BACKGROUND: Generalized arterial calcification of infancy (GACI), also known as idiopathic infantile arterial calcification, is a very uncommon genetic disorder characterized by calcifications and stenoses of large- and medium-size arteries that can lead to end-organ damage.

OBJECTIVE: To describe changes in imaging findings in 10 children with GACI at a single institution from 2010 to 2021.

MATERIALS AND METHODS: In this retrospective study we reviewed initial and follow-up body imaging in children with genetic confirmation of GACI at our hospital. All initial images were analyzed for the presence and distribution of arterial calcifications, stenoses and wall thickening/irregularity within the chest, abdomen and pelvis. We compared available follow-up studies to the initial imaging findings. We extracted clinical information including prenatal and postnatal treatment from the children's medical records.

RESULTS: We evaluated 10 children (five boys) with a diagnosis of GACI. Median age at first body imaging was 8 days (range: 1 day to 5 years). Six children were identified prenatally and four postnatally. Postnatal presentation included cardiac failure, seizures and hypertension. Images in newborns (n = 8) most commonly showed diffuse arterial calcifications (6/8; 75%), while stenoses were less common (2/8; 25%) during this period. Two children were diagnosed after the neonatal period - one in infancy and one during childhood. In total, half the children (5/10; 50%) had arterial stenoses - three cases visualized at first imaging and two identified on follow-up images during infancy. Stenoses had completely resolved in one child (1/5; 20%) at last follow-up. Eight children received prenatal or postnatal treatment or both. All children who received both prenatal and postnatal treatment (n = 4) had completely resolved calcifications at last follow-up.

CONCLUSION: Children with GACI might have characteristic vascular calcifications at birth that raise the suspicion of this disease. Arterial calcifications decrease or disappear spontaneously or after treatment, but arterial stenoses usually persist. Calcifications and arterial stenoses can be easily identified and followed with non-contrast CT and CT angiography.

OBJECTIVE: To describe quantitative CT parameters of children with a typical pattern for NEHI and compare them to controls.

MATERIALS AND METHODS: Eleven patients (7 boys) with NEHI and an available chest CT concordant NEHI were identified. Eleven age-, sex-, height-matched, with CT technique-matching were identified for comparison. An open-source software was used to segment the lung parenchyma into lobes using the fissures. Quantitative parameters such as low attenuation areas, mean lung density, kurtosis, skewness, ventilation heterogeneity, lung mass, and volume were calculated for both controls and cases.

RESULTS: Analysis of the lung parenchyma showed that patients with NEHI had a lower mean lung density (-615 HU vs -556 HU, p = 0.03) with higher ventilation heterogeneity (0.23 vs 0.19, p = 0.04), lung mass (232 g vs 146 g, p = 0.01) and volume (595 mL vs 339 mL, p = 0.008) compared to controls. Most lobes followed this trend, except the middle lobe that showed only a higher lung mass (32.9 g vs 19.6 g, p = 0.02) and volume (77.4 vs 46.9, p = 0.005) in patients with NEHI compared to controls.

CONCLUSION: Quantitative CT is a feasible technique in children with a typical pattern for NEHI and is associated with differences in attenuation, ventilation heterogeneity, and lung volume.

<p><strong>BACKGROUND: </strong>Generalized arterial calcification of infancy (GACI), also known as idiopathic infantile arterial calcification, is a very uncommon genetic disorder characterized by calcifications and stenoses of large- and medium-size arteries that can lead to end-organ damage.</p>

<p><strong>OBJECTIVE: </strong>To describe changes in imaging findings in 10 children with GACI at a single institution from 2010 to 2021.</p>

<p><strong>MATERIALS AND METHODS: </strong>In this retrospective study we reviewed initial and follow-up body imaging in children with genetic confirmation of GACI at our hospital. All initial images were analyzed for the presence and distribution of arterial calcifications, stenoses and wall thickening/irregularity within the chest, abdomen and pelvis. We compared available follow-up studies to the initial imaging findings. We extracted clinical information including prenatal and postnatal treatment from the children's medical records.</p>

