Anaesthesia considerations for cardiac MRI in infants and small children

Comprehensive Neonatal Cardiac, Feed and Wrap, Non-contrast, Non-sedated, Free-breathing Compressed Sensing 4D Flow MRI Assessment

BACKGROUND

Cardiac MRI is an important imaging tool in congenital cardiac disease, but its use has been limited in the neonatal population as general anesthesia has been needed for breath-holding. Technological advances in four-dimensional (4D) flow MRI have now made nonsedated free-breathing acquisition protocols a viable clinical option, but the method requires prospective validation in neonates.

PURPOSE

To test the feasibility of compressed sensing (CS) 4D flow MRI in the neonatal population and to compare with standard previously validated two-dimensional (2D) phase-contrast (PC) flow MRI.

STUDY TYPE

Prospective, cohort, image quality.

POPULATION

A total of 14 healthy neonates (median [range] age: 2.5 [0-80] days; 8 male).

FIELD STRENGTH AND SEQUENCE

Noncontrast 2D cine gradient echo sequence with through-plane velocity encoding (PC) sequence and compressed sensing (CS) three-dimensional (3D), time-resolved, cine phase-contrast MRI with 3D velocity-encoding (4D flow MRI) at 3 T.

ASSESSMENT

Aortic 2D PC, and aortic, pulmonary trunk and superior vena cava CS 4D flow MRI were acquired using the feed and wrap technique (nonsedated) and quantified using commercially available software. Aortic flow and peak velocity were compared between methods. Internal consistency of 4D flow MRI was determined by comparing mean forward flow of the main pulmonary artery (MPA) vs. the sum of left and right pulmonary artery flows (LPA and RPA) and by comparing mean ascending aorta forward flow (AAo) vs. the sum of superior vena cava (SVC) and descending aorta flows (DAo).

STATISTICAL TESTS

Flow and peak-velocity comparisons were assessed using paired t-tests, with P < 0.05 considered significant, and Bland-Altman analysis. Interobserver and intraobserver agreement and internal consistency were analyzed by intraclass correlation co-efficient (ICC).

RESULTS

There was no statistically significant difference between ascending aortic forward flow between 2D PC and CS 4D Flow MRI (P = 0.26) with a bias of 0.11 mL (-0.59 to 0.82 mL) nor peak velocity (P = 0.11), with a bias of -5 cm/sec and (-26 to 16 cm/sec). There was excellent interobserver and intraobserver agreement for each vessel (interobserver ICC: AAo 1.00; DAo 0.94, SVC 0.90, MPA 0.99, RPA 0.98, LPA 0.96; intraobserver ICC: AAo 1.00; DAo 0.99, SVC 0.98, MPA 1.00, RPA 1.00, LPA 0.99). Internal consistency measures showed excellent agreement for both mean forward flow of main pulmonary artery vs. the sum of left and right pulmonary arteries (ICC: 0.95) and mean ascending aorta forward flow vs. the sum of superior vena cava and descending aorta flows (ICC: 1.00).

CONCLUSION

Sedation-free neonatal feed and wrap MRI is well tolerated and feasible. CS 4D flow MRI quantification is similar to validated 2D PC free-breathing imaging with excellent interobserver and intraobserver agreement.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Parametric Mapping Cardiac Magnetic Resonance Imaging for the Diagnosis of Myocarditis in Children in the Era of COVID-19 and MIS-C

Myocarditis comprises many clinical presentations ranging from asymptomatic to sudden cardiac death. The history, physical examination, cardiac biomarkers, inflammatory markers, and electrocardiogram are usually helpful in the initial assessment of suspected acute myocarditis. Echocardiography is the primary tool to detect ventricular wall motion abnormalities, pericardial effusion, valvular regurgitation, and impaired function. The advancement of cardiac magnetic resonance (CMR) imaging has been helpful in clinical practice for diagnosing myocarditis. A recent Scientific Statement by the American Heart Association suggested CMR as a confirmatory test to diagnose acute myocarditis in children. However, standard CMR parametric mapping parameters for diagnosing myocarditis are unavailable in pediatric patients for consistency and reliability in the interpretation. The present review highlights the unmet clinical needs for standard CMR parametric criteria for diagnosing acute and chronic myocarditis in children and differentiating dilated chronic myocarditis phenotype from idiopathic dilated cardiomyopathy. Of particular relevance to today’s practice, we also assess the potential and limitations of CMR to diagnose acute myocarditis in children exposed to severe acute respiratory syndrome coronavirus-2 infections. The latter section will discuss the multi-inflammatory syndrome in children (MIS-C) and mRNA coronavirus disease 19 vaccine-associated myocarditis.

Recommendations for cardiovascular magnetic resonance and computed tomography in congenital heart disease: a consensus paper from the CMR/CCT working group of the Italian Society of Pediatric Cardiology (SICP) and the Italian College of Cardiac Radiology endorsed by the Italian Society of Medical and Interventional Radiology (SIRM) Part I

Cardiovascular magnetic resonance (CMR) and computed tomography (CCT) are advanced imaging modalities that recently revolutionized the conventional diagnostic approach to congenital heart diseases (CHD), supporting echocardiography and often replacing cardiac catheterization. Nevertheless, correct execution and interpretation require in-depth knowledge of all technical and clinical aspects of CHD, a careful assessment of risks and benefits before each exam, proper imaging protocols to maximize diagnostic information, minimizing harm. This position paper, written by experts from the Working Group of the Italian Society of Pediatric Cardiology and from the Italian College of Cardiac Radiology of the Italian Society of Medical and Interventional Radiology, is intended as a practical guide for applying CCT and CMR in children and adults with CHD, wishing to support Radiologists, Pediatricians, Cardiologists and Cardiac Surgeons in the multimodality diagnostic approach to these patients. The first part provides a review of the most relevant literature in the field, describes each modality's advantage and drawback, making considerations on the main applications, image quality, and safety issues. The second part focuses on clinical indications and appropriateness criteria for CMR and CCT, considering the level of CHD complexity, the clinical and logistic setting and the operator expertise.

