Brain Magnetic Resonance Imaging (MRI) of high-risk infants in the neonatal period (from 26 weeks postmenstrual age to Term Equivalent Age (TEA)) is increasingly being used for the detection of brain injuries, and the early prognostication of adverse outcomes such as Cerebral Palsy (CP). While most imaging is performed around TEA in clinical practice for infants born preterm (<37 weeks of gestation), this would often require families to return to hospital for imaging. In this work, we extract structural biomarkers from MRI acquired both before and at TEA in a cohort of very preterm infants from the PPREMO and PREBO studies (n = 100), to determine if either time-point, or both combined, are predictive of both Bayley Scales of Infant and Toddler Development - Third Edition (Bayley-III) and the Neuro-sensory Motor Developmental Assessment (NSMDA) at 2 years. Using multivariable regression, moderately strong and statistically significant associations were found between brain structure on both early and TEA MRIs with 2-year outcomes (r = 0.39-0.55 for early MRI, r = 0.37-0.49 for Term MRI, r = 0.37-0.56 for early and TEA MRI combined). Importantly, brain biomarkers associated with early childhood outcomes from MRIs were identified, including white and grey matter volumes, deep grey matter and cerebellar volumes, and gyrification and surface area across the whole cortex. Early MRI showed the best prognostic accuracy along with combining timepoints, indicating the potential clinical benefit of Early MRI in predicting adverse outcomes.

A prominent subarachnoid space (SAS) in infants under 24 months is a very common finding and is a normal variant that can be associated with macrocephaly. This must be differentiated from various pathological conditions that also cause a prominent SAS, including a reduction in brain volume, obstruction to the cerebrospinal fluid (CSF) or malformations of the skull. The inappropriate labelling of normal SAS prominence as enlargement due to pathology and misrepresentation of published literature by some author groups has created confusion medicolegally, contributing to inappropriate conclusions that a normal prominent SAS may cause subdural haemorrhage (SDH) and brain injury. This paper aims to review the characteristics of the SAS in infants, the terminology relating to the prominence of the SAS and the possible association between the prominence of the SAS and SDH.

Introduction: Cranial ultrasound (cUS) screening is routinely performed in preterm neonates. This study compared cranial ultrasound abnormalities (CUA) detected at 6 weeks postnatal age (PNA) and term equivalent age (TEA) with early neurodevelopment outcomes at 3-4 months corrected age. Methods: Pre-planned substudy of a prospective single-centre cohort included high-risk infants born before 32 weeks of gestation who underwent cUS at 6 weeks PNA and TEA. Severe CUAs, defined as significant intraventricular haemorrhage, white matter injury or ventricular enlargement were compared with outcomes at 3-4 months corrected age, including Hammersmith Infant Neurological Examination (HINE), General Movement Assessment (GMA), and early cerebral palsy (CP) diagnosis. Results: Fifty-four infants were included (median gestation 26.8 weeks, birthweight 782 g). Abnormal HINE scores (< 57) were found in 18 (33%), absent fidgety GMAs in 5 (9%), and early CP in 2 (4%). Severe CUAs were not significantly associated with abnormal HINE at 6 weeks PNA (p = 0.77) or TEA (p = 0.77), absent fidgety GMAs at 6 weeks PNA (p = 0.39) or TEA (p = 0.14) or early CP at 6 weeks PNA (p = 0.16) or TEA (p = 0.52). Conclusion: In this exploratory study, severe CUAs on cUS were not associated with early neurodevelopmental outcomes. Larger studies are needed to determine whether meaningful associations exist.

We extend existing techniques by using generative adversarial network (GAN) models to reduce the appearance of cast shadows in radiographs across various age groups. We retrospectively collected 11,500 adult and paediatric wrist radiographs, evenly divided between those with and without casts. The test subset consisted of 750 radiographs with cast and 750 without cast. We extended the results from a previous study that employed CycleGAN by enhancing the model using a perceptual loss function and a self-attention layer. The CycleGAN model which incorporates a self-attention layer and perceptual loss function delivered a similar quantitative performance as the original model. This model was applied to images from 20 cases where the original reports recommended CT scanning or repeat radiographs without the cast, which were then evaluated by radiologists for qualitative assessment. The results demonstrated that the generated images could improve radiologists’ diagnostic confidence, in some cases leading to more decisive reports. Where available, the reports from follow-up imaging were compared with those produced by radiologists reading AI-generated images. Every report, except two, provided identical diagnoses as those associated with follow-up imaging. The ability of radiologists to perform robust reporting with downsampled AI-enhanced images is clinically meaningful and warrants further investigation. Additionally, radiologists were unable to distinguish AI-enhanced from unenhanced images. These findings suggest the cast suppression technique could be integrated as a tool to augment clinical workflows, with the potential benefits of reducing patient doses, improving operational efficiencies, reducing delays in diagnoses, and reducing the number of patient visits.

