Radiation exposure from pediatric head CT: a bi-institutional study

Age-Dependent Changes in Effective Dose in Pediatric Brain CT: Comparisons of Estimation Methods

The effective dose (ED) in computed tomography (CT) may be calculated by multiplying the dose-length product (DLP) by a conversion factor. As children grow, automatic exposure control increases the DLP, while the conversion factor decreases; these two changes affect the ED in opposite ways. The aim of this study was to investigate the methods of ED estimation according to age in pediatric brain CT. We retrospectively analyzed 980 brain CT scans performed for various clinical indications in children. The conversion factor at each age, in integer years, was determined based on the values at 0, 1, 5, and 10 years provided by the International Commission on Radiological Protection (ICRP), using a curve (curve method) or lines (linear method). In the simple method, the ED was estimated using the ICRP conversion factor for the closest age. We also analyzed the ED estimated by a radiation dose management system. Although the median DLP at each age increased with age, the median ED estimated by the curve method was highest at 0 years, decreased with age, and then plateaued at 9 years. The linear method yielded mildly different results, especially at 2 and 3 years. The ED estimated by the simple method or the radiation dose management system showed inconsistent, up-and-down changes with age. In conclusion, the ED in pediatric brain CT decreases with age despite increased DLP. Determination of the conversion factor at each age using a curve is expected to contribute to estimating the ED in pediatric CT according to age.

Pediatric Brain Tumor Risk Associated with Head Computed Tomography: Systematic Literature Review

Computed tomography (CT) of the brain has changed diagnostic neuroradiology significantly over the past 50 years since it was firstly used back in 1971 to visualize suspected frontal lobe tumour. The safety of head CT is determined by the small amount of radiation and the low sensibility of brain tissue to cytotoxic damage due to ionizing radiation compared to other organs. However, some population groups may be at increased risk. Thus, children are more susceptible to radiation cancer than adults and lifelong attributive risk (LAR) can be more than 10 times higher for an infant than for a middle-aged adult. The authors have reviewed published studies that examined the prevalence and mortality of intracranial tumors in children undergoing head CT in comparison to unaffected individuals. Electronic search of publications in the PubMed database from 1966 to date was carried out. We have carried out intersectoral search for documents containing keywords or medical subject headings (MeSH) related to three wide categories: 1) computed tomography, 2) radiation-induced tumors, 3) risk, morbidity or epidemiology. Further search was performed in manual mode. Available epidemiological data generally confirmed correlation between head CT and tumor growth induction. Thus, current epidemiological data accept the opinion that the risk of tumor induction associated with head CT in children is very small (one tumor per 3,000–10,000 studies). The minimal estimated risk of tumor induction due to head CT in children is mostly offset by its diagnostic imaging benefits considering the clinical indications to minimize radiation dose. Understanding and quantitative risk assessment of carcinogenesis associated with CT imaging led to dose reduction in pediatric CT protocols. This trend should continue and should be implemented in all age groups. Although the decision to perform head CT is often undeniable (injury or hemorrhage), careful assessment of studies frequency is required, especially in patients who need disease monitoring. Cumulative effect in such cases may increase the minimal risk of carcinogenesis. Larger and advanced epidemiological studies are required to better understand these risks.

Differences in radiation dose for computed tomography of the brain among pediatric patients at the emergency departments: an observational study

BACKGROUND

Computed tomography (CT) is associated with a risk of cancer development. Strategies to reduce radiation doses vary between centers. We compared radiation doses of CT brain studies between pediatric and general emergency departments (EDs), and determine the proportion studies performed within the reference levels recommended by the International Commission on Radiological Protection (ICRP).

METHODS

A retrospective review was carried out in a healthcare network consisting of one pediatric ED and three general hospital EDs. Pediatric patients less than 16 years old with CT brain studies performed between 1 January 2015 and 31 December 2018 were included. Information on demographic, diagnosis, volume-averaged computed-tomography dose index and dose length product (DLP) were collected. Effective dose was then calculated from DLP using conversion factors, termed k-coefficients which were derived using a 16 cm head CT dose phantom.

