The burden of radiation exposure in children requiring percutaneous nephrolithotomy.

BACKGROUND: Children undergoing investigation and management for complex upper tract urolithiasis often require multimodal imaging. The significance of related radiation exposure in stone care pathways has received little attention in the published literature. STUDY DESIGN: Medical records of paediatric patients undergoing percutaneous nephrolithotomy were retrospectively analysed to ascertain the modalities used and determine extent of radiation exposure occurring during each care pathway. Radiation dose simulation and calculation was performed a priori. The cumulative effective dose (mSv) and cumulative organ dose (mGy) for radiosensitive organs was calculated. RESULTS: A total of 140 imaging studies were included from the care pathways of 15 children with complex upper tract urolithiasis. Median follow-up was 9.6 years (range: 6.7-16.8 years). The average number of imaging studies with ionising radiation per patient was nine, with a cumulative effective dose of 18.3 mSv across all modalities. The most common modalities were: mobile fluoroscopy (43%), x-ray (24%), and computed tomography (18%). The cumulative effective dose per study type was greatest for CT (4.09 mSv), followed by fixed and mobile fluoroscopy (2.79 mSv and 1.82 mSv, respectively). CONCLUSION: There is high general awareness of radiation exposure involved in CT scanning with resultant caution in employing this modality in paediatric patients. However, the significant radiation exposure relating to fluoroscopy (whether fixed or mobile) is less well documented in children. We recommend implementing steps to minimise radiation exposure by optimisation and avoidance of certain modalities where possible. Paediatrics urologists must employ strategies to minimise radiation exposure in children with urolithiasis, given the significant exposures encountered.

Ultra-low-dose computed tomography for torsion measurements of the lower extremities in children and adolescents.

BACKGROUND: Quantifying femoral and tibial torsion is crucial in the preoperative planning for derotation surgery in children and adolescents. The use of an ultra-low-dose computed tomography (CT) protocol might be possible for modern CT scanners and suitable for reliable torsion measurements even though the bones are not completely ossified. METHODS: This is a retrospective review of 77 children/adolescents (mean age 12.7 years) who underwent a lower extremity CT for torsion measurements on a 64-slice scanner. A stepwise dose reduction (70%, 50%, 30% of the original dose) was simulated. Torsion measurements were performed on all image datasets, and image noise, interrater agreement and subjective image quality were evaluated. Effective radiation dose of each original scan was estimated. As proof of concept, 24 children were scanned with an ultra-low-dose protocol, adapted from the 30% dose simulation, and the intra-class correlation coefficient (ICC) was determined. Ethics approval and informed consent were given. RESULTS: Torsion measurements at the simulated 30% dose level had equivalent interrater agreement compared to the 100% dose level (ICC ≥ 0.99 for all locations and dose levels). Image quality of almost all datasets was rated excellent, regardless of dose. The mean sum of the effective dose of the total torsion measurement was reduced by simulation from 0.460/0.490 mSv (boys/girls) at 100% dose to 0.138/0.147 mSv at 30%. The ICC of the proof-of-concept group was as good as that of the simulated 30% dose level. CONCLUSION: Pediatric torsion measurements of the lower extremities can be performed using an ultra-low-dose protocol without compromising diagnostic confidence.

Stratifying features for diagnosing hypertrophic stenosis on ultrasound: a diagnostic accuracy study.

BACKGROUND: Our aims were to determine if the diagnostic threshold for diagnosing hypertrophic pyloric stenosis (HPS) on ultrasound scan (USS) should be adjusted based on birth weight (BW), current weight (CW), gestational age (GA), chronological age (CA) or corrected gestational age (CGA). METHODS: All patients who underwent either an USS and pyloromyotomy (Group 1) or an USS for possible HPS (Group 2) at our tertiary centre between July 2013 and June 2019 were identified. Ideal threshold values are identified by measuring Youden's Index (J = sensitivity + specificity - 1; higher is better). Mean maximum Youden's Index for stratified results was compared to that for combined results. RESULTS: Two hundred and eighty-four patients were included (142 patients in both Group 1 and Group 2). Combined maximum Youden's Index for all patients was 0.92 for pyloric canal thickness (PMT) and 0.87 for pyloric canal length (PCL). Mean maximum Youden's Index was higher when patients were stratified by GA, CGA, BW or CW, and equivalent for CA. For pyloric canal length (PCL), mean maximum Youden's Index was lower for all variables when stratified compared to combined. There was no visual trend observed in the diagnostic thresholds between groups. CONCLUSION: Stratifying USS PMT diagnostic thresholds values based on age and weight is statistically more accurate than a single threshold in diagnosing HPS. However, the lack of visual correlation indicates a larger dataset is required to validate these results.