OBJECTIVES:This study evaluates the effectiveness of spectral filtration-specifically Tin and SilverBeam filters-in achieving ultra-low radiation doses in pediatric computed tomography (CT) imaging for craniosynostosis diagnosis. We investigate whether these filters can reduce radiation to levels comparable to or below those of standard four-view skull x-rays, while maintaining diagnostic accuracy. Unlike previous research focused broadly on dose reduction, this study highlights the potential of Tin and SilverBeam filtration as a promising solution. METHODS:CT images were acquired using a pediatric head fracture phantom, with sutures simulating craniosynostosis, on two scanners with different spectral filters. The CTDIvol was reduced by varying percentages from standard pediatric protocols using Tin and SilverBeam filters. Image quality and radiation dose were quantitatively assessed, while two radiologists performed qualitative evaluations. RESULTS:Dose comparisons showed that images with at least a 89.2% reduction in CTDIvol using the Tin filter and a 91.4% reduction when using the SilverBeam filter resulted in lower doses than a standard four-view skull x-ray (0.09 mSv). The greatest dose reduction (up to 161%) occurred with SilverBeam at a 99.9% reduction in CTDIvol. While significant pixel intensity changes were observed at the sutures, spatial resolution decreased at lower dose settings. Two pediatric radiologists observed clear skull and orbit outlines under clinical conditions, but coronal sutures became undetectable near 90% CTDIvol reduction. CONCLUSION:Spectral filtration ultra-low-dose CT significantly reduces radiation exposure compared to four-view skull x-rays, showing promise for diagnosing craniosynostosis. Further patient-based studies are needed to validate diagnostic efficacy. ADVANCES IN KNOWLEDGE:This study is the first to assess spectral filtration in ultra-low-dose pediatric head CT, highlighting significant dose reductions without compromising diagnostic quality, and stressing the need for further validation.

OBJECTIVE:To determine whether cranial ultrasound (cUS) at term equivalent age (TEA) provides additional diagnostic information compared with routine imaging at 6 wk postnatal age (PNA) in high-risk pre-term infants. METHODS:A prospective cohort study at a tertiary neonatal intensive care unit in Melbourne, Australia, was carried out. Sixty-nine pre-term neonates born <32 wk gestation or <1500 g, with one or more clinical risk factors for brain injury, underwent cUS at both 6 wk PNA and TEA. Imaging findings were classified as normal or abnormal, and changes over time were categorised as stable, resolved or new. RESULTS:cUS brain abnormalities were identified in 70% of infants at 6 wk PNA and 90% at TEA (p = 0.001), representing a significant increase in detection. Findings remained stable in 58% of cases; 38% had new abnormalities at TEA, including ventricular enlargement, widened interhemispheric fissures and parenchymal injury. Complete resolution was seen in only 4%. CONCLUSION:Cranial ultrasound at TEA significantly improved the detection of potential brain injury compared with 6 wk PNA imaging. These findings support consideration of TEA as the preferred timing for final screening, potentially replacing the 6 wk PNA scan, although larger studies are needed to confirm optimal practice.

This prospective study aimed to evaluate the capabilities of two novel vertex-toes CT protocols (ultra-low and low-dose) compared to a standard high-dose CT protocol plus radiographic skeletal survey (SS) in a post-mortem setting. The study sought to assess perceived image quality (IQ) and the fracture detection capabilities of each CT protocol. Participants aged 2 years and under received three whole-body CT scans, followed by a SS. Radiologists reviewed images in the sequence of ultra-low, low-dose, to standard-dose CT, then SS. The reviewers graded perceived IQ on a Likert scale. Gwet’s agreement coefficient (AC)-2 and cumulative link mixed models quantified interobserver agreement and IQ differences, respectively. Fractures detected by each modality were compared across anatomical regions, with positive specific agreement (PSA) assessing interobserver agreement. Radiation doses were calculated for each CT protocol. Significant differences in IQ ratings were observed across CT protocols for all anatomical regions (ribs [ultra-low–low], p = 0.0001; femur [ultra-low–low], p = 0.0001; all others, p < 0.001), alongside low interobserver agreement in IQ (lumbar spine [low-dose]-AC = 0.78; humerus [low-dose]-AC = 0.77; all others, AC < 0.7). Among 29 participants, 69 fractures were identified across modalities, all being detected by the standard-dose CT. Ultra-low and low-dose CT identified 62 (90

