Organ-based tube current modulation and bismuth eye shielding in pediatric head computed tomography.

BACKGROUND: Exposure of the eye lens to ionizing radiation results in cataract. Several dose optimization techniques to protect the lens are available for computed tomography (CT). OBJECTIVE: The radiation dose to the eye lens, volume CT dose index (CTDIvol) and image quality of various methods of dose optimization were evaluated for pediatric head CT: automated tube current modulation (ATCM), automated tube voltage selection (ATVS), organ-based tube current modulation (OBTCM) and bismuth shielding. MATERIALS AND METHODS: An anthropomorphic phantom of a 5-year-old child was scanned with nine protocols: no dose optimization technique and then adding different dose optimization techniques alone and in combination. Dose to the eye, thyroid and breast were estimated using metal oxide semiconductor field effect transistor (MOSFET) dosimetry. CTDIvol, influence of timing of shield placement, image noise and attenuation values in 13 regions of interest of the head and subjective image quality were compared. RESULTS: The eye shield significantly reduced the eye lens dose when used alone, to a similar degree as when using all software-based techniques together. When used in combination with software-based techniques, the shield reduced the eye lens dose by up to 45% compared to the no dose optimization technique. Noise was significantly increased by the shield, most pronounced in the anterior portion of the eye. CONCLUSION: The combination of ATCM, ATVS, OBTCM and a bismuth shield, with the shield placed after acquiring the localizer image, should be considered to reduce the radiation dose to the eye lens in pediatric head CT.

Grey matter injury patterns in cerebral palsy: associations between structural involvement on MRI and clinical outcomes.

AIMS: In a population cohort of children with grey matter injury (GMI) and cerebral palsy (CP), we aimed to describe and classify magnetic resonance imaging characteristics specific to GMI, and to identify key structure-function associations that serve as a basis for rating GMI in clinically relevant ways. METHOD: Symmetry, extent of cerebral injury, and pathological pattern for 54 children (37 males, 17 females) with CP and a predominant GMI pattern on chronic-phase magnetic resonance imaging were related to gross motor function, motor type and topography, epilepsy, intellectual disability, blindness, and deafness. RESULTS: Relative to mild GMI where there was no pallidal abnormality, severe GMI, comprising pallidal abnormality alone or in conjunction with other deep nuclear and generalized cortical-subcortical involvement, was strongly associated with Gross Motor Function Classification System levels IV to V (OR 35.7 [95% CI 3.5, 368.8]). Involvement of the basal ganglia was associated with non-spastic/mixed motor types, but predominantly where cortical-subcortical grey and white matter involvement was not extensive. The prevalence of epilepsy was highest where there was diffuse cortical-subcortical involvement and white matter loss. INTERPRETATION: Better understanding of structure-function relationships in CP and GMI, and how to rate the severity of GMI, will be helpful in the clinical context and also as a basis for investigation of causal pathways in CP.

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.

Population-based studies of brain imaging patterns in cerebral palsy.

AIM: The aim of this study was to review the distribution of neuroimaging findings from a contemporary population cohort of individuals with cerebral palsy (CP) and to facilitate standardization of imaging classification. METHOD: Publications from 1995 to 2012 reporting imaging findings in population cohorts were selected through a literature search, and review of the titles, abstracts, and content of studies. Relevant data were extracted, including unpublished data from Victoria, Australia. The proportions for each imaging pattern were tabulated, and heterogeneity was assessed for all individuals with CP, and for subgroups based on gestational age, CP subtype, and Gross Motor Function Classification System level. RESULTS: Studies from three geographic regions met the inclusion criteria for individuals with CP, and two additional studies reported on specific CP subtypes. Brain abnormalities were observed in 86% of scans, but were observed least often in children with ataxia (24-57%). White matter injury was the most common imaging pattern (19-45%), although the proportions showed high heterogeneity. Additional patterns were grey matter injury (21%), focal vascular insults (10%), malformations (11%), and miscellaneous findings (4-22%). INTERPRETATION: This review suggests areas where further dialogue will facilitate progress towards standardization of neuroimaging classification. Standardization will enable future collaborations aimed at exploring the relationships among magnetic resonance imaging patterns, risk factors, and clinical outcomes, and, ultimately, lead to better understanding of causal pathways and opportunities for prevention.

An Australian population study of factors associated with MRI patterns in cerebral palsy.