A review of current imaging techniques used for the detection of occult bony fractures in young children suspected of sustaining non-accidental injury.

Non-accidental injuries remain a leading cause of preventable morbidity and mortality in young children. The accurate identification of the full spectrum of injuries in children presenting with suspected abuse is essential to ensure the appropriate protective intervention is taken. The identification of occult bone fractures in this cohort is important as it raises the level of concern about the mechanism of injury and maintaining the child's safety. Radiographic imaging remains the modality of choice for skeletal assessment; however, current studies report concerns regarding the ability of radiographs to detect certain fractures in the acute stage. As such, alternative modalities for the detection of fractures have been proposed. This article reviews the current literature regarding fracture detectability and radiation dose burden of imaging modalities currently used for the assessment of occult bony injury in young children in whom non-accidental injury is suspected.

Using Computed Tomography skeletal surveys to evaluate for occult bony injury in suspected non-accidental injury cases - A preliminary experience.

INTRODUCTION: This case series summarises our institution's preliminary experience of using computed tomography skeletal surveys (CT-SS) for the assessment of infants with suspected non-accidental injury (NAI) who were unable to undergo radiographic skeletal surveys (SS). This paper describes our experience using CT-SS in terms of radiation doses achieved, occult bony injury detection and forensic utility. METHODS: Ten infants aged between two weeks and ten months underwent a CT-SS. The results of the CT-SS were compared with concurrent imaging results where available. Radiation doses from imaging procedures were calculated for each patient. RESULTS: Six infants had abnormalities identified on CT-SS. Two patients had both an ante-mortem CT-SS and post-mortem imaging. All fractures identified on alternate imaging modalities were visible on at least one CT-SS reconstruction. The radiation dose associated with CT-SS imaging ranged from 0.73 to 1.46mSv. CONCLUSION: The radiation dose received by the ten infants in this study was greater than the two skeletal survey approach but was less than the dose received during a bone scintigraphy examination, sometimes used to assess for occult bony injury in this setting. While CT-SS imaging results could not be compared with those obtained with current contemporaneous gold standard imaging techniques, CT-SS identified all fractures observed on the radiographic images where performed. CT-SS also identified additional rib fractures in two patients. Our preliminary findings indicate the need for future prospective studies to clarify the ability of CT-SS to detect metaphyseal fractures reliably.

Evaluating the validity of ultrasound in diagnosing hypertrophic pyloric stenosis: a cross-sectional diagnostic accuracy study.

BACKGROUND: Our aims were to evaluate the ultrasound scan (USS) criteria in diagnosing hypertrophic pyloric stenosis (HPS), determine the best diagnostic threshold values for pyloric muscle thickness (PMT) and pyloric canal length (PCL), and assess the accuracy of flow through the pylorus. METHODS: All patients who underwent pyloromyotomy at our tertiary paediatric surgery centre between July 2013 and June 2019 were identified (Group 1). All patients undergoing an USS to investigate for a possible HPS and did not undergo pyloromyotomy were also identified (Group 2). Accuracy was determined by Youden's Index (J) with the highest J determining the ideal cut-off value. RESULTS: Two hundred and eighty-four patients (142 patients in each group) were included in the analysis. Using only the last USS before surgery, PMT provided an area under the curve (AUC) of 0.987 (n = 275), and PCL an AUC of 0.977 (n = 267). Ideal threshold values were 3.0 mm for PMT (J = 0.92), and 14.5 mm for PCL (J = 0.87). Combining PMT ≥3.0 mm with a PCL ≥14.5 mm resulted in a sensitivity of 95% and specificity of 99% (J = 0.94). The absence of flow through the pylorus on dynamic USS provided a sensitivity of 99% and specificity of 91% (J = 0.91; n = 277). CONCLUSION: Combining threshold values of 3.0 mm for PMT and 14.5 mm PCL provides the highest accuracy for diagnosing pyloric stenosis on an ultrasound scan. These combined values were more accurate than observing for the absence of flow through the pylorus.

