Magnetic resonance imaging for congenital lung malformations.

Congenital lung malformations are most often identified on prenatal US screening. Fetal MRI is often performed to further evaluate these lesions. Although some of these lesions might cause prenatal or early postnatal symptoms that require urgent management, the majority are asymptomatic at birth and might be subtle or invisible on chest radiographs. Postnatal imaging is frequently deferred until 3-6 months of age, when surgery or long-term conservative management is contemplated. High-quality imaging and interpretation is needed to assist with appropriate decision-making. Contrast-enhanced chest CT, typically with angiographic technique, has been the usual postnatal imaging choice. In this review, the author discusses and illustrates the indications and use of postnatal MR imaging for bronchopulmonary malformations as well as some differential diagnoses and the advantages and disadvantages of MR versus CT.

Improved detection of air trapping on expiratory computed tomography using deep learning.

BACKGROUND: Radiologic evidence of air trapping (AT) on expiratory computed tomography (CT) scans is associated with early pulmonary dysfunction in patients with cystic fibrosis (CF). However, standard techniques for quantitative assessment of AT are highly variable, resulting in limited efficacy for monitoring disease progression. OBJECTIVE: To investigate the effectiveness of a convolutional neural network (CNN) model for quantifying and monitoring AT, and to compare it with other quantitative AT measures obtained from threshold-based techniques. MATERIALS AND METHODS: Paired volumetric whole lung inspiratory and expiratory CT scans were obtained at four time points (0, 3, 12 and 24 months) on 36 subjects with mild CF lung disease. A densely connected CNN (DN) was trained using AT segmentation maps generated from a personalized threshold-based method (PTM). Quantitative AT (QAT) values, presented as the relative volume of AT over the lungs, from the DN approach were compared to QAT values from the PTM method. Radiographic assessment, spirometric measures, and clinical scores were correlated to the DN QAT values using a linear mixed effects model. RESULTS: QAT values from the DN were found to increase from 8.65% ± 1.38% to 21.38% ± 1.82%, respectively, over a two-year period. Comparison of CNN model results to intensity-based measures demonstrated a systematic drop in the Dice coefficient over time (decreased from 0.86 ± 0.03 to 0.45 ± 0.04). The trends observed in DN QAT values were consistent with clinical scores for AT, bronchiectasis, and mucus plugging. In addition, the DN approach was found to be less susceptible to variations in expiratory deflation levels than the threshold-based approach. CONCLUSION: The CNN model effectively delineated AT on expiratory CT scans, which provides an automated and objective approach for assessing and monitoring AT in CF patients.

Mucus plugging, air trapping, and bronchiectasis are important outcome measures in assessing progressive childhood cystic fibrosis lung disease.

OBJECTIVE: To determine which outcome measures could detect early progression of disease in school-age children with mild cystic fibrosis (CF) lung disease over a two-year time interval utilizing chest computed tomography (CT) scores, quantitative CT air trapping (QAT), and spirometric measurements. METHODS: Thirty-six school-age children with mild CF lung disease (median [interquartile range] age 12 [3.7] years; percent predicted forced expiratory volume in 1 second (ppFEV1 ) 99 [12.5]) were evaluated by serial spirometer-controlled chest CT scans and spirometry at baseline, 3-month, 1- and 2-years. RESULTS: No significant changes were noted at 3-month for any variable except for decreased ppFEV1 . Mucus plugging score (MPS) and QATA1andA2 increased at 1- and 2-years. The bronchiectasis score (BS), and total score (TS) were increased at 2-year. All variables tested with the exception of bronchial wall thickness score, parenchymal score (PS), and ppFEV1 , were consistent with longitudinal worsening of lung disease. Multivariate analysis revealed baseline PS, baseline TS, and 1-year changes in BS and air trapping score were predictive of 2-year changes in BS. CONCLUSIONS: MPS and QATA1-A2 were the most sensitive indicators of progressive childhood CF lung disease. The 1-year change in the bronchiectasis score had the most positive predictive power for 2-year change in bronchiectasis.