AIM: The aim of this study was to describe the distribution of magnetic resonance imaging (MRI) patterns in a large population sample of children with cerebral palsy (CP) and to examine associations between MRI patterns, and antenatal and perinatal variables. METHOD: Data were retrieved from the Victorian CP Register for 884 children (527 males, 357 females) born between 1999 and 2006. Postneonatal MRI was classified for 594 children. For 563 children (329 males, 234 females) for whom classification was to a single MRI pattern, the frequency of each variable was compared between patterns and with the population frequency. RESULTS: White matter injury was the most common MRI pattern (45%), followed by grey matter injury (14%), normal imaging (13%), malformations (10%), focal vascular insults (9%), and miscellaneous patterns (7%). Parity, birth gestation, level of neonatal care, Apgar score, and time to established respiration varied between MRI patterns (p<0.01). Nulliparity was most strongly associated with focal vascular insults, whereas multiparity was associated only with malformations. Grey matter injury was not associated with birth in a tertiary unit, but was strongly associated with severe perinatal compromise. The frequency of neonatal seizures and of nursery admissions was lowest among children with malformations. INTERPRETATION: As known risk factors for CP are differentially associated with specific MRI patterns, future exploration of causal pathways might be facilitated when performed in pathogenically defined groups.

How specific is the MRI appearance of supratentorial atypical teratoid rhabdoid tumors?

BACKGROUND: Supratentorial atypical teratoid rhabdoid tumor (ATRT) in many cases has a distinctive appearance on post-gadolinium MRI. OBJECTIVE: We sought to determine whether this is a unique appearance allowing ATRT to be distinguished accurately from other types of pediatric supratentorial tumors. MATERIALS AND METHODS: Retrospective review of all available preoperative MRI of pediatric supratentorial tumors at two tertiary children's hospitals, and systematic literature review of case series and reports describing the MRI imaging appearances of supratentorial ATRT. RESULTS: We had 61 supratentorial tumors, including 32 gliomas, 6 ATRT, 8 ependymomas, 6 gangliogliomas, 2 pilomyxoid astrocytomas, 3 primitive neuro-ectodermal tumors, 2 choroid plexus papillomas, and 2 meningiomas. ATRT presented in significantly younger patients than astrocytomas (mean age 2.6 years vs. 9.9 years, P < 0.05). The visual pattern of a thick, wavy (irregular) heterogeneously enhancing wall around a cystic center was seen in 5/6 (83%) ATRTs and only 3/55 (5.4%) other tumors (P < 0.0001), for specificity of 95%, sensitivity of 83%, positive predictive value of 63% and a negative predictive value of 95%. CONCLUSION: A supratentorial tumor with a thick, wavy (irregular) heterogeneously enhancing wall surrounding a central cystic region is suggestive of ATRT in the appropriate clinical setting, especially in a child of preschool age.

Should children with cerebral palsy and normal imaging undergo testing for inherited metabolic disorders?

AIM: For the 9% to 16% of children with cerebral palsy (CP) who have normal brain imaging, further testing for metabolic and/or genetic conditions has been recommended. This study aimed to identify a cohort of children with CP with normal magnetic resonance imaging (MRI), clinically review and describe the cases, and assess the value of testing for inherited metabolic disorders in these children. METHOD: Children with congenital CP born from 1999 to 2005 were selected from a population register. Normal MRI reports were identified and the scans reassessed. Children whose scans were performed before 18 months were excluded, as were children with spastic CP (Gross Motor Function Classification System [GMFCS] level I). The remainder were reviewed clinically and offered investigations. RESULTS: Of 730 children identified, 515 had available imaging and 54 were confirmed as normal. Cases with non-spastic CP and those with milder clinical severity were more likely to have normal imaging. Twenty-three children (17 males, six females; mean age 6 y 11 mo, SD 1 y 10 mo, range 3 y 0 mo to 10 y 0 mo) were reviewed clinically and offered investigations. Twelve children had spasticity (11 with diplegia, one quadriplegia), three had dyskinesia, five ataxia, and three hypotonia. Two children functioned in GMFCS level I, 11 in level II, seven in level III and three in level IV. Four children with spasticity had unusual features. No alternative diagnoses were made. INTERPRETATION: Although important to consider in individual cases, comprehensive metabolic testing failed to clarify the aetiology of CP further in this large cohort of children with normal MRIs, even those with atypical features.

Cardiac magnetic resonance imaging prior to bidirectional cavopulmonary connection in hypoplastic left heart syndrome.

