Pediatric CT: strategies to lower radiation dose

Radiation exposure associated with computed tomography for pediatric urolithiasis evaluation: A scoping review of the literature

INTRODUCTION

Computed tomography (CT) imaging is used for assessment of pediatric urolithiasis in cases where ultrasound is inconclusive. The utility of CT imaging must be considered alongside the potential risks of radiation exposure in this patient population due to the increased risk of cancer development. The purpose of this review is to investigate the radiation exposure associated with standard-dose and low-dose computed tomography (CT) imaging for the assessment of pediatric urolithiasis.

METHODS

A scoping literature review over a 23 year period between 2000 and 2023 was conducted of all English-language studies reporting on the use of non-contrast CT imaging for assessment of pediatric urolithiasis. Patients that were specified as pediatric with age ≤20 years at time of intervention and undergoing standard-dose or low/ultra-low-dose CT were included. Low-dose and ultra-low-dose CT were defined as a radiation dose ≤3.0 mSv and ≤1.9 mSv, respectively.

RESULTS

A total of 8121 articles were identified and after screening, 6 articles representing 309 patients were included in this scoping review. Of the articles reviewed, standard non-contrast CT radiation doses for pediatric urolithiasis evaluation ranged from 2.9 to 5.5 mSv and low-dose CT radiation dose was reported to be 1.0-2.72 mSv. Only 2 studies directly evaluated low-dose CT imaging compared to standard-dose CT imaging for pediatric urolithiasis assessment. Radiation reduction approaches did not negatively impact urolithiasis detection or characterization in 2 studies reviewed.

CONCLUSIONS

CT radiation doses for suspected or known pediatric urolithiasis are underreported and vary greatly with underutilization of low-dose/ultra-dose protocols for pediatric urolithiasis especially in comparison to the adult population. Results from this scoping review support that low-dose CTprotocols for pediatric stone disease are feasible to reduce radiation exposure.

Universal 120-kV Dual-Source Ultra-High Pitch Protocol on the Photon-Counting CT System for Pediatric Abdomen of All Sizes: A Phantom Investigation Comparing With Energy-Integrating CT

OBJECTIVES

The purpose of this study is to determine if a universal 120-kV ultra-high pitch and virtual monoenergetic images (VMIs) protocol on the photon-counting computed tomography (PCCT) system can provide sufficient image quality for pediatric abdominal imaging, regardless of size, compared with protocols using a size-dependent kV and dual-source flash mode on the energy-integrating CT (EICT) system.

MATERIALS AND METHODS

One solid water insert and 3 iodine (2, 5, 10 mg I/mL) inserts were attached or inserted into phantoms of variable sizes, simulating the abdomens of a newborn, 5-year-old, 10-year-old, and adult-sized pediatric patients. Each phantom setting was scanned on an EICT using clinical size-specific kV dual-source protocols with a pitch of 3.0. The scans were performed with fixed scanning parameters, and the CTDIvol values of full dose were 0.30, 0.71, 1.05, and 7.40 mGy for newborn to adult size, respectively. In addition, half dose scans were acquired on EICT. Each phantom was then scanned on a PCCT (Siemens Alpha) using a universal 120-kV protocol with the same full dose and half dose as determined above on the EICT scanner. All other parameters matched to EICT settings. Virtual monoenergetic images were generated from PCCT scans between 40 and 80 keV with a 5-keV interval. Image quality metrics were compared between PCCT VMIs and EICT, including image noise (measured as standard deviation of solid water), contrast-to-noise ratio (CNR) (measured at iodine inserts with solid water as background), and noise power spectrum (measured in uniform phantom regions).

RESULTS

Noise at a PCCT VMI of 70 keV (7.0 ± 0.6 HU for newborn, 14.7 ± 1.6 HU for adult) is comparable (P > 0.05, t test) or significantly lower (P < 0.05, t test) compared with EICT (7.8 ± 0.8 HU for newborn, 15.3 ± 1.5 HU for adult). Iodine CNR from PCCT VMI at 50 keV (50.8 ± 8.4 for newborn, 27.3 ± 2.8 for adult) is comparable (P > 0.05, t test) or significantly higher (P < 0.05, t test) to the corresponding EICT measurements (57.5 ± 6.7 for newborn, 13.8 ± 1.7 for adult). The noise power spectrum curve shape of PCCT VMI is similar to EICT, despite PCCT VMI exhibiting higher noise at low keV levels.

CONCLUSIONS

The universal PCCT 120 kV with ultra-high pitch and postprocessed VMIs demonstrated equivalent or improved performance in noise (70 keV) and iodine CNR (50 keV) for pediatric abdominal CT, compared with size-specific kV images on the EICT.

First clinical experience following the consensus guide for calibrating a proton stopping power ratio curve in a new proton centre

BACKGROUND AND PURPOSE

This work introduces the first assessment of CT calibration following the ESTRO's consensus guidelines and validating the HLUT through the irradiation of biological material.

METHODS

Two electron density phantoms were scanned with two CT scanners using two CT scan energies. The stopping power ratio (SPR) and mass density (MD) HLUTs for different CT scan energies were derived using Schneider's and ESTRO's methods. The comparison metric in this work is based on the Water-Equivalent Thickness (WET) difference between the treatment planning system and biological irradiation measurement. The SPR HLUTs were compared between the two calibration methods. To assess the accuracy of using MD HLUT for dose calculation in the treatment planning system, MD vs SPR HLUT was compared. Lastly, the feasibility of using a single SPR HLUT to replace two different energy CT scans was explored.

RESULTS

The results show a WET difference of less than 3.5% except for the result in the Bone region between Schneider's and ESTRO's methods. Comparing MD and SPR HLUT, the results from MD HLUT show less than a 3.5% difference except for the Bone region. However, the SPR HLUT shows a lower mean absolute percentage difference as compared to MD HLUT between the measured and calculated WET difference. Lastly, it is possible to use a single SPR HLUT for two different CT scan energies since both WET differences are within 3.5%.

CONCLUSION

This is the first report on calibrating an HLUT following the ESTRO's guidelines. While our result shows incremental improvement in range uncertainty using the ESTRO's guideline, the prescriptional approach of the guideline does promote harmonization of CT calibration protocols between different centres.

"From Vision to Reality: Virtual Reality's Impact on Baffle Planning in Congenital Heart Disease"

This study aims to evaluate the feasibility and utility of virtual reality (VR) for baffle planning in congenital heart disease (CHD), specifically by creating patient-specific 3D heart models and assessing a user-friendly VR interface. Patient-specific 3D heart models were created using high-resolution imaging data and a VR interface was developed for baffle planning. The process of model creation and the VR interface were assessed for their feasibility, usability, and clinical relevance. Collaborative and interactive planning within the VR space were also explored. The study findings demonstrate the feasibility and usefulness of VR in baffle planning for CHD. Patient-specific 3D heart models generated from imaging data provided valuable insights into complex spatial relationships. The developed VR interface allowed clinicians to interact with the models, simulate different baffle configurations, and assess their impact on blood flow. The VR space's collaborative and interactive planning enhanced the baffle planning process. This study highlights the potential of VR as a valuable tool in baffle planning for CHD. The findings demonstrate the feasibility of using patient-specific 3D heart models and a user-friendly VR interface to enhance surgical planning and patient outcomes. Further research and development in this field are warranted to harness the full benefits of VR technology in CHD surgical management.

Diagnostic performance of artificial intelligence for pediatric pulmonary nodule detection on chest computed tomography: comparison of simulated lower radiation doses

The combination of low dose CT and AI performance in the pediatric population has not been explored. Understanding this relationship is relevant for pediatric patients given the potential radiation risks. Here, the objective was to determine the diagnostic performance of commercially available Computer Aided Detection (CAD) for pulmonary nodules in pediatric patients at simulated lower radiation doses. Retrospective chart review of 30 sequential patients between 12-18 years old who underwent a chest CT on the Siemens SOMATOM Force from December 20, 2021, to April 12, 2022. Simulated lower doses at 75%, 50%, and 25% were reconstructed in lung kernel at 3 mm slice thickness using ReconCT and imported to Syngo CT Lung CAD software for analysis. Two pediatric radiologists reviewed the full dose CTs to determine the reference read. Two other pediatric radiologists compared the Lung CAD results at 100% dose and each simulated lower dose level to the reference on a nodule by nodule basis. The sensitivity (Sn), positive predictive value (PPV), and McNemar test were used for comparison of Lung CAD performance based on dose. As reference standard, 109 nodules were identified by the two radiologists. At 100%, and simulated 75%, 50%, and 25% doses, lung CAD detected 60, 62, 58, and 62 nodules, respectively; 28, 28, 29, and 26 were true positive (Sn = 26%, 26%, 27%, 24%), 30, 32, 27, and 34 were false positive (PPV = 48%, 47%, 52%, 43%). No statistically significance difference of Lung CAD performance at different doses was found, with p-values of 1.0, 1.0, and 0.7 at simulated 75%, 50%, and 25% doses compared to standard dose.

