Choledochal Malformations: Surgical Implications of Radiologic Findings.

OBJECTIVE: The purpose of this article is to review the relevant pathophysiologic features, appearances, and surgical implications of choledochal malformations. CONCLUSION: Choledochal malformations, colloquially called choledochal cysts, initially described in 1723, have been recategorized multiple times, the most widely accepted being the Todani classification based on morphologic features and location. Although readily applied to imaging findings, this classification system does not correlate well with clinical and surgical management. In 2004, Visser and colleagues proposed an alternative that emphasized the etiologic factors, imaging appearance, and treatment approach.

Evaluation of image quality and patient safety: paired inspiratory and expiratory MDCT assessment of tracheobronchomalacia in paediatric patients under general anaesthesia with breath-hold technique.

OBJECTIVE: The purpose of our investigation was to evaluate image quality and patient safety in infants and young children who required general anaesthesia with breath-hold technique for paired inspiratory and expiratory multidetector CT (MDCT) assessment of tracheobronchomalacia (TBM). MATERIALS AND METHODS: Our hospital's institutional review board approved the review of radiological and clinical data of a consecutive series of 20 paediatric patients who underwent MDCT under general anaesthesia with breath-hold technique for evaluation of TBM from May 2006 to December 2008. For each MDCT study, two fellowship-trained paediatric radiologists reviewed the inspiratory and expiratory MDCT images in an independent, randomised and blinded fashion for the presence of motion artefact at three anatomic levels (upper, middle and lower central airways). The clinical history and anaesthesia outcome, including the occurrence of any adverse events during or following the MDCT examinations until discharge, were also reviewed and recorded. RESULTS: The study population consisted of 20 infants and young children (13 boys/seven girls, mean age 1.7 ± 1.4 years, age range 11 days to 4 years). The imaging quality of all 20 MDCT studies was diagnostic with no motion artefact in 16 studies (80%) and minimal motion artefact in the remaining four studies (20%). Minor adverse events occurred in three patients (15%) that included one patient (5%) with a brief (<60 s) oxygen desaturation during MDCT study, which resolved with oxygen, and two patients (5%) with either a brief (<60 s) oxygen desaturation (n = 1, 5%) or cough (n = 1, 5%) during recovery period, which were completely resolved with oxygen and dexamethasone, respectively. CONCLUSION: Diagnostic quality paired inspiratory and expiratory MDCT imaging with breath-hold technique can be safely performed in infants and young children under general anaesthesia for evaluation of TBM.

Streptococcus milleri group pleuropulmonary infection in children: computed tomographic findings and clinical features.

OBJECTIVE: Streptococcus milleri group streptococci have recently been increasingly recognized as important pulmonary pathogens, but their imaging features have not been well documented in children. We have recently observed a number of cases of this infection among pediatric patients at our tertiary care, children's hospital. Our purpose was to investigate the computed tomographic (CT) findings and clinical features of S. milleri group pleuropulmonary infection in children. MATERIALS AND METHODS: We used our hospital information system to identify all consecutive pediatric patients (<18 years of age) who had both a microbiologically proven S. milleri group infection and a chest CT scan between December 1996 and May 2009. Each scan was systemically reviewed by 2 pediatric radiologists for pleural and lung parenchymal abnormalities. Pleural effusions were classified as either simple or complex and correlated with results of pleural fluid analysis. Computed tomographic findings were compared with chest radiographic findings in the subset of patients who underwent radiography within 24 hours of CT. Microbiological data, risk factors, immune status, patient management, and clinical outcome were systematically reviewed. RESULTS: The final study cohort consisted of 15 children (6 boys and 9 girls), ranging in age from 4.2 years to 17.7 years (mean, 10.8 years). All patients were immunocompetent without recognized risk factors for this infection. Thirteen pleural effusions were identified in 10 (67%) of the 15 patients, including 10 complex and 3 simple pleural effusions. All complex effusions at CT were consistent with empyemas by pleural fluid analysis. Lung parenchymal abnormalities were identified in 7 (47%) of the 15 patients, including lung abscess in 4 patients, consolidation in 2, and multiple bilateral pulmonary nodules and lung abscesses in 1. In the subset of 7 patients with comparison radiographs, radiographic and CT findings were concordant for the detection of lung abnormalities, except one case in which consolidation was diagnosed on chest radiography, whereas CT scan showed a lung abscess. Radiographs detected all 4 complex pleural effusions seen on CT scan, although it was not possible to characterize the effusions as simple or complex on the radiographs. Interventional procedures were required in all 15 patients, most commonly thoracentesis (n = 11) and chest tube drainage (n = 9). CONCLUSIONS: In children with S. milleri group pleuropulmonary infection, CT often demonstrates complex pleural effusions and lung abscesses, which usually require interventional procedures for effective treatment.

Expiratory volumetric MDCT evaluation of air trapping in pediatric patients with and without tracheomalacia.

