ABSTRACT
This study assesses the efficacy of low-field portable MR imaging in measuring ventricular volumes in the pediatric population in the hospital setting. We compared portable and standard of care MR images from the same patient. The estimated ventricular volumes had excellent agreement with a mean bias of 2.06% by Bland-Altman analysis and a correlation of 0.99. From this initial data set, our results suggest that low-field, portable MR imaging is a promising technique for imaging and quantifying ventricular volumes.
Subject(s)
Magnetic Resonance Imaging , Humans , Retrospective Studies , Male , Female , Magnetic Resonance Imaging/methods , Child , Cerebral Ventricles/diagnostic imaging , Child, Preschool , Infant , Adolescent , Reproducibility of ResultsABSTRACT
Urinary tract infection (UTI) is a frequent infection in childhood. The diagnosis is usually made by history and physical examination and confirmed by urine analysis. Cystitis is infection or inflammation confined to the bladder, whereas pyelonephritis is infection or inflammation of kidneys. Pyelonephritis can cause renal scarring, which is the most severe long-term sequela of UTI and can lead to accelerated nephrosclerosis, leading to hypertension and chronic renal failure. The role of imaging is to guide treatment by identifying patients who are at high risk to develop recurrent UTIs or renal scarring. This document provides initial imaging guidelines for children presenting with first febrile UTI with appropriate response to medical management, atypical or recurrent febrile UTI, and follow-up imaging for children with established vesicoureteral reflux. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.
Subject(s)
Humans , Urinary Tract Infections/diagnostic imaging , Vesico-Ureteral Reflux , Fluoroscopy , UltrasonographyABSTRACT
Urinary tract infection (UTI) is a frequent infection in childhood. The diagnosis is usually made by history and physical examination and confirmed by urine analysis. Cystitis is infection or inflammation confined to the bladder, whereas pyelonephritis is infection or inflammation of kidneys. Pyelonephritis can cause renal scarring, which is the most severe long-term sequela of UTI and can lead to accelerated nephrosclerosis, leading to hypertension and chronic renal failure. The role of imaging is to guide treatment by identifying patients who are at high risk to develop recurrent UTIs or renal scarring. This document provides initial imaging guidelines for children presenting with first febrile UTI with appropriate response to medical management, atypical or recurrent febrile UTI, and follow-up imaging for children with established vesicoureteral reflux. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.
Subject(s)
Evidence-Based Medicine , Societies, Medical , Urinary Tract Infections , Humans , Urinary Tract Infections/diagnostic imaging , United States , ChildABSTRACT
Soft tissue vascular anomalies may be composed of arterial, venous, and/or lymphatic elements, and diagnosed prenatally or later in childhood or adulthood. They are divided into categories of vascular malformations and vascular tumors. Vascular malformations are further divided into low-flow and fast-flow lesions. A low-flow lesion is most common, with a prevalence of 70%. Vascular tumors may behave in a benign, locally aggressive, borderline, or malignant manner. Infantile hemangioma is a vascular tumor that presents in the neonatal period and then regresses. The presence or multiple skin lesions in an infant can signal underlying visceral vascular anomalies, and complex anomalies may be associated with overgrowth syndromes. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.
Subject(s)
Societies, Medical , Vascular Malformations , Humans , Vascular Malformations/diagnostic imaging , United States , Evidence-Based Medicine , Infant , Vascular Neoplasms/diagnostic imaging , Soft Tissue Neoplasms/diagnostic imaging , Infant, Newborn , Child , Diagnostic Imaging/methods , Hemangioma/diagnostic imaging , Practice Guidelines as TopicABSTRACT
Pediatric heart disease is a large and diverse field with an overall prevalence estimated at 6 to 13 per 1,000 live births. This document discusses appropriateness of advanced imaging for a broad range of variants. Diseases covered include tetralogy of Fallot, transposition of great arteries, congenital or acquired pediatric coronary artery abnormality, single ventricle, aortopathy, anomalous pulmonary venous return, aortopathy and aortic coarctation, with indications for advanced imaging spanning the entire natural history of the disease in children and adults, including initial diagnosis, treatment planning, treatment monitoring, and early detection of complications. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.