CONCLUSION

The Lung CAD shows low sensitivity at all simulated lower doses for the detection of pulmonary nodules in this pediatric population. However, radiation dose may be reduced from standard without further compromise to the Lung CAD performance.

WHAT IS KNOWN

• High diagnostic performance of Lung CAD for detection of pulmonary nodules in adults. • Several imaging techniques are applied to reduce pediatric radiation dose.

WHAT IS NEW

• Low sensitivity at all simulated lower doses for the detection of pulmonary nodules in our pediatric population. • Radiation dose may be reduced from standard without further compromise to the Lung CAD performance.

Implementation of AI image reconstruction in CT-how is it validated and what dose reductions can be achieved

CT reconstruction has undergone a substantial change over the last decade with the introduction of iterative reconstruction (IR) and now with deep learning reconstruction (DLR). In this review, DLR will be compared to IR and filtered back-projection (FBP) reconstructions. Comparisons will be made using image quality metrics such as noise power spectrum, contrast-dependent task-based transfer function, and non-prewhitening filter detectability index (dNPW'). Discussion on how DLR has impacted CT image quality, low-contrast detectability, and diagnostic confidence will be provided. DLR has shown the ability to improve in areas that IR is lacking, namely: noise magnitude reduction does not alter noise texture to the degree that IR did, and the noise texture found in DLR is more aligned with noise texture of an FBP reconstruction. Additionally, the dose reduction potential for DLR is shown to be greater than IR. For IR, the consensus was dose reduction should be limited to no more than 15-30% to preserve low-contrast detectability. For DLR, initial phantom and patient observer studies have shown acceptable dose reduction between 44 and 83% for both low- and high-contrast object detectability tasks. Ultimately, DLR is able to be used for CT reconstruction in place of IR, making it an easy "turnkey" upgrade for CT reconstruction. DLR for CT is actively being improved as more vendor options are being developed and current DLR options are being enhanced with second generation algorithms being released. DLR is still in its developmental early stages, but is shown to be a promising future for CT reconstruction.

Can magnetic resonance imaging replace computed tomography scans in the evaluation of pediatric post-appendectomy abscess?

BACKGROUND

Computed tomography scans have been used when cross-axial imaging is required to evaluate pediatric post-appendectomy abscesses. To reduce a source of radiation exposure, our institution converted to using contrast-enhanced magnetic resonance imaging to replace computed tomography scans in this clinical context. Our aim is to evaluate the performance of magnetic resonance imaging compared to computed tomography scans and associated clinical outcomes in this patient population.

METHODS

A contrast-enhanced comprehensive magnetic resonance imaging protocol was implemented to evaluate a post-appendectomy abscess in 2018. A retrospective chart review was performed from 2015 to 2022 for pediatric patients (<18 years old) with prior appendectomy and subsequent cross-sectional imaging to evaluate for an intraabdominal abscess. Patient characteristics and clinical parameters between the 2 modalities were abstracted and compared using standard univariate statistics.

RESULTS

There were a total of 72 post-appendectomy patients who received cross-axial imaging, which included 43 computed tomography scans and 29 magnetic resonance imaging during the study interval. Patient demographics were comparable between cohorts and rates of perforated appendicitis at the index operation (computed tomography: 79.1% vs magnetic resonance imaging: 86.2%). Missed abscess rate, abscess size, management technique, drainage culture results, readmission, and reoperation were similar between imaging modalities. Median request to scan time was longer for magnetic resonance imaging than computed tomography (191.5 vs 108 minutes, P = .04). The median duration of a comprehensive magnetic resonance imaging scan was 32 minutes (interquartile range 28-50.5 minutes).

CONCLUSION

Contrast-enhanced magnetic resonance imaging provides an alternative cross-sectional imaging modality to computed tomography scans to evaluate pediatric post-appendectomy abscesses.

An Overview on the Alignment of Radiation Protection in Computed Tomography with Maqasid al-Shari'ah in the Context of al-Dharuriyat

The increasing utilisation of computed tomography (CT) in the medical field has raised a greater concern regarding the radiation-induced health effects as CT imposes high radiation risks on the exposed individual. Adherence to radiation protection measures in CT as endorsed by regulatory bodies; justification, optimisation and dose limit, is essential to minimise radiation risks. Islam values every human being and Maqasid al-Shari'ah helps to protect human beings through its sacred principles which aim to fulfil human beings' benefits (maslahah) and prevent mischief (mafsadah). Alignment of the concept of radiation protection in CT within the framework of al-Dharuriyat; protection of faith or religion (din), protection of life (nafs), protection of lineage (nasl), protection of intellect ('aql) and protection of property (mal) is essential. This strengthens the concept and practices of radiation protection in CT among radiology personnel, particularly Muslim radiographers. The alignment provides supplementary knowledge towards the integration of knowledge fields between Islamic worldview and radiation protection in medical imaging, particularly in CT. This paper is hoped to set a benchmark for future studies on the integration of knowledge between the Islamic worldview and radiation protection in medical imaging in terms of other classifications of Maqasid al-Shari'ah; al-Hajiyat and al-Tahsiniyat.

Dual-phase computed tomography for localization of parathyroid lesions in children and adolescents with primary hyperparathyroidism

BACKGROUND

Childhood and adolescent primary hyperparathyroidism (PHPT) is a rare disease caused by single adenomas in 65-94% of patients. In this patient group, there is no data on computed tomography (CT) for pre-operative parathyroid localization that may facilitate focused parathyroidectomy.

METHODS

Two radiologists reviewed dual-phase (nonenhanced and arterial) CT images of twenty-three operated children and adolescents [20:single-gland disease(SGD), 3:multi-glandular disease(MGD)] with proven histopathological PHPT. Percentage arterial enhancement (PAE) was calculated as [100*{arterial-phase Hounsfield unit (HU)-nonenhanced phase HU}/nonenhanced HU] of the parathyroid lesion(s), thyroid, and lymph node.

RESULTS

Dual-phase CT lateralized 100%, localized to the correct quadrant/site 85% SGD (including 3/3 ectopic), and identified 1/3 MGD. PAE (cutoff ≥ 112.3%) was sensitive (91.3%) and specific (99.5%) in distinguishing parathyroid lesions from local mimics (P<0.001). The average effective dose was 3.16±1.01mSv, comparable to the planar/single photon emission CT (SPECT) Technetium 99m(Tc)-sestamibi and choline positron emission tomography (PET)/CT scans. Solid-cystic morphology identified in 4 patients harboring pathogenic germline variants (3:CDC73, 1:CASR) may serve as a radiological clue to molecular diagnosis. Nineteen out of 20 (95%) patients with SGD who had undergone single gland resection based on pre-operative CT findings were in remission over a median follow-up of 18 months.

CONCLUSION

As most children/adolescents with PHPT have SGD, dual-phase CT protocols which reduce the effective radiation dose with high localization sensitivity for single parathyroid lesions may be a sustainable pre-operative imaging modality in this patient group.

Variation in NICU Head CT Utilization Among U.S. Children's Hospitals

OBJECTIVES

Evaluate nationwide 12-year trend and hospital-level variation in head computed tomography (CT) utilization among infants admitted to pediatric hospital NICUs. We hypothesized there was significant variation in utilization.

METHODS

We conducted a retrospective cohort study examining head CT utilization for infants admitted to the NICU within 31 United States children's hospitals within the Pediatric Health Information System database between 2010 and 2021. Mixed effects logistic regression was used to estimate head CT, head MRI, and head ultrasound utilization (% of admissions) by year. Risk-adjusted hospital head CT rates were examined within the 2021 cohort.

