Reducing sedation for pediatric body MRI using accelerated and abbreviated imaging protocols

Magnetic resonance imaging (MRI) is an established diagnostic imaging tool for investigating pediatric disease. MRI allows assessment of structure, function, and morphology in cardiovascular imaging, as well as tissue characterization in body imaging, without the use of ionizing radiation. For MRI in children, sedation and general anesthesia (GA) are often utilized to suppress patient motion, which can otherwise compromise image quality and diagnostic efficacy. However, evidence is emerging that use of sedation and GA in children might have long-term neurocognitive side effects, in addition to the short-term procedure-related risks. These concerns make risk–benefit assessment of sedation and GA more challenging. Therefore, reducing or eliminating the need for sedation and GA is an important goal of imaging innovation and research in pediatric MRI. In this review, the authors focus on technical and clinical approaches to reducing and eliminating the use of sedation in the pediatric population based on image acquisition acceleration and imaging protocols abbreviation. This paper covers important physiological and technical considerations for pediatric body MR imaging and discusses MRI techniques that offer the potential of recovering diagnostic-quality images from accelerated scans. In this review, the authors also introduce the concept of reporting elements for important indications for pediatric body MRI and use this as a basis for abbreviating the MR protocols. By employing appropriate accelerated and abbreviated approaches based on an understanding of the imaging needs and reporting elements for a given clinical indication, it is possible to reduce sedation and GA for pediatric chest, cardiovascular and abdominal MRI.     

Infant Cardiac Magnetic Resonance Imaging Using Oscillatory Ventilation: Safe and Effective

Cardiac magnetic resonance imaging (CMR) for infants and young children typically requires sedation. General anesthesia with controlled ventilation can eliminate motion artifact with breath-holds during imaging to limit respiratory artifact, but these may lead to atelectasis or other complications. High-frequency oscillatory ventilation (HFOV) provides ventilation with near-constant mean airway pressure and minimal movement of chest wall and diaphragm, thus obviating the need for breath-holding. Clinical data were collected for 8 infants who underwent CMR with HFOV and 8 controls who underwent CMR with conventional ventilator and breath-hold technique. Data included demographic information, adverse events, and scan-acquisition time. Studies were reviewed for image quality by two cardiologists who were blinded to type of ventilation. There were no significant differences in patient characteristics between the two groups. There was no significant difference in average image quality for cine short-axis or black blood imaging. Total CMR scan time was not significantly different between groups, but the short-axis cine stack was acquired more quickly in the HFOV group (1.8 ± 0.8 vs. 5.0 ± 3.6 min). There were no adverse events in the HFOV group, but scans were terminated early for two patients in the conventional ventilator group. HFOV during CMR is feasible and well tolerated. Image quality is equivalent to that obtained with conventional ventilation with breath-holding technique and allows shorter cine scan times for some sequences.     

Small-bowel MRI in children and young adults with Crohn disease: retrospective head-to-head comparison of contrast-enhanced and diffusion-weighted MRI

Background

Small-bowel MRI based on contrast-enhanced T1-weighted sequences has been challenged by diffusion-weighted imaging (DWI) for detection of inflammatory bowel lesions and complications in patients with Crohn disease.

Objective

To evaluate free-breathing DWI, as compared to contrast-enhanced MRI, in children, adolescents and young adults with Crohn disease.

Materials and methods

This retrospective study included 33 children and young adults with Crohn disease ages 17?±?3 years (mean ± standard deviation) and 27 matched controls who underwent small-bowel MRI with contrast-enhanced T1-weighted sequences and DWI at 1.5 T. The detectability of Crohn manifestations was determined. Concurrent colonoscopy as reference was available in two-thirds of the children with Crohn disease.

Results

DWI and contrast-enhanced MRI correctly identified 32 and 31 patients, respectively. All 22 small-bowel lesions and all Crohn complications were detected. False-positive findings (two on DWI, one on contrast-enhanced MRI), compared to colonoscopy, were a result of large-bowel lumen collapse. Inflammatory wall thickening was comparable on DWI and contrast-enhanced MRI. DWI was superior to contrast-enhanced MRI for detection of lesions in 27% of the assessed bowel segments and equal to contrast-enhanced MRI in 71% of segments.