Subject(s)
Coronary Artery Disease , Heart Diseases , Adult , Child , Humans , Diagnosis, Differential , Diagnostic Imaging/methods , Societies, Medical , United StatesABSTRACT
BACKGROUND: Gastrostomy (G) tube or gastrojejunostomy (GJ) tube checks are radiographic procedures that are frequently ordered to confirm tube positioning. OBJECTIVE: To characterize the sensitivity and specificity of radiograph-only examinations and traditional radiologist-performed fluoroscopy exams for G-tube or GJ-tube malposition and other adverse events detectable by imaging. MATERIALS AND METHODS: We performed a retrospective cohort study at a single tertiary pediatric center that included all subjects who underwent G-tube or GJ-tube checks using fluoroscopy or radiograph-only exams between January 1, 2008, and January 1, 2019. Radiograph-only examinations were defined as checks that consist of frontal and lateral abdominal radiographs after injection of contrast through the G-tube or GJ-tube. Fluoroscopy exams were defined as exams performed by a radiologist in the fluoroscopy suite. Radiology reports were evaluated for reported tube malposition and for other adverse events that are detectable by imaging. Clinical notes from the day of the procedure and longer-term clinical follow-up notes were used as a reference standard for adverse events. The sensitivity and specificity of the two procedures were calculated. RESULTS: A total of 212 exams, including 86 (41%) fluoroscopy exams and 126 (59%) radiograph-only exams, were evaluated. The most common correctly identified adverse event was tube malposition (9 true positives). The most commonly missed adverse event was leakage around the tube (8 false negatives). Fluoroscopy exams had a sensitivity of 100% (6/6; 95% CI: 100%, 100%) and a specificity of 100% (80/80; 95% CI: 100%, 100%) for tube malposition, while radiograph-only exams had 75% sensitivity (3/4; 95% CI: 33%,100%) and 100% specificity (112/112; 95% CI: 100%, 100%). CONCLUSIONS: Fluoroscopy and radiograph-only exams have similar sensitivity and specificity for detecting G-tube or GJ-tube malposition.
Subject(s)
Gastric Bypass , Gastrostomy , Humans , Child , Gastrostomy/methods , Retrospective Studies , Fluoroscopy/methods , RadiographyABSTRACT
BACKGROUND: Aside from single-center reports, few data exist across pediatric institutions that examine overall MRI turnaround time (TAT) and the determinants of variability. OBJECTIVE: To determine average duration and determinants of a brain MRI examination at academic pediatric institutions and compare the duration to those used in practice expense relative value units (RVUs). MATERIALS AND METHODS: This multi-institutional cross-sectional investigation comprised four academic pediatric hospitals. We included children ages 0 to < 18 years who underwent an outpatient MRI of the brain without contrast agent in 2019. Our outcome of interest was the overall MRI TAT derived by time stamps. We estimated determinants of overall TAT using an adjusted log-transformed multivariable linear regression model with robust standard errors. RESULTS: The average overall TAT significantly varied among the four hospitals. A sedated brain MRI ranged from 158 min to 224 min, a non-sedated MRI from 70 min to 112 min, and a limited MRI from 44 min to 70 min. The most significant predictor of a longer overall TAT was having a sedated MRI (coefficient = 0.71, 95% confidence interval [CI]: 0.66-0.75; P < 0.001). The median MRI scan time for a non-sedated exam was 38 min and for a sedated exam, 37 min, approximately double the duration used by the Relative Value Scale (RVS) Update Committee (RUC). CONCLUSION: We found considerable differences in the overall TAT across four pediatric academic institutions. Overall, the significant predictors of turnaround times were hospital site and MRI pathway (non-sedated versus sedated versus limited MRI).