RESULTS

Between 2010 and 2021, there were 338 644 NICU admissions, of which 10 052 included head CT (3.0%). Overall, head CT utilization decreased (4.9% in 2010 to 2.6% in 2021, P < .0001), with a concomitant increase in head MRI (12.1% to 18.7%, P < .0001) and head ultrasound (41.3% to 43.4%, P < .0001) utilization. In 2021, significant variation in risk-adjusted head CT utilization was noted across centers, with hospital head CT rates ranging from 0% to 10% of admissions. Greatest hospital-level variation was noted for patients with codes for seizure or encephalopathy (hospital head CT rate interquartile range [IQR] = 11.6%; 50th percentile = 12.0%), ventriculoperitoneal shunt (IQR = 10.8%; 50th percentile = 15.4%), and infection (IQR = 10.1%; 50th percentile = 7.5%).

CONCLUSIONS

Head CT utilization within pediatric hospital NICUs has declined over the past 12-years, but substantial hospital-level variation remains. Development of CT stewardship guidelines may help decrease variation and reduce infant radiation exposure.

Imaging of Right Lower Quadrant Pain in Children and Adolescents: AJR Expert Panel Narrative Review

Right lower quadrant (RLQ) pain is a common clinical presentation in children, and accurate clinical diagnosis remains challenging given that this nonspecific presentation is associated with numerous surgical and nonsurgical conditions. The broad differential diagnosis varies by patient age and sex. Important considerations in the selection of a diagnostic imaging strategy include the sequencing, performance, and cost of tests. This article provides a comprehensive narrative review of the diagnostic imaging of RLQ pain in children and adolescents, including a discussion of the complementary roles of ultrasound, CT, and MRI; description of key imaging findings based on available evidence; and presentation of salient differential diagnoses. Subspecialized pediatric emergency medicine and surgical perspectives are also provided as further clinical insight into this common, but often challenging, scenario. Finally, the current status of imaging of RLQ pain in children and adolescents is summarized on the basis of expert consensus.

Towards the establishment of national diagnostic reference levels in Tunisia: a multicentre survey in paediatric CT

This work focuses on the determination of the radiation doses for a total sample of 916 children, categorised into four age groups (<1, 1-5, <5-10, <10-15 years) undergoing the most frequent paediatric CT scans performed in different scan facilities in Tunisia in order to establish the national diagnostic reference levels (DRLs). Dose evaluation concerned the dosimetric indicators: volume computed tomography dose index (CTDI_vol)and dose-length product (DLP). The different paediatric CT protocols and practices were also evaluated. The results show a large variation in doses between different radiology departments. For head scans, the respective DRLs for children aged <1, 1-5, 5-10 and 10-15 years were 26, 38, 51 and 51 mGy, respectively, for CTDI_voland 384, 664, 873 and 978 mGy cm, respectively, for DLP. For the chest, the equivalent respective DRLs were 8, 10, 12 and 15 mGy for CTDI_voland 118, 330, 442 and 526 mGy cm for DLP. For the abdomen, the respective DRLs were 9, 13, 19 and 18 mGy for CTDI_voland 353, 485, 592 and 1073 mGy cm for DLP. This study shows that the optimisation of paediatric CT procedures should be a priority, especially within regional hospitals. The implementation of corrective actions will take place after the initial DRLs. These actions, including recommendations and guidelines to good practice, should be a joint effort of all stakeholders, including health authorities, the radiation protection regulator, professional societies and universities.

Denoising of pediatric low dose abdominal CT using deep learning based algorithm

OBJECTIVES

To evaluate standard dose-like computed tomography (CT) images generated by a deep learning method, trained using unpaired low-dose CT (LDCT) and standard-dose CT (SDCT) images.

MATERIALS AND METHODS

LDCT (80 kVp, 100 mAs, n = 83) and SDCT (120 kVp, 200 mAs, n = 42) images were divided into training (42 LDCT and 42 SDCT) and validation (41 LDCT) sets. A generative adversarial network framework was used to train unpaired datasets. The trained deep learning method generated virtual SDCT images (VIs) from the original LDCT images (OIs). To test the proposed method, LDCT images (80 kVp, 262 mAs, n = 33) were collected from another CT scanner using iterative reconstruction (IR). Image analyses were performed to evaluate the qualities of VIs in the validation set and to compare the performance of deep learning and IR in the test set.

RESULTS

The noise of the VIs was the lowest in both validation and test sets (all p<0.001). The mean CT number of the VIs for the portal vein and liver was lower than that of OIs in both validation and test sets (all p<0.001) and was similar to those of SDCT. The contrast-to-noise ratio of portal vein and the signal-to-noise ratio (SNR) of portal vein and liver of VIs were higher than those of SDCT (all p<0.05). The SNR of VIs in test sets was the highest among three images.

CONCLUSION

The deep learning method trained by unpaired datasets could reduce noise of LDCT images and showed similar performance to SAFIRE. It can be applied to LDCT images of older CT scanners without IR.

An audit of computed tomography request practices for suspected cervical spine injury post‐guideline change in a tertiary referral paediatric hospital

BACKGROUND

Paediatric neck injuries are a common presenting complaint to emergency departments (EDs). Medical imaging can assist diagnosis, however previous research suggests computed tomography (CT) scan results do not alter management in this patient group and therefore expose children to unnecessary radiation. Following an audit by the hospital Trauma Service that identified unnecessary cervical spine CTs in patients at Women's and Children's Hospital (WCH), Adelaide, the Clinical Procedure for imaging and clearance of the cervical spine in conscious patients was modified to include CT scan only at the request of the orthopaedic service. The aim of this study was to evaluate whether a change in hospital guideline resulted in a change in practice and radiation exposure.

METHODS

A retrospective review was performed for patients that presented to the WCH ED with a suspected cervical spine injury during two defined time periods pre- and post-guideline change. Mechanism of injury, imaging requested, radiation exposure and final diagnosis were compared.

RESULTS

Three hundred seventy-nine patients were included, with 164 (43.3%) post-guideline changes. Radiograph use was similar between groups, 132/215 (61.4%) versus 101/164 (61.6%) (p = 0.97). CT scan use was lower post-guideline modification 19/215 (8.8%) versus 12/164 (7.3%), however was not statistically significant (p = 0.59), with an absolute reduction of 17%.

CONCLUSION

Guideline modification at our hospital did not significantly reduce CT scan use or eliminate unnecessary CTs. Unnecessary CT scans followed lack of knowledge of and therefore compliance with guidelines. Individual hospitals should consider strategies to reduce unnecessary CTs, given the association with cancer risk in children.

Radiation dose levels of thoracic-lumbar spine CT in pediatric trauma patients and assessment of scan parameters for dose optimization

BACKGROUND

CT is frequently used for assessing spinal trauma in children.

OBJECTIVE

To establish the local diagnostic reference levels of spine CT examinations in pediatric spinal trauma patients and analyze scan parameters to enable dose optimization.

MATERIALS AND METHODS

In this retrospective study, we included 192 pediatric spinal trauma patients who underwent spine CT. Children were divided into two age groups: 0-10 years (group 1) and 11-17 years (group 2). Each group was subdivided into thoracic, thoracolumbar and lumbar CT groups. CT acquisition parameters (tube potential, in kilovoltage [kV]; mean tube current-time product, in milliamperes [mAs]; reference mAs; collimated slice width; tube rotation time; pitch; scan length) and radiation dose descriptors (volume CT dose index [CTDI_vol] and dose-length product [DLP]) were recorded. The CTDI_vol and DLP values of spine CTs obtained with different tube potential and collimated slice width values were compared for each group.

RESULTS

CTDI_vol and DLP values of thoracolumbar spine CTs in group 1 and lumbar spine CTs in group 2 were significantly lower in CTs acquired with low tube potential levels (P<0.05). CTDI_vol and DLP values of thoracolumbar spine CTs in both groups and lumbar spine CTs in group 2 acquired with high collimated slice width values were significantly lower than in corresponding CTs acquired with low collimated slice width values (P<0.05).

CONCLUSION

Pediatric spine CT radiation doses can be notably reduced from the manufacturers' default protocols while preserving image quality.

Feasibility of Pediatric Low-Dose Facial CT Reconstructed with Filtered Back Projection Using Adequate Kernels

Purpose

Materials and Methods

Results

Conclusion

Multi-detector computed tomography in traumatic abdominal lesions: value and radiation control

Background, The context

A prospective study was conducted involving 81 patients (mean age, 20.79 years) with abdominal trauma who underwent ultrasonography and post-contrast CT on MDCT scanner. The total DLP for each patient was reviewed, and the effective dose was calculated. Purpose of the study to: explore the role of MDCT in assessing traumatic abdominal lesions, demonstrate radiation dose delivered by MDCT, and describe specific CT technical features to minimize radiation.

