RPS 1912 - The newest techniques in paediatric radiology: faster imaging, less radiation and contrast agents

Author Block: T. Alshangeeti¹, R. Ahmad¹, P. D. M. Abdullah Alshawsh¹, M. Elzaki²; ¹Kuala Lumpur/MY, ²Madinah/SA
Purpose: The study aimed to evaluate and quantify the risk of cancer in paediatric patients due to exposure to CT scans, including single and repeated exposure. To identify the types of cancer associated with radiation from CT and investigate the repeat rate, cumulative radiation doses, and reasons behind multiple exposures in paediatric populations.
Methods or Background: A review of pediatric patients' CT scan repetition found factors contributing to it and its link to cancer risk. The study, which included 33 studies through Web of Science, Scopus, and PubMed, had fivestudies with over 7 million participants in the meta-analysis. The Newcastle-Ottawa Scale was used to assess potential bias. The study offers a comprehensive evaluation of the evidence regarding exposure and outcome.
Results or Findings: A meta-analysis found an increased risk of overall cancer and brain tumours for children who underwent CT scans. The risk of brain tumours increased by 53% and the evidence for an increased risk of leukaemia was less conclusive. A dose-response effect was observed, with patients receiving two or more repeat CT scans showing a markedly elevated risk compared to those who had only one scan. Many patients undergo repeat scans for injury reassessment rather than a change in their clinical condition, particularly in head injuries. A study found a disparity in radiation exposure levels and the lack of implementation of CT dose optimization strategies in hospitals, resulting in unnecessarily high radiation doses.
Conclusion: CT scan exposure poses a significant risk of cancer, especially brain tumours. Repeat scans may increase the risk of leukaemia.
Limitations: The heterogeneity in the selection of variables used to assess cancer risk and the lack of clear explanations for why CT scans were repeated in the articles were identified.
Funding for this study: No funding was obtained for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: We registered the protocol of this systematic review in the International Prospective Register of Systematic Reviews (PROSPERO) database, which can be accessed at http://www.crd.york.ac.uk/PROSPERO, and it is identified with the record number CRD42022342579

Author Block: B. Schönnagel, M. Tavares de Sousa, P. Bannas, G. Adam, R. Fischer, L. Huber, M. Kaul, J. Herrmann, M. Dargahpour Barough; Hamburg/DE
Purpose: The aim of this study was the assessment of myocardial strain by feature tracking magnetic resonance imaging (FT-MRI) in human fetuses with and without congenital heart disease (CHD) using cardiac Doppler ultrasound (DUS) gating.
Methods or Background: Forty-three human foetuses (gestational age: 28-41 weeks) underwent dynamic cardiac MRI at 3T. Cine balanced steady-state free-precession imaging was performed using foetal cardiac DUS gating. FT-MRI was analysed using dedicated post-processing software. Endo- and epicardial contours were manually delineated from foetal cardiac 4-chamber views, followed by automated propagation to calculate global longitudinal strain (GLS) of the left (LV) and right ventricle (RV), LV radial strain, and LV strain rate.
Results or Findings: Strain assessment was successful in 38/43 fetuses (88%), 25 of them had postnatally confirmed diagnosis of CHD (e.g. coarctation, transposition of great arteries) and 13 were heart healthy. Five foetuses were excluded due to reduced image quality. In foetuses with CHD compared to healthy controls median LV-GLS (-13.2% vs. -18.9%; P<0.007), RV-GLS (-7.9% vs. -16.2%; P<0.006), and LV strain rate (1.4s-1 vs. 1.6s-1; P<0.003) were significantly higher (i.e., less negative). LV radial strain was without a statistically significant difference (20.7% vs. 22.6%; P=0.1). Bivariate discriminant analysis for LV-GLS and RV-GLS revealed sensitivity of 67% and specificity of 93% to differentiate between foetuses with CHD and healthy foetuses.
Conclusion: Myocardial strain was successfully assessed in the human foetus performing dynamic fetal cardiac MRI with DUS gating. Our study indicates that strain parameters may allow for differentiation between foetuses with and without CHD.
Limitations: No direct comparison with echocardiography. Myocardial strain was assessed from four chamber views only.
Funding for this study: This study received a grant by the Deutsche Forschungsgemeinschaft.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The ethical approval was obtained from the local ethics committee.

Author Block: S. Hosseinzadeh; Oxford/UK
Purpose: Percutaneous Hickman line insertion is a common and necessary procedure for the delivery of chemotherapeutics, long term medications, and patients with difficult vascular access. In our institution, paediatric Hickman line insertion occurs in the radiology department fluoroscopy room or in surgical theatres. Ultrasound-guided puncture of internal jugular vein is followed by guide-wire insertion and subsequently Hickman line tunnelled in the anterior chest wall. Position of the wire and line tip are confirmed fluoroscopically. We assessed differences in radiation exposure between fluoroscopy room and surgical theatres.
Methods or Background: Radiation dose and screening time were recorded from all paediatric Hickman line insertions over a three year period. Inter-room and inter-operator data was analysed. Mann-Whitney U Test was used for statistical analysis.
Results or Findings: Three hundred and thirty seven Hickman lines were inserted between January 2020 and May 2023. Radiation doses were significantly lower in the fluoroscopy room than in theatre (p<0.0001), and this effect remained when data was analysed in age subgroups and controlling for operators. Screening times were significantly reduced in the fluoroscopy room compared to theatre (p<0.05). Lower radiation dose (p<0.001) and screening time (p<0.01) was also observed in radiologist-performed insertions compared with surgeon-performed insertions in theatre.
Conclusion: The location and operator of Hickman line insertions significantly impacts the radiation dose and screening time in the procedure. Even controlling for operator, patients were exposed to lower radiation doses in our fluoroscopy room than in theatres.
Limitations: Theatre cases may be more complex than patients suitable for fluoroscopy room. Of note, however, this study spans the COVID-19 pandemic, during which many ‘routine’ procedures ordinarily carried out in fluoroscopy were performed in theatre, which may somewhat mitigate this effect.
Funding for this study: This was a student project. No specific funding was acquired.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: This study was performed as internal service evaluation using pooled anonymised data, and hence no ethics approval was required.