Conclusion

DWI facilitates fast, accurate and comprehensive workup in Crohn disease without the need for intravenous administration of contrast medium. Contrast-enhanced MRI is superior in terms of spatial resolution and multiplanar acquisition.     

Deep sedation in pediatric imaging: efficacy and safety of intravenous chlorpromazine

Background

The quality of MRI and CT depends largely on immobility of the patient during the procedure, which is often difficult to achieve without sedation in children below the age of 6 years.

Objective

To assess the efficacy and safety of intravenous chlorpromazine sedation for repeated imaging in young children treated for cancer.

Materials and methods

From July 2003 to January 2007, information on children younger than 6 years of age having MRI or CT was prospectively collected. Forty-five minutes before the scan, a 10-min infusion of chlorpromazine 0.5 mg/kg was administered and managed by non-anesthetic staff. Patient monitoring included continuous measurement of pulse, respiration, oxygen saturation and arterial blood pressure. Procedure-related parameters and adverse events were documented. Sedation was considered successful when the procedure was completed and at least 95% of images were usable.

Results

One-hundred-one procedures (82 MRI, 19 CT) were evaluated in 62 children, 3–74 months old. Adequate sedation was achieved in 96% of cases, with mean induction time, 22 min; mean duration of sleep, 72 min, and mean duration of procedure, 33 min. Mean time spent in the radiology unit was 104 min. Ninety-six percent of imaging procedures were successfully completed. No cardiac, respiratory, neurological or allergic complication occurred.

Conclusion

Intravenous chlorpromazine is safe and effective for procedural sedation in young children with cancer undergoing MRI and CT.

     

Diagnostic equivalency of fast T2 and FLAIR sequences for pediatric brain MRI: a pilot study

Background

Faster and motion robust magnetic resonance imaging (MRI) sequences are desirable in pediatric brain MRI as they can help reduce the need for monitored anesthesia care, which is a costly and limited resource that carries medical risks.

Objective

To evaluate the diagnostic equivalency of commercially available accelerated motion robust MR sequences relative to standard sequences.

Materials and methods

This was an institutional review board-approved prospective study. Subjects underwent a clinical brain MRI using conventional multiplanar images at 3 Tesla followed by fast axial T2 and FLAIR (fluid-attenuated inversion recovery) sequences optimized for an approximately 50% reduction in acquisition time. Conventional and fast images from each subject were reviewed by two blinded pediatric neuroradiologists. The readers evaluated the presence of 12 findings. Intra-observer agreement was estimated for fast versus conventional sequences. For each set of sequences, interobserver agreement calculations and chi-square tests were used to evaluate differences between fast and conventional acquisitions. An independent third reader reviewed the intra-observer discrepancies and adjudicated them as being more conspicuous on fast sequence, conventional sequence or the equivalent. The readers also were asked to rate motion artifacts with a previously validated score.

Results

Images from 77 children (mean age: 11.3 years) were analyzed. Intra-observer agreement (fast versus conventional) ranged between 89.2% and 92.3%. Interobserver agreement ranged between 86.1% and 88.4%. Interobserver agreement was significantly higher for conventional FLAIR relative to fast FLAIR for small (<5 mm) foci of T2 in the white matter. Otherwise, interobserver agreement was not different between the fast and conventional sequences. For awake subjects, fast sequences had significantly fewer artifacts (P<0.05).

Conclusion

Conventional T2 and FLAIR sequences can be optimized to shorten acquisition while maintaining diagnostic equivalency. These faster sequences were also less susceptible to motion artifacts.

     

Efficacy and safety of deep sedation by non-anesthesiologists for cardiac MRI in children

Background

Cardiac MRI has become widespread to characterize cardiac lesions in children. No study has examined the role of deep sedation performed by non-anesthesiologists for this investigation.