RESULTS

Four hundred and seventy-nine CT brain studies were performed - 379 (79.1%) at the pediatric ED. Seizure (149, 31.1%), head injury (147, 30.7%) and altered mental status (44, 9.2%) were the top three ED diagnoses. The median effective dose estimates were higher in general than pediatric EDs, particularly for those aged > 3 to ≤6 years old [1.57 mSv (IQR 1.42-1.79) versus 1.93 mSv (IQR 1.51-2.28), p = 0.047], > 6 to ≤10 years old [1.43 mSv (IQR 1.27-1.67) versus 1.94 mSv (IQR 1.61-2.59), p = 0.002) and > 10 years old (1.68 mSv (IQR 1.32-1.72) versus 2.03 mSv (IQR 1.58-2.88), p < 0.001). Overall, 233 (48.6%) and 13 (2.7%) studies were within the reference levels recommended by ICRP 60 and 103 respectively.

CONCLUSIONS

Radiation doses for CT brain studies were significantly higher at general EDs and less than half of the studies were within the reference levels recommended by ICRP. The development of diagnostic reference levels (DRLs) as a benchmark and clinical justification for performing CT studies can help reduce the radiation risks in the pediatric population.

Variation in radiation dosing among pediatric trauma patients undergoing head computed tomography scan

BACKGROUND

When head injured children undergo head computed tomography (CT), radiation dosing can vary considerably between institutions, potentially exposing children to excess radiation, increasing risk for malignancies later in life. We compared radiation delivery from head CTs at a level 1 pediatric trauma center (PTC) versus scans performed at referring adult general hospitals (AGHs). We hypothesized that children at our PTC receive a significantly lower radiation dose than children who underwent CT at AGHs for similar injury profiles.

METHODS

We retrospectively reviewed the charts of all patients younger than 18 years who underwent CT for head injury at our PTC or at an AGH before transfer between January 1 and December 31, 2019. We analyzed demographic and clinical data. Our primary outcome was head CT radiation dose, as calculated by volumetric CT dose index (CTDIvol) and dose-length product (DLP; the product of CTDIvol and scan length). We used unadjusted bivariate and multivariable linear regression (adjusting for age, weight, sex) to compare doses between Children's Hospital Los Angeles and AGHs.

RESULTS

Of 429 scans reviewed, 193 were performed at our PTC, while 236 were performed at AGHs. Mean radiation dose administered was significantly lower at our PTC compared with AGHs (CTDIvol 20.3/DLP 408.7 vs. CTDIvol 30.6/DLP 533, p < 0.0001). This was true whether the AGH was a trauma center or not. After adjusting for covariates, findings were similar for both CTDIvol and DLP. Patients who underwent initial CT at an AGH and then underwent a second CT at our PTC received less radiation for the second CT (CTDIvol 25.6 vs. 36.5, p < 0.0001).

CONCLUSIONS

Head-injured children consistently receive a lower radiation dose when undergoing initial head CT at a PTC compared with AGHs. This provides a basis for programs aimed at establishing protocols to deliver only as much radiation as necessary to children undergoing head CT.

LEVEL OF EVIDENCE

Care Management/Therapeutic, level IV.

Variability in image quality and radiation dose within and across 97 medical facilities

