Background Previous studies have challenged the concept of contrast material-induced acute kidney injury (AKI) in adults; however, limited data exist for children and adolescents. Purpose To calculate the incidence and determine the risks of AKI in patients who received intravenous iodinated contrast media for CT. Materials and Methods This retrospective study was performed at a children's hospital from January 2008 to January 2018 and included patients aged 0-17 years in whom serum creatinine levels were measured within 48 hours before and after CT with or without contrast media. The incidence of AKI was measured according to the AKI Network guidelines. A subgroup analysis with propensity score matching of cases with control patients was performed. Differences before and after stratification based on estimated glomerular filtration rate (eGFR) were explored. Adjusted risk models were developed using log-binomial generalized estimating equations to estimate relative risk (RR). Results From a total of 54 000 CT scans, 19 377 scans from 10 407 patients (median age, 8.5 years; IQR, 3-14; 5869 boys, 4538 girls) were included in the analysis. Incidence rate of AKI for the entire sample was 1.5%; it was 1.4% (123 of 8844) in the group that underwent contrast-enhanced CT and 1.6% (171 of 10 533) in the group that did not ( = .18). In the contrast-enhanced CT group, AKI incidence was higher in the group with eGFR of at least 60 mL/min/1.73 m and in the group with eGFR lower than 60 mL/min/1.73 m (1.3% and 8.5%, respectively; < .001) compared with the noncontrast group (0.1% and 2.7%, respectively; < .001). Age was found to be a protective factor against AKI, with an RR of 0.96 (95% CI: 0.94, 0.99; = .01), and contrast media increased risk in the subgroup analysis, with an RR of 2.19 (95% CI: 1.11, 4.35; = .02). Conclusion The overall incidence of acute kidney injury after contrast-enhanced CT in children and adolescents was very low, and exposure to contrast media did not increase the risk consistently for acute kidney injury among different groups and analyses. © RSNA, 2022 See also the editorial by McDonald in this issue.

PURPOSE: Children with single-ventricle congenital heart disease undergo a series of operations to maintain their pulmonary circulation including bidirectional Glenn (BDG) or hemi-Fontan in the second stage to create a superior cavopulmonary anastomosis. We aimed to optimize cardiovascular angiography protocols by determining optimal contrast timing of pulmonary and systemic circulation on magnetic resonance angiography (MRA) performed with the technique of time-resolved imaging with interleaved stochastic trajectories (TWIST).

METHODS AND MATERIALS: Cardiac TWIST MRA with lower extremity (LE) contrast injection was analyzed in 92 consecutive patients with a BDG or hemi-Fontan anastomosis. Contrast arrival time to inferior vena cava was set to zero to determine the relative time-to-peak (TTP) of the target vessels. Time-to-peak of each vessel was compared by age (<2 or ≥2 y), ejection fraction (<54% or ≥54%), the median values of heart rate (<111 or ≥111 beats per minute), body surface area (BSA, <0.59 or ≥0.59), cardiac index (<6.04 or ≥6.04), and indexed ascending aorta flow (AscAo_i, <5.3 or ≥5.3). The TTP of the vessels was also correlated with the volumetric parameters.

RESULTS: The mean age of 92 patients (32 female, 60 male) was 3.1 years (0.7-5.6 years). With LE injection, the first peak was depicted in AscAo. Time-to-peak of the pulmonary arteries was approximately 9 seconds later than AscAo. The TTP difference between pulmonary arteries and AscAo was shorter in high heart rate group (8.3 vs 10 seconds, P < 0.001). The TTP difference between AscAo and the mean of pulmonary arteries was significantly shorter in high cardiac index group (8.4 vs 9.9 seconds, P < 0.01) and high AscAo_i group (8.7 vs 9.7 seconds, P = 0.03). The TTP differences were not significant by age, ejection fraction, and BSA. Cardiac index and AscAo_i were negatively correlated with all TTPs except AscAo. The ejection fraction, stroke volume, and atrioventricular regurgitation fraction did not correlate with the TTP.

CONCLUSIONS: In patients with BDG or hemi-Fontan anastomosis, TTP of the pulmonary arteries on TWIST MRA via LE intravenous injection is approximately 9 seconds later than AscAo, approximately 8 and 10 seconds later in high and low heart rate groups, respectively. Cardiac index and AscAo_i have less effect on the TTP than the heart rate. There was no TTP difference of the pulmonary arteries by age, BSA, and ejection fraction and no correlation with ejection fraction, stroke volume, and atrioventricular regurgitation fraction. These data can be used to guide timing of pulmonary arterial enhancement of single-ventricle patients after BDG or hemi-Fontan anastomosis.