Objective

We hypothesized that deep sedation provided by non-anesthesiologists can be provided with a similar safety and efficacy profile to general anesthesia provided by anesthesiologists.

Materials and methods

This is a retrospective chart review of children who underwent cardiac MRI over a 5-year period. The following data were collected from the medical records: demographic data, cardiac lesion, American Society of Anesthesiologists (ASA) physical status, sedation type, provider, medications, sedation duration and adverse events or interventions. Image and sedation adequacy were recorded.

Results

Of 1,465 studies identified, 1,197 met inclusion criteria; 43 studies (3.6%) used general anesthesia, 506 (42.3%) had deep sedation and eight (0.7%) required anxiolysis only. The remaining 640 studies (53.5%) were performed without sedation. There were two complications in the general anesthesia group (4.7%) versus 17 in the deep sedation group (3.4%). Sedation was considered inadequate in 22 of the 506 deep sedation patients (4.3%). Adequate images were obtained in 95.3% of general anesthesia patients versus 86.6% of deep sedation patients.

Conclusion

There was no difference in the incidence of adverse events or cardiac MRI image adequacy for children receiving general anesthesia by anesthesiologists versus deep sedation by non-anesthesiologists. In summary, this study demonstrates that an appropriately trained sedation provider can provide deep sedation for cardiac MRI without the need for general anesthesia in selected cases.     

Safety and adverse effects during 24 hours after contrast-enhanced MRI with gadobenate dimeglumine (MultiHance®) in children

Background

Gadolinium-based MR contrast agents have long been considered safe for routine diagnostic imaging. However, the advent of nephrogenic systemic fibrosis (NSF) among certain patients with severe renal insufficiency has brought the issue of safety into question. Nowhere is safety of greater concern than among children who frequently require multiple contrast-enhanced MRI examinations over an extended period of time.

Objective

To retrospectively evaluate the safety of gadobenate dimeglumine for contrast-enhanced (CE) MRI across a range of indications.

Materials and methods

Two hundred pediatric inpatients (age: 4 days to 15 years) underwent CE MRI as part of clinical routine. The children received a gadobenate dimeglumine dose of either 0.05 mmol/kg body weight (liver, abdominal imaging, musculoskeletal imaging, brain and other rare indications) or 0.1 mmol/kg bodyweight (cardiovascular imaging, MR-urography). Young (< 8 years) children with congenital heart disease were intubated and underwent MRA evaluation with controlled ventilation. Monitoring for adverse events was performed for at least 24 h after each gadobenate dimeglumine injection. Depending on clinical necessity, laboratory measurements and, in some cases, vital sign and ECG determinations were made before and after contrast injection. Safety was evaluated by age group, indication and dose administered.

Results

No clinically adverse events were reported among children who had one MRI scan only or among children who had several examinations. There were no changes in creatinine or bilirubin levels even in very young children.

Conclusions

No adverse events were recorded during the first 24 h following administration of gadobenate dimeglumine in 200 children.     

Is procedural sedation with propofol acceptable for complex imaging? A comparison of short vs. prolonged sedations in children

Background

Concerns exist in the community of non-anesthesiologist sedation providers regarding the appropriateness of prolonged sedations using propofol for outpatient procedures.

Objective

To investigate interventions required, completion rate and resource use in prolonged vs. short sedations using propofol in outpatients.

Materials and methods

We reviewed retrospectively 213 children sedated with propofol by a non-anesthesiologist sedation service. Cohorts were composed a priori of children sedated for ≥1 h and <1 h. Comparisons were made regarding need for interventions, sedation duration, sedation completion to discharge time, and procedural completion rate.

Results

Most sedations were for MRI (87.5% short vs. 94.5% prolonged) with no statistically significant difference in overall need for interventions (75.2% prolonged vs. 65.4% short) nor completion to discharge times (30.7?±?11.5 min [prolonged] vs. 30.3?±?11.7 min [short]) between both groups. One child failed to complete the intended scan. No one required endotracheal intubation or unplanned admission.