Left ventricular retraining in corrected transposition: Relationship between pressure and mass.

BACKGROUND: A subset of patients with corrected transposition of the great arteries (CC-TGA) will require left ventricular (LV) retraining before undergoing a double-switch procedure. LV retraining results in an immediate increase in LV pressure but not in LV mass. The purpose of this study was to evaluate the relationship between LV pressure and mass during LV retraining. METHODS: This was a retrospective review of 36 patients with CC-TGA who were enrolled in LV retraining. The median age at enrollment was 12 months. The majority (82%) had an Ebstenoid tricuspid valve or moderate to severe tricuspid valve regurgitation before pulmonary artery banding. RESULTS: Twenty-seven of the 36 patients underwent LV retraining and a double switch, including 14 patients with a single pulmonary artery band (PAB), 12 patients with 2 PABs, and 1 patient with 3 PABs. There was no early or late mortality associated with these procedures. Ninety percent of the patients demonstrated a linear relationship between LV pressure and mass; however, 3 patients (10%) demonstrated a different LV retraining pattern characterized by excess LV mass compared to LV pressure. Two of these 3 patients are LV retraining failures, whereas the third patient did undergo a double switch. CONCLUSIONS: The data show that the majority of patients enrolled in LV retraining have a predictable relationship between LV mass and pressure. A minority demonstrate an excess accrual of mass with respect to pressure load. These results suggest there may be an important distinction between normal and pathological hypertrophy during the LV retraining process.

Tumor-induced Osteomalacia in a 3-Year-Old With Unresectable Central Giant Cell Lesions.

Tumor-induced osteomalacia (TIO) is a rare cause of hypophosphatemia involving overproduction of fibroblast growth factor 23. TIO has been described largely in adults with small mesenchymal tumors. We report a case of TIO in a child who presented with knee pain and radiographic findings concerning for rickets, and was found to have maxillomandibular giant cell lesions. The patient was treated with oral phosphorus and calcitriol, surgical debulking, and intralesional corticosteroids, which resulted in tumor regression and normalization of serum fibroblast growth factor 23 and phosphorus. This case illustrates the occurrence of this rare paraneoplastic syndrome in children and adds to our knowledge about clinical manifestations and pathologic findings associated with pediatric TIO.

Perinatal Thoracic Mass Lesions: Pre- and Postnatal Imaging.

Chest masses present a common problem in the perinatal period. Advances in prenatal ultrasound, supplemented by fetal magnetic resonance imaging, now allow early detection and detailed characterization of many thoracic lesions in utero. As such, in asymptomatic infants, assessment with postnatal computed tomography or magnetic resonance imaging can often be delayed for several months until the time at which surgery is being contemplated. Bronchopulmonary malformations comprise most of the thoracic masses encountered in clinical practice. However, a variety of other pathologies can mimic their appearances or produce similar effects such as hypoplasia of a lung or both lungs. Understanding of the key differentiating clinical and imaging features can assist in optimizing prognostication and timely management.

The incidental pulmonary nodule in a child. Part 1: recommendations from the SPR Thoracic Imaging Committee regarding characterization, significance and follow-up.

No guidelines are in place for the follow-up and management of pulmonary nodules that are incidentally detected on CT in the pediatric population. The Fleischner guidelines, which were developed for the older adult population, do not apply to children. This review summarizes the evidence collected by the Society for Pediatric Radiology (SPR) Thoracic Imaging Committee in its attempt to develop pediatric-specific guidelines.Small pulmonary opacities can be characterized as linear or as ground-glass or solid nodules. Linear opacities and ground-glass nodules are extremely unlikely to represent an early primary or metastatic malignancy in a child. In our review, we found a virtual absence of reported cases of a primary pulmonary malignancy presenting as an incidentally detected small lung nodule on CT in a healthy immune-competent child.Because of the lack of definitive information on the clinical significance of small lung nodules that are incidentally detected on CT in children, the management of those that do not have the typical characteristics of an intrapulmonary lymph node should be dictated by the clinical history as to possible exposure to infectious agents, the presence of an occult immunodeficiency, the much higher likelihood that the nodule represents a metastasis than a primary lung tumor, and ultimately the individual preference of the child's caregiver. Nodules appearing in children with a history of immune deficiency, malignancy or congenital pulmonary airway malformation should not be considered incidental, and their workup should be dictated by the natural history of these underlying conditions.