BACKGROUND: Recent evidence has suggested that haemodynamic information obtained from cardiac catheterisation is not essential in pre-operative assessment of children with hypoplastic left heart syndrome (HLHS) undergoing Bidirectional Cavopulmonary Connection (BCPC). Therefore our unit changed to cardiac Magnetic Resonance Imaging (MRI) in 2006. We aimed to compare peri-operative outcomes before and after this change. METHODS: Children with HLHS who underwent BCPC between 2004 and 2008 were identified. Data were collected regarding pre-operative findings and peri-operative outcomes. RESULTS: Forty patients were identified-catheterisation (n=21), MRI (n=19). Catheterisation patients were older at the time of BCPC (114.9+/-22.7 days vs. 95.4+/-11 days: p value 0.002), with no other differences in baseline data. Two patients required cardiopulmonary resuscitation during catheterisation; with no adverse events during MRI. Cardiopulmonary bypass time, ventilation time, inotrope score, and intensive care unit stay were similar. Length of hospital stay and oxygen saturations at discharge were also not significantly different. CONCLUSIONS: We have demonstrated that post-operative course and outcomes are similar in patients with HLHS who had MRI or catheterisation as their pre-BCPC investigation. Additionally the complementary data provided by echocardiography and MRI safely provides sufficient anatomic and functional information with which to plan the BCPC.

Magnetic resonance imaging findings in a population-based cohort of children with cerebral palsy.

The purpose of this study was to investigate the frequency and spectrum of magnetic resonance imaging (MRI) abnormalities in a population of children with cerebral palsy (CP) who were born in the years 2000 and 2001 in Victoria, Australia. In 2000 and 2001, 221 children (126 males, 95 females; mean age 6y [SD 7mo], range 5-7y) with CP, excluding those with CP due to postneonatal causes (6% of all cases), were identified through the Victorian Cerebral Palsy Register. All medical records were systematically reviewed and all available brain imaging was comprehensively evaluated by a single senior MRI radiologist. MRI was available for 154 (70%) individuals and abnormalities were identified in 129 (84%). The study group comprised 88% with a spastic motor type CP; the distribution was hemiplegia in 33.5%, diplegia in 28.5%, and quadriplegia in 37.6% of children. Overall, pathological findings were most likely to be identified in children with spastic hemiplegia (92%) and spastic quadriplegia (84%). Abnormalities were less likely to be identified in non-spastic motor types (72%) and spastic diplegia (52%). The most common abnormalities identified on MRI were periventricular white matter injury (31%), focal ischaemic/haemorrhagic lesions (16%), diffuse encephalopathy (14%), and brain malformations (12%). Dual findings were seen in 3% of patients. This is the first study to document comprehensively the neuroimaging findings of all children identified with CP born over a consecutive 24-month period in a large geographical area.

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.

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.

Chest physiotherapy in infants with cystic fibrosis: to tip or not? A five-year study.

There is controversy about the need for postural drainage physiotherapy in asymptomatic infants with cystic fibrosis (CF). We aimed to compare the effectiveness of standard postural drainage chest physiotherapy (SPT) with a modified physiotherapy regimen without head-down tilt (MPT) in young infants with CF. Twenty newly diagnosed infants with CF (mean age, 2.1 months; range, 1-4) were randomized to SPT or MPT. Parents kept a detailed symptom and treatment diary for the following 12 months. Serial chest radiographs, taken at diagnosis, 12 months, 2(1/2) years, and 5 years after diagnosis, were assessed using the Brasfield score. Pulmonary function tests were compared between groups after 5 years. Of the 20 infants, 16 (80%) completed the review at 12 months, and 14 (70%) at 2(1/2) and 5 years. Patients receiving SPT had more days with upper respiratory tract symptoms than those on MPT (70 +/- 32.8 vs. 37 +/- 24.9 days; P = 0.04) and required longer courses of antibiotics (23 +/- 28.5 vs. 14 +/- 11.2 days; P = 0.05). Chest x-ray scores were similar at diagnosis but were worse at 2(1/2) years for those receiving SPT (P = 0.03). Forced vital capacity and forced expired volume in 1 sec (FEV(1)) at 5-6 years was lower for SPT than for MPT (P < 0.05). In conclusion, MPT was associated with fewer respiratory complications than SPT in infants with CF.

Reviewing the process of preparing children for MRI.