Advanced MRI analysis to detect white matter brain injury in growth restricted newborn lambs.

BACKGROUND: Fetal growth restriction (FGR) is a serious pregnancy complication associated with increased risk of adverse neurodevelopment and neuromorbidity. Current imaging techniques, including conventional magnetic resonance imaging (MRI), are not sensitive enough to detect subtle structural abnormalities in the FGR brain. We examined whether advanced MRI analysis techniques have the capacity to detect brain injury (particularly white matter injury) caused by chronic hypoxia-induced fetal growth restriction in newborn preterm lambs. METHODS: Surgery was undertaken in twin bearing pregnant ewes at 88-90 days gestation (term = 150 days) to induce FGR in one fetus. At 127 days gestation (~32 weeks human brain development), FGR and control (appropriate for gestational age, AGA) lambs were delivered by caesarean section, intubated and ventilated. Conventional and advanced brain imaging was conducted within the first two hours of life using a 3T MRI scanner. T1-weighted (T1w) and T2-weighted (T2w) structural imaging, magnetic resonance spectroscopy (MRS), and diffusion MRI (dMRI) data were acquired. Diffusion tensor imaging (DTI) modelling and analysis of dMRI data included the following regions of interest (ROIs): subcortical white matter, periventricular white matter, cerebellum, hippocampus, corpus callosum and thalamus. Fixel-based analysis of 3-tissue constrained spherical deconvolution (CSD) of the dMRI data was performed and compared between FGR and AGA lambs. Lambs were euthanised immediately after the scans and brain histology performed in the regions of interest to correlate with imaging. RESULTS: FGR and AGA lamb (body weight, mean (SD): 2.2(0.5) vs. 3.3(0.3) kg, p = .002) MRI brain scans were analysed. There were no statistically significant differences observed between the groups in conventional T1w, T2w or MRS brain data. Mean, axial and radial diffusivity, and fractional anisotropy indices obtained from DTI modelling also did not show any statistically significant differences between groups in the ROIs. Fixel-based analysis of 3-tissue CSD, however, did reveal a decrease in fibre cross-section (FC, p < .05) but not in fibre density (FD) or combined fibre density and cross-section (FDC) in FGR vs. AGA lamb brains. The specific tracts that showed a decrease in FC were in the regions of the periventricular white matter, hippocampus and cerebellar white matter, and were supported by histological evidence of white matter hypomyelination and disorganisation in corresponding FGR lamb brain regions. CONCLUSIONS: The neuropathology associated with FGR in neonatal preterm lambs is subtle and imaging detection may require advanced MRI and tract-based analysis techniques. Fixel-based analysis of 3-tissue CSD demonstrates that the preterm neonatal FGR brain shows evidence of macrostructural (cross-sectional) deficits in white matter subsequent to altered antenatal development. These findings can inform analysis of similar brain pathology in neonatal infants.

Establishing content validity and fidelity of a novel paediatric intussusception air enema reduction simulator.

BACKGROUND: Intussusception is a common, potentially life-threatening paediatric condition. Non-operative treatment with an air enema has been established as the clinical gold standard. There is no validated model for the training of this procedure. Our aim was to produce a novel air enema reduction simulator and validate its use as a training tool. METHODS: A low-cost paediatric intussusception air enema simulator was created. It was designed to include essential key clinical procedural steps. Participants included both procedural experts and novices from the Departments of Paediatric Radiology and Surgery. The simulator was assessed for face and content validity and its physical, conceptual and experiential fidelity by a structured questionnaire using a 5-point Likert's scale. Statistical analysis included a t-test, and a P-value of <0.05 was considered significant. RESULTS: Twenty-four clinicians completed the simulation activity (expert: 13 and novices: 11). All experts had performed a minimum of 40 clinical procedures, and 46% had performed >50 procedures. All scores were favourable in all domains for face and content validity: 3.5 (physical appearance), 3.3 (insertion of the tube and taping), 3.1 (holding of the buttocks) and 3.5 (performing the air enema). The simulator also scored highly with fidelity assessment; visual 3.5, conceptual 3.4. There was no difference in procedural confidence with experts (3.8 versus 3.6, P = 0.28), but there was for novices (1.0 versus 2.9, P = 0.0002). CONCLUSIONS: This low-cost air enema reduction simulator for intussusception has an excellent educational potential for use in a training program in a tertiary centre, as well as, resource-constrained environments.