BACKGROUND AND OBJECTIVES:How children prepare for magnetic resonance imaging (MRI) can help reduce the need for sedation and improve access to pediatric health care. Embedding virtual reality (VR) tools within routine preparation for MRI may support this process. The aim of this study was to qualitatively describe the process of preparing a child for MRI in a tertiary health care setting. We sought to understand the roles of health care workers, parents, and special equipment, such as VR, in preparing children for a successful and a high-quality diagnostic scan. PATIENTS AND METHODS:There were 29 participants (13 children, 13 caregivers, and 3 health professionals). Children scheduled for clinically indicated noncontrast head MRI scans were recorded on video throughout routine MRI preparation with their parents and health care professionals, with VR included as part of standard care. Interviews with children and caregivers were completed on arrival, immediately before MRI, and post MRI. Using an interpretive description methodology, we integrated coded data from the audio and video to identify themes within an attachment theory framework. RESULTS:Our qualitative analysis of child MRI preparation strategies revealed 2 main categories: (1) strategies that support self-efficacy and (2) a sense of agency. Strategies employed by child life therapists and caregivers included providing opportunities for accomplishment, practicing sensations, and fostering relational connections through play and collaboration. VR tools enhanced the children's sense of agency and confidence and offer additional educational and coaching possibilities. CONCLUSIONS:MRI preparation methods emphasized attachment between child, caregiver, staff, and MR environment by enhancing the child's self-efficacy and sense of agency. VR offers a platform for MR education and building trust between the child, staff, and MRI setting, with potential utility in underserved medical settings.

Abstract Background Exposure to maternal inflammation in-utero is associated with an increased risk of neurocognitive developmental disorders in offspring, including cerebral palsy (CP). An increased risk of CP and neurological morbidity has been reported in infants of women with CD and UC in registry but not prospective cohort studies. Unsedated neonatal cerebral MRI (nMRI) allows for early assessment of brain microstructural integrity, with bipartietal diameter (BPD) predictive of cognitive and motor outcomes in preterm infants. Generalised movement assessments evaluate the character of infant’s spontaneous movements, can be undertaken remotely by parents with app-based technology (BabyMoves (BM) and are an early indicator of being high risk for cerebral palsy. nMRI & BM have not been used to screen for adverse neurocognitive outcomes in infants born to women with inflammatory disorders. We aimed to assess the feasibility of nMRI and BM in infants born to women with IBD and correlate abnormalities with maternal biochemical inflammation antenatally. Methods Pregnant women with IBD were assessed clinically and biochemically (faecal calprotectin (FC), CRP) in each trimester of pregnancy in this single centre prospective pilot study. Biochemically active disease was defined by FC >100ug/g or CRP >15mg/L. Infants underwent nMRI using a 1.5T MRI with T1-weighted and T2/proton density-weighted sequences performed at 6-12 weeks post-corrected term. Parents filmed 2 BM videos at 12-14 & 14-16 weeks post-corrected term. nMRIs (Figure 1) and BMs were scored by blinded reviewers with validated scoring systems. Metric nMRI data were corrected for gestational age (cGA). Descriptive statistics and spearman correlation coefficients were performed. Results 40 mother-baby pairs, 19 with CD & 20 exposed to a biologic drug, were recruited. Most patients were in biochemical remission throughout pregnancy with median FC <50ug/g and <13% having a CRP >15g/L in trimesters 1-3. At delivery 2/40 infants were premature, 4/40 low birth weight & 3/40 required neonatal intensive care. The median cGA at nMRI was 46 weeks 6 days (range 42 + 5-53 + 4). 2/39 MRI were of insufficient quality for scoring. 5/37 nMRI and 4/35 BM were abnormal, with 1/7 having a clinically significant adverse outcome (Table 1). Biparietal diameter did not correlate with maternal CRP or FC in any trimester of pregnancy. Conclusion nMRI & BM for infant neurocognitive disorder screening is feasible in the setting of maternal IBD. In this cohort of 40 infants, one clinically significant abnormality was identified in an infant of a mother with inactive IBD. Larger studies are required to stratify the risk of adverse neurocognitive outcomes in infants born to women with maternal inflammatory disorders.