Purpose: To characterize variability in image quality and radiation dose across a large cohort of computed tomography (CT) examinations and identify the scan factors with the highest influence on the observed variabilities. Approach: This retrospective institutional-review-board-exempt investigation was performed on 87,629 chest and abdomen-pelvis CT scans acquired for 97 facilities from 2018 to 2019. Images were assessed in terms of noise, resolution, and dose metrics (global noise, frequency in which modulation transfer function is at 0.50, and volumetric CT dose index, respectively). The results were fit to linear mixed-effects models to quantify the variabilities as affected by scan parameters and settings and patient characteristics. A list of factors, ranked by t -value with p < 0.05 , was ascertained for each of the six mixed effects models. A type III p -value test was used to assess the influence of facility. Results: Across different facilities, image quality and dose were significantly different ( p < 0.05 ), with little correlation between their mean magnitudes and consistency (Pearson's correlation coefficient < 0.34 ). Scanner model, slice thickness, recon field-of-view and kernel, mAs, kVp, patient size, and centering were the most influential factors. The two body regions exhibited similar rankings of these factors for noise (Spearman's correlation coefficient = 0.76 ) and dose (Spearman's correlation coefficient = 0.86 ) but not for resolution (Spearman's correlation coefficient = 0.52 ). Conclusions: Clinical CT scans can vary in image quality and dose with broad implications for diagnostic utility and radiation burden. Average scan quality was not correlated with interpatient scan-quality consistency. For a given facility, this variability can be quite large, with magnitude differences across facilities. The knowledge of the most influential factors per body region may be used to better manage these variabilities within and across facilities.

Cochlear implantation in children without preoperative computed tomography diagnostics. Analysis of procedure and rate of complications

INTRODUCTION

To evaluate the safety in cochlear implantation without preoperative computed tomography diagnostics, which was implemented into the protocol of cochlear implantation in 2013, since in the year before, new evidence concerning the risks of ionizing radiation especially in children arose.

METHODS

In this retrospective data analysis 89 children under 36 months, which were cochlear implanted from 2008 until 2018 at a tertiary referral centre with a large cochlear implant program were analysed. Fortyfour of the children were implanted before the date of change in 2013 and 45 in the following years up to now. The data about the operative procedures, the postoperative care and the complication rate before and after implementation of the new protocol were compared.

RESULTS

Before the date of change in 2013, 100% of patients received preoperative CT diagnostics, in the following years 13.3%. No difference in the duration of surgery, the procedure related and the late complications between the two groups was identified.

CONCLUSION

Cochlear implantation in very young children under the age of 36 months without preoperative radiological diagnostics by CT scan of the temporal bone is a safe procedure without additional risks for the patients.

Implementation of a brain injury screen MRI for infants at risk for abusive head trauma

BACKGROUND

Head computed tomography (CT) is the current standard of care for evaluating infants at high risk of abusive head trauma.

OBJECTIVE

To both assess the feasibility of using a previously developed magnetic resonance imaging (MRI) brain injury screen (MRBRscreen) in the acute care setting in place of head CT to identify intracranial hemorrhage in high-risk infants and to compare the accuracy of a rapid imaging pulse sequence (single-shot T2 fast spin echo [ssT2FSE]) to a conventional pulse sequence (conventional T2 fast spin echo [conT2FSE]).

MATERIALS AND METHODS

This was a quality improvement initiative to evaluate infants <12 months of age who were screened for intracranial hemorrhage using an MRBRscreen as part of clinical care. The MRBRscreen included axial conT2FSE, axial gradient recalled echo, coronal T1-weighted inversion recovery, axial diffusion-weighted image and an axial ssT2FSE. A comparison of ssT2FSE to conT2FSE with respect to lesion detection was also performed.

RESULTS

Of 158 subjects, the MRBRscreen was able to be completed in 155 (98%); 9% (14/155) were abnormal. Ninety-four percent (137/145) of subjects underwent only an MRBRscreen and avoided both radiation from head CT and sedation from MRI. The axial ssT2FSE and conT2FSE results were congruent 99% of the time.

CONCLUSION

An MRBRscreen in place of a head CT is feasible and potentially could decrease head CT use by more than 90% in this population. Using a rapid ssT2FSE in place of a conT2FSE can reduce total scan time without losing lesion detection. If an MRBRscreen is readily available, physicians' threshold to perform neuroimaging may be lowered and lead to earlier detection of abusive head trauma.