Subject(s)
Magnetic Resonance Imaging , Outpatients , Child , Humans , Cross-Sectional Studies , Magnetic Resonance Spectroscopy , Brain/diagnostic imagingABSTRACT
Magnetic resonance (MR) angiography and MR venography imaging with contrast and non-contrast techniques are widely used for pediatric vascular imaging. However, as with any MRI examination, imaging the pediatric population can be challenging because of patient motion, which sometimes requires sedation. There are multiple benefits of non-contrast MR angiographic techniques, including the ability to repeat sequences if motion is present, the decreased need for sedation, and avoidance of potential risks associated with gadolinium administration and radiation exposure. Thus, MR angiography is an attractive alternative to CT or conventional catheter-based angiography in pediatric populations. Contrast-enhanced MR angiographic techniques have the advantage of increased signal to noise. Blood pool imaging allows long imaging times that result in high-spatial-resolution imaging, and thus high-quality diagnostic images. This article outlines the technique details, indications, benefits and downsides of non-contrast-enhanced and contrast-enhanced MR angiographic techniques to assist in protocol decision-making.
Subject(s)
Contrast Media , Magnetic Resonance Angiography , Humans , Child , Magnetic Resonance Angiography/methods , Magnetic Resonance Imaging , Phlebography , CystographyABSTRACT
OBJECTIVE: A portable, low-field MRI system is now Food and Drug Administration cleared and has been shown to be safe and useful in adult intensive care unit settings. No neonatal studies have been performed. The objective is to assess our preliminary experience and assess feasibility of using the portable MRI system at the bedside in a neonatal intensive care unit (NICU) at a quaternary children's hospital. STUDY DESIGN: This was a single-site prospective cohort study in neonates ≥2 kg conducted between October and December 2020. All parents provided informed consent. Neonates underwent portable MRI examination in the NICU with support equipment powered on and attached to the neonate during the examination. A paediatric radiologist interpreted each portable MRI examination. The study outcome variable was percentage of portable MRI examinations completed without artefacts that would hinder diagnosis. Findings were compared between portable MRI examinations and standard of care examinations. RESULTS: Eighteen portable, low-field MRI examinations were performed on 14 neonates with an average age of 29.7 days (range 1-122 days). 94% (17 of 18) of portable MRI examinations were acquired without significant artefact. Significant intracranial pathology was visible on portable MRI, but subtle abnormalities were missed. The examination reads were concordant in 59% (10 of 17) of cases and significant pathology was missed in 12% (2 of 17) of cases. CONCLUSION: This single-centre series demonstrated portable MRI examinations can be performed safely with standard patient support equipment present in the NICU. These findings demonstrate that portable MRI could be used in the future to guide care in the NICU setting. TRIAL REGISTRATION NUMBER: NCT04629469.
Subject(s)
Intensive Care Units, Neonatal , Magnetic Resonance Imaging , Humans , Infant, Newborn , Clinical Competence , Feasibility Studies , Prospective StudiesABSTRACT
ABSTRACT: The aim of this study was to determine if machine learning can improve the specificity of detecting transplant hepatic artery pathology over conventional quantitative measures while maintaining a high sensitivity.This study presents a retrospective review of 129 patients with transplanted hepatic arteries. We illustrate how beyond common clinical metrics such as stenosis and resistive index, a more comprehensive set of waveform data (including flow half-lives and Fourier transformed waveforms) can be integrated into machine learning models to obtain more accurate screening of stenosis and occlusion. We present a novel framework of Extremely Randomized Trees and Shapley values, we allow for explainability at the individual level.The proposed framework identified cases of clinically significant stenosis and occlusion in hepatic arteries with a state-of-the-art specificity of 65%, while maintaining sensitivity at the current standard of 94%. Moreover, through 3 case studies of correct and mispredictions, we demonstrate examples of how specific features can be elucidated to aid in interpreting driving factors in a prediction.This work demonstrated that by utilizing a more complete set of waveform data and machine learning methodologies, it is possible to reduce the rate of false-positive results in using ultrasounds to screen for transplant hepatic artery pathology compared with conventional quantitative measures. An advantage of such techniques is explainability measures at the patient level, which allow for increased radiologists' confidence in the predictions.