Results

The spleen was the most commonly injured organ (49.4%) followed by liver (39.5%) and kidney (24.7%). Pancreatic injury occurred in seven patients, whereas only two patients had intestinal injuries. One patient had adrenal injury. Minimal, mild and moderate free intra-peritoneal fluid collection was detected in 21 (25.9%), 47 (58%) and 10 (12.3%) patients, respectively. Only three (3.7%) patients had no collection. One patient had active uncontrolled bleeding and died. Radiation dose was below the detrimental level (calculated effective dose), with optimal image quality.

Conclusions

MDCT is sensitive to all types of traumatic abdominal lesions. Not only in determining the injury, but also in its grading. MDCT has affected the treatment directions, spotting a focus on conservative treatment by raising the diagnostic confidence. FAST cannot be the sole imaging modality. The individual radiation risk is small but real. Advancements in medical imaging reduce radiation risk.

SIMPLE METHOD OF MEASURING SSDE FOR HEAD CT: FACILITATING PRE-CT SCAN DOSE CALCULATION USING SPECIALIZED HEAD SCAN BAND

In this study, scaled scan band was developed to provide size-specific dose estimation (SSDE) values based on head circumference of patients undergoing computed tomography (CT) scans. The scan band was tested in 40 consecutive head CT examinations. The accuracy of the specialized scan band method was determined by comparing SSDEband with SSDE293,forehead, SSDEmean and SSDEcenter. SSDE293,forehead was used as the control value. The results of the linear fit of SSDEband, SSDEmean and SSDEcenter against SSDE293, forehead, were R2 = 0.958, R2 = 0.984 and R2 = 0.936, respectively. There was no significant difference between SSDEband, SSDEmean and SSDEcenter for SSDE293,forehead. Use of the proposed scan band method makes it possible to accurately determine the required radiation dose before a CT examination is performed.

Diagnostic reference levels for computed tomography examinations in pediatric population - A systematic review

Computed tomography (CT) has vital role in diagnosis of various pathologies using cross sectional images. Besides the advantages of CT in pediatric radiology, radiation dose has a significant adverse effect as children are more vulnerable than adults. Establishing Diagnostic Reference levels (DRLs) will determine unusual increase in radiation doses and therefore helps in optimizing the radiation dose by maintaining optimum diagnostic image quality. The objective of the review is to explore the literature on DRLs in pediatric CT examinations and techniques that have been used to establish them. Detailed search was done in PubMed-Medline, Scopus CINAHL, Web of Science, and the Cochrane Library databases to find studies that have established DRLs for pediatric CT examinations. The Preferred Reporting Items for Systematic Review and Meta-Analyses methodology was used to assess the relevant articles. The articles which assessed DRLs in pediatric CT examinations were included. A total of 501 articles were identified, of which 21 articles were included after a detailed screening process. Our review showed increased in pediatric patient dose surveys across the world and also increased in awareness for establishing DRLS among pediatric CT examinations. The review also demonstrated wide variation in DRLs and also deviation in the scanning techniques, protocols used and categorization methods used for establishing DRLs. As the pediatric population is more sensitive to radiation, the current review emphasizes the need for optimization of protocols and international standardization for establishing DRLs to facilitate a more feasible way of comparison of dose globally across CT sites.

Transcranial ultrasonography as a reliable instrument for the measurement of the cerebral ventricles in rats with experimental hydrocephalus: a pilot study

PURPOSES

Demonstrate that transcranial ultrasonography (TUS) scanning is viable and useful as a diagnostic method in experimental hydrocephalus, as well as to compare measurements of cerebral and ventricular width obtained from TUS scans of hydrocephalic rats with post-mortem anatomical specimens, aiming for the development of accurate criteria to establish ventricular enlargement and progression of hydrocephalus subsequently.

METHODS

Thirty-five male Wistar rats were used. Following hydrocephalus induction, they underwent a transcranial ultrasound scan to measure cerebral and ventricular dimensions, in the fourth and 21 post-induction days. By the end of the experiments, measurements obtained from TUS scans were compared with actual values as seen in the post-mortem specimens of each animal.

RESULTS

Ventricular dilation could be clearly visualized in hydrocephalic animals. We performed intraclass correlation coefficient and linear regression analyses that have demonstrated a precise correlation between measurements of TUS scans and post-mortem specimens; we have found a similarity of 0,95 for the cerebral diameter and 0,97 for ventricular width.

CONCLUSIONS

Transcranial ultrasonography is a useful and reliable diagnostic tool for experimental hydrocephalus; also, it can be used to assess the progression of ventriculomegaly in animal models of hydrocephalus.

Cumulative diagnostic imaging radiation exposure in premature neonates

BACKGROUND

To date, there has been limited work evaluating the total cumulative effective radiation dose received by infants in the neonatal intensive care unit. Most previous publications report that the total radiation dose received falls within the safe limits but does not include all types of ionizing radiation studies typically performed on this vulnerable patient population. We aimed to provide an estimate of the cumulative effective ionizing radiation dose (cED) in microSieverts (μSv) received by premature infants ≤32 weeks from diagnostic studies performed throughout their NICU stay, and predictors of exposures.

METHODS

Retrospective chart review from 2004-2011. Data included demographics, gestational age (GA), birth weight (BW), length of stay (LOS), clinical diagnosis, and radiological studies.

RESULTS

1045 charts were reviewed. Median GA = 30.0 weeks (SD 2.7, range 22.0-32.6). Median BW = 1340.0 grams (SD 445.4, range 420-2470). Median number of radiographic studies = 9 (SD 28.5, range 0-210). Median cED = 162μSv (range 0-9248). The cED was positively associated with LOS (p <  0.001) and inversely correlated with GA (p <  0.001) and BW (p <  0.001). Infants with intestinal perforation had the highest median cED 1661μSv compared to 162μSv for others (p <  0.001).

CONCLUSION

Our results provide an estimate of the cumulative effective radiation dose received by premature infants in a level 4 neonatal intensive care unit from all radiological studies involving ionizing radiation and identifies risk factors and predictors of such exposure. Radiation exposure in NICU is highest among the most premature and among infants who suffer from intestinal perforation.

Radiation use in diagnostic imaging in children: approaching the value of the pediatric radiology community

Medical imaging is foundational in the care of children, and much of the medical imaging province depends on ionizing radiation: radiography, fluoroscopy, CT and nuclear imaging. Many considerations for this imaging in children are distinct in the domains of appropriate radiation use, other factors that determine examination quality, the opportunities to engage and educate through networking, and the translation of research efforts. Given these needs, it is worth approaching the contributions and their impact by the pediatric radiology community, especially to the enhancement of this value in the care of children.

The diagnostic performance of chest computed tomography in the detection of rib fractures in children investigated for suspected physical abuse: a systematic review and meta-analysis

Objectives

To assess the diagnostic performance of chest CT in the detection of rib fractures in children investigated for suspected physical abuse (SPA).

Methods

Medline, Web of Science and Cochrane databases were searched from January 1980 to April 2020. The QUADAS-2 tool was used to assess the quality of the eligible English-only studies following which a formal narrative synthesis was constructed. Studies reporting true-positive, false-positive, true-negative, and false-negative results were included in the meta-analysis. Overall sensitivity and specificity of chest CT for rib fracture detection were calculated, irrespective of fracture location, and were pooled using a univariate random-effects meta-analysis. The diagnostic accuracy of specific locations along the rib arc (anterior, lateral or posterior) was assessed separately.

Results

Of 242 identified studies, 4 met the inclusion criteria. Of these, 2 were included in the meta-analysis. Chest CT identified 142 rib fractures compared to 79 detected by initial skeletal survey chest radiographs in live children with SPA. Post-mortem CT (PMCT) has low sensitivity (34%) but high specificity (99%) in the detection of rib fractures when compared to the autopsy reference standard. PMCT has low sensitivity (45%, 21% and 42%) but high specificity (99%, 97% and 99%) at anterior, lateral and posterior rib locations, respectively.

Conclusions

Chest CT detects more rib fractures than initial skeletal survey chest radiographs in live children with SPA. PMCT has low sensitivity but high specificity for detecting rib fractures in children investigated for SPA.

Key Points

• PMCT has low sensitivity (34%) but high specificity (99%) in the detection of rib fractures; extrapolation to CT in live children is difficult.

• No studies have compared chest CT with the current accepted practice of initial and follow-up skeletal survey chest radiographs in the detection of rib fractures in live children investigated for SPA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-07775-3.