Conclusion

Prolonged outpatient sedations with propofol conducted by appropriately trained non-anesthesiology sedation providers appears effective for imaging procedures with no increase in interventions or increased resource burden compared to short sedations. This information can assist all stakeholders in determining scope of practice and guidelines for moderately longer pediatric sedations with propofol.     

Pediatric neuroimaging using magnetic resonance imaging during non-sedated sleep

Background

Etiological studies of many neurological and psychiatric disorders are increasingly turning toward longitudinal investigations of infant brain development in order to discern predisposing structural and/or functional differences prior to the onset of overt clinical symptoms. While MRI provides a noninvasive window into the developing brain, MRI of infants and toddlers is challenging due to the modality’s extreme motion sensitivity and children’s difficulty in remaining still during image acquisition.

Objective

Here, we outline a broad research protocol for successful MRI of children under 4 years of age during natural, non-sedated sleep.

Materials and methods

All children were imaged during natural, non-sedated sleep. Active and passive measures to reduce acoustic noise were implemented to reduce the likelihood of the children waking up during acquisition. Foam cushions and vacuum immobilizers were used to limit intra-scan motion artifacts.

Results

More than 380 MRI datasets have been successfully acquired from 220 children younger than 4 years of age within the past 39 months. Implemented measures permitted children to remain asleep for the duration of the scan and allowed the data to be acquired with an overall 97% success rate.

Conclusion

The proposed method greatly advances current pediatric imaging techniques and may be readily implemented in other research and clinical settings to facilitate and further improve pediatric neuroimaging.     

High success rates of sedation-free brain MRI scanning in young children using simple subject preparation protocols with and without a commercial mock scanner–the Diabetes Research in Children Network (DirecNet) experience

Background

The ability to lie still in an MRI scanner is essential for obtaining usable image data. To reduce motion, young children are often sedated, adding significant cost and risk.

Objective

We assessed the feasibility of using a simple and affordable behavioral desensitization program to yield high-quality brain MRI scans in sedation-free children.

Materials and methods

222 children (4–9.9 years), 147 with type 1 diabetes and 75 age-matched non-diabetic controls, participated in a multi-site study focused on effects of type 1 diabetes on the developing brain. T1-weighted and diffusion-weighted imaging (DWI) MRI scans were performed. All children underwent behavioral training and practice MRI sessions using either a commercial MRI simulator or an inexpensive mock scanner consisting of a toy tunnel, vibrating mat, and video player to simulate the sounds and feel of the MRI scanner.

Results

205 children (92.3%), mean age 7?±?1.7 years had high-quality T1-W scans and 174 (78.4%) had high-quality diffusion-weighted scans after the first scan session. With a second scan session, success rates were 100% and 92.5% for T1-and diffusion-weighted scans, respectively. Success rates did not differ between children with type 1 diabetes and children without diabetes, or between centers using a commercial MRI scan simulator and those using the inexpensive mock scanner.

Conclusion

Behavioral training can lead to a high success rate for obtaining high-quality T1-and diffusion-weighted brain images from a young population without sedation.     

Percutaneous Closure of Atrial Septal Defects in Spontaneously Breathing Children Under Deep Sedation: A Feasible and Safe Concept