Subject(s)
Hepatic Artery , Vascular Diseases , Humans , Hepatic Artery/diagnostic imaging , Constriction, Pathologic , Algorithms , Machine Learning , Retrospective StudiesABSTRACT
Imaging in hematopoietic stem cell transplantation patients is not targeted at evaluating the transplant per se. Rather, imaging is largely confined to evaluating peri-procedural and post-procedural complications. Alternatively, imaging may be performed to establish a baseline study for comparison should the patient develop certain post-procedural complications. This article looks to describe the various imaging modalities available with recommendations for which imaging study should be performed in specific complications. We also provide select imaging protocols for different indications and modalities for the purpose of establishing a set minimal standard for imaging in these complex patients.
Subject(s)
Hematopoietic Stem Cell Transplantation , Surface Plasmon Resonance , Child , Humans , Hematopoietic Stem Cell Transplantation/adverse effects , Hematopoietic Stem Cell Transplantation/methods , Medical Oncology , Transplant RecipientsABSTRACT
BACKGROUND. MRI utilization and the use of sedation or anesthesia for MRI have increased in children. Emerging alternative payment models (APMs) require a detailed understanding of the health system costs of performing these examinations. OBJECTIVE. The purpose of this study was to use time-driven activity-based costing (TDABC) to assess health system costs for outpatient noncontrast brain MRI examinations across three children's hospitals. METHODS. Direct costs for outpatient noncontrast brain MRI examinations at three academic free-standing pediatric hospitals were calculated using TDABC. Examinations were categorized as sedated MRI (i.e., sedation or anesthesia), nonsedated MRI, or limited MRI. Process maps were created to describe patient workflows based on input from key personnel and direct observation. Time durations for each process activity were determined; time stamps from retrospective EMR review were used when possible. Capacity cost rates were calculated for resource types within three cost categories (labor, equipment, and space); cost was calculated in a fourth category (supplies). Resources were allocated to each activity, and the cost of each process step was determined by multiplying step-specific capacity costs by the time required for each step. The costs of all steps were summed to yield a base-case total examination cost. Sensitivity analysis for sedated MRI was performed using minimum and maximum time duration inputs for each activity to yield minimum and maximum costs by hospital. RESULTS. The mean base-case cost for a sedated brain MRI examination was $842 (range, $775-924 across hospitals), for a nonsedated brain MRI examination was $262 (range, $240-285), and for a limited brain MRI examination was $135 (range, $127-141). For all examination types, the largest cost category as well as the largest source of difference in cost between hospitals was labor. Sensitivity analysis found that the greatest influence on overall cost at each hospital was the duration of the MRI acquisition. CONCLUSION. The health system cost of performing a sedated MRI examination was substantially greater than that of performing a nonsedated MRI examination. However, the cost of each individual examination type did not vary substantially among hospitals. CLINICAL IMPACT. Health systems operating within APMs can use this comparative cost information for purposes of cost reduction efforts and establishment of bundled prices.
