Case 321: Leigh Syndrome.

HISTORY: A 9-month-old preterm male infant born at 33 weeks gestation presented with a 2-month history of developmental decline. The parents reported that over the past several months, they noted regression of milestones, where the infant stopped smiling, crying, expressing himself, or making eye contact. The parents also reported that the infant had multiple seizures during which he would wake up stiff and stare into space for 10-20 seconds while his lips would become blue. The parents were referred to a neurologist, where physical examination was notable for hypotonia. Electroencephalography (EEG) revealed frequent bilateral parietal epileptiform discharges. The patient was subsequently started on lacosamide. The patient's medical history was notable for abnormally low citrulline levels at birth, with negative results of urea cycle disorder testing at the time, along with left inguinal hernia repair performed 3 months ago. More recent laboratory analysis had shown persistently elevated serum lactate and alanine levels. There was no history of travel, recent infection, or vaccine administration. MRI of the brain with spectroscopy was performed for further evaluation.

Case 321.

HISTORY: A 9-month-old preterm male infant born at 33 weeks gestation presented with a 2-month history of developmental decline. The parents reported that over the past several months, they noted regression of milestones, where the infant stopped smiling, crying, expressing himself, or making eye contact. The parents also reported that the infant had multiple seizures during which he would wake up stiff and stare into space for 10-20 seconds while his lips would become blue. The parents were referred to a neurologist, where physical examination was notable for hypotonia. Electroencephalography (EEG) revealed frequent bilateral parietal epileptiform discharges. The patient was subsequently started on lacosamide. The patient's medical history was notable for abnormally low citrulline levels at birth, with negative results of urea cycle disorder testing at the time, along with left inguinal hernia repair performed 3 months ago. More recent laboratory analysis had shown persistently elevated serum lactate and alanine levels. There was no history of travel, recent infection, or vaccine administration. MRI of the brain with spectroscopy was performed for further evaluation (Figs 1-6).

Gadolinium-based contrast agents in pediatric magnetic resonance imaging.

Gadolinium-based contrast agents can increase the accuracy and expediency of an MRI examination. However the benefits of a contrast-enhanced scan must be carefully weighed against the well-documented risks associated with administration of exogenous contrast media. The purpose of this review is to discuss commercially available gadolinium-based contrast agents (GBCAs) in the context of pediatric radiology. We discuss the chemistry, regulatory status, safety and clinical applications, with particular emphasis on imaging of the blood vessels, heart, hepatobiliary tree and central nervous system. We also discuss non-GBCA MRI contrast agents that are less frequently used or not commercially available.

Advanced imaging techniques in pediatric body MRI.

While there are many challenges specific to pediatric abdomino-pelvic MRI, many recent advances are addressing these challenges. It is therefore essential for radiologists to be familiar with the latest advances in MR imaging. Laudable efforts have also recently been implemented in many centers to improve the overall experience of pediatric patients, including the use of dedicated radiology child life specialists, MRI video goggles, and improved MR suite environments. These efforts have allowed a larger number of children to be scanned while awake, with fewer studies being done under sedation or anesthesia; this has resulted in additional challenges from patient motion and difficulties with breath-holding and tolerating longer scan times. In this review, we highlight common challenges faced in imaging the pediatric abdomen and pelvis and discuss the application of the newest techniques to address these challenges. Additionally, we highlight the newest advances in quantified imaging techniques, specifically in MR liver iron quantification. The techniques described in this review are all commercially available and can be readily implemented.

Renal myxoma in a pediatric transplant recipient.

Renal myxoma is a very rare benign neoplasm seen almost exclusively in adults with only 16 reported cases in the literature. All of these cases have been reported in native kidneys with none being reported in a transplant kidney. We report the case of a renal myxoma in a 17-year-old boy's transplant kidney that was found as an incidental mass on ultrasonography and further evaluated with CT and PET scans. PET findings of a renal myxoma are reported here for the first time, and imaging findings from previous cases are briefly reviewed. This case report highlights the fact that adult-predominant tumors and pathology should always be a consideration in pediatric patients who receive organ transplants from adult donors.

Pre-procedural scout radiographs are unnecessary for routine pediatric fluoroscopic examinations.