Multisection computed tomography: Results from a Chinese survey on radiation dose metrics

BACKGROUND

As multisection spiral computed tomography (MSCT) have been extensively used, it is important to consider the amounts of doses the patients are exposed during a computed tomography (CT) examination. The aim of the current study was to summarize MSCT doses in Chinese patients to establish the diagnostic reference levels (DRLs).

METHODS

Radiation dose metrics were retrospectively collected from 164,073 CT examinations via the Radimetrics Enterprise Platform. Radiation dose metrics (volume CT dose index [CTDIvol], dose-length product [DLP], effective dose [ED], and organ dose) and size-specific dose estimate (SSDE) were calculated for adults and children based on anatomic area and scanner type.

RESULTS

The median CTDIvol and DLP values were highest in the head at 51.7 mGy (interquartile range [IQR], 33.2-51.7 mGy) and 906.5 mGy·cm (IQR, 582.4-1068.2 mGy·cm) and lowest in the chest at 7.9 mGy (IQR, 7.9-10.3 mGy) and 284.8 mGy·cm (IQR, 249.0-412.6 mGy·cm), respectively. The median SSDE values of chest and pelvis were 12.1 mGy (IQR, 10.8-14.1 mGy) and 36.3 mGy (IQR, 34.0-38.9 mGy), respectively. EDs for children were similar to adults except for an increased 1.5-, 0.77-, and 1.7-fold in the chest, neck, and pelvis, respectively (p < 0.001). Furthermore, radiation doses tended to increase with increasing slice number and decrease when exposure reduction techniques were used.

CONCLUSION

Our findings provide a basis for the evaluation of CT radiation doses and evidence for establishment of DRLs in China.

Noncontrast Head CT in Children: National Variation in Radiation Dose Indices in the United States

BACKGROUND AND PURPOSE

Radiologists should manage the radiation dose for pediatric patients to maintain reasonable diagnostic confidence. We assessed the variation in estimated radiation dose indices for pediatric noncontrast head CT in the United States.

MATERIALS AND METHODS

Radiation dose indices for single-phase noncontrast head CT examinations in patients 18 years of age and younger were retrospectively reviewed between July 2011 and June 2016 using the American College of Radiology CT Dose Index Registry. We used the reported volume CT dose index stratified by patient demographics and imaging facility characteristics.

RESULTS

The registry included 295,296 single-phase pediatric noncontrast head CT studies from 1571 facilities (56% in male patients and 53% in children older than 10 years of age). The median volume CT dose index was 33 mGy (interquartile range = 22-47 mGy). The volume CT dose index increased as age increased. The volume CT dose index was lower in children's hospitals (median, 26 mGy) versus academic hospitals (median, 32 mGy) and community hospitals (median, 40 mGy). There was a lower volume CT dose index in level I and II trauma centers (median, 27 and 32 mGy, respectively) versus nontrauma centers (median, 40 mGy) and facilities in metropolitan locations (median, 30 mGy) versus those in suburban and rural locations (median, 41 mGy).

CONCLUSIONS

Considerable variation in the radiation dose index for pediatric head CT exists. Median dose indices and practice variations at pediatric facilities were both lower compared with other practice settings. Decreasing dose variability through proper management of CT parameters in pediatric populations using benchmarks generated by data from registries can potentially decrease population exposure to ionizing radiation.

Risk of Brain Tumor Induction from Pediatric Head CT Procedures: A Systematic Literature Review