Subject(s)
Health Care Costs , Outpatients , Child , Humans , Retrospective Studies , Hospitals , Magnetic Resonance Imaging , Brain/diagnostic imagingABSTRACT
Importance: The ability of computed tomography (CT) to distinguish between benign congenital lung malformations and malignant cystic pleuropulmonary blastomas (PPBs) is unclear. Objective: To assess whether chest CT can detect malignant tumors among postnatally detected lung lesions in children. Design, Setting, and Participants: This retrospective multicenter case-control study used a consortium database of 521 pathologically confirmed primary lung lesions from January 1, 2009, through December 31, 2015, to assess diagnostic accuracy. Preoperative CT scans of children with cystic PPB (cases) were selected and age-matched with CT scans from patients with postnatally detected congenital lung malformations (controls). Statistical analysis was performed from January 18 to September 6, 2020. Preoperative CT scans were interpreted independently by 9 experienced pediatric radiologists in a blinded fashion and analyzed from January 24, 2019, to September 6, 2020. Main Outcomes and Measures: Accuracy, sensitivity, and specificity of CT in correctly identifying children with malignant tumors. Results: Among 477 CT scans identified (282 boys [59%]; median age at CT, 3.6 months [IQR, 1.2-7.2 months]; median age at resection, 6.9 months [IQR, 4.2-12.8 months]), 40 cases were extensively reviewed; 9 cases (23%) had pathologically confirmed cystic PPB. The median age at CT was 7.3 months (IQR, 2.9-22.4 months), and median age at resection was 8.7 months (IQR, 5.0-24.4 months). The sensitivity of CT for detecting PPB was 58%, and the specificity was 83%. High suspicion for malignancy correlated with PPB pathology (odds ratio, 13.5; 95% CI, 2.7-67.3; P = .002). There was poor interrater reliability (κ = 0.36 [range, 0.06-0.64]; P < .001) and no significant difference in specific imaging characteristics between PPB and benign cystic lesions. The overall accuracy rate for distinguishing benign vs malignant lesions was 81%. Conclusions and Relevance: This study suggests that chest CT, the current criterion standard imaging modality to assess the lung parenchyma, may not accurately and reliably distinguish PPB from benign congenital lung malformations in children. In any cystic lung lesion without a prenatal diagnosis, operative management to confirm pathologic diagnosis is warranted.
Subject(s)
Lung Diseases , Lung Neoplasms , Case-Control Studies , Child , Female , Humans , Lung/diagnostic imaging , Lung/pathology , Lung Neoplasms/diagnostic imaging , Male , Pregnancy , Pulmonary Blastoma , Reproducibility of Results , Tomography, X-Ray ComputedABSTRACT
Imaging plays an integral role in the evaluation of suspected musculoskeletal infections in children, not only in the accurate identification of infection such as osteomyelitis or septic arthritis, but also in guiding management. Various diagnostic modalities serve different purposes in the assessment of suspected pediatric musculoskeletal infections. The purpose of this document is to provide imaging guidance in the most frequently encountered clinical scenarios in which osteomyelitis and/or septic arthritis are suspected, outside of the axial skeleton. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion.
Subject(s)
Arthritis, Infectious , Osteomyelitis , Arthritis, Infectious/diagnostic imaging , Child , Evidence-Based Medicine , Humans , Osteomyelitis/diagnostic imaging , Skeleton , Societies, Medical , United StatesABSTRACT
Crohn disease is an inflammatory condition of the gastrointestinal tract with episodes of exacerbation and remission occurring in children, adolescents, and adults. Crohn disease diagnosis and treatment depend upon a combination of clinical, laboratory, endoscopic, histological, and imaging findings. Appropriate use of imaging provides critical information in the settings of diagnosis, assessment of acute symptoms, disease surveillance, and therapy monitoring. Four variants are discussed. The first variant discusses the initial imaging for suspected Crohn disease before established diagnosis. The second variant pertains to appropriateness of imaging modalities during suspected acute exacerbation. The third variant is a substantial discussion of recommendations related to disease surveillance and monitoring of Crohn disease. Finally, panel recommendations and discussion of perianal fistulizing disease imaging completes the document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
Subject(s)
Crohn Disease , Adolescent , Crohn Disease/diagnostic imaging , Diagnosis, Differential , Diagnostic Imaging , Evidence-Based Medicine , Humans , Societies, Medical , United StatesABSTRACT
Non-contrast magnetic resonance (MR) angiography and MR venography techniques are gaining popularity for vascular imaging because they are faster, more forgiving and less costly compared with contrast-enhanced MR angiography. Non-contrast MR angiography also avoids gadolinium deposition, which is especially important in imaging children. Non-contrast MR angiography has an array of specific applications for numerous clinical indications. This review summarizes the non-contrast MR angiography methods and their relative advantages and disadvantages. The paper also guides the reader on which technique to consider when determining the optimal imaging modality for each individual patient.