Sudden Cardiac Arrest in the Paediatric Population

Sudden cardiac arrest in the young is a rare event with a range of potential causes including cardiomyopathies, ion channelopathies, and autonomic nervous system dysfunction. Investigations into the cause involve a multidisciplinary team, including cardiologists, geneticists, and psychologists. In addition to a detailed medical history, family history and circumstances surrounding the event are important in determining the cause. Clinical investigations including an electrocardiogram are fundamental in diagnosis and should be interpreted cautiously because some children may have atypical presentations and an evolving phenotype. The potential for misdiagnosis exists that could lead to incorrect long-term management strategies. If an inherited condition is suspected, genetic testing of the patient and cascade screening of family members is recommended with genetic counselling and psychological support. Medical management is left to the treating physician acknowledging that a clear diagnosis cannot be made in approximately half of cases. Secondary prevention implantable defibrillators are widely deployed but can be associated with complications in young patients. A plan for safe return to activity is recommended along with a proper transition of care into adulthood. Broad screening of the general population for arrhythmia syndromes is not recommended; preventative measures include screening paediatric patients for risk factors by their primary care physician. Several milestone events or activities that take place in youth could be used as opportunities to promote safety. Further work into risk stratification of this paediatric population through patient registries and greater awareness of cardiopulmonary resuscitation and automated external defibrillator use in saving lives is warranted.

Survey of centers performing cardiovascular magnetic resonance in pediatric and congenital heart disease: a report of the Society for Cardiovascular Magnetic Resonance

BACKGROUND

There are few data on practice patterns and trends for cardiovascular magnetic resonance (CMR) in pediatric and congenital heart disease. The Society for Cardiovascular Magnetic Resonance (SCMR) sought to address this deficiency by performing an international survey of CMR centers.

METHODS

Surveys consisting of 31 (2014) and 33 (2018) items were designed to collect data on the use of CMR for the evaluation of pediatric and congenital heart disease patients. They were sent to all SCMR members in 2014 and 2018. One response per center was collected.

RESULTS

There were 93 centers that responded in 2014 and 83 in 2018. The results that follow show data from 2014 and 2018 separated by a dash. The median annual number of pediatric/congenital CMR cases per center was 183-209. The median number of scanners for CMR was 2-2 (range, 1-8) with 58-63% using only 1.5T scanners and 4-4% using only 3T scanners. The mean number of attending/staff reading CMRs was 3.7-2.6; among them, 52-61% were pediatric or adult cardiologists and 47-38% were pediatric or adult radiologists. The median annual case volume per attending was 54-86. The median number of technologists per center doing CMRs was 4-5. The median scanner time allocated for a non-sedated examination was 75-75 min (range, 45-120). Among the 21 centers responding to both surveys, the mean annual case volume increased from 320 in 2014 to 445 in 2018; 17 (81%) of the centers had an increase in annual case volume. For this subgroup, the median attending/staff per center was 4 in both 2014 and 2018. The median scanner time allotted per study was unchanged at 90 min. The mean time for an attending/staff physician to perform a typical CMR examination including reporting was 143-141 min.

CONCLUSION

These survey data provide a novel comprehensive view of CMR practice in pediatric and congenital heart disease. This information is useful for internal benchmarking, resource allocation, addressing practice variation, quality improvement initiatives, and identifying unmet needs.

Comparison of cine and real-time cardiac MRI in rhesus macaques

Cardiac MRI in rhesus macaques, a species of major relevance for preclinical studies on biological therapies, requires artificial ventilation to realize breath holding. To overcome this limitation of standard cine MRI, the feasibility of Real-Time (RT) cardiac MRI has been tested in a cohort of ten adult rhesus macaques using a clinical MR-system. In spite of lower tissue contrast and sharpness of RT-MRI, cardiac functions were similarly well assessed by RT-MRI compared to cine MRI (similar intra-subject repeatability). However, systematic underestimation of the end-diastolic volume (31 ± 9%), end-systolic volume (20 ± 11%), stroke volume (40 ± 12%) and ejection fraction (13 ± 9%) hamper the comparability of RT-MRI results with those of other cardiac MRI methods. Yet, the underestimations were very consistent (< 5% variability) for repetitive measurements, making RT-MRI an appropriate alternative to cine MRI for longitudinal studies. In addition, RT-MRI enabled the analysis of cardio-respiratory coupling. All functional parameters showed lower values during expiration compared to inspiration, most likely due to the pressure-controlled artificial ventilation. In conclusion, despite systematic underestimation of the functional parameters, RT-MRI allowed the assessment of left ventricular function in macaques with significantly less experimental effort, measurement time, risk and burden for the animals compared to cine MRI.

Study to evaluate the optimal dose of remifentanil required to ensure apnea during magnetic resonance imaging of the heart under general anesthesia

BACKGROUND

Magnetic resonance (MRI) scanning of the heart is an established part of the investigation of cardiovascular conditions in children. In young children, sedation is likely to be needed, and multiple controlled periods of apnea are often required to allow image acquisition. Suppression of spontaneous ventilation is possible with remifentanil; however, the dose required is uncertain.

AIMS

To establish the dose of remifentanil, by infusion, required to suppress ventilation sufficiently to allow a 30-s apnea during MRI imaging of the heart.

METHOD

Patients aged 1-6 years were exposed to different doses of remifentanil, and the success in achieving a 30-s apnea was recorded. A dose recommendation was made for each patient, informed by responses of previous patients using an adaptive Bayesian dose-escalation design. Other aspects of anesthesia were standardized. A final estimate of the dose needed to achieve a successful outcome in 80% of patients (ED80) was made using logistic regression.

RESULTS

38 patients were recruited, and apnea achieved in 31 patients. The estimate of the ED80 was 0.184 µg/kg/min (95% CI 0.178-0.190). Post hoc analysis revealed that higher doses were required in younger patients.

CONCLUSION

The ED80 for this indication was 0.184 µg/kg/min (95% CI 0.178-0.190). This is different from optimal dosing identified for other indications and dosing of remifentanil should be specific to the clinical context in which it is used.