Computed tomography technology continues to undergo evolution and improvement with each passing decade. From its inception in 1971, to the advent of commercially available dual-energy CT just over a decade ago, and now to the latest innovation, photon-counting detector CT, CT's utility for resolving and discriminating tissue types improves. In this review we discuss the impact of spectral imaging, including dual-energy CT and the recently available photon-counting detector CT, on the imaging of the pediatric chest. We describe the current capabilities and future directions of CT imaging, encompassing both the lungs and the surrounding tissues.

The gold standard for pediatric chest imaging remains the CT scan. An ideal pediatric chest CT has the lowest radiation dose with the least motion degradation possible in a diagnostic scan. Because of the known inherent risks and costs of anesthesia, non-sedate options are preferred. Dual-source CTs are currently the fastest, lowest-dose CT scanners available, utilizing an ultra-high-pitch mode resulting in sub-second CTs. The dual-energy technique, available on dual-source CT scanners, gathers additional information such as pulmonary blood volume and includes relative contrast enhancement and metallic artifact reduction, features that are not available in high-pitch flash mode. In this article we discuss the benefits and tradeoffs of dual-source CT scan modes and tips on image optimization.

<p>Magnetic resonance imaging (MRI) is a routinely used imaging modality for the diagnosis and treatment planning of many health conditions in children and adults. Yet, its use has been limited in many institutions for patients with cardiac implantable electronic devices (CIEDs) due to safety concerns. Current evidence relates primarily to devices with transvenous leads. However, patients with complex cardiac anatomy and palliative surgery procedures often require epicardial pacemakers. To date, very few studies have addressed MRI safety considerations with non-conditional CIEDs or abandoned epicardial leads in infants, and to our knowledge, this is the first report that shows Fontan palliation patients who underwent Dynamic Contrast enhanced MR Lymphangiography (DCMRL) with these types of devices. We present our institutional experience with five cases where a DCMRL was safely performed in three children and two adults with Fontan palliation to evaluate their lymphatic anatomy and guide interventional procedures. Regarding our brief experience, we concluded that DCMRL may be considered in post-Fontan patients with non-conditional CIEDs, including epicardial leads, seeking the best diagnostic and treatment options available. Institutional protocols must be revised in advance to perform this technique in a controlled setting.</p>

<p><strong>PURPOSE: </strong>To assess the feasibility of direct intra-lymphatic administration of diluted ferumoxytol as a T1-positive contrast agent for dynamic contrast-enhanced MR lymphangiography (DCMRL) imaging of the central lymphatics in children with renal disease.</p>

<p><strong>METHODS: </strong>In vitro scan of dilute ferumoxytol was initially performed using time-resolved and high-resolution 3D gradient echo (GRE) sequences with short TE values (1 to 1.5&nbsp;ms). A ferumoxytol concentration of 0.25 to 0.40&nbsp;mg/mL was found to retain high signal in the T1-weighted sequences. DCMRL was then performed in 4 children with renal disease with the same 3D GRE sequences administrating diluted ferumoxytol via intra-mesenteric (IM), intra-hepatic (IH), and intra-nodal (IN) routes (6 to 9&nbsp;mL to each site; average total dose of 0.75&nbsp;mg/kg) by slow hand injection (0.5 to 1.0&nbsp;mL/min). The signal-to-noise ratio (SNR) of the lymphatics was measured for quantitative evaluation.</p>

<p><strong>RESULTS: </strong>Ferumoxytol-enhanced DCMRL was technically successful in all patients. Contrast conspicuity within the lymphatics was sufficient without subtraction. The mean SNR was significantly higher than the muscle (50.1 ± 12.2 vs 13.2 ± 2.8; t = 15.9; p &lt; .001). There were no short-term complications attributed to the administration of ferumoxytol in any of the four patients.</p>

<p><strong>CONCLUSION: </strong>Magnetic resonance lymphangiography using ferumoxytol via IN, IH, and IM access is a new method to directly visualize the central lymphatic system and can be applied safely in patients with renal failure based on our preliminary report of four cases. Ferumoxytol-enhanced DCMRL shows diagnostic image quality by using 3D GRE sequences with short TE values and appropriate dilution of ferumoxytol.</p>