<p><strong>RESULTS: </strong>We evaluated 10 children (five boys) with a diagnosis of GACI. Median age at first body imaging was 8&nbsp;days (range: 1&nbsp;day to 5&nbsp;years). Six children were identified prenatally and four postnatally. Postnatal presentation included cardiac failure, seizures and hypertension. Images in newborns (n = 8) most commonly showed diffuse arterial calcifications (6/8; 75%), while stenoses were less common (2/8; 25%) during this period. Two children were diagnosed after the neonatal period - one in infancy and one during childhood. In total, half the children (5/10; 50%) had arterial stenoses - three cases visualized at first imaging and two identified on follow-up images during infancy. Stenoses had completely resolved in one child (1/5; 20%) at last follow-up. Eight children received prenatal or postnatal treatment or both. All children who received both prenatal and postnatal treatment (n = 4) had completely resolved calcifications at last follow-up.</p>

<p><strong>CONCLUSION: </strong>Children with GACI might have characteristic vascular calcifications at birth that raise the suspicion of this disease. Arterial calcifications decrease or disappear spontaneously or after treatment, but arterial stenoses usually persist. Calcifications and arterial stenoses can be easily identified and followed with non-contrast CT and CT angiography.</p>

<p>Background Accurate and precise methods to predict growth remain lacking. Diffusion tensor imaging (DTI) depicts the columnar structure of the physis and metaphyseal spongiosa and provides measures of tract volume and length that may help predict growth. Purpose To validate physeal DTI metrics as predictors of height velocity (1-year height gain from time of MRI examination) and total height gain (height gain from time of MRI examination until growth stops) and compare the prediction accuracy with bone age-based models. Materials and Methods Femoral DTI studies ( values = 0 and 600 sec/mm; directions = 20) of healthy children who underwent MRI of the knee between February 2012 and December 2016 were retrospectively analyzed. Children with height measured at MRI and either 1 year later (height velocity) or after growth cessation (total height gain, mean = 34 months from MRI) were included. Physeal DTI tract volume and length were correlated with height velocity and total height gain. Multilinear regression was used to assess the potential of DTI metrics in the prediction of both parameters. Bland-Altman plots were used to compare root mean square error (RMSE) and bias in height prediction using DTI versus bone age methods. Results Eighty-nine children (mean age, 13 years ± 3 [SD]; 47 boys) had height velocity measured, and 70 (mean age, 14 years ± 1; 36 girls) had total height gain measured. Tract volumes correlated with height velocity ( = 0.49) and total height gain ( = 0.46) ( &lt; .001 for both) after controlling for age and sex. Tract volume was the strongest predictor for height velocity and total height gain. An optimal multilinear model including tract volume improved prediction of height velocity ( = 0.63, RMSE = 1.7 cm) and total height gain ( = 0.59, RMSE = 1.8 cm) compared with bone age-based methods (height velocity: = 0.32, RMSE = 2.9 cm; total height gain: = 0.42, RMSE = 5.0 cm). Conclusion Models using tract volume derived from diffusion tensor imaging may perform better than bone age-based models in children for the prediction of height velocity and total height gain. © RSNA, 2022.</p>

<p><strong>OBJECTIVE: </strong>To evaluate clinical applications of Dual-Energy CT (DECT) in pediatric-specific lung diseases and compare ventilation and perfusion findings with those from single-photon emission CT (SPECT-CT) V/Q.</p>

<p><strong>METHODS: </strong>All patients at our institution who underwent exams using both techniques within a 3-month period were included in this study. Two readers independently described findings for DECT, and two other readers independently analyzed the SPECT-CT V/Q scan data. All findings were compared between readers and disagreements were reassessed and resolved by consensus. Inter- modality agreements are described throughout this paper.</p>