Echocardiographic assessment of right ventricular systolic function in healthy Beagle dogs compared to high field cardiac magnetic resonance imaging

Ten healthy Beagle dogs were used to compare selected echocardiographic parameters of right ventricular (RV) systolic function with high field cardiac magnetic resonance imaging (MRI). All dogs underwent complete transthoracic echocardiography before and during anesthesia, as well as cardiac MRI with determination of morphology-based ejection fraction, and phase contrast angiography-derived stroke volume. A correlation analysis was carried out between echocardiographic and MRI parameters. The values of fractional area change, tricuspid annular plane systolic excursion, tissue Doppler imaging derived peak velocity of the isovolumic contraction wave and systolic wave of the lateral tricuspid valve annulus showed lower values under general anesthesia. Of all echocardiographic parameters of RV systolic function, only fractional area change (r = 0.671, P = 0.034) and tissue Doppler imaging derived peak velocity of the systolic wave of the lateral tricuspid valve annulus (r = 0.768; P = 0.01), showed a significant correlation with MRI derived stroke volume. None of the echocardiographic parameters correlated with MRI derived ejection fraction. When evaluating the RV echocardiographically, fractional area change and peak velocity of the systolic wave of the lateral tricuspid valve annulus appear to be the most reliable predictors of RV systolic function when compared to MRI under anesthesia.

Assessment of the practice of pediatrics procedural sedation and analgesia for magnetic resonance imaging and computed tomography scan at a teaching hospital, Ethiopia, 2020: A clinical audit

BACKGROUND

The main goals of paediatric sedation/general anesthesia vary according to the specific imaging procedure, but generally includes anxiety relief, pain control and control of excessive movement. The quality of magnetic resonance imaging (MRI) and computed tomography (CT) depends largely on immobility of the patient during the procedure, which is often difficult to achieve without sedation in children. Sedation is the depression of the central nervous system and reflexes by the administration of drugs. Brain imaging is routinely used to identify stroke, hemorrhage, and structural abnormalities. All patients undergoing procedural sedation and those receiving general anesthesia should be evaluated equally.

AIM

The study aimed to perform a clinical audit of sedation and analgesia practices for magnetic resonance imaging and computed tomography compared against the guidelines/standards to determine if practice meets the standards and identify areas of non-compliance at a teaching Referral Hospital in Ethiopia.

METHODS

This clinical audit was conducted from January 1 to May 30/2020 for 5 months at a teaching Referral Hospital in Ethiopia. All children below the age of 6 years underwent MRI and CT imaging procedures under sedation during a study period were included. Data were collected through direct observation using checklists of standards by a trained data collector. Descriptive statistics were presented with tables, graphs of sums and percentages of items using SPSS version 20.

RESULTS

A total of 40 children underwent MRI and CT imaging were observed at the Hospital imaging sites. Among the 20 standards, 6 of them had 100% compliance rate, 3 of the standards had 0% complaince rate and 11 of the standards had the compliance rate of between 0 and 100%.

CONCLUSIONS AND RECOMMENDATIONS

In general, even though the practice guidelines of procedural sedation for MRI and CT recommend to practice procedures based on the standards, this study showed there were a number of standards that had <100% compliance rate. Therefore, it is recommended that staff should adopt standards or locally prepared protocols for their day-to-day practice.

Effect of General Anesthesia on Cardiac Magnetic Resonance-Derived Cardiac Function in Repaired Tetralogy of Fallot

Cardiac magnetic resonance imaging (CMR)-derived ejection fraction (EF) predicts adverse outcomes in repaired tetralogy of Fallot (rTOF) and drives timing of pulmonary valve replacement. Certain patient populations require sedation for successful CMR image acquisition. General anesthesia (GA) has been shown to depress EF and heart rate (HR) in animal models, however, its effect on congenital heart disease is unknown. A retrospective review was conducted of all CMR patients referred with rTOF between January 2011 and May 2019. The cohort was separated into GA and non-GA groups. Propensity score matching (PSM) adjusted for selection bias. A kernel matching algorithm was used to match subjects and the differences in mean treatment effect on the treated were computed for left ventricular (LV) and right ventricular (RV) EF, HR, and cardiac index (CI). 143 patients met criteria, 37 patients under GA (mean age 15 years, range 2-45, 59% male), and 106 patients without GA (mean age 21 years, range 10-53, 50% male). Unmatched analysis showed significant depression of LV EF (50 vs. 57%, p < 0.001) and RV EF (42 vs. 48%, p < 0.001) in the GA group compared to the non-GA group. There was no significant difference in HR or CI. After matching and PSM adjustment, the GA group had a significant decrease in LV EF (49 vs. 56%, p < 0.001), RV EF (41 vs. 48%, p < 0.001), CI (2728 vs. 3701 ml/min/m², p < 0.001), and HR (72 vs. 79 bpm, p = 0.04). General anesthesia with sevoflurane results in depressed CMR-derived EF.

Recommendations for standardized plane definition in canine cardiac MRI

With the growing interest in cardiac magnetic resonance imaging (cMRI), veterinary radiologists will increasingly be asked to use this modality to answer complex cardiological questions. Plane alignment is crucial for reproducible assessment of the heart. Anesthesia time is a limiting factor in cMRI. Aims of this prospective experimental study were to introduce a flow chart for standardized cMRI-examination in dogs, to test it for reproducibility using a cardiac CT simulation and to estimate time requirements needed to complete the examination accurately. Six operators (3 radiologists, 1 cardiologist, 1 imaging-resident, 1 technician) simulated a cMRI examination on CT-scans of 6 healthy Beagle dogs twice within two to four weeks. Assessment included qualitative and quantitative scoring of plane quality and time requirements. The quality of planes was high for the left and moderate for the right side of the heart. The intraclass correlation coefficient (ICC) of linear measurements of structures on the left was good to excellent (ICC-range: 0.789-0.948) but dropped to moderate to poor levels for the right side (ICC-range: 0.429-0.738). The median time required to complete a full examination was 30 (range: 13-103) min in the first and 24 (range: 15-62) min in the second evaluation. It differed significantly between operators and was consistently shorter for the left than for the right side. In conclusion, a new standardized scheme for cMRI can be quickly adopted by radiologists with some expertise in cross sectional imaging. Qualitative and quantitative results were highly reproducible for the left but less for the right side.

Assessment of Myocardial Perfusion at Rest and During Stress Using Dynamic First-Pass Contrast-Enhanced Magnetic Resonance Imaging in Healthy Dogs

Objective: To assess the feasibility of myocardial perfusion analysis in healthy dogs using dynamic contrast-enhanced cardiac magnetic resonance (DCE-MR) imaging at rest and during simulated stress with two doses of adenosine.