This paper investigated cortical thickness and volumetric changes in children to better understand the impact of obstructive sleep disordered breathing (SDB) on the neurodevelopment of specific regions of the brain. We also aimed to investigate how these changes were related to the behavioral and cognitive deficits observed in the condition. Neuroimaging, behavioral, and sleep data were obtained from 30 children (15 non-snoring controls, 15 referred for assessment of SDB) aged 7 to 17 years. Gyral-based regions of interest were identified using the Desikan-Killiany atlas. Student's t-tests were used to compare regions of interest between the controls and SDB groups. We found that the cortical thickness was significantly greater in the right caudal anterior cingulate and right cuneus regions and there were volumetric increases in the left caudal middle frontal, bilateral rostral anterior cingulate, left, right, and bilateral caudate brain regions in children with SDB compared with controls. Neither cortical thickness nor volumetric changes were associated with behavioral or cognitive measures. The findings of this study indicate disruptions to neural developmental processes occurring in structural regions of the brain; however, these changes appear unrelated to behavioural or cognitive outcomes.

Background:Exposure to maternal inflammation is associated with an increased risk of neurocognitive and developmental disorders in offspring. Early diagnosis and intervention improves childhood motor and cognitive functioning. Neonatal cerebral MRI and remote app-based generalised movement assessments (GMAs) are both predictive of adverse neurocognitive outcomes but have only been used in infants at significantly increased risk for these outcomes, rather than following in utero exposure to maternal inflammatory disorders. Methods:Pregnant women with inflammatory bowel disease were assessed clinically and biochemically in each trimester of pregnancy in this single centre prospective study. Neonatal cerebral MRIs were performed at 6-12 weeks post-corrected term. Two GMA videos were filmed using the 'BabyMoves' app from 12 to 16 weeks of age. MRIs and GMAs were assessed by a blinded highly qualified practitioner using validated scoring systems. Results:40/53 of invited maternal-infant dyads were recruited. C-reactive protein was elevated antenatally in less than 13%. 5/37 neonatal MRIs had incidental or obstetric trauma related gross anatomical abnormalities, with none abnormal on validated gross abnormality scoring. 3/35 GMAs were abnormal, with one GMA abnormality being clinically significant. Of those with abnormal GMAs, 2/3 were in exposed to severely active IBD in-utero. Conclusion:Neonatal cerebral MRI and GMA for neurocognitive screening is feasible in the setting of maternal inflammatory bowel disease, where the risk of cerebral palsy is poorly defined and thus burdensome screening interventions are less appealing to parents. Larger studies are required to stratify adverse neurocognitive outcome risk in infants born to women with maternal inflammatory disorders, but these data are reassuring for women with IBD in remission antenatally.

Aim: To evaluate and compare a cranial ultrasound (cUS) scoring system to conventional reporting of cranial ultrasound abnormalities (CUAs) for prediction of early neurodevelopmental outcomes in preterm infants.Materials and methods: This retrospective, single-center study compared cUS scores to results from late ultrasound examination reports for any cUS abnormality (CUA) (any hemorrhage or white matter lesion) or severe CUA [severe intraventricular hemorrhage (IVH)], cystic periventricular leukomalacia (PVL), parenchymal or cerebellar hemorrhage) for predicting early signs of cerebral palsy (CP) or developmental delay in preterm infants.Results: Six-weeks postnatal cUS examinations were analyzed against early neurodevelopmental outcomes at 3-4-months corrected age of 242 preterm infants (median gestational age, 26.5 weeks; interquartile range [IQR, 4 weeks] and median body weight 880 grams [IQR, 356.5 grams]).We did not find any statistically significant differences between cUS score and any CUA for sensitivity (57% vs 57% [95% confidence interval (CI): from -19 to 19]) and specificity (68% vs 64% [95% CI: from -3 to 10]) for predicting CP.Similarly, there was no difference in sensitivity (44% vs 46% [95% CI: from -12 to 7]) and specificity (74% vs 70% [95% CI: from -5 to 13]) for predicting any developmental delay.However, in comparison to severe CUA, cUS score had significantly higher sensitivity (57% vs 27% [95% CI: from 12 to 49]) but significantly lower specificity (68% vs 96% [95% CI: from -21 to -34]) for predicting CP.There was higher sensitivity (44% vs 12 % [95% CI: from 23 to 41]) but lower specificity (74% vs 98% [95% CI: from -15 to -32]) for any delay.Conclusions: Cranial ultrasound score was similar to any reported CUA for predicting neurodevelopmental outcomes; however, when compared to severe CUA, it had better sensitivity but poor specificity for predicting early neurodevelopmental outcomes.Clinical significance: Objective scoring of cUS examinations on late neonatal scans was found to be similar to conventional reporting of any CUA for the prediction of early neurodevelopmental outcomes in this retrospective study.This indicates that scoring does not value add to the diagnosis of these infants.