Head computed tomography (CT) is instrumental for managing patients of all ages. However, its low dose radiation may pose a low but non-zero risk of tumor induction in pediatric patients. Here, we present a systematic literature review on the estimated incidence of brain tumor induction from head CT exams performed on children and adolescents. MEDLINE was searched using an electronic protocol and bibliographic searches to identify articles related to CT, cancer, and epidemiology or risk assessment. Sixteen studies that predicted or measured head CT-related neoplasm incidence or mortality were identified and reviewed. Epidemiological studies consistently cited increased tumor incidence in pediatric patients (ages 0–18) exposed to head CTs. Excess relative risk of new brain tumor averaged 1.29 (95% confidence interval, 0.66–1.93) for pediatric patients exposed to one or more head CTs. Tumor incidence increased with number of pediatric head CTs in a dose-dependent manner, with measurable excess incidence even after a single scan. Converging evidence from epidemiological studies supported a small excess risk of brain tumor incidence after even a single CT exam in pediatric patients. However, refined epidemiological methods are needed to control for confounding variables that may contribute to reverse causation, such as patients with pre-existing cancer or cancer susceptibility. CT remains an invaluable technology that should be utilized so long as there is clinical indication for the study and the radiation dose is as small as reasonably achievable.

BODY SIZE-SPECIFIC EFFECTIVE DOSE CONVERSION COEFFICIENTS FOR CT SCANS

Effective dose from computed tomography (CT) examinations is usually estimated using the scanner-provided dose-length product and using conversion factors, also known as k-factors, which correspond to scan regions and differ by age according to five categories: 0, 1, 5, 10 y and adult. However, patients often deviate from the standard body size on which the conversion factor is based. In this study, a method for deriving body size-specific k-factors is presented, which can be determined from a simple regression curve based on patient diameter at the centre of the scan range. Using the International Commission on Radiological Protection reference paediatric and adult computational phantoms paired with Monte Carlo simulation of CT X-ray beams, the authors derived a regression-based k-factor model for the following CT scan types: head-neck, head, neck, chest, abdomen, pelvis, abdomen-pelvis (AP) and chest-abdomen-pelvis (CAP). The resulting regression functions were applied to a total of 105 paediatric and 279 adult CT scans randomly sampled from patients who underwent chest, AP and CAP scans at the National Institutes of Health Clinical Center. The authors have calculated and compared the effective doses derived from the conventional age-specific k-factors with the values computed using their body size-specific k-factor. They found that by using the age-specific k-factor, paediatric patients tend to have underestimates (up to 3-fold) of effective dose, while underweight and overweight adult patients tend to have underestimates (up to 2.6-fold) and overestimates (up to 4.6-fold) of effective dose, respectively, compared with the effective dose determined from their body size-dependent factors. The authors present these size-specific k-factors as an alternative to the existing age-specific factors. The body size-specific k-factor will assess effective dose more precisely and on a more individual level than the conventional age-specific k-factors and, hence, improve awareness of the true exposure, which is important for the clinical community to understand.

Computed Tomography and Shifts to Alternate Imaging Modalities in Hospitalized Children

BACKGROUND

Many studies have demonstrated a rise in computed tomography (CT) utilization in abstract children's hospitals. However, CT utilization may be declining, perhaps due to awareness of potential hazards of pediatric ionizing radiation, such as increased risk of malignancy. Th e objective is to assess the trend in CT utilization in hospitalized children at freestanding children's hospitals from 2004 to 2012 and we hypothesize decreases are associated with shifts to alternate imaging modalities.

METHODS

Multicenter cross-sectional study of children admitted to 33 pediatric tertiary-care hospitals participating in the Pediatric Health Information System between January 1, 2004, and December 31, 2012. The rates of CT, ultrasound, and MRI for the top 10 All-Patient Refined Diagnosis Related Groups (APR-DRGs) for which CT was performed in 2004 were determined by billing data. Rates of each imaging modality for those top 10 APR-DRGs were followed through the study period. Odds ratios of imaging were adjusted for demographics and illness severity.

RESULTS

For all included APR-DRGs except ventricular shunt procedures and nonbacterial gastroenteritis, the number of children imaged with any modality increased. CT utilization decreased for all APR-DRGs (P values , .001). For each of the APR-DRGs except seizure and infections of upper respiratory tract, the decrease in CT was associated with a significant rise in an alternative imaging modality (P values # .005).