Evaluation of Organ Doses for Pediatric Computed Tomography Using a Newly Designed Radiophotoluminescence Glass Dosimeter and Comparison with a Monte Carlo Simulation-based Dose Calculator

ABSTRACT

Management of patient dose is an effective way to help optimize computed tomography (CT) scanning conditions and CT dose. Organ dose is one of the preferred quantities for radiation protection because of its correlation with radiation risk. To date, the WAZA-ARI dose calculator is the only freely available CT dose calculator also applicable for pediatric patients. However, no reports of its evaluation have appeared since the latest version of WAZA-ARI was released. In this study, to evaluate the latest version of WAZA-ARI, we measured the organ dose in a 5-y-old anthropomorphic phantom by a newly developed radiophotoluminescence glass dosimeter (RGD) dosimetry system and compared these results with the calculation results from WAZA-ARI. The newly designed RGDs have less angular dependence because of the additional filter. RGDs were individually calibrated with the ISOVOLT TITAN-320 x-ray generator. All the experimental measurements for this study were performed using a CT scanner. To consider the difference of CT output between the nominal and actual machine, the measured CTDIair was used to correct the calculation results obtained from WAZA-ARI. After the corrections using the measured CTDIair, the calculation results from WAZA-ARI were relatively lower than the measured results with a range of 8-20%, which corresponds to the dose difference caused by the difference in effective diameter. In conclusion, the calculation accuracy of WAZA-ARI is guaranteed when the normalization factor specific to each CT scanner (CTDIair) and the shape of the phantom are taken into consideration.

Radiation dose evaluation of pediatric patients in CT brain examination: multi-center study

There is currently no Pediatric Regulatory Diagnostic Reference Level (DRL) in Cameroon to standardize protocols in hospitals. France, a European country, has DRL allowing them to optimize their examination protocol. For the sake of radiation protection, we have proposed to evaluate the dose and acquisition parameters delivered to our pediatric patients to optimize the protocols used. We also compared the 75th percentile values of dose parameters by acquisition between the three hospitals to Diagnostic Reference Level (DRL) of France. In this retrospective and evaluative multicenter study, a total of 320 patients who had at least one cranial CT scan were enrolled from three medical centers. The CT acquisition parameters including tube potential (kV), tube current (mA), slice Thickness (T), spiral or sequential scanning techniques, volume CT dose index (CTDIvol), and dose length product (DLP) were analyzed. CTDIvol values in our centers were found up to 17.42%, 46.01%, 21.56% respectively for children aged 1-4 higher than values of France's DRL. For those aged 5-9, we obtained 44.58%, 43.15%, 42.21% respectively. In addition, for children aged 10-14 there are also up to 47.73%, 44.11%, 46.39% respectively higher than values of France's DRL. It is similary for DLP values. The study showed a significant dosimetric overshoot compared to the France's DRL and prompted us to make corrections to the protocols used and to a more rigorous monitoring of the principles of radiation protection and optimization rules in pediatric computed tomography in our hospitals. Our results have led us to make changes to our protocols which are the subject of a new dosimetric evaluation. The development of DRL for improving the pediatric CT scan in our country is necessary to optimize our protocols. Our results have led us to make changes to our protocols which are the subject of a new dosimetric evaluation. It would be necessary to set up a quality control structure in Cameroon and their applications in current practice.

PATIENT-SPECIFIC ORGAN DOSES FROM PEDIATRIC HEAD CT EXAMINATIONS

The aim of this work was to estimate patient's organ absorbed doses from pediatric helical head computed tomography (CT) examinations using the Size-Specific Dose Estimate (SSDE) methodology and to determine organ dose to SSDE conversion coefficients for clinical routine. Patient-specific organ and tissue absorbed doses from 139 Head CT scans performed in pediatric patients from 0 to 15 years old in a Public Hospital in Tunja, Colombia were estimated. The calculations were made through Monte Carlo simulations, based on patient-specific information, dosimetric CT quantities (CTDIvol, DLP) and age-specific computational human phantoms matched to patients on the basis of gender and size. SSDE showed to be a good quantity for estimate patient-specific organ doses from pediatric head CT examinations when appropriate phantom's attenuation-based size metrics are chosen to match for any patient size. Strong correlations between absorbed dose and SSDE were found for skin (R2 = 0.99), brain (R2 = 0.98) and eyes (R2 = 0.97), respectively. Besides, a good correlation between SSDE and absorbed dose to the red bone marrow (tissue extended outside the scan coverage) was observed (R2 = 0.94). SSDE-to-organ-dose conversion coefficients obtained in this study provide a practical way to estimate patient-specific organ head CT doses.

Evaluation of Impact of Factors Affecting CT Radiation Dose for Optimizing Patient Dose Levels

The dose metrics and factors influencing radiation exposure for patients undergoing head, chest, and abdominal computed tomography (CT) scans were investigated for optimization of patient dose levels. The local diagnostic reference levels (DRLs) of adult CT scans performed in our hospital were established based on 28,147 consecutive examinations, including 5510 head scans, 9091 chest scans, and 13,526 abdominal scans. Among the six CT scanners used in our hospital, four of them are 64-slice multi-detector CT units (MDCT64), and the other two have detector slices higher than 64 (MDCTH). Multivariate analysis was conducted to evaluate the effects of body size, kVp, mAs, and pitch on volume CT dose index (CTDIvol). The local DRLs expressed in terms of the 75th percentile of CTDIvol for the head, chest, and abdominal scans performed on MDCT64 were 59.32, 9.24, and 10.64 mGy, respectively. The corresponding results for MDCTH were 57.90, 7.67, and 9.86 mGy. In regard to multivariate analysis, CTDIvol showed various dependence on the predictors investigated in this study. All regression relationships have coefficient of determination (R2) larger than 0.75, indicating a good fit to the data. Overall, the research results obtained through our workflow could facilitate the modification of CT imaging procedures once the local DRLs are unusually high compared to the national DRLs.

Existing and emerging methods of diagnosis and monitoring of pediatric musculoskeletal infection

Methods of diagnosing and monitoring pediatric musculoskeletal infections are rapidly evolving. Key serologic tests are typically used in screening patients with suspected infections, and remain an integral part of the initial work-up. Synovial studies from arthrocentesis in possible septic arthritis, and source-specific cultures have been the foundation of our treatment algorithm. Given the prevalence of soft tissue abscesses and osteoarticular infections, advanced imaging is an advantageous tool. More affordable use and expanded access to MRI has made it a valuable adjunct to clinical picture and existing tests in order to comprehensively visualize the extent of musculoskeletal infections in children. Ongoing validation for criteria to help determine the patients that stand to benefit the most from MRI, even when surgical intervention may be delayed, remains of significant clinical interest. Given the rates of culture-negative infections, and the need for timely diagnosis, new diagnostic techniques are always being considered. The search for more accurate biomarkers, and technology such as Whole genome sequencing (WGS) and next-generation sequencing (NGS) that can rapidly identify pathogens of all types of phyla based on a small sample of DNA, has promising clinical implications. While once novel and prohibitively expensive, these tests are now being applied in university and tertiary care centers in certain scenarios. Applying these techniques to pediatric musculoskeletal will require a large change in lab workflow and training. However, the benefits of acquiring diagnostic information along with will make them a superior tool in our arsenal of diagnostic tests.

Diagnostic Reference Level of Radiation Dose and Image Quality among Paediatric CT Examinations in A Tertiary Hospital in Malaysia

Pediatrics are more vulnerable to radiation and are prone to dose compared to adults, requiring more attention to computed tomography (CT) optimization. Hence, diagnostic reference levels (DRLs) have been implemented as part of optimization process in order to monitor CT dose and diagnostic quality. The noise index has recently been endorsed to be included as a part of CT optimization in the DRLs report. In this study, we have therefore set local DRLs for pediatric CT examination with a noise index as an indicator of image quality. One thousand one hundred and ninety-two (1192) paediatric patients undergoing CT brain, CT thorax and CT chest-abdomen-pelvis (CAP) examinations were analyzed retrospectively and categorized into four age groups; group 1 (0-1 year), group 2 (1-5 years), group 3 (5-10 years) and group 4 (10-15 years). For each group, data such as the volume-weighted CT dose index (CTDIvol), dose-length product (DLP) and the effective dose (E) were calculated and DRLs for each age group set at 50th percentile were determined. Both CT dose and image noise values between age groups have differed significantly with p-value < 0.05. The highest CTDIvol and DLP values in all age groups with the lowest noise index value reported in the 10-15 age group were found in CT brain examination. In conclusion, there was a significant variation in doses and noise intensity among children of different ages, and the need to change specific parameters to fit the clinical requirement.