Animals: Ten healthy beagle dogs.

Procedures: Dogs were anesthetized and positioned in dorsal recumbency in a 3.0 Tesla MR scanner. Electrocardiogram-triggered dynamic T1-weighted ultrafast gradient echo images of three slices in short-axis orientation of the heart were acquired during breath holds and the first pass of gadolinium contrast. Image acquisition was performed after 4 min infusion of 140 μg/kg/min and 280 μg/kg/min adenosine and, after a washout period, without adenosine, respectively. Images were processed by dividing each slice into 6 radial segments and perfusion analysis was performed from signal intensity-time data.

Results: No differences in perfusion parameters were found between segments within any of the slices, but significant differences were found between slices for peak enhancement, accumulated enhancement, and the maximum upslope. In addition, significant differences were found within each slice between data at rest and during adenosine-induced stress for the relative and absolute maximum upslope, relative peak enhancement, time to peak, and accumulated enhancement although inter-individual variation was large and no difference was found between the two stress tests for some parameters.

Conclusion and Clinical Relevance: Results of this study showed that rest and stress myocardial perfusion can be assessed using DCE-CMR in dogs using the methods described. Both, adenosine dose and slice appear to affect perfusion parameters in healthy dogs and individual response to adenosine was variable.

Screening protocols to monitor respiratory status in primary immunodeficiency disease: findings from a European survey and subclinical infection working group

Many patients with primary immunodeficiency (PID) who have antibody deficiency develop progressive lung disease due to underlying subclinical infection and inflammation. To understand how these patients are monitored we conducted a retrospective survey based on patient records of 13 PID centres across Europe, regarding the care of 1061 adult and 178 paediatric patients with PID on immunoglobulin (Ig) G replacement. The most common diagnosis was common variable immunodeficiency in adults (75%) and hypogammaglobulinaemia in children (39%). The frequency of clinic visits varied both within and between centres: every 1-12 months for adult patients and every 3-6 months for paediatric patients. Patients diagnosed with lung diseases were more likely to receive pharmaceutical therapies and received a wider range of therapies than patients without lung disease. Variation existed between centres in the frequency with which some clinical and laboratory monitoring tests are performed, including exercise tests, laboratory testing for IgG subclass levels and specific antibodies, and lung function tests such as spirometry. Some tests were carried out more frequently in adults than in children, probably due to difficulties conducting these tests in younger children. The percentage of patients seen regularly by a chest physician, or who had microbiology tests performed following chest and sinus exacerbations, also varied widely between centres. Our survey revealed a great deal of variation across Europe in how frequently patients with PID visit the clinic and how frequently some monitoring tests are carried out. These results highlight the urgent need for consensus guidelines on how to monitor lung complications in PID patients.

Cardiovascular Magnetic Resonance Findings Late After the Arterial Switch Operation

Background—

Despite its robust diagnostic capabilities in adolescents and adult patients after the arterial switch operation, little information is available on the cardiovascular magnetic resonance findings in this population.

Methods and Results—

The cardiovascular magnetic resonance findings of 220 consecutive patients evaluated in our center were retrospectively reviewed (median age at cardiovascular magnetic resonance, 15.4 years; 66.8% male sex). Compared with published normal values, left and right ventricular end-diastolic volume z scores were mildly enlarged (0.48±1.76 and 0.33±1.5; P =0.0003 and 0.0038, respectively), with 26% of patients having left ventricular dilatation and 20% having right ventricular dilatation. Left ventricular dysfunction was present in 21.5% of patients (mild in most), and only 5.1% of patients had mild right ventricular dysfunction. Myocardial scar was found in 1.8% of patients. Dilatation of the neoaortic root was common (76%), and root z score increased at an average rate of 0.03 points per year. By multivariable analysis, neoaortic root dilatation was associated with worse neoaortic valve regurgitation (OR, 5.29; P =0.0016). The diameters of the thoracic aorta distal to the root were near-normal in most patients, whereas the neomain pulmonary artery was typically oval shaped with decreased anteroposterior and normal lateral diameters.

Conclusions—

Although the majority of arterial switch operation patients have normal ventricular size and function and myocardial scar is rare, an important minority exhibits ventricular enlargement or dysfunction. Neoaortic root dilatation, which is present in most patients and progresses over time, is strongly associated with significant neoaortic valve regurgitation. The findings of this study provide reference values against which arterial switch operation patients can be compared with their peers.

Advanced flow MRI: emerging techniques and applications

Magnetic resonance imaging (MRI) techniques provide non-invasive and non-ionising methods for the highly accurate anatomical depiction of the heart and vessels throughout the cardiac cycle. In addition, the intrinsic sensitivity of MRI to motion offers the unique ability to acquire spatially registered blood flow simultaneously with the morphological data, within a single measurement. In clinical routine, flow MRI is typically accomplished using methods that resolve two spatial dimensions in individual planes and encode the time-resolved velocity in one principal direction, typically oriented perpendicular to the two-dimensional (2D) section. This review describes recently developed advanced MRI flow techniques, which allow for more comprehensive evaluation of blood flow characteristics, such as real-time flow imaging, 2D multiple-venc phase contrast MRI, four-dimensional (4D) flow MRI, quantification of complex haemodynamic properties, and highly accelerated flow imaging. Emerging techniques and novel applications are explored. In addition, applications of these new techniques for the improved evaluation of cardiovascular (aorta, pulmonary arteries, congenital heart disease, atrial fibrillation, coronary arteries) as well as cerebrovascular disease (intra-cranial arteries and veins) are presented.

Cardiovascular magnetic resonance: Diagnostic utility and specific considerations in the pediatric population

Cardiovascular magnetic resonance is a non-invasive imaging modality which is emerging as important tool for the investigation and management of pediatric cardiovascular disease. In this review we describe the key technical and practical differences between scanning children and adults, and highlight some important considerations that must be taken into account for this patient population. Using case examples commonly seen in clinical practice, we discuss the important clinical applications of cardiovascular magnetic resonance, and briefly highlight key future developments in this field.