Retrospective review of screening for Sturge-Weber syndrome with brain magnetic resonance imaging and electroencephalography in infants with high-risk port-wine stains.

BACKGROUND: There is a lack of consensus regarding how best to screen children with facial port-wine stains for Sturge-Weber syndrome. Many favor brain magnetic resonance imaging, and adjunctive electroencephalography is increasingly used. However, the sensitivity, specificity, and negative and positive predictive value of magnetic resonance imaging and electroencephalography and whether screening improves seizure recognition is unclear. METHODS: A retrospective review of children with high-risk port-wine stains presenting consecutively to the outpatient laser clinic of a tertiary pediatric hospital between December 2015 and November 2016 was undertaken. Primary outcome measures were yield, accuracy, age of and protocols for screening magnetic resonance imaging and electroencephalography, type of and age at presenting seizure, and percentage referred to neurology. RESULTS: Of 126 patients with facial port-wine stains, 25.4% (32/126) were at high risk of Sturge-Weber syndrome (hemifacial, median, and forehead PWS phenotypes); 43.7% of these (14/32) underwent screening magnetic resonance imaging. Sturge-Weber syndrome was detected in 7.1% (1/14). Magnetic resonance imaging had false-negative results in 23.1% (3/13) of those screened. Screening magnetic resonance imaging had sensitivity of 25%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 76.9% for the detection of Sturge-Weber syndrome (hemifacial, median and forehead PWS phenotypes). Only one-third of those with false-negative magnetic resonance imaging were referred to neurology. Mean age of first seizure in those with false-negative screening magnetic resonance imaging was 28 months, vs 14 months in those not screened. Abnormal electroencephalographic signs were detected in the two infants who underwent presymptomatic electroencephalography. CONCLUSIONS: Findings from this small cohort of individuals with port-wine stains that put them at high risk of Sturge-Weber syndrome suggest that children with positive screening magnetic resonance imaging will almost certainly develop Sturge-Weber syndrome but that negative screening magnetic resonance imaging cannot exclude Sturge-Weber syndrome (in up to 23.1% of cases). False-negative magnetic resonance imaging may delay seizure recognition. Seizure education, monitoring, and consideration of adjunctive electroencephalography are important irrespective of magnetic resonance imaging findings.

Screening for Sturge-Weber syndrome: A state-of-the-art review.

Infants with a high-risk distribution of port-wine stains are commonly screened for Sturge-Weber syndrome using brain magnetic resonance imaging. There is no consensus about which port-wine stain phenotypes to screen, optimal timing, screening sensitivity, or whether presymptomatic diagnosis improves neurodevelopmental outcomes. This state-of-the-art review examines the evidence in favor of screening for Sturge-Weber syndrome, based on its effect on neurodevelopmental outcomes, against the risks and limitations of screening magnetic resonance imaging and electroencephalography. A literature search of PubMed/MEDLINE was conducted between January 2005 and May 2017 using key search terms. Relevant articles published in English were reviewed; 34 articles meeting the search criteria were analyzed according to the following outcome measures: neurodevelopmental outcome benefit of screening, diagnostic yield, financial costs, procedural risks, and limitations of screening magnetic resonance imaging and electroencephalography. There is no evidence that a presymptomatic Sturge-Weber syndrome diagnosis with magnetic resonance imaging results in better neurodevelopmental outcomes. The utility of electroencephalographic screening is also unestablished. In Sturge-Weber syndrome, neurodevelopmental outcomes depend on prompt recognition of neurologic red flags and early seizure control. Small numbers and a lack of prospective randomized controlled trials limit these findings. For infants with port-wine stain involving skin derived from the frontonasal placode (forehead and hemifacial phenotypes), we recommend early referral to a pediatric neurologist for parental education, counselling, and monitoring for neurologic red flags and seizures and consideration of electroencephalography regardless of whether magnetic resonance imaging is performed or its findings.