Application of Vendor-Neutral Iterative Reconstruction Technique to Pediatric Abdominal Computed Tomography

Objective

To compare image qualities between vendor-neutral and vendor-specific hybrid iterative reconstruction (IR) techniques for abdominopelvic computed tomography (CT) in young patients.

Materials and Methods

In phantom study, we used an anthropomorphic pediatric phantom, age-equivalent to 5-year-old, and reconstructed CT data using traditional filtered back projection (FBP), vendor-specific and vendor-neutral IR techniques (ClariCT; ClariPI) in various radiation doses. Noise, low-contrast detectability and subjective spatial resolution were compared between FBP, vendor-specific (i.e., iDose1 to 5; Philips Healthcare), and vendor-neutral (i.e., ClariCT1 to 5) IR techniques in phantom. In 43 patients (median, 14 years; age range 1–19 years), noise, contrast-to-noise ratio (CNR), and qualitative image quality scores of abdominopelvic CT were compared between FBP, iDose level 4 (iDose4), and ClariCT level 2 (ClariCT2), which showed most similar image quality to clinically used vendor-specific IR images (i.e., iDose4) in phantom study. Noise, CNR, and qualitative imaging scores were compared using one-way repeated measure analysis of variance.

Results

In phantom study, ClariCT2 showed noise level similar to iDose4 (14.68–7.66 Hounsfield unit [HU] vs. 14.78–6.99 HU at CT dose index volume range of 0.8–3.8 mGy). Subjective low-contrast detectability and spatial resolution were similar between ClariCT2 and iDose4. In clinical study, ClariCT2 was equivalent to iDose4 for noise (14.26–17.33 vs. 16.01–18.90) and CNR (3.55–5.24 vs. 3.20–4.60) (p > 0.05). For qualitative imaging scores, the overall image quality ([reader 1, reader 2]; 2.74 vs. 2.07, 3.02 vs. 2.28) and noise (2.88 vs. 2.23, 2.93 vs. 2.33) of ClariCT2 were superior to those of FBP (p < 0.05), and not different from those of iDose4 (2.74 vs. 2.72, 3.02 vs. 2.98; 2.88 vs. 2.77, 2.93 vs. 2.86) (p > 0.05).

Conclusion

Vendor-neutral IR technique shows image quality similar to that of clinically used vendor-specific hybrid IR technique for abdominopelvic CT in young patients.

Pediatric Thyroid Cancer Incidence and Mortality Trends in the United States, 1973-2013

Importance

The incidence of thyroid cancer is increasing by 3% annually. This increase is often thought to be attributable to overdiagnosis in adults. A previous study reported a 1.1% annual increase in the incidence of pediatric thyroid cancer. However, the analysis was limited to the period from 1973 to 2004 and was performed in a linear fashion, which does not account for changes in incidence trends over time.

Objective

To analyze trends in pediatric thyroid cancer incidence based on demographic and tumor characteristics at diagnosis.

Design, Setting, and Participants

This cross-sectional study included individuals younger than 20 years who had a diagnosis of thyroid cancer in the Surveillance, Epidemiology, and End Results (SEER) 9 database from 1973 to 2013. Cases of thyroid cancer were identified using the International Classification of Diseases for Oncology, Third Edition and were categorized by histologic type, stage, and tumor size.

Main Outcomes and Measures

Annual percent change (APC) in the incidence rates was calculated using joinpoint regression analysis.

Results

Among 1806 patients included in the analysis, 1454 (80.5%) were female and 1503 (83.2%) were white; most patients were aged 15 to 19 years. The overall incidence rates of thyroid cancer increased annually from 0.48 per 100 000 person-years in 1973 to 1.14 per 100 000 person-years in 2013. Incidence rates gradually increased from 1973 to 2006 (APC, 1.11%; 95% CI, 0.56%-1.67%) and then markedly increased from 2006 to 2013 (APC, 9.56%; 95% CI, 5.09%-14.22%). The incidence rates of large tumors (>20 mm) gradually increased from 1983 to 2006 (APC, 2.23%; 95% CI, 0.93%-3.54%) and then markedly increased from 2006 to 2013 (APC, 8.84%; 95% CI, 3.20%-14.79%); these rates were not significantly different from incidence rates of small (1-20 mm) tumors. The incidence rates of regionally extended thyroid cancer gradually increased from 1973 to 2006 (APC, 1.44%; 95% CI, 0.68%-2.21%) and then markedly increased from 2006 to 2013 (APC, 11.16%; 95% CI, 5.26%-17.40%); these rates were not significantly different from the incidence rates of localized disease.

Conclusions and Relevance

The incidence rates of pediatric thyroid cancer increased more rapidly from 2006 to 2013 than from 1973 to 2006. The findings suggest that there may be a co-occurring increase in thyroid cancer in the pediatric population in addition to enhanced detection.

Diagnostic Ultrasound Safety Review for Point-of-Care Ultrasound Practitioners

Potential ultrasound exposure safety issues are reviewed, with guidance for prudent use of point-of-care ultrasound (POCUS). Safety assurance begins with the training of POCUS practitioners in the generation and interpretation of diagnostically valid and clinically relevant images. Sonographers themselves should minimize patient exposure in accordance with the as-low-as-reasonably-achievable principle, particularly for the safety of the eye, lung, and fetus. This practice entails the reduction of output indices or the exposure duration, consistent with the acquisition of diagnostically definitive images. Informed adoption of POCUS worldwide promises a reduction of ionizing radiation risks, enhanced cost-effectiveness, and prompt diagnoses for optimal patient care.

Individualization of computed tomography protocols for suspected pulmonary embolism: a national investigation of routines

Objective

Given the extensive use of computed tomography (CT) in radiation-sensitive patients such as pregnant and pediatric patients, and considering the importance of tailoring CT protocols to patient characteristics for both the radiation dose and image quality, this study was performed to investigate the extent to which individualization of CT protocols is practiced across Norway.

Methods

This cross-sectional study involved collection of CT protocols and administration of a mini-questionnaire to obtain additional information about how CT examinations are individualized. All public hospitals performing CT to detect pulmonary embolism were invited, and 41% participated.

Results

Tailoring a standard protocol to different patient groups was more common than using dedicated protocols. Most of the available radiation dose-reduction approaches were used. However, implementation of these strategies was not systematic. Children and pregnant patients were examined without using dedicated CT protocols or by using protocol adjustments focusing on radiation dose reduction in 30% and 39% of the hospitals, respectively.

Conclusion

Practice optimization is needed, especially the development of dedicated CT protocols or guidelines that tailor the existing protocol to pediatric and pregnant patients. Practice might benefit from a more systematic approach to individualization of CT examinations, such as inserting tailoring instructions into CT protocols.

Correlation between age and head diameters in the paediatric patients during CT examination of the head

An estimate of patient dose, patient size should be used to normalise the output dose of CT machine in the terms of volume CT dose index, CTDIvol. There are two metrics to characterise the patient size, i.e. the effective diameter (Deff) and the water-equivalent diameter (Dw). These two metrics could be estimated by patient age. However, to date, relationships between the age and head patient size (Deff and Dw) have not been established for the pediatric patients. The aim of this study was to establish the relationships between the age and head patient size (Deff and the Dw) as the basis for calculating the size-specific dose estimate (SSDE) for paediatric head CT examination. The data were retrospectively collected from serial images of the CT head in the DICOM file from one hundred and thirteen paediatric patients aged 0-17 years (63 male and 50 female patients) underwent head CT examinations. The patient’s sizes (Deff and Dw) were calculated from the patient’s images using the IndoseCT version 15a software. The Deff and Dw values were correlated with age of patients using regression analysis. It was found that patient size (Deff and Dw) correlated well with the age of the patient with R2 more than 0.8. The size of the Dw is bigger than the Deff. The Deff values for male patients are 12.38 to 16.21 cm, and Dw values are 11.96 to 18.16 cm, respectively. For female patients, the values of Deff are from 11.54 to 16.87 cm, and the values of Dw are from 11.60 to 17.86 cm, respectively.

