Children, computed tomography radiation dose, and the As Low As Reasonably Achievable (ALARA) concept

Booster administration of Tc-99m PMT for delayed static imaging in patients with biliary atresia

OBJECTIVE

Tc-99m N-pyridoxyl-5-methyl-tryptophan (PMT) hepatobiliary scintigraphy has high diagnostic performance for biliary atresia. Our hospital implements standard Tc-99m PMT administration followed by a 6 h static imaging review; booster doses are given in cases requiring 24 h delayed scans. This study aimed to evaluate the diagnostic performance of this method.

METHODS

A total of 37 pediatric patients who underwent Tc-99m PMT biliary scintigraphy were classified into the surgically-diagnosed biliary atresia or non-biliary atresia groups. The absence of tracer accumulation in the small bowel was considered a hepatobiliary scintigraphic diagnosis of biliary atresia. The Clopper-Pearson method was used to calculate the 95% confidence intervals (CIs) for determining the diagnostic accuracy, negative predictive value, positive predictive value, sensitivity, and specificity of Tc-99m PMT biliary scintigraphy.

RESULTS

Among the 37 patients, 12 were classified into the diagnosis of biliary atresia group. Regarding biliary scintigraphy findings, 16 of 37 patients demonstrated tracer accumulation in the small bowel within 6 h of testing. These cases were diagnosed as non-biliary atresia, requiring no further testing or booster administration. In contrast, 21 patients underwent delayed testing requiring booster administration, which revealed 13 without tracer excretion and 11 who were diagnosed with biliary atresia. Among the eight patients with tracer accumulation, only one was diagnosed with biliary atresia. Furthermore, two cases without tracer excretion and seven cases with tracer excretion were clinically diagnosed as non-biliary atresia. The diagnostic performance of our examination was as follows: a diagnostic accuracy of 91.9% (34/37; 95% CIs 78.0-98.3%), sensitivity of 91.6% (11/12; 95% CIs 61.5-99.8%), specificity of 92.0% (23/25; 95% CIs 74.0-99.0%), a positive predictive value of 84.6% (11/13; 95% CIs 54.6-98.0%), and a negative predictive value of 95.8% (23/24; 95% CIs 78.9-99.9%).

CONCLUSIONS

Our protocol for Tc-99m PMT biliary scintigraphy using tracer booster administration demonstrated reliable diagnostic performance for biliary atresia. Notably, 43% of cases did not require booster administration, indicating that lesser radiation exposure may still yield comparable diagnostic accuracy.

Expansion of Typical Values for Paediatric Patients in Ireland and Comparison with Published DRLs - Experiences of a Single Institution

INTRODUCTION

To reduce the risks involved with ionising radiation exposure, typical values (TVs) and diagnostic reference levels (DRLs) have been established to help keep radiation doses 'as low as reasonably practicable. TVs/DRLs provide standardised radiation dose metrics that can be used for comparative purposes. However, for paediatrics, such values should consider the size of the child instead of their age. This study aimed to establish and compare paediatric TVs for chest, abdomen and pelvis radiography.

METHODS

Study methods followed processes for establishing paediatric DRLs as outlined by the Health Information and Quality Authority (HIQA). Kerma-area product (KAP) values, excluding rejected images, were retrospectively acquired from the study institution's Picture Archiving and Communications System (PACS). Paediatric patients were categorised into the following weight-based groupings (5 to <15 kg, 15 to <30 kg, 30 to <50 kg, 50 to 80 kg) and stratified based on the examination that was performed (chest, abdomen, and pelvis), and where it was performed (the different X-ray rooms). Anonymised data were inputted into Microsoft Excel for analysis. Median and 3rd quartile KAP values were reported together with graphical illustrations.

RESULTS

Data from 407 X-ray examinations were analysed. For the previously identified weight categories (5 to <15 kg, 15 to <30 kg, 30 to <50 kg, 50 to 80 kg), TVs for the chest were 0.10, 0.19, 0.37 and 0.53 dGy.cm2, respectively. For the abdomen 0.39, 1.04, 3.51 and 4.05 dGy.cm2 and for the pelvis 0.43, 0.87, 3.50 and 7.58 dGy.cm2. Between X-ray rooms TVs varied against the institutional TVs by -60 to 119 % (chest), -50 to 103 % (abdomen) and -14 and 24 %% (pelvis).

CONCLUSION

TVs in this study follow established trends with patient weight and examination type and are comparable with published literature. Variations do exist between individual examination rooms and reasons are multifactorial. Given that age and size do not perfectly correlate further work should be undertaken around weight-based TVs/DRLs in the paediatric setting.

Cardiac computed tomography angiography with and without bolus tracking methods in infants with congenital heart disease

The study investigated radiation dose, vascular computed tomography (CT) enhancement and image quality of cardiac computed tomography angiography (CCTA) with and without bolus tracking (BT) methods in infants with congenital heart disease (CHD). The volume CT dose index (CTDIvol) and dose length product (DLP) were recorded for all CT scans, and the effective dose was obtained using a conversion factors. The CT number for the ascending aorta (AO) and pulmonary artery (PA), image noise of muscle tissue and contrast-to-noise ratio (CNR) were measured and calculated. The median values in the groups with and without BT were 2.20 mGy versus 0.44 mGy for CTDIvol, 8.10 mGy·cm versus 6.20 mGy·cm for DLP, and 0.66 mSv versus 0.51 mSv for effective dose (p < 0.001). There were no statistical differences in vascular CT enhancement, image noise, and CNR. CCTA without BT methods can reduce the radiation dose while maintaining vascular CT enhancement and image quality compared to CCTA with BT methods.

Is the use of gonad protection protectors necessary during infants chest radiography?

INTRODUCTION AND OBJECTIVES

To compare gonad doses with and without a gonad protector and to optimize the use of gonadal protectors in infants thorax radiography.

MATERIALS AND METHODS

Two pediatric anthropomorphic phantoms are used: an X-ray system for KXO-50SS/DRX-3724HD, and a digital radiography system for CALNEO Smart C12, with and without a gonad protector during infants thorax radiography. A real time skin dosimeter is placed on the X-ray system, and a real time skin dosimeter is inserted on the front side of the mammary gland, the front and back sides of the true pelvis level, and on the ovaries and testes. The X-ray system is irradiated 15 times using phantoms with and without a gonad protector. The measured entrance patient doses values of for the real time skin dosimeter are compared for each phantom, with and without the gonad protector.

RESULTS

The medium of measured entrance patient doses values for front side dose of the true pelvis level with and without the protector are 10.00 and 5.00 μGy at newborn, and 10.00 and 0.00μGy at one year, respectively. The medium of measured entrance patient doses values for the back side dose of the true pelvis level with and without the protector are 0.00 and 0.00 μGy at both newborn one year, respectively. The measured entrance patient doses cannot be detected in the ovaries and testes with or without the protector. No significant differences are observed in the measured entrance patient doses values for the front and back side doses of the pelvis, ovaries, and testes at newborn and one year, with and without the protector (p>0.05).

CONCLUSIONS

No significant difference was observed in gonad dose measurements with and without the gonad protector during infants chest radiography. We believe that gonadal protector wearing is not necessary.

MRI-based synthetic CT for assessment of the bony elements of the sacroiliac joints in children

OBJECTIVES

The purpose of this study is to assess the equivalency of MRI-based synthetic CT (sCT) to conventional CT for sacroiliac joint bony morphology assessment in children.

METHODS

A prospective study was performed. Children who had (PET-)CT-scan underwent additional MRI. sCT-CT image quality was analyzed by two readers subjectively overall, semi-quantitatively in terms of cortical delineation, joint facet defects, growth plate fusion, ossified nuclei, lumbosacral transitional anomaly, and bony bridges, and quantitatively for disc space height, spinal canal width, and sacral vertebrae width and height. Cohen's kappa and equivalence analyses with Bland-Altman plots were calculated for categorical and continuous measures respectively.

RESULTS

Ten patients were included (6 boys; aged 9-16 years; mean age 14 years). Overall sCT image quality was rated good. Semi-quantitative assessment of cortical delineation of sacroiliac joints, bony bridges, and joint facet defects on the right iliac and sacral sides showed perfect agreement. Correlation was good to excellent (kappa 0.615-1) for the presence of lumbosacral transitional anomaly, fusion of sacral growth plates, joint facet defect, and presence of ossified nuclei. sCT-CT measurements were statistically equivalent and within the equivalence margins (-1-1 mm) for intervertebral disc space height and spinal canal width. Intra- and inter-reader reliability was excellent for quantitative assessment (0.806 < ICC < 0.998). For categorical scoring, kappa ranged from substantial to excellent (0.615-1).