<p><strong>RESULTS: </strong>Eight patients were included for evaluation. The median age for DECT scanning was 3.5 months (IQR=2). Five of these patients were scanned for both DECT and SPECT-CT V/Q studies the same day, and three had a time gap of 7, 65, and 94 days between studies. The most common indications were chronic lung disease (5/8; 63%) and pulmonary hypertension (6/8; 75%). DECT and SPECT-CT V/Q identified perfusion abnormalities in concordant lobes in most patients (7/8; 88%). In one case, atelectasis limited DECT perfusion assessment. Three patients ultimately underwent lobectomy with corresponding perfusion abnormalities identified by all reviewers on both DECT and SPECT-CT V/Q in all resected lobes.</p>

<p><strong>CONCLUSION: </strong>DECT is a feasible technique that could be considered as an alternative for SPECT-CT V/Q for lung perfusion evaluation in infants. This article is protected by copyright. All rights reserved.</p>

<p><strong>OBJECTIVE: </strong>To evaluate changes in the utilization of computed tomography angiography (CTA) for evaluating suspected pulmonary embolism (PE) and the positive rate of ancillary for those studies negative for PE in the last 13&nbsp;years.</p>

<p><strong>MATERIALS AND METHODS: </strong>A retrospective review of patient&nbsp;≤&nbsp;20&nbsp;years of age who underwent a chest CT angiography to rule out PE was performed in a 13-year-period. CT angiographies were grouped into three categories: Positive for PE, negative for PE and positive for ancillary findings, and negative for any pathology. From the exams with ancillary findings, we examined how many of these had a chest radiograph perform within 24&nbsp;h prior to the CTA and how many of them had an impression stating the same conclusion as the CTA.</p>

<p><strong>RESULTS: </strong>307 chest CT angiographies for suspected PE were included. 50 (16%) were reported as positive for PE and 91 (30%) were negative for PE but positive for ancillary findings. The most frequent ancillary findings were pneumonia (n = 26) and pleural effusion (n = 11). Out of 91, 73 patients had a previous chest radiograph and 28 of them reported a similar diagnosis than the CTA. The number of CT angiographies indicated for PE increased by 3.2 studies per year. The rate of CT angiographies positive for ancillary findings (slope = 1.5) and positive for PE (slope = 0.3) remained similar throughout the same period.</p>

<p><strong>CONCLUSIONS: </strong>CTA orders for PE have been increasing without any increased detection of PE or ancillary findings in children.</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>Dual-energy computer tomography (DECT) technology has experienced rapid growth in recent years, now allowing for the collection of 2 CT data sets and opening the potential for functional data acquisition. Data from a single postcontrast phase are deconstructed and Iodine can be subtracted to create a virtual noncontrast image, or selectively represented as a contrast map that allows for the qualification and quantification of lung perfusion. Virtual monoenergetic images can also be used to reduce beam-hardening artifact from concentrated contrast or metal implants. In children, DECT is of particular interest because it has been shown to be dose neutral in most applications, dose-reducing in multiphase studies, and to increase the contrast to noise ratio in suboptimal studies. We review the basics of acquisition, postprocessing, and thoracic applications of DECT with a focus on pulmonary blood volumes as a surrogate for perfusion imaging. The discussed applications include pulmonary embolism, hypoplastic lung, pulmonary hypertension in bronchopulmonary dysplasia, and pediatric lung masses.</p>