Congenital peribronchial myofibroblastic tumor: case report of an asymptomatic infant with a rapidly enlarging pulmonary mass and review of the literature.

BACKGROUND: Congenital peribronchial myofibroblastic tumor (CPMT) is a rare, benign lung tumor of infants, with only 19 reported cases worldwide. It is often diagnosed by prenatal imaging or in the immediate postnatal period due to co-morbidities like polyhydramnios, fetal hydrops, respiratory distress, and heart failure. OBSERVATION: We report the oldest known infant (8 weeks old) diagnosed with CPMT, and present his clinical course including the relevant radiographic and histopathologic findings. CONCLUSIONS: CPMT is a rare tumor that should be considered among other primary lung tumors of infancy (developmental, benign, and malignant) even if not detected prenatally or in the immediate postnatal period.

Cystic lung lesions in newborns and young children: differential considerations and imaging.

Numerous diverse entities produce cystic lung changes in neonates and young children. This review provides an evidence-based, age-appropriate, differential diagnostic framework to use when confronted with pulmonary cystic changes. The categories of diseases that have been discussed include congenital cystic bronchopulmonary malformations, neoplastic conditions, infections, collagen or soft tissue abnormalities, and mimics of cystic lung disease. An understanding of the pathophysiology, imaging appearance, and demographics of these entities is essential in guiding optimal care. Important educational points include differentiating bronchopulmonary malformations from neoplasms and the management and surveillance of lung cysts in young children.

Heterotaxy syndromes and abnormal bowel rotation.

BACKGROUND: Bowel rotation abnormalities in heterotaxy are common. As more children survive cardiac surgery, the management of gastrointestinal abnormalities has become controversial. OBJECTIVE: To evaluate imaging of malrotation in heterotaxy with surgical correlation and provide an algorithm for management. MATERIALS AND METHODS: Imaging reports of heterotaxic children with upper gastrointestinal (UGI) and/or small bowel follow-through (SBFT) were reviewed. Subsequently, fluoroscopic images were re-reviewed in conjunction with CT/MR studies. The original reports and re-reviewed images were compared and correlated with surgical findings. RESULTS: Nineteen of 34 children with heterotaxy underwent UGI, 13/19 also had SBFT. In 15/19 reports, bowel rotation was called abnormal: 11 malrotation, 4 non-rotation, no cases of volvulus. Re-review, including CT (10/19) and MR (2/19), designated 17/19 (90%) as abnormal, 10 malrotation (abnormal bowel arrangement, narrow or uncertain length of mesentery) and 7 non-rotation (small bowel and colon on opposite sides plus low cecum with probable broad mesentery). The most useful CT/MR findings were absence of retroperitoneal duodenum in most abnormal cases and location of bowel, especially cecum. Abnormal orientation of mesenteric vessels suggested malrotation but was not universal. Nine children had elective bowel surgery; non-rotation was found in 4/9 and malrotation was found in 5/9, with discrepancies (non-rotation at surgery, malrotation on imaging) with 4 original interpretations and 1 re-review. CONCLUSION: We recommend routine, early UGI and SBFT studies once other, urgent clinical concerns have been stabilized, with elective laparoscopic surgery in abnormal or equivocal cases. Cross-sectional imaging, usually obtained for other reasons, can contribute diagnostically. Attempting to assess mesenteric width is important in differentiating non-rotation from malrotation and more accurately identifies appropriate surgical candidates.

Comparison of different methods of calculating CT radiation effective dose in children.