CONCLUSION

sCT appears to be visually equivalent to CT for the assessment of pediatric sacroiliac joints. sCT may aid in visualizing sacroiliac joints compared to conventional MRI, with the benefit that no ionizing radiation is used, especially important in children.

CRITICAL RELEVANCE STATEMENT

MRI-based synthetic CT, a new technique that generates CT-like images without ionizing radiation, appears to be visually equivalent to CT for assessment of normal pediatric sacroiliac joints and can potentially assess structural damage as it clearly depicts bony cortex.

KEY POINTS

• MRI-based sCT is a new image technique that can generate CT-like images. • We found that sCT performs similarly to CT in displaying bony structures of pediatric sacroiliac joints. • sCT has already been clinically validated in the sacroiliac joints in adults. • sCT can potentially assess structural damage from erosions or ankylosis as it clearly depicts bony cortex.

Effectiveness of low tube voltage scan in the exposure dose for lenses during paediatric thoracic CT examination: anthropomorphic phantoms study

To determine whether using lower-tube voltage reduces the scattered dose for the lens during paediatric thoracic computed tomography (CT). Two paediatric anthropomorphic phantoms (ATOM Phantom, CIRS, Norfolk, Virginia, USA) representing a newborn and 5-year-old were placed on the gantry of CT scanner, and optically stimulated luminescence dosemeters were placed on the left and right lenses, in front of the left and right thyroid glands, in front of the left and right mammary glands, and in front of and behind the mammary gland level and we measured scattered dose of the optically stimulated luminescence dosemeter was compared for each phantom between 80 and 120 kVp. Significant differences were observed in the scatter doses for the lens between 80 and 120 kVp (p < 0.01). Compared with the 120 kVp scan, the scatter doses for the lens were ~15-40% lower in newborn and 5-year-olds using the 80 kVp scan during paediatric CT.

Factors contributing to uncertainty in paediatric abdominal ultrasound reports in the paediatric emergency department

BACKGROUND

Abdominal pain, which is a common cause of children presenting to the paediatric emergency department (PED), is often evaluated by ultrasonography (US). However, uncertainty in US reports may necessitate additional imaging.

OBJECTIVE

In this study, we evaluated factors contributing to uncertainty in paediatric abdominal US reports in the PED.

MATERIALS AND METHODS

This retrospective cohort study included children younger than 18 years of age who underwent abdominal US in the PED of the study hospital between January 2017 and December 2019. After exclusion, the researchers manually reviewed and classified all US reports as 'certain' or 'uncertain'. Univariate and multivariate logistic regression analyses were performed to identify the factors contributing to uncertain reports.

RESULTS

In total, 1006 patients were included in the final analysis., 796 patients were tagged as having certain reports, and 210 as having uncertain reports. Children with uncertain reports had a significantly higher rate of undergoing an additional computed tomography (CT) scan (31.0% vs. 2.5%, p < 0.001) and a longer PED median length of stay (321.0 (Interquartile range (IQR); 211.3-441.5) minutes vs. 284.5 (IQR; 191.8-439.5) minutes, p = 0.042). After logistic regression, US performed by a radiology resident (odds ratio, 5.01; 95% confidence interval, 3.63-7.15) was the most significant factor contributing to uncertainty in paediatric abdominal US reports followed by obesity and age.

CONCLUSION

Several factors contribute to uncertainty in paediatric abdominal US reports. Uncertain radiological reports increase the likelihood of additional CT scans. Measures to improve the clarity of radiological reports must be considered to improve the quality of care for children visiting the PED.

The burden of radiation exposure in children requiring percutaneous nephrolithotomy

BACKGROUND

Children undergoing investigation and management for complex upper tract urolithiasis often require multimodal imaging. The significance of related radiation exposure in stone care pathways has received little attention in the published literature.

STUDY DESIGN

Medical records of paediatric patients undergoing percutaneous nephrolithotomy were retrospectively analysed to ascertain the modalities used and determine extent of radiation exposure occurring during each care pathway. Radiation dose simulation and calculation was performed a priori. The cumulative effective dose (mSv) and cumulative organ dose (mGy) for radiosensitive organs was calculated.

RESULTS

A total of 140 imaging studies were included from the care pathways of 15 children with complex upper tract urolithiasis. Median follow-up was 9.6 years (range: 6.7-16.8 years). The average number of imaging studies with ionising radiation per patient was nine, with a cumulative effective dose of 18.3 mSv across all modalities. The most common modalities were: mobile fluoroscopy (43%), x-ray (24%), and computed tomography (18%). The cumulative effective dose per study type was greatest for CT (4.09 mSv), followed by fixed and mobile fluoroscopy (2.79 mSv and 1.82 mSv, respectively).

CONCLUSION

There is high general awareness of radiation exposure involved in CT scanning with resultant caution in employing this modality in paediatric patients. However, the significant radiation exposure relating to fluoroscopy (whether fixed or mobile) is less well documented in children. We recommend implementing steps to minimise radiation exposure by optimisation and avoidance of certain modalities where possible. Paediatrics urologists must employ strategies to minimise radiation exposure in children with urolithiasis, given the significant exposures encountered.

A Pediatric Cervical Spine Clearance Guideline Leads to Fewer Unnecessary Computed Tomography Scans and Decreased Radiation Exposure

OBJECTIVES

Physical examination and computed tomography (CT) are useful to rule out cervical spine injury (CSI). Computed tomography scans increase lifetime cancer risk in children from radiation exposure. Most CSI in children occur between the occiput and C4. We developed a cervical spine (C-spine) clearance guideline to reduce unnecessary CTs and radiation exposure in pediatric trauma patients.

METHODS

A pediatric C-spine clearance guideline was implemented in September 2018 at our Level 2 Pediatric Trauma Center. Guidance included CT of C1 to C4 to scan only high-yield regions versus the entire C-spine and decrease radiation dose. A retrospective cohort study was conducted comparing preguideline and postguideline of all pediatric trauma patients younger than 8 years screened for CSI from July 2017 to December 2020. Primary endpoints included the following: number of full C-spine and C1 to C4 CT scans and radiation dose. Secondary endpoints were CSI rate and missed CSI. Results were compared using χ 2 and Wilcoxon rank-sum test with P < 0.05 significant.

RESULTS

The review identified 726 patients: 273 preguideline and 453 postguideline. A similar rate of total C-spine CTs were done in both groups (23.1% vs 23.4%, P = 0.92). Full C-spine CTs were more common preguideline (22.7% vs 11.9%, P < 0.001), whereas C1 to C4 CT scans were more common post-guideline (11.5% vs 0.4%, P < 0.001). Magnetic resonance imaging utilization and CSIs identified were similar in both groups. The average radiation dose was lower postguideline (114 vs 265 mGy·cm -1 ; P < 0.001). There were no missed CSI.

CONCLUSIONS

A pediatric C-spine clearance guideline led to increasing CT of C1 to C4 over full C-spine imaging, reducing the radiation dose in children.

LEVEL OF EVIDENCE

Level IV, therapeutic.

Machine Learning-Driven Clinical Image Analysis to Identify Craniosynostosis: A Pilot Study of Telemedicine and Clinic Patients

BACKGROUND

The authors have developed pretrained machine learning (ML) models to evaluate neonatal head shape deformities using top-down and facial orthogonal photographs of the patient's head. In previous preliminary analysis, this approach was tested with images from an open-source data bank.

OBJECTIVE

To determine the accuracy of pretrained ML models in identifying craniosynostosis among patients seen in our outpatient neurosurgery clinic.

METHODS

We retrospectively reviewed top-down and facial orthogonal images of each patient's head and provider clinical diagnosis from the same encounters. Head shape classifications generated from 3 pretrained ML models (random forest, classification and regression tree, and linear discriminant analysis) were applied to each patient's photograph data set after craniometric extraction using a predefined image processing algorithm. Diagnoses were codified into a binary scheme of craniosynostosis vs noncraniosynostosis. Sensitivity, specificity, and Matthew correlation coefficient were calculated for software vs provider classifications.

RESULTS

A total of 174 patients seen for abnormal head shape between May 2020 and February 2021 were included in the analysis. One hundred seven patients (61%) were seen in-person and 67 (39%) through telemedicine. Twenty-three patients (13%) were diagnosed with craniosynostosis. The best-performing model identified craniosynostosis with an accuracy of 94.8% (95% CI 90.4-97.6), sensitivity of 87.0% (95% CI 66.4-97.2), specificity of 96.0% (95% CI 91.6-98.5), and Matthew correlation coefficient of 0.788 (95% CI 0.725-0.839).