BACKGROUND: MRI is a common medical imaging investigation. Patients, including young children, can be required to keep still for up to 60 min for the study to be completed successfully. Children often find the confined space, noise, need to lie still and possibility of intravenous administration of contrast agent anxiety-provoking and sometimes so distressing that they are unable to cope and require general anaesthesia. OBJECTIVE: A practice MRI intervention was introduced at the Royal Children's Hospital in Melbourne, Australia. The program is conducted by educational play therapists in conjunction with the Department of Medical Imaging. This study explored the effectiveness of this intervention. MATERIALS AND METHODS: The intervention was conducted in a practice MRI unit devoid of magnets. Data were collected as a clinical audit with respect to age, gender, times of scans, position in bore, diagnostic scans and movement artefact. Epidata and Stata were used to analyze the data. RESULTS: A total of 291 children were included; their ages ranged from 3 years 7 months to 17 years (mean 7.9 years), and 48.8% were male. Of the 291 children, 218 (74.9%) were considered a pass at practice, 35 (12 %) were considered borderline pass, and diagnostic images were obtained from 218 (96%) of those children who went onto a clinical MRI. CONCLUSION: We conclude that practice MRI intervention facilitated by educational play therapists is a useful intervention in supporting children to cope with MRI without general anaesthesia.

Time course of transient cortical scintigraphic defects associated with acute pyelonephritis.

BACKGROUND: Acute pyelonephritis is distinguished from renal scarring using repeat cortical scintigraphy. The defects of acute pyelonephritis resolve, while those of scars persist. OBJECTIVE: To determine the duration of reversible cortical defects following acute pyelonephritis and the time interval required to differentiate infection from scars. MATERIALS AND METHODS: An observational prospective study of 193 children (386 kidneys) aged less than 5 years following their first proven urinary tract infection (UTI). Renal cortical scintigraphic defects were detected in 112 (29%) kidneys within 15 days of diagnosis. Of these, 95 underwent repeat renal cortical scans 2 years after the UTI, including 50 with additional scans performed within 2-6 months of infection. RESULTS: Of the 50 kidneys undergoing a second renal cortical scan within 2-6 months of the first UTI, 22 (44%) had persistent defects. A third scan was performed on 17 (77%) kidneys after 2 years, by which time defects had resolved in another 8 (47%) kidneys. The predictive value of defects detected within 2-6 months of UTI representing scars is 53% (95% CI 28, 77). Overall, nine (18%) kidneys with initial renal cortical abnormalities had permanent defects. In the 45 kidneys undergoing a second cortical scan more than 6 months after the UTI, 11 (24%) had persistent defects. None of the 95 kidneys undergoing serial scans developed new or larger defects. CONCLUSIONS: Renal scars may not be reliably diagnosed by cortical scintigraphy performed within 6 months of UTI because the inflammatory lesions may not have fully resolved.

Persistent renal cortical scintigram defects in children 2 years after urinary tract infection.

BACKGROUND: Renal cortical scintigraphic studies challenge the role of vesicoureteric reflux in renal scar development, emphasizing instead the part played by acute pyelonephritis. OBJECTIVE: To determine the prevalence of renal cortical defects in a child cohort 2 years after the child's first diagnosed urinary tract infection and to analyze the relationship of these defects with acute illness variables, primary vesicoureteric reflux and recurrent infections. MATERIALS AND METHODS: In a prospective cohort study, 193 children younger than 5 years with their first proven urinary tract infection underwent renal sonography, voiding cystourethrogram, and renal cortical scintigraphy within 15 days of diagnosis. Two years later, 150 of the 193 children, or 77.7%, had a further renal cortical scintigram, including 75, or 86.2%, of the 87 children who had acute scintigraphic defects. The relationship of cortical defects to age, gender, pre-treatment symptom duration, hospitalization, presence and grade of vesicoureteric reflux, and recurrent urinary tract infections was evaluated. RESULTS: Overall, 20 of the 150 (13.3%; 95% confidence interval (CI) 8.3, 19.8) children had persistent defects 2 years after infection. This included 20 of 75 (26.7%; 95% CI 17.1, 38.1) with initially abnormal scintigrams. No new defects were detected. Although acute defects were more common in the young, those with persistent defects were older (median ages 16.4 vs. 6.8 months, P=0.004) than those with transient abnormalities. After adjustment for age, persistent defects were no longer associated with gender and were not predicted by acute illness variables, primary vesicoureteric reflux or recurrent infections. CONCLUSIONS: Renal cortical scintigraphic defects persisted in approximately one-quarter of young children after their first proven urinary tract infection. The associated clinical features, however, failed to predict scar formation. It is possible that some of the scintigraphic defects preceded the infection by arising from either previously undiagnosed acute pyelonephritis or from underlying congenital dysplasia. The etiology of scars may be best addressed by determining whether prevention of urinary tract infections from birth avoids post-natal scar acquisition or extension.