<p><strong>KEY POINTS: </strong>• MR lymphangiography using ferumoxytol via intra-nodal, intra-hepatic, and intra-mesenteric access is a new method to directly visualize the central lymphatic system from the groin to the venous angle. • FDCMRL can be applied safely in patients with renal failure based on our preliminary report of four cases. • FDCMRL shows diagnostic image quality by using 3D GRE sequences with short TE values and appropriate dilution of the ferumoxytol.</p>

<p>Magnetic resonance imaging (MRI) and CT perform an important role in the evaluation of neonates with congenital heart disease (CHD) when echocardiography is not sufficient for surgical planning or postoperative follow-up. Cardiac MRI and cardiac CT have complementary applications in the evaluation of cardiovascular disease in neonates. This review focuses on the indications and technical aspects of these modalities and special considerations for imaging neonates with CHD.</p>

<p>The presence of airway and lung disease in children with congenital heart disease is commonly observed with both cardiac CT angiography and routine chest CT. In this review we discuss abnormalities encountered on CT imaging of the chest beyond the heart and central vasculature, focusing on the airways, lung parenchyma and peripheral vasculature. Preoperative and postoperative findings are reviewed as well.</p>

<p><strong>OBJECTIVE: </strong>To characterize the normal progression of quantitative CT parameters in normal children from birth to adulthood.</p>

<p><strong>MATERIALS AND METHODS: </strong>Patients aged 0-18&nbsp;years with non-contrast-enhanced chest CT and evidence of normal lung parenchyma were included. Patients with respiratory symptoms, incomplete anthropometric measurements, or sub-optimal imaging technique were excluded. Segmentation was performed using an open-source software with an automated threshold segmentation. The following parameters were obtained: mean lung density, kurtosis, skewness, lung volume, and mass. Linear and exponential regression models were calculated with age and height as independent variables. A p-value of &lt;0.05 was considered significant.</p>

<p><strong>RESULTS: </strong>220 patients (111 females, 109 males) were included. Mean age was 9.6&nbsp;±&nbsp;5.9&nbsp;years and mean height was 133.9&nbsp;±&nbsp;35.1&nbsp;cm. Simple linear regression showed a significant relationship between mean lung density with age (R 2&nbsp;=&nbsp;0.70) and height (R 2&nbsp;=&nbsp;0.73). Kurtosis displayed a significant exponential correlation with age (R 2&nbsp;=&nbsp;0.70) and height (R 2&nbsp;=&nbsp;0.71). Skewness showed a significant exponential correlation with age (R 2&nbsp;=&nbsp;0.71) and height (R 2&nbsp;=&nbsp;0.73). Lung mass showed a correlation with age (R 2&nbsp;=&nbsp;0.93) and height (R 2&nbsp;=&nbsp;0.92). Exponential regression showed a significant relationship between lung volume with age (R 2&nbsp;=&nbsp;0.88) and height (R 2&nbsp;=&nbsp;0.93).</p>

<p><strong>CONCLUSION: </strong>Quantitative CT parameters of the lung parenchyma demonstrate changes from birth to adulthood. As children grow, the mean lung density decreases, and the lung parenchyma becomes more homogenous.</p>

<p>To assess the diagnostic efficiency of CT angiography (CTA) to detect pulmonary vein stenosis in children. We retrospectively identify patients between 0 and 3&nbsp;years old with confirmed pulmonary vein stenosis with conventional angiography or surgery and available CTA. Patients without confirmed stenosis of the pulmonary veins were included as controls. We excluded patients with previous surgery involving the pulmonary veins, exclusively right-heart conventional angiography or insufficient data in the operation note to confirm the status of the pulmonary veins. Two pediatric radiologists evaluated and determine the presence of stenosis and the pulmonary veins affected. Disagreement between the readers were solved by consensus with a third reader. A pediatric cardiologist reviewed the available angiographic images to determine the presence of stenosis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated. Kappa statistics was performed. 26 patients (15 boys, 11 Girls) were included. Conventional angiography (n = 20) and cardiothoracic surgery (n = 6) confirmed the diagnosis of pulmonary vein stenosis in 13 children. The diagnostic performance at patient level showed the sensitivity, specificity, PPV, and NPV were 84.6%, 92.3%, 91.6%, 87.5%, and 88.4%, respectively. The interobserver was k = 0.76. The performance at pulmonary vein level showed the sensitivity, specificity, PPV, and NPV were 63.3%, 97.4%, 90.4%,85.7% and 87.9%, respectively. The interobserver agreement was k = 0.62. Computed Tomography Angiography is an excellent and reliable image technique for ruling in pulmonary vein stenosis in young children.</p>