Comparison of safety and efficacy of image-guided enema reduction techniques for paediatric intussusception: A review of the literature.

There is variable international practice regarding the technique used for image-guided enema reduction in paediatric intussusception. A recent meta-analysis found pneumatic reduction to be more effective than hydrostatic techniques. Clinical practice variation may impact on perforation rates, ionizing radiation exposure and requirement for surgery. The aim of this study was to review the literature regarding the efficacy and safety of fluoroscopically guided pneumatic reduction (FGPR) compared to ultrasound (US) guided intussusception reduction (USGIR) techniques for paediatric intussusception treatment. Articles were identified by searching OVID Medline on 21/02/14 and by scanning retrieved articles reference lists. The search was repeated on 30/09/15. Systematic reviews (SR) were appraised with the PRISMA critical appraisal tool. Primary studies underwent a separate critical appraisal process. Successful reductions and perforations per attempt were calculated for each study. Pooled estimates of proportions were calculated for each of these dichotomous outcomes. A SR and 42 primary studies were included in the review. No randomised control trial (RCT) study was included. Non-randomised comparative studies and non-comparative studies suggest that hydrostatic reduction under US control has a similar efficacy and safety profile to pneumatic reduction under fluoroscopic control, but USGIR data are dominated by a single large, non-comparative study performed in China. US-guided intussusception reduction should be considered an alternative to FGPR as it has similar efficacy and safety, and affords no ionised radiation exposure. However, RCT data are required to inform practice.

Relationship between characteristics on magnetic resonance imaging and motor outcomes in children with cerebral palsy and white matter injury.

In a population cohort of children with white matter injury (WMI) and cerebral palsy (CP), we aimed to describe the magnetic resonance imaging (MRI) characteristics, identify key structure-function relationships, and classify the severity of WMI in a clinically relevant way. Stratified on MRI laterality/symmetry, variables indicating the extent and location of cerebral abnormalities for 272 children with CP and WMI on chronic-phase MRI were related to gross motor function and motor topography using univariable and multivariable approaches. We found that symmetrical involvement, severe WM loss in the hemispheres and corpus callosum, and cerebellar involvement were the strongest predictors of poor gross motor function, but the final model explained only a small proportion of the variability. Bilateral, extensive WM loss was more likely to result in quadriplegia, whereas volume loss in the posterior-mid WM more frequently resulted in diplegia. The extent and location of MRI abnormalities differed according to laterality/symmetry; asymmetry was associated with less extensive hemispheric involvement than symmetrical WMI, and unilateral lesions were more focal and located more anteriorly. In summary, laterality/symmetry of WMI, possibly reflecting different pathogenic mechanisms, together with extent of WM loss and cerebellar abnormality predicted gross motor function in CP, but to a limited extent.

Does fetal growth restriction lead to increased brain injury as detected by neonatal cranial ultrasound in premature infants?

AIM: Intra-uterine growth restriction (IUGR) is an important cause for prematurity as well as a significant risk factor for neurodevelopmental deficits. In this study, we aimed to examine the association between IUGR and early brain injury on neonatal cranial ultrasound in preterm infants. METHODS: This retrospective cohort study examined the relationship between IUGR and neonatal cranial ultrasound findings in preterm infants <32 weeks gestation with IUGR, compared with gestation and year of birth-matched appropriately grown infants, in a tertiary level neonatal unit. Primary outcome was incidence and severity of intraventricular haemorrhage (IVH), periventricular leucomalacia (PVL) and hydrocephalus detected by cranial ultrasound in the neonatal period. RESULTS: A total of 153 IUGR and 306 non-IUGR preterm infants <32 weeks were included. The rates of IVH (21.6% vs. 23.9%), severe IVH (3.9% vs. 4.6%), PVL (8.4% vs. 9.4%), cystic PVL (2.6% vs. 0%) and hydrocephalus (0.7% vs. 0.3%) were similar in the two groups. Composite outcome of death and severe brain injury (severe IVH, cystic PVL and hydrocephalus) was greater (20.2% vs. 9.1%, P = 0.001) in IUGR infants. CONCLUSION: IUGR did not lead to increased neonatal brain injury on cranial ultrasound but was associated with increased mortality. Advanced neonatal neuroimaging techniques may be necessary to estimate risk and to provide prognostic information of adverse neurological outcomes in this vulnerable population.