Fatigue may be among the most profound and debilitating consequences of pediatric traumatic brain injury (TBI); however, neurostructural risk factors associated with post-injury fatigue remain elusive. This prospective study aimed to evaluate the independent value of susceptibility-weighted imaging (SWI) biomarkers, over-and-above known risk factors, to predict fatigue symptom severity in children with TBI.Forty-two children were examined with structural magnetic resonance imaging (sMRI), including a SWI sequence, within eight weeks post-injury. The PedsQL Multi-Dimensional Fatigue Scale (MFS) was administered 24 months post-injury. Compared with population expectations, the TBI group displayed significantly higher levels of general fatigue (Cohen d = 0.44), cognitive fatigue (Cohen d = 0.59), sleep/rest fatigue (Cohen d = 0.37), and total fatigue (Cohen d = 0.63). In multi-variate models adjusted for TBI severity, child demographic factors, and depression, we found that subacute volume of SWI lesions was independently associated with all fatigue symptom domains. The magnitude of the brain-behavior relationship varied by fatigue symptom domain, such that the strongest relationships were observed for the cognitive fatigue and total fatigue symptom scales. Overall, we found that total subacute volume of SWI lesions explained up to 24% additional variance in multi-dimensional fatigue, over-and-above known risk factors. The subacute SWI has potential to improve prediction of post-injury fatigue in children with TBI. Our preliminary findings suggest that volume of SWI lesions may represent a novel, independent biomarker of post-injury fatigue, which could help to identify high-risk children who are likely to benefit from targeted psychoeducation and/or preventive strategies to minimize risk of long-term post-injury fatigue.

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 9.6years (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 expo-sure 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.

Cranial ultrasound examinations are routinely performed in very preterm neonates. There is no widespread agreement on the optimal timing of these examinations. This review examines screening protocols and recommendations available for the timing of cranial ultrasound examinations in preterm neonates born before 32 wk of gestation. A systematic search was performed to find published screening protocols, and 18 articles were included in the final review. The protocols varied in their recommendations on timing, although at least one examination in the first week of life was universally recommended. The recommended timing for a "late" or final ultrasound examination was variable, and included at 6 wks of postnatal age, term-equivalent age or hospital discharge. There was no agreement as to whether weekly or fortnightly sequential ultrasound imaging should be performed after the first week of life. Further studies are required to establish an optimal protocol for these very preterm neonates to improve detection and monitoring of brain injuries.

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.

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.

Abstract 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.

Background Resorption of magnesium-based alloy bioabsorbable screws produces hydrogen gas, which can be mistaken as a sign of infection and may affect the physis or fixed bone fragment. Objective We evaluated the temporal and spatial occurrence of gas and the occurrence of a breakage of the fixed bone fragment or screw following magnesium screw fixation. Materials and methods Radiographs of paediatric patients treated with magnesium screws were retrospectively reviewed. Temporal occurrence and distribution of gas in the bone, the physis and soft tissues, breakage of the screw or fixed bone fragment and joint effusion were assessed. Results One hundred and three radiographs in 35 paediatric patients were reviewed (mean age: 10.6 years). Follow-up ranged from 1 to 730 days. Gas in the bone increases up to week 5, remains constant up to week 16 and then decreases. Gas in soft tissues, intra-articular gas and joint effusions gradually reduce over time. In 1/23 (4.3%) patients with an open physis, gas intrusion into the physis occurred. Breakage of the bone fragment fixated by the screw was observed in 4/35 (11.4%) patients within the first 6 weeks. Screw breakage was observed in 16/35 (45.7%) patients, with a median time to first detection of 300 days. Conclusion Gas bubbles in bone and soft tissue are normal findings in the context of screw resorption and should not be confused with soft-tissue infection or osteomyelitis. Gas is rarely visible in the physis. Breakage of the fixed bone fragment and/or screw can occur.