OBJECTIVE: CT radiation dose is a subject of intense interest and concern, especially in children. Effective dose, a summation of whole-body exposure weighted by specific organ sensitivities, is most often used to compute and compare radiation dose; however, there is little standardization, and there are numerous different methods of calculating effective dose. This study compares five such methods in a group of children undergoing routine chest CT and explores their advantages and pitfalls. MATERIALS AND METHODS: Patient data from 120 pediatric chest CT examinations were retrospectively used to calculate effective dose: two scanner dose-length product (DLP) methods using published sets of conversion factors by Shrimpton and Deak, the imaging performance and assessment of CT (ImPact) calculator method, the Alessio online calculator, and the Huda method. RESULTS: The Huda method mean effective dose (4.4 ± 2.2 mSv) and Alessio online calculator (5.2 ± 2.8 mSv) yielded higher mean numbers for effective dose than both DLP calculations (Shrimpton, 3.65 ± 1.8 mSv, and Deak, 3.2 ± 1.5 mSv) as well as the ImPact calculator effective dose (3.4 ± 1.7 mSv). Mean differences ranged from 10.2% ± 10.1% lower to 28% ± 37.3% higher than the Shrimpton method (used as the standard for comparison). Differences were more marked at 120 kVp than at 80 or 100 kVp and varied at different ages. Concordance coefficients relative to the Shrimpton DLP method were Deak DLP, 0.907; Alessio online calculator, 0.735; ImPact calculator, 0.926; and Huda, 0.777. CONCLUSION: Different methods of computing effective dose for pediatric CT produce varying results. The method used must be clearly described to allay confusion about documenting and communicating dose for archiving as well as comparative research purposes.

Pulmonary reperfusion injury after the unifocalization procedure for tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collateral arteries.

OBJECTIVE: The aims of our study are to describe the incidence, clinical profile, and risk factors for pulmonary reperfusion injury after the unifocalization procedure for tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collateral arteries. We hypothesized the following: (1) Pulmonary reperfusion injury is more likely to occur after unifocalization procedures in which a septated circulation is not achieved, (2) pulmonary reperfusion injury is directly related to the severity of stenosis in major aortopulmonary collateral arteries, and (3) pulmonary reperfusion injury leads to longer intubation time and longer hospitalization. METHODS: Consecutive patients with tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries who underwent unifocalization procedures over a 5-year period were identified in our institutional database. Chest radiographs before the unifocalization procedure, from postoperative days 0 to 4, and from 2 weeks after the unifocalization procedure or at discharge were evaluated by a pediatric radiologist for localized pulmonary edema. Determination of stenosis severity was based on review of preoperative angiograms. Statistical analyses using multivariate repeated-measures analyses were performed with generalized estimating equations. RESULTS: Pulmonary reperfusion injury was present after 42 of 65 (65%) unifocalization procedures. In 36 of 42 cases of reperfusion injury, unilateral injury was present. Risk factors for the development of reperfusion injury included bilateral unifocalization (P = .01) and degree of stenosis (P = .03). We did not identify an association between pulmonary reperfusion injury and time to tracheal extubation or hospital discharge. CONCLUSIONS: Pulmonary reperfusion injury is common after the unifocalization procedure for tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries. Severity of stenosis and bilateral unifocalization are associated with the development of reperfusion injury.

Point/counterpoint: dose-related issues in cardiac CT imaging.

This manuscript reviews some of the more controversial dose-related issues in cardiac CT imaging. Discussion covers the relative merits of cardiac CT versus MR, advantages and concerns regarding gated versus nongated cardiac CT and advantages and concerns regarding the use of breast shields in girls undergoing cardiac CT imaging.

Ultrasound body applications in children.

A major goal of imaging is to obtain the correct examination to answer the clinical questions with the lowest possible radiation exposure. While CT examination provides essential information in many cases, other modalities that do not entail ionizing radiation exposure may be appropriate substitutes either as an initial screening study or as an alternative to CT. US has become a valuable imaging tool in children encompassing many different clinical scenarios. This manuscript highlights some of the less well-accepted applications of US as the first imaging study in pediatric patients, especially in the emergency room environment. These include evaluation of suspected appendicitis, abdominal mass, pleural effusion/empyema, thymic abnormality vs. mediastinal mass and extremity soft-tissue mass or vessel patency. Adoption of US imaging as a problem-solving tool for issues such as these requires appropriate allocation of resources to ensure high-quality performance and interpretation of pediatric US studies around the clock.