High-resolution computed tomography features of lung disease in perinatally HIV-infected adolescents on combined antiretroviral therapy

INTRODUCTION

Chronic lung disease is common in perinatally HIV-infected children as they increasingly surviving into adolescence. There are few data on the radiologic spectrum of disease in this population.

METHODS

Contrasted high-resolution computed tomography (HRCT) was performed in ambulatory South African adolescents enrolled in a prospective study of perinatally-infected adolescents aged 9 to 14 years established on combined antiretroviral therapy (cART) and followed for 36 months. Consecutive participants with reduced lung function (defined by a forced expiratory volume in 1 second [FEV1] of <80% normal and/or lung diffusion capacity [DLCO] <80% normal] underwent HRCT. History, clinical, and laboratory data were collected. Two radiologists blinded to clinical data and to each other, reported scans using standardized methodology; a third radiologist resolved discrepancies.

RESULTS

Amongst 100 participants undergoing HRCT, median age was 13.8 years (12.8-15.1). The median duration on cART was 8.4 years (IQR = 5.7-9.8). Mosaic attenuation was the most common finding (73%). Of these 71 (91%) demonstrated associated air trapping radiologically consistent with bronchiolitis obliterans. Bronchiectasis occurred in 39% with significant correlation between extent of bronchiectasis and mosaic attenuation (r = 0.57, P < .001). Prior hospitaliszation for childhood pneumonia at any time before enrollment was associated with mosaic attenuation (OR = 3.9, 95%CI, [1.2-12.5]); prior pulmonary tuberculosis (TB) was associated with the combination of mosaic attenuation and bronchiectasis (OR = 4.9, 95%CI, [1.6-15.7]). Most participants (86%) with mosaic attenuation had stage III or IV HIV disease at time of HIV diagnosis (OR = 3.6; [0.9-14.9]). Inter observer agreement between the two readers was good for bronchiectasis (K = 0.71) and moderate for mosaic attenuation (K = 0.51).

DISCUSSION

Despite well-controlled HIV and long duration of cART, HRCT changes were common in perinatally HIV-infected adolescents. There was a high prevalence of small airways disease with and without associated bronchiectasis. These changes were associated with prior pulmonary TB or prior severe pneumonia. Strategies to prevent and treat early life respiratory infection must be strengthened to reduce the burden of chronic lung disease in HIV-infected adolescents.

Radiation Dose and Image Quality in Pediatric Neck CT

BACKGROUND AND PURPOSE

Optimization of pediatric neck CT protocols is of critical importance in order to maintain good diagnostic image quality while reducing the radiation burden. Our aim was to evaluate the image quality of pediatric neck CT studies before and after the implementation of a low radiation dose protocol.

MATERIALS AND METHODS

We retrospectively reviewed 179 pediatric neck CT studies, 75 before and 104 after the implementation of low-dose protocols, performed in children 0-16 years of age. The 2 cohorts were divided into 3 age groups, 0-4, 5-9, and 10-16 years. The signal-to-noise ratio was calculated using the axial image through the true vocal folds. Three neuroradiologists assessed the image quality of the same CT scan using a 5-point scoring system. We compared the CT dose index volume, dose-length product, image-quality ratings, and SNR of studies conducted at baseline and with low-dose protocols.

RESULTS

Image-quality ratings were lower in the low-dose than in the baseline cohort in children 10-16 years of age, but not in children 0-4 and 5-9 years of age. The SNR was lower in the low-dose cohort than in the baseline cohort in children 0-4 and 10-16 years of age, but not in children 5-9 years of age. Despite the decrease in image-quality scores in older children, 97% of the studies (73/75) in the baseline cohort and 96% of studies (100/104) in the low-dose cohort were considered of sufficient image quality.

CONCLUSIONS

Images acquired with the low-dose CT protocols were deemed to be of sufficient quality for making a clinical diagnosis. Our initial results suggest that there may be an opportunity for further radiation dose reduction without compromising diagnostic image quality using iterative reconstruction algorithms.

Thorax CT Dose Reduction Based on Patient Features: Effect of Patient Characteristics on Image Quality and Effective Dose

Computed tomography (CT) radiation dose reduction is vital without compromising image quality. The aim was to determine the effects of patient characteristics on the received radiation dose and image quality in chest CT examinations and to be able to predict dose and image quality prior to scanning. Consecutive 230 patients underwent routine chest CT examinations were included. CT examination and patients input parameters were recorded for each patient. The effect of patients' demographics/anthropometrics on received dose and image quality was investigated by linear regression analysis. All parameters were evaluated using an artificial neural network (ANN). Of all parameters, patient demographics/anthropometrics were found to be 98% effective in calculating dose reduction. Using ANN on 60 new patients was more than 90% accurate for output parameters and 91% for image quality. Patient characteristics have a significant impact on radiation dose and image quality. Dose and image quality can be determined before CT. This will allow setting the most appropriate scanning parameters before the CT scan.

Effect of low tube voltage and low iodine concentration abdominal CT on image quality and radiation dose in children: preliminary study

PURPOSE

To evaluate the image quality of a double-low protocol (low tube voltage and low iodine concentration) for abdominal CT in children.

MATERIALS AND METHODS

The double-low protocol was compared to the conventional protocol in pediatric patients weighing less than 40 kg from May 2016 to December 2016. Double-low protocol (Group A, n = 18): tube voltage, 70 kVp; and iodine concentration,: 250 mgI/mL versus Conventional protocol (Group B, n = 13): tube voltage, 80-100 kVp; and iodine concentration, 350 mgI/mL. Mean attenuation, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were compared between the two groups. Image contrast, noise, beam-hardening artifacts, and overall image quality were subjectively scored. Reader performance for correctly differentiating two groups by visual assessment was evaluated. Radiation dose and total iodine load were recorded.

RESULTS

The mean attenuations of the portal vein and liver and the mean image noise in Group A were higher than in Group B (p = 0.04, 0.03, 0.004, respectively). The mean SNR and CNR of the main portal vein and liver were lower in Group A without any statistically significant difference. There were no statistically significant differences between the two groups in qualitative analysis (image contrast, image noise, and overall image quality) with substantial agreement between the reviewers (weighted kappa values; 0.59-0.76). Significantly diminished radiation dose and iodine load were observed in Group A compared with Group B (25.0%, 36.8% reduction; p = 0.007, 0.006, respectively).

CONCLUSION

The double-low protocol was feasible for pediatric abdominal CT and reduced both radiation dose and iodine load, while maintaining image quality.

External validation of a five-variable clinical prediction rule for identifying children at very low risk for intra-abdominal injury after blunt abdominal trauma

BACKGROUND

A clinical prediction rule was previously developed by the Pediatric Surgery Research Collaborative (PedSRC) to identify patients at very low risk for intra-abdominal injury (IAI) and intra-abdominal injury receiving an acute intervention (IAI-I) who could safely avoid abdominal computed tomography (CT) scans after blunt abdominal trauma (BAT). Our objective was to externally validate the rule.

METHODS

The public-use dataset was obtained from the Pediatric Emergency Care Applied Research Network (PECARN) Intra-abdominal Injury Study. Patients 16 years of age and younger with chest x-ray, completed abdominal history and physical examination, aspartate aminotransferase (AST), and amylase or lipase collected within 6 hours of arrival were included. We excluded patients who presented greater than 6 hours after injury or missing any of the five clinical prediction variables from the PedSRC prediction rule.

RESULTS

We included 2,435 patients from the PECARN dataset, with a mean age of 9.4 years. There were 235 patients with IAI (9.7%) and 60 patients with IAI-I (2.5%). The clinical prediction rule had a sensitivity of 97.5% for IAI and 100% for IAI-I. In patients with no abnormality in any of the five prediction rule variables, the rule had a negative predictive value of 99.3% for IAI and 100.0% for IAI-I. Of the "very low-risk" patients identified by the rule, 46.8% underwent abdominal CT imaging.

CONCLUSIONS

A highly sensitive clinical prediction rule using history and abdominal physical examination, laboratory values, and chest x-ray was successfully validated using a large public-access dataset of pediatric BAT patients.

LEVEL OF EVIDENCE

Epidemiologic/prognostic study, level III; therapeutic care/management study, level IV.