BACKGROUND: Although practice patterns vary, scout radiographs are often routinely performed with pediatric fluoroscopic studies. However few studies have evaluated their utility in routine pediatric fluoroscopy. OBJECTIVE: To evaluate the value of scout abdomen radiographs in routine barium or water-soluble enema, upper gastrointestinal (GI) series, and voiding cystourethrogram pediatric fluoroscopic procedures. MATERIALS AND METHODS: We retrospectively evaluated 723 barium or water-soluble enema, upper GI series, and voiding cystourethrogram fluoroscopic procedures performed at our institution. We assessed patient history and demographics, clinical indication for the examination, prior imaging findings and impressions, scout radiograph findings, additional findings provided by the scout radiograph that were previously unknown, and whether the scout radiograph contributed any findings that significantly changed management. RESULTS: We retrospectively evaluated 723 fluoroscopic studies (368 males and 355 females) in pediatric patients. Of these, 700 (96.8%) had a preliminary scout radiograph. Twenty-three (3.2%) had a same-day radiograph substituted as a scout radiograph. Preliminary scout abdomen radiographs/same-day radiographs showed no new significant findings in 719 (99.4%) studies. New but clinically insignificant findings were seen in 4 (0.6%) studies and included umbilical hernia, inguinal hernia and hip dysplasia. No findings were found on the scout radiographs that would either alter the examination performed or change management with regard to the exam. CONCLUSION: Pre-procedural scout abdomen radiographs are unnecessary in routine barium and water-soluble enema, upper GI series, and voiding cystourethrogram pediatric fluoroscopic procedures and can be substituted with a spot fluoroscopic last-image hold.

Radiation exposure contribution of the scout abdomen radiograph in common pediatric fluoroscopic procedures.

BACKGROUND: Contrast enema, voiding cystourethrography and upper gastrointestinal studies are the most common fluoroscopic procedures in children. Scout abdomen radiographs have been routinely obtained prior to fluoroscopy and add to the radiation exposure from these procedures. Elimination of unnecessary routine scout radiographs in select studies might significantly reduce radiation exposure to children and improve the overall benefit-to-risk ratio of these fluoroscopic procedures. OBJECTIVE: To determine the radiation exposure contribution of the preliminary/scout abdomen radiographs with respect to the radiation exposure of the total procedure. MATERIALS AND METHODS: We retrospectively collected demographic information and radiation exposure values of dose area product (in Gy-cm(2)) and entrance air kerma (in mGy) - initially for the scout abdomen radiographs done prior to fluoroscopy and subsequently the total procedural radiation values (the combined values of the scout radiograph and fluoroscopic radiation exposure) - in children who underwent contrast enemas, voiding cystourethrograms and upper gastrointestinal studies in a 4-month period. The radiation parameters, including fluoroscopy time, dose area product and entrance air kerma, were available in the log book maintained in the fluoroscopy suite. Fluoroscopy procedures were performed on a single fluoroscopy machine using four frames per second pulse rate and other radiation-minimizing techniques. Usage of the grid to obtain scout radiographs was also recorded. The proportion of radiation exposure from the scout radiograph relative to that of the total procedure was calculated by dividing the individual parameters of the scout to the total procedural values and multiplied by 100 to express these values as a percentage. We calculated mean, median and range and performed statistical analysis of the data. RESULTS: A total of 151 procedures performed on 71 males and 80 females qualified for the study. The age range of the patients was 2 days to 18 years, with a mean of nearly 3.5 years (40 months) and median of 15 months. There were 63 upper gastrointestinal studies, 65 voiding cystourethrography studies and 23 contrast enema studies. The fluoroscopy time for all procedures combined ranged from 0.1 min (6 s) to 2 min, with mean and median values of 0.4 min and 0.3 min, respectively. The fractional radiation exposure contribution for the dose area product of scout abdomen radiograph to the total procedure ranged from 4% to 98%, with mean and median values of 51% and 49%, respectively. The fractional contribution of the scout radiograph to the total procedure for the entrance air kerma values ranged from 6% to 97%, with mean and median values of 29% and 26%, respectively. There was a significant negative correlation (P<0.001) between fluoroscopy radiation time and the proportion of radiation parameters of scout radiograph to total procedural values. CONCLUSION: Scout radiographs can contribute a significant proportion (median values of approximately 50% for the dose area product and 26% for the entrance air kerma) of radiation exposure in common fluoroscopy procedures in children.

ECG-synchronized CT angiography in 324 consecutive pediatric patients: spectrum of indications and trends in radiation dose.