Interventional cardiac catheterization in children and adolescents is traditionally performed with the patient under general anesthesia and endotracheal intubation. However, percutaneous closure of atrial septum defect (ASD) without general anaesthesia is currently being attempted in a growing number of children. The study objective was to evaluate the success and complication rate of percutaneous ASD closure in spontaneously breathing children under deep sedation. Retrospective single centre cohort study of consecutive children undergoing percutaneous ASD closure at a tertiary care pediatric cardiology centre. Transesophageal echocardiography (TEE) and percutaneous ASD closure were performed with the patient under deep sedation with intravenous bolus of midazolam and ketamine for induction and propofol continuous infusion for maintenance of sedation in spontaneously breathing children. One hundred and ninety-seven patients (median age 6.1 years [minimum 0.5; maximum 18.8]) underwent TEE and ASD balloon sizing. Percutaneous ASD closure was attempted in 174 patients (88 %), and device implantation was performed successfully in 92 %. To achieve sufficient deep sedation, patients received a median ketamine dose of 2.7 mg/kg (0.3; 7) followed by a median propofol continuous infusion rate of 5 mg/kg/h (1.1; 10.7). There were no major cardiorespiratory complications associated with deep sedation, and only two patients (1 %) required endotracheal intubation due to bronchial obstruction immediately after induction of sedation. Seventeen patients (8 %) had minor respiratory complications and required frequent oral suctioning or temporary bag-mask ventilation. TEE and percutaneous ASD closure can be performed safely and successfully under deep sedation in spontaneously breathing children of all ages.     

Diffusion-weighted MRI of abscess formations in children and young adults

Background

Diffusion-weighted MRI (DWI) is helpful for detection of brain abscess and pelvic abscess in adults. In the present study, we evaluated the diagnostic performance of DWI in children and young adults with abdominal and soft tissue abscess formations.

Methods

Seventeen patients (11 females, aged 13 ± 6 years) with suspected abdominal or soft-tissue abscess underwent routine MRI including free-breathing DWI and contrast-enhanced T1w imaging. Seventeen random age-matched patients with non-purulent abdominal fluid collections served as controls. Mean apparent diffusion coefficent (ADC) was measured for abscess, muscle, liver, spleen and kidney tissue as well as for cerebrospinal fluid, urine and free abdominal fluid.

Results

All fluid collections were identified on diffusion-weighted images. Thirteen of 14 confirmed abscess formations showed an ADC < 1.0 × 10^?3 mm²/s with a mean value of 0.80 ± 0.38 mm²/s. One tuberculous softtissue abscess had a higher ADC of 1.85 × 10^?3 mm²/s. Ring enhancement on T1w imaging was seen in three nonpurulent fluid collections. There were no false-positive findings in the control group.

Conclusions

Diffusion-weighted MRI is highly sensitive for abscess and may add specificity to contrast-enhanced T1w imaging of ring-enhancing fluid collections. DWI with free-breathing rapid image acquisition and without the need of intravenous contrast application constitutes a particularly useful choice in pediatric imaging.     

Paediatric MRI under sedation: is it necessary? What is the evidence for the alternatives?

To achieve diagnostic images during MRI examinations, small children need to lie still to avoid movement artefact. To reduce patient motion, obviate the need for voluntary immobilisation or breath-holding and therefore obtain high-quality images, MRI of infants is frequently carried out under sedation or general anaesthesia, but this is not without risk and expense. However, many other techniques are available for preparing children for MRI, which have not been fully evaluated. Here, we evaluate the advantages and disadvantage of sedation and anaesthesia for MRI. We then evaluate the alternatives, which include neonatal comforting techniques, sleep manipulation, and appropriate adaptation of the physical environment. We summarize the evidence for their use according to an established hierarchy. Lastly, we discuss several factors that will influence the choice of imaging preparation, including patient factors, imaging factors and service provision. The choice of approach to paediatric MRI is multi-factorial, with limited scientific evidence for many of the current approaches. These considerations may enable others to image children using MRI under different circumstances.     

Abdominal sonography in the evaluation of heterotaxy in children

Heterotaxy is a rare congenital disorder characterised by abnormal viscero-vascular situs with either left or right isomerism that usually coincides with complex cardiac malformation. A precise diagnosis must be made for the selection of the most appropriate treatment. The diagnosis and evaluation of these conditions have been dependent on invasive studies such as angiocardiography, although more recently magnetic resonance imaging (MRI) has been advocated. In paediatric patients MRI is far from ideal because of the need for sedation and monitoring during the examination. The authors reviewed the modalities used in the evaluation of heterotaxy with emphasis on the use of ultrasonography, including pulse and colour flow Doppler imaging. A series of 14 children with heterotaxy is presented; ten with left abdominal isomerism (polysplenia) and four with right isomerism (asplenia). Results of abdominal sonography were compared with those of echo- and angiocardiography, surgery and autopsy. Of the ten children with left abdominal isomerism, two had no cardiac abnormalities. All those with right isomerism had a complex vitium. One patient with left abdominal isomerism proved to have right atrial isomerism. Some new reproducible patterns in viscero-vascular derangement are reported. The predictable patterns of left and right isomerism are outlined and atypical features discussed.