Author Block: L. Ren¹, N. Guo², Y. Zhang¹, Y. Wang¹; ¹Zhenzhou/CN, ²Beijing/CN
Purpose: The objective of this study was to explore the feasibility of reduced radiation dose and contrast medium using dual-layer spectral CT in pediatric patients.
Methods or Background: This study has been approved by the ethics committee. One hundred and twelve peadiatric patients were enrolled in this study and randomly separated into two groups. The study group underwent scanning with a DRI index of 13. The contrast agent volume was reduced with 0.2 ml/kg compared to the control group. Fifty keV monoenergetic images were reconstructed. The control group underwent scanning with a DRI index of 16, and the contrast agent volume were 1.2 to 1.8 ml/kg based on patient’s weight. Hundred kVp polyenergetic images were reconstructed. CT values and standard deviations (SD) of the abdominal aorta, abdominal aorta branches, hepatic veins, portal vein main trunk, liver parenchyma and paraspinal muscles were measured. Subjective evaluations of overall image quality were performed. Statistical analysis was conducted with student t-tests and rank sum tests.
Results or Findings: There were no statistically significant differences in age and weight between two groups (P>0.05). The CTDIvol, SSDE, and DLP of the study group were lower than those of the control group (each P<0.05). The contrast medium volume of the study group was reduced by approximately 24.0% compared to the control group. CT values for vessels and organs in the study group were higher than those in the control group (P<0.001). There was no statistically significant difference in subjective image quality scores between two groups (P>0.05). Both groups had image quality sufficient for diagnostic requirements.
Conclusion: In paediatric patients, dual-layer spectral CT can significantly reduce radiation dose and iodine contrast medium volume of abdominal and pelvic spectral imaging without compromising image quality.
Limitations: This study is a single-center study.
Funding for this study: No funding was obtained for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Not applicable

Author Block: C. E. Kelly, O. Arthurs, I. C. Simcock; London/UK
Purpose: The aim of this study was to identify the optimal arm position for paediatric CT chest scanning if patients cannot raise both arms alongside their head, considering image quality and radiation dose.
Methods or Background: Positioning the arms outside of the field of view, (alongside the head) during CT chest scans reduces radiation dose and artifacts. However, some children are unable to achieve this optimal positioning due to physical disability or an inability to co-operate. In this study we measured the effect of sub-optimal arm positioning on absorbed patient dose and image quality. We evaluated 154 chest CT scans performed with arms in the suboptimal position between January 2022 and July 2023 (age range 4 days and 16 years old), compared to mean age-weighted CTDIvol for patients with arms up.
Results or Findings: The highest doses were seen when one or both arms were positioned perpendicular to the torso and this was commoner in younger patients. Overall, mean radiation dose was 125% higher with both arms perpendicular, 50% higher with one arm perpendicular, 88% higher with both arms down, and 63% higher with one arm down. All scans were of diagnostic quality, but streaking was present in 47% of scans when both arms were perpendicular, 24% of scans with one arm perpendicular and 14% when both arms were down alongside the body.
Conclusion: Sub-optimal positioning of the arms during paediatric CT chest scans increases patient dose and reduces image quality. Arms should be placed alongside the body if they cannot be raised, to reduce radiation dose and improve image quality.
Limitations: The range of weights meant absolute CTDIvol values could not be compared but instead were compared as a proportion of the optimum CTDIvol value.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: The study utilised retrospective anonymous data analysis.

Author Block: S. Saini, K. S. Sodhi, A. Bhatia, A. K. Saxena, J. Mathew; Chandigarh/IN
Purpose: Dynamic airway disorders are an important cause of stridor in children. Fiberoptic bronchoscopy (FOB) is the gold standard and an invasive method of diagnosis of these disorders. There is lack of objective criteria for diagnosis of paediatric dynamic airway disorders. The study aims to assess the diagnostic utility of low-dose 4D dynamic airway CT in paediatric stridor on comparison with FOB.
Methods or Background: We conducted a prospective study in 24 children (age:13 days-1.5 years, boys: 18) with stridor. Low-dose 4D dynamic airway CT was performed with 70kVp and 15 mAs. The number of acquisition cycles varied from five to ten. Stridor during CT acquisition was also noted. Image analysis was done using volume rendered reconstruction and axial CT images and degree of collapse was noted. FOB was performed within 72 hours of CT with blinding of both the respective observers. The findings were compared with FOB as the gold standard.
Results or Findings: The diagnostic accuracy of 4D dynamic airway CT was 91.6%, 95.7%, and 95.5% for the diagnosis of laryngomalacia, tracheomalacia, and bronchomalacia respectively. The sensitivity and specificity of 4D dynamic airway CT for the diagnosis of laryngomalacia was 94.7% and 80.0% respectively with substantial agreement between the two modalities (k=0.777). Sensitivity for detection of tracheomalacia and bronchomalacia was 90.9% and 75% respectively with 100% specificity. There was near perfect agreement between the two modalities with kappa coefficient of 0.913 for tracheomalacia and 0.831 for bronchomalacia. Mean radiation dose was 0.827 mSv. The presence of stridor during CT had a positive association with prediction of abnormality detection on CT.
Conclusion: 4D dynamic airway CT can be used as a robust and non-invasive objective tool in assessing dynamic airway diseases in children.
Limitations: Not applicable for this study.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by institutional ethics committee.