Thoracic neoplasms in children.

This article presents an overview of the benign and malignant neoplasms that affect the chest in children and their imaging characteristics. The relative roles of plain film, fluoroscopy, ultrasound, CT, MR imaging, and nuclear imaging in assessing these lesions are reviewed. Areas covered include the mediastinum, heart, lungs, airway, pleura, and chest wall.

Effectiveness of a staged US and CT protocol for the diagnosis of pediatric appendicitis: reducing radiation exposure in the age of ALARA.

PURPOSE: To evaluate the effectiveness of a staged ultrasonography (US) and computed tomography (CT) imaging protocol for the accurate diagnosis of suspected appendicitis in children and the opportunity for reducing the number of CT examinations and associated radiation exposure. MATERIALS AND METHODS: This retrospective study was compliant with HIPAA, and a waiver of informed consent was approved by the institutional review board. This study is a review of all imaging studies obtained in children suspected of having appendicitis between 2003 and 2008 at a suburban pediatric emergency department. A multidisciplinary staged US and CT imaging protocol for the diagnosis of appendicitis was implemented in 2003. In the staged protocol, US was performed first in patients suspected of having appendicitis; follow-up CT was recommended when US findings were equivocal. Of 1228 pediatric patients who presented to the emergency department for suspected appendicitis, 631 (287 boys, 344 girls; age range, 2 months to 18 years; median age, 10 years) were compliant with the imaging pathway. The sensitivity, specificity, negative appendectomy rate (number of appendectomies with normal pathologic findings divided by the number of surgeries performed for suspected appendicitis), missed appendicitis rate, and number of CT examinations avoided by using the staged protocol were analyzed. RESULTS: The sensitivity and specificity of the staged protocol were 98.6% and 90.6%, respectively. The negative appendectomy rate was 8.1% (19 of 235 patients), and the missed appendicitis rate was less than 0.5% (one of 631 patients). CT was avoided in 333 of the 631 patients (53%) in whom the protocol was followed and in whom the US findings were definitive. CONCLUSION: A staged US and CT imaging protocol in which US is performed first in children suspected of having acute appendicitis is highly accurate and offers the opportunity to substantially reduce radiation.

Evaluation of a radiation dose reduction strategy for pediatric chest CT.

OBJECTIVE: The purpose of our study was to quantify the effect of changes made to the CT chest protocol on patient dose, image quality, and image noise when using a kilovoltage (kVp)-lowering strategy. MATERIALS AND METHODS: We retrospectively selected 120 children who underwent chest CT: 60 in 2006 and 60 in 2008. In each group there were 30 children weighing less than 15 kg and 30 between 15 and 60 kg. In 2006 the CT protocol was 120 kVp and the reference current (mAs) was 65. In 2008, the kVp was 80 for < 15 kg and 100 for 15-60 kg, with reference mAs of 55. For each examination, the volume CT dose index (CTDI(vol)) and dose-length product (DLP) were recorded. Effective dose (ED) was estimated using the DLP method. Image noise was measured. Overall image quality was subjectively evaluated. RESULTS: For a weight < 15.0 kg, the CTDI(vol), DLP, and ED were reduced by 73%, 75%, and 73%, respectively (p < 0.05). For the weight range 15-60 kg, the CTDI(vol), DLP, and ED were reduced by 45%, 44%, and 48%, respectively (p < 0.05). Measured noise increased by 55% in the younger children and 41% in the older group (p < 0.05). All studies were considered diagnostically adequate. CONCLUSION: Significant radiation dose reduction can be achieved for routine pediatric chest CT by weight-based decreases in kVp in addition to low mAs. Increased noise was considered an acceptable trade-off for decreased dose, and image quality was acceptable.