     

Sedation for intra-articular corticosteroid injections in juvenile idiopathic arthritis: the views of patients and their parents

Intra-articular corticosteroid injections (IACI) are one of the mainstays of treatment for children with juvenile idiopathic arthritis. The most important disadvantage of IACI is the pain associated with the procedure. Little is known about the children or parents' perception of this pain. This study was undertaken to determine whether patients and their parents prefer sedation to receive IACI or not and why. A survey form was presented to patients and/or their parents from January to March 2010 to evaluate their choice of anesthesiologist-controlled deep sedation (with sevoflurane) vs. no sedation–no local anesthesia and the reasons for it. All participants had experienced the two options. In addition, there were two visual analog scales (VAS) to evaluate pain associated with blood draws and IACI, respectively. A total of 45 patients and their parents filled out the survey form. There were 34 females; the median age was 10.6 years, and the median duration of the disease was 6.4 years. Median VAS score was 1.3 for pain associated with blood draws, and 6, for IACI. Most children preferred sedation for IACI (26 vs. 15), although four did not show preference for either method. Children who preferred sedation for IACI were younger (p?=?0.03) and had a shorter course of disease (p?=?0.04). Conclusions: While most children prefer to receive IACI under sedation, a majority of parents prefer to avoid its risks. Children who prefer IACI without sedation are significantly older and have a longer course of disease.     

Muscular magnetic resonance imaging for evaluation of myopathies in children

BACKGROUND: Myopathies present with a broad diagnostic spectrum which may ultimately require muscle biopsy. MRI has been established as a non-invasive method in diagnosing adult myopathies; not only does MRI reveal characteristic findings which point in a diagnostic direction, but also aids in determining optimal biopsy sites and controlling therapeutic interventions. Muscle MRI is increasingly finding application to pediatric myopathies, especially dystrophies and myositides. The following paper serves to illustrate the use of MRI using exemplary clinical vignettes. PATIENTS/METHODS: From 1999 until 2006, 180 children with myopathies of unknown aetiology, ages 10 months to 18 years, were examined with a standardised MRI protocol (axial T1-SE and T2-weighted TIRM sequences). The protocol included imaging of the lower extremities whereas sequences displaying the upper extremities were only acquired in selected patients. Furthermore, intravenous contrast agent was only administered in selected children. RESULTS: All investigations could be performed without sedation due to an examination time of 12 to 15 minutes. The illustrated cases of limb-girdle muscular dystrophy, Duchenne's muscular dystrophy, dermatomyositis, pyomyositis, and chronic neurogenic disease with secondary myopathy all showed disease-characteristic MRI patterns which substantially helped to reach the ultimate diagnosis. CONCLUSIONS: Muscle MRI is a non-invasive and effective instrument in helping to diagnose pediatric myopathies of unknown aetiology. It may facilitate muscle biopsy and serves to control therapeutical effects and disease course. Furthermore, muscle MRI may be applicated even to children of less than 4 years of age without sedation.     

The impact of preparation and support procedures for children with sickle cell disease undergoing MRI

Background

Children with sickle cell disease (SCD) often undergo MRI studies to assess brain injury or to quantify hepatic iron. MRI requires the child to lie motionless for 30–60?min, thus sedation/anesthesia might be used to facilitate successful completion of exams, but this poses additional risks for SCD patients. To improve children’s ability to cope with MRI examinations and avoid sedation, our institution established preparation and support procedures (PSP).

Objective

To investigate the impact of PSP in reducing the need for sedation during MRI exams among children with SCD.