Indications for cardiovascular magnetic resonance in children with congenital and acquired heart disease: an expert consensus paper of the Imaging Working Group of the AEPC and the Cardiovascular Magnetic Resonance Section of the EACVI

This article provides expert opinion on the use of cardiovascular magnetic resonance (CMR) in young patients with congenital heart disease (CHD) and in specific clinical situations. As peculiar challenges apply to imaging children, paediatric aspects are repeatedly discussed. The first section of the paper addresses settings and techniques, including the basic sequences used in paediatric CMR, safety, and sedation. In the second section, the indication, application, and clinical relevance of CMR in the most frequent CHD are discussed in detail. In the current era of multimodality imaging, the strengths of CMR are compared with other imaging modalities. At the end of each chapter, a brief summary with expert consensus key points is provided. The recommendations provided are strongly clinically oriented. The paper addresses not only imagers performing CMR, but also clinical cardiologists who want to know which information can be obtained by CMR and how to integrate it in clinical decision-making.

Practice advisory on anesthetic care for magnetic resonance imaging: an updated report by the american society of anesthesiologists task force on anesthetic care for magnetic resonance imaging

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Anesthetic Care for Magnetic Resonance Imaging presents an updated report of the Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging.

Supplemental Digital Content is available in the text.

Indications for cardiovascular magnetic resonance in children with congenital and acquired heart disease: an expert consensus paper of the Imaging Working Group of the AEPC and the Cardiovascular Magnetic Resonance Section of the EACVI

This article provides expert opinion on the use of cardiovascular magnetic resonance (CMR) in young patients with congenital heart disease (CHD) and in specific clinical situations. As peculiar challenges apply to imaging children, paediatric aspects are repeatedly discussed. The first section of the paper addresses settings and techniques, including the basic sequences used in paediatric CMR, safety, and sedation. In the second section, the indication, application, and clinical relevance of CMR in the most frequent CHD are discussed in detail. In the current era of multimodality imaging, the strengths of CMR are compared with other imaging modalities. At the end of each chapter, a brief summary with expert consensus key points is provided. The recommendations provided are strongly clinically oriented. The paper addresses not only imagers performing CMR, but also clinical cardiologists who want to know which information can be obtained by CMR and how to integrate it in clinical decision-making.

High-field MR imaging in pediatric congenital heart disease: initial results

BACKGROUND

Comprehensive assessment of pediatric congenital heart disease (CHD) at any field strength mandates evaluation of both vascular and dynamic cardiac anatomy for which diagnostic quality contrast-enhanced magnetic resonance angiography (CEMRA) and cardiac cine are crucial.

OBJECTIVE

To determine whether high-resolution (HR) CEMRA and steady-state free precession (SSFP) cine can be performed reliably at 3.0 T in children with CHD and to compare the image quality to similar techniques performed at 1.5 T.

MATERIALS AND METHODS

Twenty-eight patients with a median age of 5 months and average weight 9.0 ± 7.8 kg with suspected or known CHD were evaluated at 3.0 T. SSFP cine (n = 86 series) and HR-CEMRA (n = 414 named vascular segments) were performed and images were scored for image quality and artifacts. The findings were compared to those of 28 patients with CHD of similar weight who were evaluated at 1.5 T.

RESULTS

Overall image quality on HR-CEMRA was rated as excellent or good in 96% (397/414) of vascular segments at 3.0 T (k = 0.49) and in 94% (349/371) of vascular segments at 1.5 T (k = 0.36). Overall image quality of SSFP was rated excellent or good in 91% (78/86) of cine series at 3.0 T (k = 0.55) and in 81% (87/108) at 1.5 T (k = 0.47). Off-resonance artifact was common at both field strengths, varied over the cardiac cycle and was more prevalent at 3.0 T. At 3.0 T, off-resonance dark band artifact on SSFP cine was absent in 3% (3/86), mild in 69% (59/86), moderate in 27% (23/86) and severe in 1% (1/86) of images; at 1.5 T, dark band artifact was absent in 16% (17/108), mild in 69% (75/108), moderate in 12% (13/108) and severe in 3% (3/108) of cine images. The signal-to-noise ratio and contrast-to-noise ratio of both SSFP cine and HR-CEMRA images were significantly higher at 3.0 T than at 1.5 T (P < 0.001).

CONCLUSION

Signal-to-noise ratio and contrast-to-noise ratio of high-resolution contrast-enhanced magnetic resonance angiography and SSFP cine were higher at 3.0 T than at 1.5 T. Artifacts on SSFP cine were cardiac phase specific and more prevalent at 3.0 T such that frequency-tuning was required in one-third of exams. In neonates, high spatial resolution CEMRA was highly reliable in defining extracardiac vascular anatomy.

Trends in pediatric cardiovascular magnetic resonance imaging

Cardiac magnetic resonance (CMR) imaging has significantly evolved over the last decade, becoming an integral part of the contemporary assessment of both congenital and acquired pediatric heart disease. Recent trends show that there is a growing interest in clinical applications and research in this field. An attempt to discuss the evolving technologies, techniques, and applications of CMR in pediatrics is not complete without understanding the current strengths of the modality. CMR complements readily available echocardiography, in many cases information from CMR can remove the need for invasive angiographic catheterization, and in other cases can be used to augment cardiac catheterisation.

Cardiac magnetic resonance imaging in a premature baby with interrupted aortic arch and aortopulmonary window

Aortopulmonary window is a communication between the main pulmonary artery and the ascending aorta in the presence of two separate semilunar valves. The combination of an aortopulmonary window with interrupted aortic arch is rare. We discuss the unique case of an extremely premature infant weighing 1.7 kilograms who underwent cardiovascular magnetic resonance imaging as a pre-operative assessment in a high-field open 1.0 Tesla magnetic resonance imaging system as a one-stop investigation before complete repair.

Can we improve the outcomes of pediatric congenital heart disease survivors?

Appreciating the complexity and evolving pathophysiology after palliation of CHD is critical to improving the outcome. Despite a growing patient population because of greater survival over the years, detailed data on the long-term outcomes of these patients is surprisingly sparse. The establishment in 2001 of the Pediatric Heart Network by the National Heart, Lung and Blood Institute has provided a collaborative multicenter platform to conduct large trials in CHD and to characterize outcomes. This chapter has emphasized how CHD care spans the continuum from fetal life to adulthood. Current research efforts aspire to better characterize short-term and long-term outcomes, continue advancement of technologies to better diagnose and treat CHD, and to elucidate the role of genetics and biomarkers in predicting outcome. Focused studies on variations in perioperative practice and quality will help us provide better clinical outcomes for CHD survivors.

Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease

Cardiovascular magnetic resonance (CMR) has taken on an increasingly important role in the diagnostic evaluation and pre-procedural planning for patients with congenital heart disease. This article provides guidelines for the performance of CMR in children and adults with congenital heart disease. The first portion addresses preparation for the examination and safety issues, the second describes the primary techniques used in an examination, and the third provides disease-specific protocols. Variations in practice are highlighted and expert consensus recommendations are provided. Indications and appropriate use criteria for CMR examination are not specifically addressed.

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.

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.

[Clinical indications for the use of cardiac MRI. By the SIRM Study Group on Cardiac Imaging]

Cardiac magnetic resonance (CMR) is considered an useful method in the evaluation of many cardiac disorders. Based on our experience and available literature, we wrote a document as a guiding tool in the clinical use of CMR. Synthetically we describe different cardiac disorders and express for each one a classification, I to IV, depending on the significance of diagnostic information expected.

Safety of cardiac magnetic resonance and contrast angiography for neonates and small infants: a 10-year single-institution experience

BACKGROUND

With increasing applications of cardiac magnetic resonance (CMR) and magnetic resonance angiography (MRA) for evaluation of congenital heart disease (CHD), safety of this technology in the very young is of particular interest.

OBJECTIVE

We report our 10-year experience with CMR in neonates and small infants with particular focus on the safety profile and incidence of adverse events (AEs).

MATERIALS AND METHODS

We reviewed clinical, anesthesia and nursing records of all children ≤120 days of age who underwent CMR. We recorded variables including cardiac diagnosis, study duration, anesthesia type and agents, prostaglandin E1 (PGE1) dependence and gadolinium (Gd) use. Serially recorded temperature, systemic saturation (SpO(2)) and cardiac rhythm were analyzed. Primary outcome measure was any AE during or <24 h after the procedure, including minor AEs such as hypothermia (axillary temperature ≤95 °F), desaturation (SpO(2) drop ≥10% below baseline) and bradycardia (heart rate ≤100 bpm). Secondary outcome measure was unplanned overnight hospitalization of outpatients.

RESULTS

Children (n = 143; 74 boys, 69 girls) had a median age of 6 days (1-117), and 98 were ≤30 days at the time of CMR. The median weight was 3.4 kg (1.4-6 kg) and body surface area 0.22 m(2) (0.13-0.32 m(2)). There were 118 (83%) inpatients (108 receiving intensive care) and 25 (17%) outpatients. Indications for CMR were assessment of aortic arch (n = 57), complex CHD (n = 41), pulmonary veins (n = 15), vascular ring (n = 8), intracardiac mass (n = 8), pulmonary artery (n = 7), ventricular volume (n = 4), and systemic veins (n = 3). CMR was performed using a 1.5-T scanner and a commercially available coil. CMR utilized general anesthesia (GA) in 86 children, deep sedation (DS) in 50 and comforting methods in seven. MRA was performed in 136 children. Fifty-nine children were PGE1-dependent and 39 had single-ventricle circulation. Among children on PGE1, 43 (73%) had GA and 10 (17%) had DS. Twelve children (9%) had adverse events (AEs)-one major and 11 minor. Of those 12, nine children had GA (10%) and three had DS (6%). The single major AE was respiratory arrest after DS in a neonate (resuscitated without sequelae). Minor AEs included desaturations (n = 2), hypothermia (n = 5), bradycardia (n = 2), and bradycardia with hypoxemia (n = 2). Incidence of minor AEs was 9% for inpatients (vs. 4% for outpatients), and 8% for neonates (vs. 9% for age ≥30 days). Incidence of minor AEs was similar between PGE1-dependent infants and the non-PGE1 group. There were no adverse events related to MRA. Of 25 outpatients, 5 (20%) were admitted for overnight observation due to desaturations.

CONCLUSION

CMR and MRA can be accomplished safely in neonates and infants ≤120 days old for a wide range of pre-surgical cardiac indications. Adverse events were unrelated to patient age, complexity of heart disease, type of anesthesia or PGE1 dependence.

A prospective audit of safety issues associated with general anesthesia for pediatric cardiac magnetic resonance imaging

BACKGROUND/OBJECTIVES

Cardiac MRI (CMR) is increasingly used for surgical planning and serial monitoring of children with congenital heart disease (CHD). For small children, general anesthesia (GA) is required. We describe our experience of the safety of GA for pediatric CMR, using data collected prospectively over 3 years.

METHODS

All consecutive infants undergoing GA for CMR at our institution, between November 2005 and May 2008, were included. Informed and written consent to participate in research investigation was acquired from the guardians of every patient prior to CMR. The cardiac anesthetist completed a standardized data collection form during each procedure. Information collected included demographics, diagnosis, surgical history, anesthetic management, significant incidents, and discharge circumstances.

RESULTS

A total of 120 patients with varying cardiac physiology and a range of hemodynamics underwent GA for CMR during the study period. Gas induction was predominantly used, even in those with impaired ventricular function. The majority (71%) of procedures were undertaken without significant incident. Minor adverse incidents were recorded in 32 patients, mild hypotension being most frequent. One major adverse event occurred. A patient with hypoplastic left heart syndrome (HLHS) suffered hypotension then cardiac arrest in the scanner. This patient was successfully resuscitated.

CONCLUSION

Although the majority of cases were safe and without incident, the complication rate in children with CHD receiving a GA for CMR is higher than in the general pediatric population. This reinforces the need for a senior, multidisciplinary team to be involved in the care of these children during imaging.

Performance validation of a modified magnetic resonance imaging-compatible temperature probe in children

INTRODUCTION

During magnetic resonance imaging (MRI), children are at risk for body temperature variations. The cold MRI environment that preserves the MRI magnet can cause serious hypothermia. On the other hand, hyperthermia may also develop because of radiofrequency-induced heating of the tissues, particularly in prolonged examinations. Because of a lack of MRI-compatible core temperature probes, temperature assessment is unreliable, and specific absorption rate-related patient heat gain must be calculated to determine the allowable scan duration. We compared an MRI-compatible temperature probe and a modification thereof to a standard esophageal core body temperature probe in children.

