measures.

MATERIALS AND METHODS

Twenty-five typically developing subjects were imaged twice using a 3T scanner. Axial DTI images of the cervical spinal cord were acquired with this sequence. After motion correction, DTI indices were calculated using regions of interest manually drawn at every axial section location along the cervical spinal cord for both acquisitions. Various DTI indices were calculated: FA, AD, RD, MD, RA, and VR. Geometric diffusion measures were also calculated: Cp, Cl, and Cs.

RESULTS

The following average values for each index were obtained: FA = 0.50 ± 0.11; AD = 0.97 ± 0.20 × 10(-3)mm(2)/s; RD = 0.41 ± 0.13 × 10(-3)mm(2)/s; MD = 0.59 ± 0.15 × 10(-3)mm(2)/s; RA = 0.35 ± 0.08; VR = 0.03 ± 0.00; Cp = 0.13 ± 0.07; Cl = 0.29 ± 0.09; and Cs = 0.58 ± 0.11. The reproducibility tests showed moderate to strong ICC in all subjects for all DTI parameters (ICC>0.72).

CONCLUSIONS

This study showed that accurate and reproducible DTI parameters can be estimated in the pediatric cervical spinal cord using an iFOV EPI sequence.