CONCLUSION

Machine learning-driven image analysis represents a promising strategy for the identification of craniosynostosis in a real-world practice setting. This approach has potential to reduce the need for imaging and facilitate referral by primary care providers.

Postnatal diagnosis of single-suture craniosynostosis with cranial ultrasound: a systematic review

INTRODUCTION

The optimal protocol for diagnostic workup of craniosynostosis and the role of specific imaging modalities remain controversial. Skull X-rays and 3-dimensional head CTs are options when physical exam is equivocal but involve ionizing radiation. Ultrasound has emerged as an alternative modality for visualization of cranial sutures, but its use is not widespread.

METHODS

The authors performed a systematic review of the literature on the use of ultrasound for the diagnosis of craniosynostosis.

RESULTS

A total of 12 studies involving 1062 patients were included. Overall, 300 patients (28.2%) were diagnosed with craniosynostosis. A total of 369 (34.7%) patients had their diagnosis (craniosynostosis vs. patent sutures) confirmed with another imaging modality in addition to ultrasound. Among studies, the specificity of ultrasound ranged from 86 to 100%, and the sensitivity from 71 to 100%.

CONCLUSIONS

Ultrasonography of cranial sutures is a feasible and accurate tool for the diagnosis of single-suture craniosynostosis when physical exam findings are insufficient. Although technical aspects of ultrasonography and its interpretation have an associated learning curve, ultrasound can achieve high sensitivity and specificity among patients with suspected craniosynostosis.

Pediatric Pulmonary Nodules: Imaging Guidelines and Recommendations

Incidental pulmonary nodules are not infrequently identified on computed tomography imaging in the pediatric population and can be a challenge in suggesting appropriate follow-up recommendations. An evidence-based and practical imaging approach for diagnosis and appropriate directed management is essential for optimal patient care. This article provides an up-to-date review of the pediatric pulmonary nodule literature and suggests a practical algorithm to manage pulmonary nodules in the pediatric population.

Computed tomography associated radiation exposure in children with craniosynostosis

BACKGROUND

The role of computed tomography (CT) for diagnosis and surgical planning for craniosynostosis (CS) is well-established. The aim of this study was to quantify the cumulative medical radiation exposure from CT in patients with CS at a tertiary care children's hospital.

METHODS

Medical records of patients who presented at < 2 years of age and underwent surgical intervention for CS were examined for demographic information. Effective radiation dose (ERD) in mSv was calculated for each head CT. Descriptive statistics and ANOVA were performed. Mean ± SD is reported; p < 0.05 was considered significant.

RESULTS

Two hundred seventy-two patients met inclusion criteria: 241 nonsyndromic and 31 with syndromic diagnoses. For nonsyndromic patients, mean age at first head CT was 6.0 ± 4.9 months, mean number of CT scans obtained was 2.1 ± 1.1, and the mean total combined ERD was 9.1 ± 4.8 mSv. CT scans obtained at < 6 months of age had a significantly greater ERD than those obtained at > 6 months, 5.3 ± 1.9 versus 4.3 ± 1.4 mSv, respectively (p = 0.001).

CONCLUSIONS

Patients with nonsyndromic CS undergo 2 CT scans on average related to their diagnosis, with a mean total ERD of 9.1 mSv; this is equivalent to 1.5 years of the average annual background radiation dose a person living in the USA will encounter from environmental radiation, medical exposures, and consumer products. A CT obtained at < 6 months is associated with a higher ERD; thus, we recommend delaying imaging from the initial presentation to the time of pre-operative planning when possible.

Edge-Preserving Median Filter and Weighted Coding with Sparse Nonlocal Regularization for Low-Dose CT Image Denoising Algorithm

The impulse noise in CT image was removed based on edge-preserving median filter algorithm. The sparse nonlocal regularization algorithm weighted coding was used to remove the impulse noise and Gaussian noise in the mixed noise, and the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) were calculated to evaluate the quality of the denoised CT image. It was found that in nine different proportions of Gaussian noise and salt-and-pepper noise in Shepp-Logan image and CT image processing, the PSNR and SSIM values of the proposed denoising algorithm based on edge-preserving median filter (EP median filter) and weighted encoding with sparse nonlocal regularization (WESNR) were significantly higher than those of using EP median filter and WESNR alone. It was shown that the weighted coding algorithm based on edge-preserving median filtering and sparse nonlocal regularization had potential application value in low-dose CT image denoising.

Preoperative imaging patterns and intracranial findings in single-suture craniosynostosis: a study from the Synostosis Research Group

OBJECTIVE

The diagnosis of single-suture craniosynostosis can be made by physical examination, but the use of confirmatory imaging is common practice. The authors sought to investigate preoperative imaging use and to describe intracranial findings in children with single-suture synostosis from a large, prospective multicenter cohort.

METHODS

In this study from the Synostosis Research Group, the study population included children with clinically diagnosed single-suture synostosis between March 1, 2017, and October 31, 2020, at 5 institutions. The primary analysis correlated the clinical diagnosis and imaging diagnosis; secondary outcomes included intracranial findings by pathological suture type.

RESULTS

A total of 403 children (67% male) were identified with single-suture synostosis. Sagittal (n = 267), metopic (n = 77), coronal (n = 52), and lambdoid (n = 7) synostoses were reported; the most common presentation was abnormal head shape (97%), followed by a palpable or visible ridge (37%). Preoperative cranial imaging was performed in 90% of children; findings on 97% of these imaging studies matched the initial clinical diagnosis. Thirty-one additional fused sutures were identified in 18 children (5%) that differed from the clinical diagnosis. The most commonly used imaging modality by far was CT (n = 360), followed by radiography (n = 9) and MRI (n = 7). Most preoperative imaging was ordered as part of a protocolized pathway (67%); some images were obtained as a result of a nondiagnostic clinical examination (5.2%). Of the 360 patients who had CT imaging, 150 underwent total cranial vault surgery and 210 underwent strip craniectomy. The imaging findings influenced the surgical treatment 0.95% of the time. Among the 24% of children with additional (nonsynostosis) abnormal findings on CT, only 3.5% required further monitoring.

CONCLUSIONS

The authors found that a clinical diagnosis of single-suture craniosynostosis and the findings on CT were the same with rare exceptions. CT imaging very rarely altered the surgical treatment of children with single-suture synostosis.

Cephalometry without complex dedicated postprocessing in an oriented magnetic resonance imaging dataset: a pilot study

OBJECTIVES

Magnetic resonance imaging (MRI) enables a 3D-volume-imaging without ionizing radiation. Therefore, it was the aim of this study to present a post-processing-free method for cephalometric analysis of a MRI-dataset and to examine whether there is a significant difference between cephalometric analysis of conventional 2D cephalograms and MRI scans.

METHODS

One MRI scan each was performed on three cadaver heads using a 3T-MR-scanner. Cephalometric analysis was conducted directly on the 3D dataset. All reference points were projected onto a virtual sagittal plane that was perpendicular to the Frankfort horizontal plane. Double-sided points were averaged. Cephalometric angles were measured from the projected points. Results were compared with cephalometric measurements on conventional lateral cephalometric radiographs (LCRs). The cephalometric analysis was performed by five raters.

RESULTS

390-angle measurements were obtained. The inter-rater reliability was high [intraclass correlation coefficients (ICCs) ≥ 0.74 for all angles]. Differences between the measurements on the cephalograms and MRI scans ranged between -0.91° (-1.88°, 0.07°) and 0.97° (-0.63°, 2.57°) on average and were equivalent with respect to a margin of [-2°, 2°] in all angles except L1-Me-Tgo (Bonferroni-Holm-corrected P < 0.05 in all angles except L1-Me-Tgo). The best match was found for the SNA angle.

CONCLUSION

The clinical comparability of the MRI- and LCR-based cephalometry could be stated. Using MRI in orthodontics would reduce radiation exposure and the risk of stochastic radiation damage, which is of importance especially in younger patients.

Estimation of CARE Dose 4D quality reference mAs conversion factors for child to adult reference patient in child protocols on Siemens Symbia SPECT-CT systems

OBJECTIVES

CARE Dose 4D modulates mAs through several mechanisms according to patient size and shape, whilst maintaining user-defined reference image quality on Siemens Symbia single-photon emission computed tomography (SPECT)-computed tomography (CT) systems. A 20 kg child reference was used in child protocols prior to software version VB10 and a 75 kg adult thereafter. Quality reference mAs conversion factors are estimated for delivering equivalent mAs to children between two comparable SPECT-CT systems using adult and child references for topogram-based patient-size-related dose level adaptations.