The aim of the study is to describe the spectrum of indications for pediatric ECG-synchronized CT angiography (CTA), the main determinants of radiation exposure, and trends in radiation dose over time at a single, tertiary referral center. The study was IRB approved and HIPAA compliant with informed consent waived. Between 2005 and 2013, 324 pediatric patients underwent ECG-synchronized CTA to evaluate known or suspected cardiovascular abnormalities (109 female, median age 8.1 years). The effective dose (ED) was calculated using age-specific correction factors. Univariate and multivariate regression analyses were performed to identify predictors of radiation dose. The most common primary indications for the CTA examinations included known or suspected coronary pathologies (n = 166), complex congenital heart disease (n = 73), and aortic pathologies (n = 41). Median radiation exposure decreased from 12 mSv for patients examined in the years 2005-2007 to 1.2 mSv for patients examined in the years 2011-2013 (p < 0.001). Patients scanned using a tube potential of 80 kV (n = 259) had a significantly lower median radiation dose (1.4 mSv) compared to patients who were scanned at 100 kV (n = 46, median 6.3 mSv) or 120 kV (n = 19, median 19 mSv, p < 0.001). Tube voltage, followed by tube current and the method of ECG-synchronization were the strongest independent predictors of radiation dose. Growing experience with dose-saving techniques and CTA protocols tailored to the pediatric population have led to a tenfold reduction in radiation dose over recent years and now allow routinely performing ECG-synchronized CTA in children with a radiation dose on the order of 1 mSv.

Congenital lung anomalies in children and adults: current concepts and imaging findings.

This article presents the broad spectrum of congenital lung anomalies, which manifest both in childhood and can be first identified in the adult patient. Each lesion is described in terms of underlying cause, clinical presentation, imaging characteristics with emphasis on advanced cross-sectional imaging, and current treatment options. Up-to-date knowledge of currently available imaging studies and techniques as well as a clear knowledge of imaging characteristics of various congenital lung anomalies are essential for accurate diagnosis and optimal management.

Diagnostic accuracy of CT angiography in infants with tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral arteries.

BACKGROUND: CT angiography (CTA) is increasingly used for the evaluation of congenital heart disease. OBJECTIVE: The aim was to determine the diagnostic accuracy of CTA in infants with tetralogy of Fallot with pulmonary atresia (ToF-PA) and major aortopulmonary collateral arteries (MAPCAs). METHODS: We retrospectively evaluated 18 consecutive patients (7 girls; median age, 6 days; range, 1-334 days) with ToF-PA and MAPCAs. Findings on CTA were compared with diagnostic catheterization (n = 16) or intraoperative findings (n = 2) for the number of MAPCAs, their diameter, origin, and supplied lung lobes and for the presence and diameter of central pulmonary arteries. Spearman correlation coefficient was calculated to assess the correlation between diameter measurements on CTA and catheterization. CTA dose-length product and catheterization dose-area product were recorded, and effective radiation doses were calculated with the use of age-specific conversion factors. RESULTS: Agreement was found between CTA and catheterization or intraoperative findings for the number of MAPCAs, their origin, and supplied lung lobes in all cases. In 11 of 13 patients, CTA accurately demonstrated central pulmonary arteries. A good correlation was found between diameter measurements on CTA and catheterization for MAPCAs (r = 0.83) and central pulmonary arteries (r = 0.82). Median effective doses were 0.9 mSv for CTA and 14.4 mSv for catheterization (P < .001). CONCLUSION: CTA is accurate in the preoperative evaluation of infants with ToF-PA and MAPCAs and is associated with a substantially lower radiation dose than catheterization. Preoperative diagnostic catheterization, therefore, may only be necessary in select patients with small MAPCAs in whom the precise assessment of central pulmonary arteries is required for surgical planning.

Preterm infant with subdural hematoma from malpositioned scalp intravenous catheter.

Vascular access is critical in the care of sick infants and children for the direct administration of medications and fluids. In infants, especially preterm infants, the use of scalp veins is a common practice because of less subcutaneous fat and less mobility around the catheter site decreasing the risk of dislodgement. We describe a case of a 24-week preterm infant girl born via caesarean section delivery who developed signs of increased intracranial pressure on day of life 11. A head computed tomography (CT) demonstrated large bilateral subdural hematomas with midline shift secondary to packed red blood cell infusion via an incorrectly positioned scalp intravenous catheter in the subdural space. In general, the use of scalp veins for intravenous access is a common method for direct administration of medications and fluids in small infants, with risks that are comparable to those associated with peripheral venous access. The use of scalp intravenous catheters is a fairly safe practice when correctly positioned. Position confirmation before and during use is vital to avoid potential intracranial complications.