Advanced CT Techniques for Decreasing Radiation Dose, Reducing Sedation Requirements, and Optimizing Image Quality in Children

CT is an invaluable diagnostic tool for pediatric patients; however, concerns have arisen about the potential risks of ionizing radiation associated with diagnostic imaging in young patients, particularly for pediatric populations that may require serial CT examinations. Recent attention has also been focused on the immediate and long-term risks of administration of anesthetic medications to infants and young children who require sedation to undergo imaging examinations. These concerns can be mitigated with use of advanced CT techniques that can decrease scan time and radiation dose while preserving image quality. In this article, current state-of-the-art CT acquisition techniques are reviewed as part of a comprehensive strategy to reduce radiation dose, decrease sedation needs, and optimize image quality in infants and young children. Three imaging strategies are discussed, including (a) dual-energy CT (DECT), (b) imaging with a low tube potential, and (c) rapid scanning. Consolidating multiphase imaging protocols into a single phase with virtual nonenhanced imaging on DECT scanners, as well as use of low tube voltage, can reduce the radiation dose while increasing the conspicuity of contrast material-enhanced structures with a reduced volume of iodinated contrast material and a reduced rate of injection. Rapid scanning techniques with either ultrahigh pitch at dual-source CT or with wide-area detector single-source CT facilitate scanning without the need for sedation in many children. ^©RSNA, 2019 See discussion on this article by Szczykutowicz .

A survey of pediatric CT doses in the Shanghai metropolitan area

The purpose of this study was to evaluate computed tomography (CT) doses in child examinees at different ages throughout the Shanghai metropolitan area. The head and body CT dose indices (CTDIs) of 50 CT scanners were tested by phantom measurements using standard imaging protocols. The values of CTDI_w, CTDI_vol and dose length product (DLP) were calculated and saved in a table along with the parameters of routine head and chest scans for different age groups of children and adults. The effective doses were estimated from the K-factors by age and DLP. The CTDI_vol, DLP and effective dose for multi-detector row CT (MDCT) in children during routine head scans were larger than those for single-detector row CT (SDCT) and dual-detector row CT (DDCT). The CTDI_vol, DLP and effective dose for MDCT and DDCT in children during routine chest scans were lower than those for SDCT. Radiation risks are higher for children in CT examinations compared to adults.

Manipulation Under Anesthesia in Infants With Arthrogenic Newborn Torticollis: A Retrospective Case Series

Objective

The purpose of this report is to describe the manipulation under anesthesia (MUA) treatment of 6 infants with newborn torticollis with a segmental dysfunction at C1/C2.

Clinical Features

Six infants aged 4 1/2 to 15 months previously diagnosed with newborn torticollis were referred to a doctor of chiropractic owing to a failure to respond adequately to previous conservative therapies. Common physical findings were limited range of motion of the upper cervical spine. Radiographs demonstrated rotational malpositions and translation of atlas on axis in all 6 infants, and 1 had a subluxation of the C1/C2 articulation.

Interventions and Outcome

Selection was based on complexity and variety of different clinical cases qualifying for MUA. Treatment consisted of 1 mobilization and was performed in the operating room of a children's hospital by a certified chiropractic physician with the author assisting. Along with the chiropractor and his assistant, a children's anesthesiologist, 1 to 2 operating nurses, a children's radiologist, and in 1 case a pediatric surgeon were present. Before the mobilization, plain radiographs of the cervico-occipital area were taken. Three infants needed further investigation by a pediatric computed tomography scan of the area because of asymmetric bony conditions on the plain radiographs. Follow-up consultations at 2, 3, 5, or 6 weeks were done. Patient records were analyzed for restriction at baseline before MUA compared with after MUA treatment for active rotation, passive rotation, and passive rotation in full flexion of the upper cervical spine. All 3 measurements showed significant differences. The long-term outcome data was collected via phone calls to the parents at 6 to 72 months. The initial clinical improvements were maintained.

Conclusion

These 6 infants with arthrogenic newborn torticollis, who did not respond to previous conservative treatment methods, responded to MUA.

RADIATION DOSE AND IMAGE QUALITY IN PEDIATRIC HEAD CT

Our goal was to define a pediatric head CT protocol able to provide images of diagnostic quality, using the least amount of radiation, in children <10 years of age, while using a filtered back projection reconstruction algorithm. Image quality of 119 pediatric head CTs was assessed using a 5-point scoring system. Exams with scores ≥2.5 were considered of sufficient diagnostic quality. The contrast-to-noise ratio (CNR) was also measured. For children <1 year and 1-9 years, all studies performed with CTDIvol ≥ 20.1 mGy (range: 9-46 mGy) and CTDIvol ≥ 27.5 mGy (range: 15-60 mGy) yielded images of diagnostic quality. All diagnostic studies had a minimum CNR of 1.4. These CTDIvol values represent a good balance between image quality and radiation burden. This information can be helpful in designing pediatric head CT protocols with further dose-reduction, namely, iterative reconstruction algorithms and automated exposure control.

Computed Tomography Dose in Paediatric Care: Simple Dose Estimation Using Dose Length Product Conversion Coefficients

BACKGROUND

The use of multislice computed tomography (MSCT) is increasing worldwide; at the same time, there is a growing awareness of the future risk of cancer associated with greater exposure to radiation. Therefore, there is a need for an accessible method of effective dose estimation. This study aims to estimate the effective doses (EDs) of a variety of paediatric computed tomography (CT) examinations in five age groups using recently published age- and region-specific dose length products (DLPs) as effective dose conversion coefficients.

METHODS

A retrospective review was performed over a 12-month period. Patients were assigned to one of five age groups: neonatal, 1-, 5-, 10- and 15-years-old. Age- and region-specific conversion coefficients were applied to the DLP data displayed on the CT console in order to estimate the ED.

RESULTS

Over the 12-month period, there were a total of 283 CT scans, 211 of which were selected for study. The ED estimates for plain CT brain scans in neonatal, 1-, 5-, 10- and 15-yearolds were 2.5, 1.5, 1.4, 1.3 and 0.8 mSv, respectively. For the corresponding CT abdominal scans, the results were 18.8, 12.9, 7.8, 8.6 and 7.5 mSv; these were the highest values recorded. High-resolution CT (HRCT) temporal scans showed EDs of 2.9, 1.8, 1.5 and 1.1 mSv in 1-, 5-, 10- and 15-years-old, respectively. CT scans of the helical thorax had an estimated ED of 4.8, 4.2 and 7.0 mSv in 5-, 10- and 15-years-old, respectively.

CONCLUSION

An inverse relationship between age and effective dose was demonstrated in CT scans of the brain and abdomen/pelvis. In general, our study showed lower overall EDs compared to other centres.

Radiation dose and image conspicuity comparison between conventional 120 kVp and 150 kVp with spectral beam shaping for temporal bone CT

OBJECTIVE

The purpose of this article is to compare radiation doses and conspicuity of anatomic landmarks of the temporal bone between the CT technique using spectral beam shaping at 150 kVp with a dedicated tin filter (150 kVp-Sn) and the conventional protocol at 120 kVp.

METHODS

25 patients (mean age, 46.8 ± 21.2 years) were examined using the 150-kVp Sn protocol (200 reference mAs using automated tube current modulation, 64 × 0.6 mm collimation, 0.6 mm slice thickness, pitch 0.8), whereas 30 patients (mean age, 54.5 ± 17.8 years) underwent the 120-kVp protocol (180 mAs, 128 × 0.6 mm collimation, 0.6 mm slice thickness, pitch 0.8). Radiation doses were compared between the two acquisition techniques, and dosimetric data from the literature were reviewed for comparison of radiation dose reduction. Subjective conspicuity of 23 anatomic landmarks of the temporal bone, expressed by 5-point rating scale and objective conspicuity by signal-to-noise ratio (SNR) which measured in 4 different regions of interest (ROI), were compared between 150-kVp Sn and 120-kVp acquisitions.

RESULTS

The mean dose-length-product (DLP) and effective dose were significantly lower for the 150-kVp Sn scans (0.26 ± 0.26 mSv) compared with the 120-kVp scans (0.92 ± 0.10 mSv, p < 0.001). The lowest effective dose from the literature-based protocols was 0.31 ± 0.12 mSv, which proposed as a low-dose protocol in the setting of spiral multislice temporal bone CT. SNR was slightly superior for 120-kVp images, however analyzability of the 23 anatomic structures did not differ significantly between 150-kVp Sn and 120-kVp scans.

CONCLUSION

Temporal bone CT performed at 150 kVp with an additional tin filter for spectral shaping markedly reduced radiation exposure when compared with conventional temporal bone CT at 120 kVp while maintaining anatomic conspicuity. The decreased radiation dose of the 150-kVp Sn was also lower in comparison to the previous literature-based low-dose temporal bone CT protocol.