METHODS

A child phantom was scanned using child protocols on a Siemens Symbia T16 (child reference) and a Siemens Symbia Intevo Bold (adult reference). On each system, scans of the thorax, abdomen and pelvis were acquired with arms up and down, at 80 and 110 kVp. Quality reference mAs settings of 10-50 were used on the Symbia T16 and 40-200 on the Symbia Intevo Bold. These data were used to propose quality reference mAs (adult/child reference) conversion factors according to scan range, arm position and tube voltage.

RESULTS

Quality reference mAs for child protocols using the adult reference should multiply the child quality reference mAs by the following factors, to give comparable delivered mAs: arms up 80 kV: 3.8 (thorax), 3.8 (abdomen), 4.3 (pelvis); arms up at 110 kV: 3.8 (thorax), 4.1 (abdomen), 4.6 (pelvis); arms down at 80 kV: 4.0 (thorax), 3.7 (abdomen), 3.9 (pelvis); arms down at 110 kV: 4.3 (thorax), 4.0 (abdomen), 4.2 (pelvis).

CONCLUSION

Conversion factors for child to adult dose modulation references are proposed, allowing comparable delivered mAs to a child.Video abstract: http://links.lww.com/NMC/A178.

Feasibility of rapid magnetic resonance imaging (rMRI) for the emergency evaluation of suspected pediatric orbital cellulitis

PURPOSE

To determine the feasibility of noncontrast rapid magnetic resonance imaging (rMRI), compared with traditional contrast-enhanced computed tomography (CT) in assessing pediatric emergency department patients with suspected orbital cellulitis or orbital abscess.

METHODS

All subjects <19 years of age who presented emergently with suspected orbital cellulitis from July 1, 2017, to July 31, 2019, were included. Participants received both the standard contrast orbital CT, if deemed necessary, with the addition of the noncontrast rMRI after informed consent was obtained. No sedation was used for either examination. All clinical decisions were based on CT findings; rMRI was interpreted within 24 hours of the visit. Three pediatric radiologists, with 8-21 years' experience of pediatric neuroradiology, interpreted the rMRI, masked to the CT and clinical results. Results were analyzed for interobserver bias.

RESULTS

A total of 14 patients were enrolled during the study period. Mean age was 5.9 years (range, 0.33-13). Of the 14 patients, 13 (93%) were able to complete the rMRI at 1.5 and 3T; 1 patient (1.67 years of age) was unable to complete the rMRI (no images obtained). Of the 26 unilateral orbital units assessed, 3 were positive for retroseptal orbital cellulitis by CT and were diagnosed correctly by rMRI. Interobserver agreement was 100% in detecting presence or absence of retroseptal cellulitis. CT and rMRI findings were concordant in 100% of cases in differentiating preseptal vs orbital cellulitis. Kappa statistics for three-category ratings by three raters for right eye/orbit was 0.921 and for left eye/orbit was 0.9288, suggesting almost perfect agreement. Concordance correlation coefficients were 0.938 for the right eye and 0.955 for the left eye.

CONCLUSIONS

Noncontrast rMRI orbits showed findings concordant in all cases with contrast-enhanced CT for differentiating preseptal cellulitis from orbital cellulitis.

Emergency department implementation of abbreviated magnetic resonance imaging for pediatric traumatic brain injury

Pediatric head injury is a common presenting complaint in the emergency department (ED), often requiring neuroimaging or ED observation for diagnosis. However, the traditional diagnostic neuroimaging modality, head computed tomography (CT), is associated with radiation exposure while prolonged ED observation impacts patient flow and resource utilization. Recent scientific literature supports abbreviated, or focused and shorter, brain magnetic resonance imaging (MRI) as a feasible and accurate diagnostic alternative to CT for traumatic brain injury. However, this is a relatively new application and its use is not widespread. The aims of this review are to describe the science and applications of abbreviated brain MRI and report a model protocol's development and ED implementation in the evaluation of children with head injury for replication in other institutions.

Cone-Beam Computed Tomography in Orthodontics

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.

Hybrid PET/MRI imaging in healthy unsedated newborn infants with quantitative rCBF measurements using 15O-water PET

In this study, a new hybrid PET/MRI method for quantitative regional cerebral blood flow (rCBF) measurements in healthy newborn infants was assessed and the low values of rCBF in white matter previously obtained by arterial spin labeling (ASL) were tested. Four healthy full-term newborn subjects were scanned in a PET/MRI scanner during natural sleep after median intravenous injection of 14 MBq ¹⁵O-water. Regional CBF was quantified using a one-tissue-compartment model employing an image-derived input function (IDIF) from the left ventricle. PET rCBF showed the highest values in the thalami, mesencephalon and brain stem and the lowest in cortex and unmyelinated white matter. The average global CBF was 17.8 ml/100 g/min. The average frontal and occipital unmyelinated white matter CBF was 10.3 ml/100 g/min and average thalamic CBF 31.3 ml/100 g/min. The average white matter/thalamic ratio CBF was 0.36, significantly higher than previous ASL data. The rCBF ASL measurements were all unsuccessful primarily owing to subject movement. In this study, we demonstrated for the first time, a minimally invasive PET/MRI method using low activity ¹⁵O-water PET for quantitative rCBF assessment in unsedated healthy newborn infants and found a white/grey matter CBF ratio similar to that of the adult human brain.

Reduction in Head Computed Tomography Ordering in Pediatric Emergency Patients: Effect of National Publication and Local Availability of Urgent Neurology Appointments

OBJECTIVE

The objective of this study was to evaluate the effect of the Pediatric Emergency Care Applied Research Network (PECARN) blunt head trauma guidelines and implementation of urgent neurology follow-up (UNF) appointments on an observed decline in head computed tomography (CT) use for pediatric emergency department (PED) patients presenting with headache, seizure, and trauma.

METHODS

Patients ages 0 to 18 years presenting to and discharged from an urban tertiary care PED with chief complaint of trauma, headache, and seizure between 2007 and 2013 were retrospectively included. The total number of head CTs obtained in the trauma, headache, and seizure groups was compared before and after the publication of the PECARN guidelines in 2009 and the implementation of urgent UNF within a week from PED discharge in 2011, respectively.

RESULTS

Between 2007 and 2013, 24,434 encounters were identified with 2762 head CTs performed. Analysis demonstrated a decline in pediatric head CTs for trauma (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.8-2.2) after the publication of the PECARN study on blunt head trauma, for headache (OR, 1.4; 95% CI, 1.1-1.8) and seizure (OR, 1.9; 95% CI, 1.4-2.6) with UNF. However, cross comparison (headache and seizure with PECARN and trauma with UNF) also demonstrated similar significant declines.

CONCLUSIONS

The decline in head CTs observed at our institution demonstrated a strong linear relationship, yet cannot be solely attributed to the PECARN blunt head trauma study or the implementation of UNF.

Agreement between magnetic resonance imaging and computed tomography in the postnatal evaluation of congenital lung malformations: a pilot study

OBJECTIVES

To compare postnatal magnetic resonance imaging (MRI) with the reference standard computed tomography (CT) in the identification of the key features for diagnosing different types of congenital lung malformation (CLM).

METHODS

Respiratory-triggered T2-weighted single-shot turbo spin echo (ss-TSE), respiratory-triggered T1-weighted turbo field echo (TFE), balanced fast field echo (BFFE), and T2-weighted MultiVane sequences were performed at 1.5 T on 20 patients prospectively enrolled. Two independent radiologists examined the postnatal CT and MRI evaluating the presence of cysts, hyperinflation, solid component, abnormal arteries and/or venous drainage, and bronchocele. Diagnostic performance of MRI was calculated and the agreement between the findings was assessed using the McNemar-Bowker test. Interobserver agreement was measured with the kappa coefficient.

RESULTS

CT reported five congenital pulmonary airway malformations (CPAMs), eight segmental bronchial atresias, five bronchopulmonary sequestrations (BPS), one congenital lobar overinflation, one bronchogenic cyst, and three hybrid lesions. MRI reported the correct diagnosis in 19/20 (95%) patients and the malformation was correctly classified in 22/23 cases (96%). MRI correctly identified all the key findings described on the CT except for the abnormal vascularization (85.7% sensitivity, 100% specificity, 100% PPV, 94.1% NPV, 95% accuracy for arterial vessels; 57.1% sensitivity, 100% specificity, 100% PPV, 84.2% NPV, 87% accuracy for venous drainage).

CONCLUSIONS

MRI can represent an effective alternative to CT in the postnatal assessment of CLM. In order to further narrow the gap with CT, the use of contrast material and improvements in sequence design are needed to obtain detailed information on vascularization, which is essential for surgical planning.

KEY POINTS

• Congenital lung malformations (CLMs) can be effectively studied by MRI avoiding radiation exposure. • Crucial features of CLM have similar appearance when comparing CT with MRI. • MRI performs very well in CLM except for aberrant vessel detection and characterization.