METHODS

Children undergoing general anesthesia were recruited, each patient serving as his/her own control. Core body temperature was measured using 3 different devices: (1) a fiberoptic MRI-compatible skin surface temperature probe (MRI-skin) located on the child's skin surface; (2) a fiberoptic MRI-compatible temperature probe modified with a single-use sleeve at the tip (MRI-core), located in the nasopharynx; and (3) a standard temperature monitor (STRD) located in the esophagus or nasopharynx. The Bland-Altman method was used for statistical analysis.

RESULTS

We enrolled 60 children aged 7.8 ± 6 years (mean ± SD) weighing 32.4 (±26.4) kg. The estimated difference between the STRD and MRI-core measurements of core temperature was 0.06°C (confidence interval [CI]: -0.02, 0.15), and between the STRD and the MRI-skin 1.19°C (CI: 0.97, 1.41). According to the Bland-Altman analysis, the 95% limits of agreement ranged from -0.9 to 3.4 and from -1.3 to 1.2 between the STRD and the MRI-skin probe and the MRI-core probe, respectively.

DISCUSSION

Our results show good agreement between standard esophageal measurements of core temperature and core temperature measured using a modified MRI-core probe during general anesthesia in a general surgical pediatric population. The ability to accurately assess core temperature in the MRI suite may safely allow longer scan times and therefore reduce repeat anesthetic exposure, improve patient safety, and enhance the quality of care in children.

The role of cardiovascular magnetic resonance in pediatric congenital heart disease

Cardiovascular magnetic resonance (CMR) has expanded its role in the diagnosis and management of congenital heart disease (CHD) and acquired heart disease in pediatric patients. Ongoing technological advancements in both data acquisition and data presentation have enabled CMR to be integrated into clinical practice with increasing understanding of the advantages and limitations of the technique by pediatric cardiologists and congenital heart surgeons. Importantly, the combination of exquisite 3D anatomy with physiological data enables CMR to provide a unique perspective for the management of many patients with CHD. Imaging small children with CHD is challenging, and in this article we will review the technical adjustments, imaging protocols and application of CMR in the pediatric population.

Anaesthesia for Paediatric Cardiac MRI

BACKGROUND

General anaesthesia (GA) for cardiac magnetic resonance imaging (MRI) in patients with congenital heart disease (CHD) is challenging for the anaesthesiologist.

METHODS

A retrospective review of anaesthesia for cardiac MRI between January 2002 and December 2005 was undertaken.

RESULT

28 children with cardiac disease were subjected to general anaesthesia for cardiac MRI, of which four patients were in ASA Grade I, five in Grade II, seventeen in Grade III and two in Grade IV. Two patients had undergone previous cardiac surgery. All the cases were managed as inpatients, of which 18 had cyanotic cardiac defects (SpO2 between 65 and 85%). On two occasions scans were interrupted because of low oxygen saturation or haemodynamic instability during GA. No patient was admitted to the hospital for complications related to general anaesthesia though all were kept under observation for two hours before being shifted to ward. Five patients had a brief episode of hypotension/desaturation during the MRI and responded quickly to interventions.

CONCLUSION

General anaesthesia for cardiac MRI can be administered safely in children with CHD.

Comparison and usefulness of cardiac magnetic resonance versus computed tomography in infants six months of age or younger with aortic arch anomalies without deep sedation or anesthesia

The present project investigated whether cardiac magnetic resonance (CMR) of aortic arch anomalies can be performed successfully in infants <6 months of age without the use of cardiac anesthesia or deep sedation. We performed a retrospective review of infants ≤6 months old from 2005 to 2009 who underwent either CMR or computed tomography angiography to investigate aortic arch abnormalities. The CMR procedure used a "feed and swaddle" protocol without deep sedation or cardiac anesthesia. Of the 52 infants referred for CMR, 24 underwent the feed and swaddle protocol (aged 2.6 ± 1.4 months). One patient awoke during the study, and examination of the remaining 23 yielded a definitive diagnosis (success rate 96%). The scanning time was 6.2 ± 3.1 minutes, with the large airways evaluation accounting for 1/2 the time. Single-shot axial steady-state free precession, in which the definitive diagnosis was made, accounted for 0.59 ± 0.3 minutes. Fifteen infants were diagnosed with a vascular ring. Of the 8 infants who underwent surgery, the diagnostic accuracy was 100%. During the same period, 19 patients, who had undergone computed tomography angiography (aged 1.67 ± 1.20 months), were referred for aortic arch evaluation. Of these 19 patients, 6 (32%) underwent sedation or anesthesia. The imaging time was 0.08 ± 0.06 minutes, significantly different from the CMR times (p <0.01). However, the overall room times (31.3 ± 22.3 and 35.8 ± 3.86 minutes, respectively) were not different between the CMR and angiographic groups. The radiation dose was 1.41 ± 1.03 mSv. In conclusion, CMR evaluation of aortic arch anomalies in children <6 months old can be successfully completed quickly using a feed and swaddle approach with high diagnostic accuracy. This protocol avoids the risks of sedation, as well as the radiation associated with computed tomography angiography.

An echocardiographic model predicting severity of aortic regurgitation in congenital heart disease

Background- Multiple echocardiographic parameters have been identified to predict the severity of aortic regurgitation (AR) with variable reliability. This study was performed to identify which echocardiographic parameters best predict the severity of AR in a cohort of patients with congenital heart disease, using cardiovascular MRI quantification as a reference standard. Methods and Results- The study involved 2 phases. In phase 1, predictive models were developed on the basis of multivariable analysis of various morphometric and Doppler variables obtained from 174 echocardiograms that best predicted the severity of AR as defined by paired cardiovascular MRI examinations. A nonlinear estimate of regurgitation fraction, using the variables parasternal vena contracta-derived area divided by body surface area and abdominal aorta Doppler retrograde velocity-time integral divided by antegrade velocity-time integral, was identified through multivariable analysis as the best predictive model for AR fraction. In phase 2, the predictive models were prospectively tested on 43 echocardiographic examinations for which a paired cardiovascular MRI was performed. The agreement between the observed and predicted AR fraction was assessed using Bland-Altman analysis. For the 30 studies of the validation data set that had adequate quality images of both the parasternal vena contracta width and the abdominal aorta flow profile, the predicted AR values had a mean bias±SD of 0.4±7.3% (P=0.80). Conclusions- A model using the 2 variables parasternal vena contracta-derived area divided by body surface area and abdominal aorta Doppler retrograde velocity-time integral divided by antegrade velocity-time integral can predict AR severity in patients with a wide variety of congenital heart disease.