OBJECTIVE: The purpose of this study was to use paired inspiratory-expiratory volumetric MDCT to compare the frequency, severity, and pattern of air trapping in pediatric patients with tracheomalacia with the findings in children without tracheomalacia. MATERIALS AND METHODS: The study group consisted of 15 consecutively registered pediatric patients (younger than 18 years) who had tracheomalacia, defined as 50% or greater reduction in tracheal cross-sectional luminal area between end inspiration and end expiration, diagnosed with MDCT and confirmed with bronchoscopy. The comparison group consisted of 15 consecutively registered pediatric patients without evidence of tracheomalacia at MDCT and bronchoscopy. Two blinded pediatric radiologists working in consensus interpreted the randomly viewed end-expiratory thin-section CT images of both groups of children for the presence, severity, and pattern of air trapping at three anatomic levels (upper, middle, and lower lung zones). The severity of air trapping was graded visually on a 5-point scale. The total air trapping scores, obtained by summing the values for the three anatomic levels for the study and comparison groups, were compared by Wilcoxon's rank sum test. The pattern of air trapping was categorized as lobular, segmental, lobar, diffuse, or mixed, and the patterns in the two study groups were compared by Pearson's chi-square test. RESULTS: The study cohort with tracheomalacia consisted of 15 patients (10 boys, five girls; mean age, 2.4 +/- 2.8 years; range, 1 month-11.8 years). The comparison group without tracheomalacia consisted of 15 patients (nine boys, six girls; mean age, 2.7 +/- 2.4 years; range, 1 month-8.1 years). Air trapping was identified in all 15 patients with tracheomalacia (median score, 5.0; range, 3-11) and in 10 of 15 children (67%) in the comparison group (median score, 3.0; range, 1-4). The median total air trapping score was significantly higher in the study cohort than in the comparison group (p = 0.002), but there were no significant differences in the air trapping patterns between the study groups (p = 0.53). CONCLUSION: Pediatric patients with tracheomalacia have a higher frequency and greater severity of air trapping than do children without tracheomalacia.

Comparison of standard-dose and reduced-dose expiratory MDCT techniques for assessment of tracheomalacia in children.

RATIONALE AND OBJECTIVES: The aim of this study was to assess the effects of radiation dose reduction on the assessment of the tracheal lumen on expiratory multidetector computed tomographic (MDCT) images of pediatric patients referred for evaluation for tracheomalacia (TM). MATERIALS AND METHODS: The hospital information system was used to retrospectively identify 20 standard-dose and 20 reduced-dose paired inspiratory and expiratory MDCT studies performed for the evaluation of suspected TM in pediatric patients (aged or=50% expiratory reduction in tracheal cross-sectional luminal area) on MDCT imaging was compared to bronchoscopic results for the subset of 32 patients who underwent both procedures. RESULTS: A high level of confidence was reported for measuring the tracheal lumen on MDCT imaging for both standard-dose (median, 3.0) and reduced-dose (median, 3.0) expiratory sequences (P = .80). The total radiation dose of the paired inspiratory-expiratory computed tomographic (CT) exam was decreased by 23% with the reduced-dose technique. TM was diagnosed by CT imaging in seven patients who underwent standard-dose and six patients who underwent reduced-dose paired inspiratory and expiratory MDCT studies. CT results for the presence or absence of TM were concordant with the results of bronchoscopy in all 32 patients who underwent both procedures. CONCLUSION: The radiation dose of paired inspiratory-expiratory CT imaging can be reduced by 23% while maintaining similar diagnostic confidence for assessment of the tracheal lumen compared to a standard-dose technique in pediatric patients. Thus, a reduced-dose technique is recommended for evaluating TM in children.

Motion artifact on high-resolution CT images of pediatric patients: comparison of volumetric and axial CT methods.

OBJECTIVE: The purpose of this study was to address the controversy whether the quality of volumetric high-resolution CT (HRCT) images is as good as that of axial nonvolumetric HRCT images by assessing the degree of motion artifact on images acquired with the two methods at MDCT of pediatric patients with known or suspected lung disease. MATERIALS AND METHODS: A search of the hospital information system was conducted to identify the cases of pediatric patients with clinically suspected or known interstitial lung disease who underwent 16-MDCT of the chest with both volumetric and axial HRCT acquisitions (both 1.25-mm slice thickness) from March 2005 to July 2008. Two pediatric radiologists reviewed the images for the presence of motion artifacts at three anatomic levels (upper, middle, and lower lung zones). Motion artifacts were given numerical grades representing no artifact to severe artifact, and the paired Student's t test was used to compare the scores for the two acquisition methods. A total motion score for each acquisition was calculated by summing the scores for each of the three lung zones, and the scores for the two imaging methods were compared. Correlation between degree of motion artifact and age was evaluated. Effective radiation doses were estimated for volumetric and axial CT acquisitions. RESULTS: The study population consisted of 54 children (28 boys, 26 girls; mean age, 11.7 +/- 3.8 years; range, 5-18 years; eight inpatients, 46 outpatients) who underwent a total of 54 MDCT chest studies with volumetric and axial HRCT acquisitions. Motion artifact scores were higher for axial than for volumetric HRCT images of the upper (1.2 vs 1.0), middle (1.6 vs 1.2), and lower (2.2 vs 1.5) lung zones (p < 0.05 at each level). The total motion score of the axial HRCT images (mean, 5; range, 1-9) was higher than that of the volumetric HRCT images (mean, 3.6; range, 1-8) (p < 0.05). Younger age correlated with higher motion artifact score on axial HRCT images (r = -0.36, p < 0.01), whereas no correlation was found between age and motion artifact score on volumetric HRCT images (r = -0.12, p = 0.38). The effective radiation doses were 0.57 mSv for axial HRCT acquisition and 7.6 mSv for volumetric acquisition. The addition of axial acquisition increased the total radiation dose of the MDCT examination 7.1%. CONCLUSION: At CT of pediatric patients, reconstructed HRCT images from volumetric MDCT acquisition have significantly less motion artifact than images obtained with traditional axial acquisition.