Follow-Up Computed Tomography Requirement of Pediatric Head Trauma Patients with Abnormal Imaging Findings

OBJECTIVE

We investigated pediatric patients presenting with isolated head trauma to emergency service. Where abnormal findings were detected on brain computed tomography (CT) scan, we evaluated the follow-up scan rate and whether follow-up scans affected the treatment protocol.

METHODS

Pediatric patients who presented to emergency service between 2014 and 2017 with isolated head trauma and were later found to have abnormal findings on CT scan were evaluated. The patients were evaluated in terms of age, sex, pediatric Glasgow Coma Scale score at emergency service, trauma mechanism, and abnormal findings on CT scan. We also documented whether follow-up CT scan altered the treatment decision in patients as to whether they underwent surgery or received conservative treatment.

RESULTS

The 105 head trauma patients with abnormal findings on CT scan consisted of 58 boys (55.2%) and 47 girls (44.8%). After the first brain CT examination, 5 of the patients (4.7%) underwent emergency surgery. For patients with linear fractures, the number of follow-up CT scans was 2.3. For patients with linear fractures, vomiting was found to be a symptom with statistical meaning as a sign of additional cranial pathology compared with headache, drowsiness, and irritability. A total of 280 follow-up CT scans with a mean number of 2.66 per patient were performed.

CONCLUSIONS

Follow-up CT scan for patients with abnormal findings on the initial CT scan after head trauma does not influence the decision to choose clinical observation or surgery except in patients with neurologic deterioration.

Radiation Exposure of Premature Infants Beyond the Perinatal Period

OBJECTIVES

To determine the odds of premature compared with term infants exceeding the recommended radiation exposure threshold in the first year after discharge from birth hospitalization.

METHODS

In this observational retrospective cohort study, we compared the radiation exposure of premature and term infants between 2008 and 2015 in an urban hospital system. The primary outcome was crossing the radiation exposure threshold of 1 millisievert. We assessed prematurity's effect on this outcome with multivariable logistic regression.

RESULTS

In our study, 20 049 term and 2047 preterm infants met inclusion criteria. The population was approximately one-half female, predominantly multiracial or people of color (40% African American and 44% multiracial), and of low socioeconomic status. Premature infants had 2.25 times greater odds of crossing the threshold compared with term infants after adjustment for demographics (95% confidence interval [CI]: 1.66-3.05). Adjustment for complex chronic conditions, which are validated metrics of pediatric chronic illness, attenuated this association; however, premature infants still had 1.58 times greater odds of crossing the threshold (95% CI: 1.16-2.15). When the final model was analyzed by degree of prematurity, very preterm and extremely preterm infants were significantly more likely to cross the threshold (1.85 [95% CI: 1.03-3.32] and 2.53 [95% CI: 1.53-4.21], respectively), whereas late preterm infants were not (1.14 [95% CI: 0.73-1.78]).

CONCLUSIONS

Premature infants crossed the recommended radiation threshold more often than term infants in the year after discharge from birth hospitalization.

Predictive value of pediatric respiratory-induced diaphragm motion quantified using pre-treatment 4DCT and CBCTs

Background

In adults, a single pre-treatment four-dimensional CT (4D-CT) acquisition is often used to account for respiratory-induced target motion during radiotherapy. However, studies have indicated that a 4D-CT is not always representative for respiratory motion. Our aim was to investigate whether respiratory-induced diaphragm motion in children on a single pre-treatment 4DCT can accurately predict respiratory-induced diaphragm motion as observed on cone beam CTs (CBCTs).

Methods

Twelve patients (mean age 14.5 yrs.; range 8.6–17.9 yrs) were retrospectively included based on visibility of the diaphragm on abdominal or thoracic imaging data acquired during free breathing. A 4DCT for planning purposes and daily/weekly CBCTs (total 125; range 4–29 per patient) acquired prior to dose delivery were available. The amplitude, corresponding to the difference in position of the diaphragm in cranial-caudal direction in end-inspiration and end-expiration phases, was extracted from the 4DCT (A_4DCT). The amplitude in CBCTs (A_CBCT) was defined as displacement between averaged in- and expiration diaphragm positions on corresponding projection images, and the distribution of A_CBCT was compared to A_4DCT (one-sample t-test, significance level p < 0.05).

Results

Over all patients, the mean A_4DCT was 10.4 mm and the mean A_CBCT 11.6 mm. For 9/12 patients, A_4DCT differed significantly (p < 0.05) from A_CBCT. Differences > 3 mm were found in 69/125 CBCTs (55%), with A_4DCT mostly underestimating A_CBCT. For 7/12 patients, diaphragm positions differed significantly from the baseline position.

Conclusion

Respiratory-induced diaphragm motion determined on 4DCT does not accurately predict the daily respiratory-induced diaphragm motion observed on CBCTs, as the amplitude and baseline position differed statistically significantly in the majority of patients. Regular monitoring of respiratory motion during the treatment course using CBCTs could yield a higher accuracy when a daily adaptation to the actual breathing amplitude takes place.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1143-6) contains supplementary material, which is available to authorized users.

Repeat Head CT for Expectant Management of Traumatic Epidural Hematoma

BACKGROUND AND OBJECTIVES

Guidelines regarding the role of repeated head computed tomography (CT) imaging in the nonoperative management of traumatic epidural hematomas (EDHs) do not exist. Consequently, some children may be exposed to unnecessary additional ionizing radiation. We describe the frequency, timing, and utility of reimaging of EDHs to identify patients who might avoid reimaging.

METHODS

A retrospective cohort study of subjects aged 0 to 18 years with a traumatic EDH treated at a level I pediatric trauma center from 2003 to 2014. Radiographic and clinical findings, the frequency and timing of reimaging, and changes in neurologic status were compared between subjects whose management changed because of a meaningful CT scan and those whose did not.

RESULTS

Of the 184 subjects who were analyzed, 19 (10%) had a meaningful CT. There was no difference in the frequency of CT scans between the meaningful CT scan and no meaningful CT groups (median 1 [interquartile range 1-2] in no meaningful CT and median 1 [interquartile range 1-2] in meaningful CT scans; P = .7). Only 7% of repeated CTs changed management. Neurologic status immediately before the repeat scan (odds ratio 45; 95% confidence interval 10-200) and mass effect on the initial CT (odds ratio 4; 95% confidence interval 1.5-13) were associated with a meaningful CT. Reimaging only subjects with concerning pre-CT neurologic findings or mass effect on initial CT would have decreased imaging by 54%.

CONCLUSIONS

Reimaging is common, but rarely changes management. Limiting reimaging to patients with concerning neurologic findings or mass effect on initial evaluation could reduce imaging by >50%.

Low-dose CT examination for rib fracture evaluation: A pilot study

The aim of this study was to assess the applicability of low-dose thoracic computed tomography (CT) in the diagnosis of rib fractures.A total of 37 trauma patients were selected for CT scanning using a noise index (NI) model. Each patient was scanned at both NI = 11 and NI = 26, while the other scanning parameters were kept the same. The scanning dose length product (DLP) and effective dose (ED) were recorded after each examination. Two radiologists diagnosed the rib fractures by degree (I, II, III, and IV) using Bone Reading software and axial images. Image quality was scored by 2 experienced radiologists using a 5-point scale. The numbers and degrees of rib fractures for different NIs were recorded and tested using the Chi-squared test. The interobserver differences were determined by kappa statistics.The CTDIvols and EDs for NI = 11 and NI = 26 were 9.82 ± 4.78, 5.75 ± 2.75, and 2.14 ± 1.19 and 1.24 ± 0.73, respectively; the latter was decreased by 78.2% and 78.4% relative to the former. Low-dose thoracic CT was feasible for the auxiliary diagnosis of rib fractures using Bone Reading software (P > .05). There was perfect interobserver concordance in terms of diagnostic acceptability (kappa = 0.931, 0.905).The use of an appropriate low-dose CT scanning technique is satisfactory for the assessment and diagnosis of rib fractures.

Trends in diagnostic approaches for pediatric appendicitis: nationwide population-based study

BACKGROUND

To define the benefits of different methods for diagnosis of pediatric appendicitis in Taiwan, a nationwide cohort study was used for analysis.

METHODS

We identified 44,529 patients under 18 years old who had been hospitalized with a diagnosis of acute appendicitis between 2003 and 2012. We analyzed the percentages of cases in which ultrasound (US) and/or computed tomography (CT) were performed and non-perforated and perforated appendicitis were diagnosed for each year. Multivariate logistic regression analyses were performed to evaluate risk factors for perforated appendicitis.