Subject(s)
Gadolinium , Magnetic Resonance Angiography , Child , Contrast Media , Humans , Magnetic Resonance Imaging , PhlebographyABSTRACT
The liver is the primary organ responsible for clearing most drugs from the body and thus determines systemic drug concentrations over time. Drug clearance by the liver appears to be directly related to organ size. In children, organ size changes as children age and grow. Liver volume has been correlated with body surface area (BSA) in healthy children and adults and has been estimated by functions of BSA. However, these relationships were derived from "typical" populations and it is unknown whether they extend to estimations of liver volumes for population "outliers," such as children with overweight or obesity, who today represent one-third of the pediatric population. Using computerized tomography or magnetic resonance imaging, this study measured liver volumes in 99 children (2-21 years) with normal weight, overweight, or obesity and compared organ measurements with estimates calculated using an established liver volume equation. A previously developed equation relating BSA to liver volume adequately estimates liver volumes in children, regardless of weight status.
Subject(s)
Body Surface Area , Liver/anatomy & histology , Obesity/physiopathology , Overweight/physiopathology , Adolescent , Child , Child, Preschool , Datasets as Topic , Female , Hepatobiliary Elimination , Humans , Liver/diagnostic imaging , Liver/metabolism , Magnetic Resonance Imaging/statistics & numerical data , Male , Metabolic Clearance Rate , Organ Size/physiology , Retrospective Studies , Tomography, X-Ray Computed/statistics & numerical data , Young AdultABSTRACT
Obesity is the single greatest risk factor for nonalcoholic fatty liver disease (NAFLD). Without intervention, most pediatric patients with NAFLD continue to gain excessive weight, making early, effective weight loss intervention key for disease treatment and prevention of NAFLD progression. Unfortunately, outside of a closely monitored research setting, which is not representative of the real world, lifestyle modification success for weight loss in children is low. Bariatric surgery, though effective, is invasive and can worsen NAFLD postoperatively. Thus, there is an evolving and underutilized role for pharmacotherapy in children, both for weight reduction and NAFLD management. In this perspective article, we provide an overview of the efficacy of weight reduction on pediatric NAFLD treatment, discuss the pros and cons of currently approved pharmacotherapy options, as well as drugs commonly used off-label for weight reduction in children and adolescents. We also highlight gaps in, and opportunities for, streamlining obesity trials to include NAFLD assessment as a valuable, secondary, therapeutic outcome measure, which may aid drug repurposing. Finally, we describe the already available, and emerging, minimally-invasive biomarkers of NAFLD that could offer a safe and convenient alternative to liver biopsy in pediatric obesity and NAFLD trials.
Subject(s)
Life Style , Non-alcoholic Fatty Liver Disease/drug therapy , Obesity/physiopathology , Weight Loss , Child , Humans , Non-alcoholic Fatty Liver Disease/pathology , Prognosis , Risk FactorsABSTRACT
Magnetic resonance imaging (MRI) is a powerful diagnostic tool that can be optimized to display a wide range of clinical conditions. An MRI system consists of four major components: a main magnet formed by superconducting coils, gradient coils, radiofrequency (RF) coils, and computer systems. Each component has safety considerations. Unless carefully controlled, the MRI machine's strong static magnetic field could turn a ferromagnetic object into a harmful projectile or cause vertigo and headache. Switching magnetic fields in the gradients evokes loud noises in the scanner, which can be mitigated by ear protection. Gradients also generate varying magnetic fields that can cause peripheral nerve stimulation and muscle twitching. Magnetic fields produced by RF coils deposit energy in the body and can cause tissue heating (with the potential to cause skin burns). In this review, we provide an overview of the components of a typical clinical MRI scanner and its associated safety issues. We also discuss how the relationship between the scanning parameters can be manipulated to improve image quality while ensuring a safe operational environment for the patients and staff. Understanding the strengths and limitations of these parameters can enable users to choose optimal techniques for image acquisition, apply them in clinical practice, and improve the diagnostic accuracy of an MRI examination.