Recommendations for cardiovascular magnetic resonance in adults with congenital heart disease from the respective working groups of the European Society of Cardiology

This paper aims to provide information and explanations regarding the clinically relevant options, strengths, and limitations of cardiovascular magnetic resonance (CMR) in relation to adults with congenital heart disease (CHD). Cardiovascular magnetic resonance can provide assessments of anatomical connections, biventricular function, myocardial viability, measurements of flow, angiography, and more, without ionizing radiation. It should be regarded as a necessary facility in a centre specializing in the care of adults with CHD. Also, those using CMR to investigate acquired heart disease should be able to recognize and evaluate previously unsuspected CHD such as septal defects, anomalously connected pulmonary veins, or double-chambered right ventricle. To realize its full potential and to avoid pitfalls, however, CMR of CHD requires training and experience. Appropriate pathophysiological understanding is needed to evaluate cardiovascular function after surgery for tetralogy of Fallot, transposition of the great arteries, and after Fontan operations. For these and other complex CHD, CMR should be undertaken by specialists committed to long-term collaboration with the clinicians and surgeons managing the patients. We provide a table of CMR acquisition protocols in relation to CHD categories as a guide towards appropriate use of this uniquely versatile imaging modality.

MR and CT imaging of the pediatric patient with structural heart disease

Cardiac magnetic resonance imaging (MRI) and computed tomography (CT) are imaging modalities increasingly used in the diagnosis and management of structural heart disease. They are powerful imaging tools that have individual strengths and weaknesses. Rational choice between MRI and CT should be based on a sound understanding of these issues. Management guidelines that incorporate the use of MRI and CT are currently being developed, and their utilizations are expected to grow rapidly in the future.

Partial anomalous pulmonary venous drainage in young pediatric patients: the role of magnetic resonance imaging

Studies of larger patient groups for systematic assessment of the anatomical accuracy of magnetic resonance imaging (MRI) for partial anomalous pulmonary venous drainage (PAPVD) have been performed so far only in adults. This study was undertaken to evaluate whether MRI can precisely depict pulmonary venous anatomy in infants and young children. Data on 26 children under 10 years old that underwent MRI over the past 2 years for suspected PAPVD were assessed. The MRI protocol included shunt quantification by velocity-encoded cine as well as morphological and functional assessment by multislice multiphase and contrast-enhanced MR techniques. MRI was performed in the compliant patient in breath-hold (n = 8; age range, 4.6-9.5 years) and in the noncompliant patient in conscious-sedation free breathing (n = 18; age range, 0.4 to 7.5 years). In 22 patients, PAPVD was diagnosed with MRI and confirmed during surgery. In four patients with large atrial septal defects not accessible to percutaneous closure, normal pulmonary venous return was demonstrated by MRI and confirmed during surgery. MRI under conscious sedation accurately specifies the anatomy of pulmonary veins in infants and small children. Therefore, we suggest performing MRI in patients with inconclusive transthoracic echocardiographic results in the preoperative assessment of PAPVD.

Cardiovascular magnetic resonance imaging for intensive care infants: safe and effective?

BACKGROUND

Cardiac magnetic resonance imaging (MRI) is an important diagnostic tool for congenital heart disease (CHD), as reflected by class 1 recommendations for the use of cardiac MRI by various consensus panels. However, little is known about the safety and clinical utility of cardiac MRI for these critically ill infants with CHD, whose further management cannot be directed by echocardiography. This study aimed to assess the safety, the potential hemodynamic side effects, and the clinical benefits of cardiac MRI for infants with complex CHD during their intensive care unit stay.

METHODS

Infants referred from the pediatric cardiac intensive care unit (PCICU) to the authors' cardiac MRI program in the past 2 years were retrospectively analyzed using the electronic chart system available at their institution. Data collected included age, diagnosis, inotropic support, urine output, diuretic medication, body temperature and lactate levels, length of MRI examination, adverse effects during and after the procedure, clinical implications of MRI, length of stay in the PCICU, and mean blood pressure and heart rate before, during, and after MRI.

RESULTS

Among 592 patients in the past 2 years, 20 (3.4%) were referred for MRI testing during their stay in the PCICU. The mean age of the infants was 4.8+/-3.2 months. Four of the patients were neonates, and eight were postoperative patients. Intracardiac malformations were present in 16 of the infants, vascular rings causing tracheal stenosis in 3 patients, and cardiomyopathy in 1 patient. The mean stay in the PCICU was 28+/-43 days. Eight of the infants were ventilated, with a mean fraction of inspired oxygen (FiO2) of 0.30+/-0.15. Four were receiving inotropic support. All the nonventilated children were intubated for the MRI and extubated in the MRI laboratory. The mean duration of the MRI (door-to-door time) was 110+/-27 min. All except one patient were hemodynamically stable, and no increase in catecholamine support was necessary during or after the scans. A 10-month-old girl receiving inotropic support needed a single dose of epinephrine due to a short episode of bradycardia after a breathhold for a contrast agent MRI angiography. Mean body core temperature at arrival to the PCICU was 36.8+/-0.7 degrees C. The mean serum lactate level after the MRI was 1.2+/-0.4 mmol/l. The mean blood pressure and heart rate before, during, and after MRI were unchanged. The mean diuresis on examination day was insignificantly lower (2.4%) than the day before with unchanged medication (5.09+/-1.58 vs 5.53+/-1.77 ml/kg/h). For 14 (70%) of the 20 patients, surgical or catheter interventional procedures were initiated based on novel MRI information.

CONCLUSION

Cardiac MRI can be performed safely with low risk and limited hemodynamic changes for infants during their stay in the PCICU. Cardiac MRI provides key information for invasive management decisions in this subset of patients.