Duplex kidney: not just a drooping lily.

INTRODUCTION: Duplex kidneys are common, mostly asymptomatic and of no clinical significance. However, they can be associated with significant pathology, often with long-term morbidity. There is minimal literature on the review of the duplex kidney, its associated anomalies and complications. The purpose of this paper is to review our experience of imaging the spectrum of abnormalities associated with duplex kidneys in the paediatric population and correlate this with contemporary literature. METHOD: A retrospective review of the radiology database in a tertiary paediatric centre was performed. A word search of the Radiology Information System for 'duplex' of patients under the age of 16 was undertaken and limited to studies performed between 2006 and 2013. RESULTS: Two hundred seventy-four patients were identified (age range 0-16, median 3 years, gender 59.9% female) who had 836 studies: ultrasound 598/836 (71.6%), nuclear medicine 180/836 (21.5%), micturating cystourethrogram 52/836 (6.2%), MRI 5/836 (<1%) and CT scan 1/836 (<1%). Patients were categorised as duplex and no complication (151/274 = 55.1%), upper moiety obstruction, lower moiety reflux/scarring, multicystic dysplastic kidney, abnormal ureteric insertion and other pathology. CONCLUSION: Duplex kidneys are common and often not clinically significant. However, this study demonstrates almost 50% of paediatric patients investigated for duplex kidneys had complications requiring treatment. The most common complications were upper moiety obstruction associated with a ureterocele and lower moiety vesicoureteric reflux. Ultrasound was the most common modality for early detection of these complications.

The role of whole-body MRI in pediatric oncology.

Pediatric whole-body (WB) magnetic resonance imaging (MRI) is an established technique that, with improved accessibility and advances in technology, is being used with increasing frequency for a wide variety of applications. The advantages of WB MRI (over other imaging modalities), particularly its lack of ionizing radiation (of particular concern in pediatric imaging due to children's increased sensitivity to ionizing radiation) and the ability of MRI to image the bone marrow, solid organs, and soft tissues with superior soft-tissue contrast resolution to other techniques, promise that WB MRI has great potential in conditions that are diffuse or multifocal. There is particular interest in its role in the field of pediatric oncology (eg, lymphoma, neuroblastoma, sarcoma, and Langerhans cell histiocytosis). The main disadvantages of WB MRI are its relatively long scanning times, artifacts from motion (requiring patient cooperation or general anesthesia), and limited specificity. However, advances in hardware and imaging techniques, including additional sequences (out-of-phase imaging, diffusion-weighted imaging, and contrast enhancement) are reducing the impact of some of these challenges.

Normal paediatric bone marrow: magnetic resonance imaging appearances from birth to 5 years.

INTRODUCTION: Bone marrow (BM) assessment is an important aspect of paediatric MRI, with the marrow cavity visible on almost every clinical MR examination. In practice, however, assessment for marrow infiltration in paediatric patients can be challenging. Our aim was to review the MRI appearance of normal BM from 0 to 5 years. METHODS: Consecutive body MR examinations over 7 years were retrospectively reviewed in patients aged 0-5 years. Patients with anticipated BM abnormality were excluded. All patients had imaging of the spine and/or pelvis with T1-weighted (T1) ± T2 with fat saturation, post-contrast T1-weighted, diffusion-weighted or out-of-phase sequences. RESULTS: Nineteen patients were included: nine (47%) infants, 11 (58%) boys, mean age 18.2 months (range 1 day to 3 years and 10 months). On T1 imaging, 69% infant marrow sites and 24% in children >1 year were isointense, the remainder were hyperintense. One hundred per cent BM was T2 fat saturation hyperintense. Enhancement following contrast was seen in 16% of BM sites. Restricted diffusion was seen in 100% infant BM and 50% BM in children >1 year. On out-of-phase imaging, no signal loss was seen in infants, and 21% BM in children >1 year showed signal loss. CONCLUSION: Due to normal age-related differences in BM histology, MRI for marrow assessment in infants and young children can be misleading and may mimic marrow infiltration.