RESULTS

There were more cases of non-perforated appendicitis (N = 32,491) than perforated appendicitis (N = 12,038). The rate of non-perforated cases decreased from 0.068% in 2003 to 0.049% in 2012; perforated cases remained relatively stable at 0.024%~0.023% from 2003 to 2012. The percentage of CT evaluation increased from 3% in 2003 to 20% in 2012; the rates of US or both US and CT evaluations were similar annually. The percentage of neither CT nor US evaluation gradually decreased from 97% in 2003, to 79% in 2012. The odds ratios of a perforated appendix for those patients diagnosed by US, CT, or both US and CT were 1.227 (95% confidence interval (CI) 0.91, 1.65; p = 0.173), 2.744 (95% CI 2.55, 2.95; p < 0.001), and 5.062 (95% CI = 3.14, 8.17; p < 0.001), respectively, compared to patients who did not receive US or CT. The odd ratios of a perforated appendix for those patients 7-12 and ≤6 years old were 1.756 (95% CI 1.67, 1.84; p < 0.001) and 3.094 (95% CI 2.87, 3.34; p < 0.001), respectively, compared to those 13-18 years old.

CONCLUSIONS

Our study demonstrated that using CT scan as a diagnostic tool for acute appendicitis increased annually; most patients especially those ≤6 years old who received CT evaluation had a greater risk of having perforated appendicitis. We recommend a prompt appendectomy in those pediatric patients with typical clinical symptoms and physical findings for non-complicated appendicitis to avoid the risk of appendiceal perforation.

Malocclusion Class II division 1 skeletal and dental relationships measured by cone-beam computed tomography

OBJECTIVES

The purpose of this study was to locate traditionally-used landmarks in two-dimensional (2D) images and newly-suggested ones in three-dimensional (3D) images (cone-beam computer tomographies [CBCTs]) and determine possible relationships between them to categorize patients with Class II-1 malocclusion.

METHODS

CBCTs from 30 patients diagnosed with Class II-1 malocclusion were obtained from the University of Alberta Graduate Orthodontic Program database. The reconstructed images were downloaded and visualized using the software platform AVIZO^®. Forty-two landmarks were chosen and the coordinates were then obtained and analyzed using linear and angular measurements. Ten images were analyzed three times to determine the reliability and measurement error of each landmark using Intra-Class Correlation coefficient (ICC). Descriptive statistics were done using the SPSS statistical package to determine any relationships.

RESULTS

ICC values were excellent for all landmarks in all axes, with the highest measurement error of 2mm in the y-axis for the Gonion Left landmark. Linear and angular measurements were calculated using the coordinates of each landmark. Descriptive statistics showed that the linear and angular measurements used in the 2D images did not correlate well with the 3D images. The lowest standard deviation obtained was 0.6709 for S-GoR/N-Me, with a mean of 0.8016. The highest standard deviation was 20.20704 for ANS-InfraL, with a mean of 41.006.

CONCLUSION

The traditional landmarks used for 2D malocclusion analysis show good reliability when transferred to 3D images. However, they did not reveal specific skeletal or dental patterns when trying to analyze 3D images for malocclusion. Thus, another technique should be considered when classifying 3D CBCT images for Class II-1malocclusion.

Laryngotracheal anomalies and airway fluoroscopy in infants

OBJECTIVES

The role of airway fluoroscopy in the diagnosis of laryngotracheal anomalies in infants is controversial. We aimed to (i) compare airway fluoroscopic characteristics with endoscopic findings in infants presenting for evaluation of upper airway obstruction and (ii) assess the as low as is reasonably achievable (ALARA) status for airway fluoroscopy as an initial diagnostic test in suspected laryngotracheal anomalies.

MATERIALS AND METHODS

We performed a retrospective review of children who underwent fluoroscopy and endoscopic evaluation of the airway in the operating room for suspected laryngotracheal anatomic abnormalities. Thirty-four infants who underwent both procedures at a tertiary level university-based children's hospital from January 1, 2008 to December 1, 2013 were included. Infants with suspected foreign bodies or an existing tracheostomy were excluded. Intraoperative findings from endoscopy and radiologic interpretation from fluoroscopy were compared using standard tools for validation of a diagnostic test. These metrics were compared with historic data that suggested good correlation between radiologic and endoscopic findings in older children.

RESULTS

The median age was 3.6 months (range 1-8 months). The sensitivity of airway fluoroscopy for determining laryngotracheal pathology was 18%. Specificity, positive predictive value and negative predictive value were 83%, 67% and 35%, respectively. Although each fluoroscopic exposure was optimized for pediatric patients, the median cumulative exposure to ionizing radiation was 19 mR (range 10-34 mR).

CONCLUSIONS

Airway fluoroscopy yields metrics that are overall poor to be considered a valid and accurate universal radiologic diagnostic test in infants evaluated for laryngotracheal pathology. The cumulative exposure to ionizing radiation from use of a fluoroscope cannot be justified by the sensitivity of the test and may not conform to ALARA standards for imaging in this population.

Evaluation of an imaging protocol using ultrasound as the primary diagnostic modality in pediatric patients with superficial soft tissue infections of the face and neck

OBJECTIVE

To determine the clinical impact of an initiative to use ultrasound (US) as the primary diagnostic modality for children with superficial face and neck infections versus use of computed tomography (CT).

METHODS

Children with a diagnosis of lymphadenitis, face or neck abscess, or face and neck cellulitis were retrospectively evaluated by the otolaryngology service. Patients were separated into two groups based on implementation of a departmental initiative to use US as the primary diagnostic modality. The pre-implementation cohort consisted of patients treated prior to the initiative (2006-2009) and the current protocol cohort consisted of patients treated after the initiative was started (2010-2013). Demographics, use of US or CT, necessity of surgical intervention, and failure of medical management were compared.

RESULTS

Three hundred seventy three children were evaluated; 114 patients were included in the pre-implementation cohort and 259 patients were included in the current protocol cohort for comparison. Patients presenting during the current protocol period were more likely to undergo US (pre-implementation vs. current protocol, p-value) (12% vs. 49%, p < 0.0001) and less likely to undergo CT (66% vs. 41%, p < 0.0001) for their initial evaluation. There were no differences in the percentage of children who underwent prompt surgical drainage, prompt discharge without surgery, or trial inpatient observation. There were also no differences in the rate of treatment failure for patients undergoing prompt surgery or prompt discharge on antibiotics. For those patients who underwent repeat evaluation following trial medical management, US was used more frequently in the current protocol period (4% vs. 20%, p = 0.002) with no difference in CT use, selected treatment strategy, or treatment failure rates.

CONCLUSION

Increased use of US on initial evaluation of children with superficial face and neck infections resulted in decreased CT utilization, without negatively impacting outcome. Decreasing pediatric radiation exposure and potential long-term effects is of primary importance.

Radiation dose reduction in pediatric great vessel stent computed tomography using iterative reconstruction: A phantom study

BACKGROUND

To study dose reduction using iterative reconstruction (IR) for pediatric great vessel stent computed tomography (CT).

METHODS

Five different great vessel stents were separately placed in a gel-containing plastic holder within an anthropomorphic chest phantom. The stent lumen was filled with diluted contrast gel. CT acquisitions were performed at routine dose, 52% and 81% reduced dose and reconstructed with filtered back projection (FBP) and IR. Objective image quality in terms of noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as subjective image quality were evaluated.

RESULTS

Noise, SNR and CNR were improved with IR at routine and 52% reduced dose, compared to FBP at routine dose. The lowest dose level resulted in decreased objective image quality with both FBP and IR. Subjective image quality was excellent at all dose levels.

CONCLUSION

IR resulted in improved objective image quality at routine dose and 52% reduced dose, while objective image quality deteriorated at 81% reduced dose. Subjective image quality was not affected by dose reduction.