Materials and methods

Data on successful completion of MRI testing were compared among 5- to 12-year-olds who underwent brain MRI or liver R2*MRI with or without receiving PSP.

Results

Seventy-one children with SCD (median age 9.85?years, range 5.57–12.99?years) underwent a brain MRI (n?=?60) or liver R2*MRI (n?=?11). Children who received PSP were more likely to complete an interpretable MRI exam than those who did not (30 of 33; 91% vs. 27 of 38; 71%, unadjusted OR?=?4.1 (P?=?0.04) and OR?=?8.5 (P?<?0.01) when adjusting for age.

Conclusion

PSP can help young children with SCD complete clinically interpretable, nonsedated MRI exams, avoiding the risks of sedation/anesthesia.     

Characterization of acoustic noise in a neonatal intensive care unit MRI system

Background

To eliminate the medical risks and logistical challenges of transporting infants from the neonatal intensive care unit (NICU) to the radiology department for magnetic resonance imaging, a small-footprint 1.5-T MRI scanner has been developed for neonatal imaging within the NICU. MRI is known to be noisy, and exposure to excessive acoustic noise has the potential to elicit physiological distress and impact development in the term and preterm infant.

Objective

To measure and compare the acoustic noise properties of the NICU MRI system against those of a conventional 1.5-T MRI system.

Materials and methods

We performed sound pressure level measurements in the NICU MRI scanner and in a conventional adult-size whole-body 1.5-T MRI system. Sound pressure level measurements were made for six standard clinical MR imaging protocols.

Results

The average sound pressure level value, reported in unweighted (dB) and A-weighted (dBA) decibels for all six imaging pulse sequences, was 73.8 dB and 88 dBA for the NICU scanner, and 87 dB and 98.4 dBA for the conventional MRI scanner. The sound pressure level values measured on the NICU scanner for each of the six MR imaging pulse sequences were consistently and significantly (P?=?0.03) lower, with an average difference of 14.2 dB (range 10–21 dB) and 11 dBA (range 5–18 dBA). The sound pressure level frequency response of the two MR systems showed a similar harmonic structure above 200 Hz for all imaging sequences. The amplitude, however, was appreciably lower for the NICU scanner, by as much as 30 dB, for frequencies below 200 Hz.

Conclusion

The NICU MRI system is quieter than conventional MRI scanners, improving safety for the neonate and facilitating siting of the unit within the NICU.     

Incidental pineal cysts in children who undergo 3-T MRI

Background

Pineal cysts, both simple and complex, are commonly encountered in children. More cysts are being detected with MR technology; however, nearly all pineal cysts are benign and require no follow-up.

Objective

To discover the prevalence of pineal cysts in children at our institution who have undergone high-resolution 3-T MRI.

Materials and methods

We retrospectively reviewed 100 consecutive 3-T brain MRIs in children ages 1 month to 17 years (mean 6.8 ± 5.1 years). We evaluated 3-D volumetric T1-W imaging, axial T2-W imaging, axial T2-W FLAIR (fluid attenuated inversion recovery) and coronal STIR (short tau inversion recovery) sequences. Pineal parenchymal and cyst volumes were measured in three planes. Cysts were analyzed for the presence and degree of complexity.

Results

Pineal cysts were present in 57% of children, with a mean maximum linear dimension of 4.2 mm (range 1.5–16 mm). Of these cysts, 24.6% showed thin septations or fluid levels reflecting complexity. None of the cysts demonstrated complete T2/FLAIR signal suppression. No cyst wall thickening or nodularity was present. There was no significant difference between the ages of children with and without cysts. Cysts were more commonly encountered in girls than boys (67% vs. 52%; P?=?0.043). There was a slight trend toward increasing pineal gland volume with age.

Conclusion

Pineal cysts are often present in children and can be incidentally detected by 3-T MRI. Characteristic-appearing pineal cysts in children are benign, incidental findings, for which follow-up is not required if there are no referable symptoms or excessive size.