Dynamic volumetric computed tomographic assessment of the young paediatric airway: Initial experience of rapid, non-invasive, four-dimensional technique.

INTRODUCTION: The aim of this study was to evaluate the dynamic volumetric CT in the assessment of the paediatric airway. METHODS: Ethics board approval was obtained for this retrospective review. Eight infants (median age 6 months, range 3 weeks to 1 year, 50% female) at a tertiary paediatric centre with complex clinical respiratory presentation underwent volumetric CT assessment of their airways. The entire lungs were examined over 1-2 respiratory cycles. In four patients, intravenous contrast was administered to assess for vascular airway compression. The patients were not intubated. CT findings were correlated with bronchography and bronchoscopy, where available. RESULTS: Two patients had diffuse tracheobronchomalacia associated with chronic lung disease. One patient demonstrated focal severe cervical tracheomalacia. One patient had a double aortic arch causing fixed narrowing with superimposed malacia of the distal trachea. Four patients had normal airways; one with chronic lung disease, one demonstrating air trapping. CT findings were concordant with bronchography (one case) and bronchoscopy (four cases) in all but one (CT negative, bronchoscopy positive) but did not alter patient management. CONCLUSION: The assessment of the paediatric airway, and in particular for tracheobronchomalacia, is difficult. Assessment with bronchography, bronchoscopy, helical CT and MR have issues with reliability, intubation, intratracheal/bronchial contrast administration and ionising radiation. Volumetric CT assesses the entire central airway in children at much lower radiation dose compared with previous dynamic CT imaging. This non-invasive, rapid assessment obviates the need for patient cooperation and enables evaluation of extratracheal intrathoracic structures. Volumetric CT enables four-dimensional assessment for paediatric tracheobronchomalacia without intubation or patient cooperation and at low radiation dose.

Paediatric urological investigations--dose comparison between urology-related and CT irradiation.

BACKGROUND: Urological investigation in children frequently involves high radiation doses; however, the issue of radiation for these investigations receives little attention compared with CT. OBJECTIVE: To compare the radiation dose from paediatric urological investigations with CT, which is commonly regarded as the more major source of radiation exposure. MATERIALS AND METHODS: We conducted a retrospective audit in a tertiary paediatric centre of the number and radiation dose of CT scans, micturating cystourethrography exams and urological nuclear medicine scans from 2006 to 2011. This was compared with radiation doses in the literature and an audit of the frequency of these studies in Australia. RESULTS: The tertiary centre audit demonstrated that the ratio of the frequency of urological to CT examinations was 0.8:1 in children younger than 17 years. The ratio of the radiation dose of urological to CT examinations was 0.7:1. The ratio in children younger than 5 years was 1.9:1. In Australia the frequency of urological procedures compared with CT was 0.4:1 in children younger than 17 years and 3.1:1 in those younger than 5 years. The ratio of radiation-related publications was 1:9 favouring CT. CONCLUSION: The incidence and radiation dose of paediatric urological studies is comparable to those of CT. Nevertheless the radiation dose of urological procedures receives considerably less attention in the literature.

Evolution of acquired tracheobronchomalacia in an infant studied by multidetector computed tomography.

Acquired tracheobronchomalacia (TBM) is an uncommon complication of severe lung disease in infancy. We report a case of TBM in an ex-premature infant with severe chronic lung disease (CLD). Multidetector computed tomography (MDCT) was used to dynamically assess the patency of the large airways at different time periods during the infant's hospital course. Initially at 3 months of age, the airways maintained patency during both phases of the respiratory cycle, but at 6 months of age, diffuse TBM was evident on MDCT. Appropriate management with long-term positive end expiratory pressure (PEEP) was initiated for the infant once the diagnosis of acquired TBM was confirmed. The case highlights the efficacy and relative ease of early diagnosis of acquired TBM by MDCT in infants at risk of this condition.