Usefulness of low dose chest CT for initial evaluation of blunt chest trauma

We aimed to compare the diagnostic performance and inter-observer consistency between low dose chest CT (LDCT) and standard dose chest CT (SDCT) in the patients with blunt chest trauma.A total of 69 patients who met criteria indicative of blunt chest trauma (77% of male; age range, 16-85) were enrolled. All patients underwent LDCT without intravenous (IV) contrast and SDCT with IV contrast using parameters as following: LDCT, 40 mAs with automatic tube current modulation (ATCM) and 100 kVp (BMI <25, n = 51) or 120 kVp (BMI>25, n = 18); SDCT, 180 mAs with ATCM and 120 kVp. Transverse, coronal, sagittal images were reconstructed with 3-mm slice thickness without gap and provided for evaluation of 3 observers. Reference standard images (transverse, coronal, sagittal) were reconstructed using SDCT data with 1-mm slice thickness without gap. Reference standard was established by 2 experienced thoracic radiologists by consensus. Three observers independently evaluated each data set of LDCT and SDCT.Multiple-reader receiver operating characteristic analysis for comparing areas under the ROC curves demonstrated that there was no significant difference of diagnostic performance between LDCT and SDCT for the diagnosis of pulmonary injury, skeletal trauma, mediastinal injury, and chest wall injury (P > 0.05). The intraclass correlation coefficient was measured for inter-observer consistency and revealed that there was good inter-observer consistency in each examination of LDCT and SDCT for evaluation of blunt chest injury (0.8601-1.000). Aortic and upper abdominal injury could not be appropriately compared as LDCT was performed without using contrast materials and this was limitation of this study.The effective radiation dose of LDCT (average DLP = 1.52 mSv⋅mGy cm) was significantly lower than those of SDCT (7.21 mSv mGy cm).There is a great potential benefit to use of LDCT for initial evaluation of blunt chest trauma because LDCT could maintain diagnostic image quality as SDCT and provide significant radiation dose reduction. A further study of LDCT with IV contrast for evaluation of aortic and upper abdominal injury is needed.

Pediatric and adult trauma centers differ in evaluation, treatment, and outcomes for severely injured adolescents

BACKGROUND/PURPOSE

This study aims to investigate differences in imaging, procedure utilization, and clinical outcomes of severely injured adolescents treated at adult versus pediatric trauma centers.

METHODS

The National Trauma Data Bank was queried retrospectively for adolescents, 15-19years old, with a length of stay (LOS) >1day and Injury Severity Score (ISS) >25 treated at adult (ATC) or pediatric (PTC) Level 1 trauma centers from 2007 to 2011. Patient demographics and utilization of imaging and procedures were analyzed. Univariate and multivariate regression analysis was used to compare outcomes.

RESULTS

Of 12,861 adolescents, 51% were treated at ATC. Older age and more nonwhites were seen at ATC (p<0.01). Imaging and invasive procedures were more common at ATC (p<0.01). Shorter LOS (p=0.03) and higher home discharge rates (p<0.01) were seen at PTC. ISS and mortality did not differ. Age, race, ATC care (all p<0.01), and admission systolic blood pressure (SBP) (p=0.03) were predictors of CT utilization. ISS, SBP, and race (p<0.01) were risk factors for overall mortality; SBP (p=0.03) and ISS (p<0.01) predicted death from penetrating injury.

CONCLUSIONS

Severely injured adolescents experience improved outcomes and decreased imaging and invasive procedures without additional mortality risk when treated at PTC. PTC is an appropriate destination for severely injured adolescents.

Statistical model based iterative reconstruction in clinical CT systems. Part III. Task-based kV/mAs optimization for radiation dose reduction

PURPOSE

For a given imaging task and patient size, the optimal selection of x-ray tube potential (kV) and tube current-rotation time product (mAs) is pivotal in achieving the maximal radiation dose reduction while maintaining the needed diagnostic performance. Although contrast-to-noise (CNR)-based strategies can be used to optimize kV/mAs for computed tomography (CT) imaging systems employing the linear filtered backprojection (FBP) reconstruction method, a more general framework needs to be developed for systems using the nonlinear statistical model-based iterative reconstruction (MBIR) method. The purpose of this paper is to present such a unified framework for the optimization of kV/mAs selection for both FBP- and MBIR-based CT systems.

METHODS

The optimal selection of kV and mAs was formulated as a constrained optimization problem to minimize the objective function, Dose(kV,mAs), under the constraint that the achievable detectability index d'(kV,mAs) is not lower than the prescribed value of d'R for a given imaging task. Since it is difficult to analytically model the dependence of d' on kV and mAs for the highly nonlinear MBIR method, this constrained optimization problem is solved with comprehensive measurements of Dose(kV,mAs) and d'(kV,mAs) at a variety of kV-mAs combinations, after which the overlay of the dose contours and d' contours is used to graphically determine the optimal kV-mAs combination to achieve the lowest dose while maintaining the needed detectability for the given imaging task. As an example, d' for a 17 mm hypoattenuating liver lesion detection task was experimentally measured with an anthropomorphic abdominal phantom at four tube potentials (80, 100, 120, and 140 kV) and fifteen mA levels (25 and 50-700) with a sampling interval of 50 mA at a fixed rotation time of 0.5 s, which corresponded to a dose (CTDIvol) range of [0.6, 70] mGy. Using the proposed method, the optimal kV and mA that minimized dose for the prescribed detectability level of d'R=16 were determined. As another example, the optimal kV and mA for an 8 mm hyperattenuating liver lesion detection task were also measured using the developed framework. Both an in vivo animal and human subject study were used as demonstrations of how the developed framework can be applied to the clinical work flow.

RESULTS

For the first task, the optimal kV and mAs were measured to be 100 and 500, respectively, for FBP, which corresponded to a dose level of 24 mGy. In comparison, the optimal kV and mAs for MBIR were 80 and 150, respectively, which corresponded to a dose level of 4 mGy. The topographies of the iso-d' map and the iso-CNR map were the same for FBP; thus, the use of d'- and CNR-based optimization methods generated the same results for FBP. However, the topographies of the iso-d' and iso-CNR map were significantly different in MBIR; the CNR-based method overestimated the performance of MBIR, predicting an overly aggressive dose reduction factor. For the second task, the developed framework generated the following optimization results: for FBP, kV = 140, mA = 350, dose = 37.5 mGy; for MBIR, kV = 120, mA = 250, dose = 18.8 mGy. Again, the CNR-based method overestimated the performance of MBIR. Results of the preliminary in vivo studies were consistent with those of the phantom experiments.

CONCLUSIONS

A unified and task-driven kV/mAs optimization framework has been developed in this work. The framework is applicable to both linear and nonlinear CT systems such as those using the MBIR method. As expected, the developed framework can be reduced to the conventional CNR-based kV/mAs optimization frameworks if the system is linear. For MBIR-based nonlinear CT systems, however, the developed task-based kV/mAs optimization framework is needed to achieve the maximal dose reduction while maintaining the desired diagnostic performance.

Ultrasound for Distal Forearm Fracture: A Systematic Review and Diagnostic Meta-Analysis

Study Objective

To determine the diagnostic accuracy of ultrasound for detecting distal forearm fractures.

Methods

A systematic review and diagnostic meta-analysis was performed according to the PRISMA statement. We searched MEDLINE, Web of Science and the Cochrane Library from inception to September 2015. All prospective studies of the diagnostic accuracy of ultrasound versus radiography as the reference standard were included. We excluded studies with a retrospective design and those with evidence of verification bias. We assessed the methodological quality of the included studies with the QUADAS-2 tool. We performed a meta-analysis of studies evaluating ultrasound to calculate the pooled sensitivity and specificity with 95% confidence intervals (CI95%) using a bivariate model with random effects. Subgroup and sensitivity analysis were used to examine the effect of methodological differences and other study characteristics.

Results

Out of 867 publications we included 16 studies with 1,204 patients and 641 fractures. The pooled test characteristics for ultrasound were: sensitivity 97% (CI95% 93–99%), specificity 95% (CI95% 89–98%), positive likelihood ratio (LR) 20.0 (8.5–47.2) and negative LR 0.03 (0.01–0.08). The corresponding pooled diagnostic odds ratio (DOR) was 667 (142–3,133). Apparent differences were shown for method of viewing, with the 6-view method showing higher specificity, positive LR, and DOR, compared to the 4-view method.

Conclusion

The present meta-analysis showed that ultrasound has a high accuracy for the diagnosis of distal forearm fractures in children when used by proper viewing method. Based on this, ultrasound should be considered a reliable alternative, which has the advantages of being radiation free.

CT versus ultrasound guidance for percutaneous drainages in the pediatric population: an institutional review meant to limit radiation

Computed tomography (CT)-guided percutaneous drainage is a minimally invasive procedure that allows for accurate diagnosis and therapy with minimal complications. The drawback is that CT guidance carries a significant amount of radiation exposure. CT-guided percutaneous drainages have been widely used in adults and have been gaining momentum within the pediatric population. Through a thorough review of our institution's (Montefiore Medical Center) CT-guided percutaneous drainages within our pediatric patients, we assessed the radiation exposure per study as well as which studies were deemed possible under ultrasound guidance as a possible alternative.