<p><strong>Background</strong> MRI performed at 3.0 T offers greater signal-to-noise ratio and better spatial resolution than does MRI performed at 1.5 T; however, for fetal MRI, there are concerns about the potential for greater radiofrequency energy administered to the fetus at 3.0-T MRI. <strong>Purpose</strong> To compare the specific absorption rate (SAR) and specific energy dose (SED) of fetal MRI at 1.5 and 3.0 T. <strong>Materials and Methods</strong> In this retrospective study, all fetal MRI examinations performed with 1.5- and 3.0-T scanners at one institution between July 2012 and October 2016 were evaluated. Two-dimensional (2D) and three-dimensional (3D) steady-state free precession (SSFP), single-shot fast spin-echo, 2D and 3D T1-weighted spoiled gradient-echo (SPGR), and echo-planar imaging sequences were performed. SAR, SED, accumulated SED, and acquisition time were retrieved from the Digital Imaging and Communications in Medicine header. Data are presented as mean ± standard deviation. Two one-sided tests with equivalence bounds of 0.5 (Cohen effect size) were performed, with statistical equivalence considered at &lt; .05. <strong>Results</strong> A total of 2952 pregnant women were evaluated. Mean maternal age was 30 years ± 6 (age range, 12-49 years), mean gestational age was 24 weeks ± 6 (range, 17-40 weeks). A total of 3247 fetal MRI scans were included, with 2784 (86%) obtained at 1.5 T and 463 (14%) obtained at 3.0 T. In total, 93 764 sequences were performed, with 81 535 (87%) performed at 1.5 T and 12 229 (13%) performed at 3.0 T. When comparing 1.5- with 3.0-T MRI sequences, mean SAR (1.09 W/kg ± 0.69 vs 1.14 W/kg ± 0.61), mean SED (33 J/kg ± 27 vs 38 J/kg ± 26), and mean accumulated SED (965 J/kg ± 408 vs 996 J/kg ± 366, &lt; .001) were equivalent. <strong>Conclusion</strong> Fetal 1.5- and 3.0-T MRI examinations were found to have equivalent energy metrics in most cases. The 3.0-T sequences, such as two-dimensional T1-weighted spoiled gradient-echo and three-dimensional steady-state free precession, may require modification to keep the energy delivered to the patient as low as possible. © RSNA, 2020</p>

<p><strong>OBJECTIVE: </strong>To compare quantitative chest CT parameters in perinatally HIV-infected adolescents with and without bronchiolitis obliterans compared with HIV-uninfected controls and their association with lung function measurements.</p>

<p><strong>MATERIALS AND METHODS: </strong>Seventy-eight (41 girls) HIV-infected adolescents with a mean age of 13.8 ± 1.65&nbsp;years and abnormal pulmonary function tests in the prospective Cape Town Adolescent Antiretroviral Cohort underwent contrast-enhanced chest CT on inspiration and expiration. Sixteen age-, sex-, and height-matched non-infected controls were identified retrospectively. Fifty-one HIV-infected adolescents (28 girls) displayed mosaic attenuation on expiration suggesting bronchiolitis obliterans. Pulmonary function tests were collected. The following parameters were obtained: low- and high-attenuation areas, mean lung density, kurtosis, skewness, ventilation heterogeneity, lung mass, and volume.</p>

<p><strong>RESULTS: </strong>HIV-infected adolescents showed a significantly higher mean lung density, ventilation heterogeneity, mass, and high- and low-attenuation areas compared with non-infected individuals. Kurtosis and skewness were significantly lower as well. HIV-infected adolescents with bronchiolitis obliterans had a significantly lower kurtosis and skewness compared with those without bronchiolitis obliterans. Lung mass and volume showed the strongest correlations with forced expiratory volume in 1&nbsp;s (FEV), forced vital capacity (FVC), and alveolar volume. Low-attenuation areas below -&nbsp;950&nbsp;HU and ventilation heterogeneity showed the strongest correlation with FEV/FVC (range, - 0.51 to - 0.34) and forced expiratory flow between 25 and 75% of FVC (range, - 0.50 to - 0.35).</p>

<p><strong>CONCLUSION: </strong>Quantitative chest CT on inspiration is a feasible technique to differentiate perinatally HIV-infected adolescents with and without bronchiolitis obliterans. Quantitative CT parameters correlate with spirometric measurements of small-airway disease.</p>

<p><strong>KEY POINTS: </strong>• Perinatally HIV-infected adolescents showed a more heterogeneous attenuation of the lung parenchyma with a higher percentage of low- and high-attenuation areas compared with non-infected patients. • Kurtosis and skewness are able to differentiate between HIV-infected adolescents with and without bronchiolitis obliterans using an inspiratory chest CT. • Quantitative CT parameters of the chest correlate significantly with pulmonary function test. Low-attenuation areas and ventilation heterogeneity are particularly associated with spirometric parameters related to airway obstruction.</p>