Feasibility and Safety of Substituting Lung Ultrasonography for Chest Radiography When Diagnosing Pneumonia in Children: A Randomized Controlled Trial

BACKGROUND

Chest radiography (CXR) is the test of choice for diagnosing pneumonia. Lung ultrasonography (LUS) has been shown to be accurate for diagnosing pneumonia in children and may be an alternative to CXR. Our objective was to determine the feasibility and safety of substituting LUS for CXR when evaluating children suspected of having pneumonia.

METHODS

We conducted a randomized control trial comparing LUS with CXR in 191 children from birth to 21 years of age suspected of having pneumonia in an ED. Patients in the investigational arm underwent LUS. If there was clinical uncertainty after ultrasonography, physicians had the option to perform CXR. Patients in the control arm underwent sequential imaging with CXR followed by LUS. The primary outcome was the rate of CXR reduction; secondary outcomes were missed pneumonia, subsequent unscheduled health-care visits, and adverse events between the investigational and control arms.

RESULTS

There was a 38.8% reduction (95% CI, 30.0%-48.9%) in CXR among investigational subjects compared with no reduction (95% CI, 0.0%-3.6%) in the control group. Novice and experienced physician-sonologists achieved 30.0% and 60.6% reduction in CXR use, respectively. There were no cases of missed pneumonia among all study participants (investigational arm, 0.0%: 95% CI, 0.0%-2.9%; control arm, 0.0%: 95% CI, 0.0%-3.0%), or differences in adverse events, or subsequent unscheduled health-care visits between arms.

CONCLUSIONS

It may be feasible and safe to substitute LUS for CXR when evaluating children suspected of having pneumonia with no missed cases of pneumonia or increase in rates of adverse events.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01654887; URL: www.clinicaltrials.gov.

Pediatric Head Trauma

Traumatic brain injury (TBI) refers to a spectrum of brain injury that can result in significant morbidity and mortality in pediatric patients. Pediatric head trauma is distinct from adult TBI. The purpose of this review article is to discuss pediatric TBI and current treatment modalities available.

Risk factors for traumatic blunt cerebrovascular injury diagnosed by computed tomography angiography in the pediatric population: a retrospective cohort study

OBJECT Computed tomography angiography (CTA) is frequently used to examine patients for blunt cerebrovascular injury (BCVI) after cranial trauma, but the pediatric population at risk for BCVI is poorly defined. Although CTA is effective for BCVI screening in adults, the increased lifetime risk for malignant tumors associated with this screening modality warrants efforts to reduce its use in children. The authors' objective was to evaluate the incidence of BCVI diagnosed by CTA in a pediatric patient cohort and to create a prediction model to identify children at high risk for BCVI. METHODS Demographic, clinical, and radiographic data were collected retrospectively for pediatric patients who underwent CTA during examination for traumatic cranial injury from 2003 through 2013. The primary outcome was injury to the carotid or vertebral artery diagnosed by CTA. RESULTS The authors identified 234 patients (mean age 8.3 years, range 0.04-17 years, 150 [64%] boys) who underwent CTA screening for BCVI. Of these, 24 (10.3%) had a focal neurological deficit, and 153 (65.4%) had intracranial hemorrhage on a head CTA. Thirty-seven BCVIs were observed in 36 patients (15.4%), and 16 patients (6.8%) died. Multivariate regression analysis identified fracture through the carotid canal, petrous temporal bone fracture, Glasgow Coma Scale (GCS) score of < 8, focal neurological deficit, and stroke on initial CT scan as independent risk factors for BCVI. A prediction model for identifying children at high risk for BCVI was created. A score of ≤ 2 yielded a 7.9% probability of BCVI and a score of ≥ 3 a risk of 39.3% for BCVI. CONCLUSIONS For cranial trauma in children, fracture of the petrous temporal bone or through the carotid canal, focal neurological deficit, stroke, and a GCS score of < 8 are independent risk factors for BCVI.

Bedside emergency department ultrasonography availability and use for blunt abdominal trauma in Canadian pediatric centres

Objectives:

To quantify the current availability and use of bedside emergency department ultrasonography (EDUS) for blunt trauma at Canadian pediatric centres and to identify any perceived barriers to the use of bedside EDUS in such centres.

Methods:

An electronic survey was sent to 162 pediatric emergency physicians and 12 site directors from the 12 pediatric emergency departments across Canada.

Results:

Ninety-two percent (11 of 12) of centres completed the survey. The individual physician response rate was 65% (106 of 162), with 100% of site directors responding. Ultrasound machines were available in 45% (5 of 11) of centres. Forty-two percent (32 of 77) of emergency physicians working in equipped pediatric centres used bedside EDUS to evaluate blunt abdominal trauma (BAT). In the subgroup of staff who also worked at adults sites, the frequency of ultrasonography use for the evaluation of pediatric BAT was 75%. In the 55% (6 of 11) of centres without ultrasonography, 88% of staff intend to incorporate its use in the future and 81% indicated that they believed the incorporation of ultrasonography would have a positive impact on patient care. The main perceived barriers to the use of ultrasonography in the evaluation of BAT were a lack of training (41%) and a lack of equipment (26%).

Conclusion:

Bedside EDUS is currently used in almost half of pediatric trauma centres, a frequency that is significantly lower than adult centres. Physicians in pediatric centres who use ultrasonography report that it has a high utility, and a great majority of physicians at pediatric centres without EDUS plan to incorporate it in the future. The main reported barriers to its use are a lack of training and a lack of equipment availability.

Natural history of incidental pulmonary nodules in children

RATIONALE

As there are no evidence based guidelines for the diagnosis and/or management of pulmonary nodules in children, there is an over reliance on the adult based algorithms when dealing with pulmonary nodules in children. We present our experience of pediatric patients evaluated for incidentally found pulmonary nodules.

METHODS

Retrospective chart review of patients diagnosed with a pulmonary nodule and evaluated at Goryeb Children's Hospital between January 2000 and December 2012.

PRIMARY OUTCOME

change in the size of the pulmonary nodule between the initial and follow-up imaging.

RESULTS

Thirty six patients with pulmonary nodule (21 male/15 female; Median [range] age 15 [5-20] years.) were included in the study. Chest CT was obtained for respiratory symptoms and/or abnormal chest radiograph in 19 (52%). Nine pulmonary nodules (25%) were identified on abdominal CT obtained for abdominal symptoms. A total of 46 nodules were identified in 36 patients. Nine of the pulmonary nodules (9 patients) were ≤4 mm in size, 37 of the pulmonary nodules (27 patients) were >4 mm in size. Twenty-two of the 27 (81%) patients with nodule size >4 mm had follow-up CT: 14 nodules (54%) remained unchanged in size, 5 nodules (19%) decreased in size, and 7 nodules (27%) were not detected.

CONCLUSION

Our review of 36 patients with pulmonary nodules shows no obvious growth of the nodules over the study period, suggesting low risk of malignancy. Routine follow-up chest computer tomography using ACCP/Fleischner Society guidelines may not apply in children without known malignancy.

Variation in CT pediatric head examination radiation dose: results from a national survey

OBJECTIVE. The purpose of this article is to examine the variation in radiation dose, CT dose index volume (CTDIvol), and dose-length product (DLP) for pediatric head CT examinations as a function of hospital characteristics across the United States. MATERIALS AND METHODS. A survey inquiring about hospital information, CT scanners, pediatric head examination protocol, CTDIvol, and DLP was mailed to a representative sample of U.S. hospitals. Follow-up mailings were sent to nonrespondents. Descriptive characteristics of respondents and nonrespondents were compared using design-based Pearson chi-square tests. Dose estimates were compared across hospital characteristics using Bonferroni-adjusted Wald test. Hospital-level factors associated with dose estimates were evaluated using multiple linear regressions and modified Poisson regression models. RESULTS. Surveys were sent out to 751 hospitals; 292 responded to the survey, of which 253 were eligible (35.5% response rate, calculated as number of hospitals who completed surveys [n = 253] divided by sum of number who were eligible and initially consented [n = 712] plus estimated number who were eligible among those who refused [n = 1]). Most respondents reported using MDCT scanners (99.2%) and having a dedicated pediatric head CT protocol (93%). Estimated mean reported CTDIvol values were 27.3 mGy (95% CI, 24.4-30.1 mGy), and DLP values were 390.9 mGy × cm (95% CI, 346.6-435.1 mGy × cm). These values did not vary significantly by region, trauma level, teaching status, CT accreditation, number of CT scanners, or report of a dedicated pediatric CT protocol. However, estimated CTDIvol reported by children's hospitals was 19% lower than that reported by general hospitals (p < 0.01). CONCLUSION. Most hospitals (82%) report doses that meet American College of Radiology accreditation levels. However, [corrected] the mean CTDI(vol) at children's hospitals was approximately 7 mGy (21%, adjusted for covariates), lower than that at nonchildren's hospitals.