CONCLUSIONS

For the 10 most common APR-DRGs for which children received CT in 2004,a decrease in CT utilization was found in 2012. Alternative imaging modalities for 8 of the diagnoses were used.

Radiographic evaluation of pediatric cerebrospinal fluid shunt malfunction in the emergency setting

Children with ventricular cerebrospinal fluid shunts for treatment of hydrocephalus require frequent evaluation for potential shunt malfunction. Current practice relies heavily on neuroimaging, particularly cranial computed tomography, which repeatedly exposes children to ionizing radiation. Rapid cranial magnetic resonance imaging is a new radiation-sparing alternative to CT for evaluation of potential shunt malfunction. We review the diagnostic test performance, radiation exposure, advantages, and limitations of the major neuroimaging modalities available to providers caring for children with possible shunt malfunction in the emergent setting.

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.

Advanced neuroimaging of mild traumatic brain injury

This article focuses on advancements in neuroimaging techniques, compares the advantages of each of the modalities in the evaluation of mild traumatic brain injury, and discusses their contribution to our understanding of the pathophysiology as it relates to prognosis. Advanced neuroimaging techniques discussed include anatomic/structural imaging techniques, such as diffusion tensor imaging and susceptibility-weighted imaging, and functional imaging techniques, such as functional magnetic resonance imaging, perfusion-weighted imaging, magnetic resonance spectroscopy, and positron emission tomography.

Variation in the use of skull radiographs by emergency physicians in young children with minor head trauma

BACKGROUND

Minor head trauma in young children is a major cause of emergency department visits. Conflicting guidelines exist regarding radiologic evaluation in such cases.

OBJECTIVE

To determine the practice pattern among Canadian emergency physicians for ordering skull radiographs in young children suffering from minor head trauma. Physicians were also surveyed on their willingness to use a clinical decision rule in such cases.

DESIGN/METHODS

A self-administered email questionnaire was sent to all members of the Pediatric Emergency Research Canada (PERC) group. It consisted of clinical vignettes followed by multiple-option answers on the management plan. The study was conducted using the principles of the Dillman Tailored Design method and included multiple emailings to maximize the response rate. The research protocol received Institutional Review Board approval.

RESULTS

A total of 158 of 295 (54%) PERC members responded. Most participants were trained in pediatric emergency medicine and assessed more than 500 children per year. Imaging management for the vignettes was highly variable: 6 of the 11 case scenarios had a proportion of radiograph ordering between 20 and 80%. Ninety-five percent of respondents stated that they would apply a validated clinical decision rule for the detection of skull fracture in young children with minor head trauma. The minimum sensitivity deemed acceptable for such a rule was 98%.

CONCLUSION

Canadian emergency physicians have a wide variation in skull radiography ordering in young children with minor head trauma. This variation, along with the need expressed by physicians, suggests that further research to develop a clinical decision rule is warranted.

Risk of malignancy associated with head and neck CT in children: a systematic review

OBJECTIVE

To perform a systematic review to evaluate the risk of malignancy associated with computed tomography (CT) of the head and/or neck in infants, children, and adolescents.

DATA SOURCES

Pubmed, EMBASE, and the Cochrane Library were assessed from the date of their inception to January 2014. Additionally, manual searches of bibliographies were performed and topic experts were contacted.

REVIEW METHODS

Data were obtained from studies measuring or estimating the risks of malignancy associated with radiation from head and/or neck CT in pediatric populations according to an a priori protocol. Two independent evaluators corroborated the extracted data.

RESULTS

There were 16 criterion-meeting studies that included data from n = 858,815 patients. The radiation-related risk of malignancy was estimated using primary patient data for both the exposure and outcome in a minority of studies, with most analyses utilizing mathematical modeling techniques. The data regarding otolaryngology-specific studies were limited and suggested a borderline significant increase in the risk of all combined cancers after facial CT (incidence rate ratio [IRR] = 1.14; 95% CI, 1.01-1.28) and neck/spine CT (IRR = 1.13; 95% CI, 1.00-1.28). Cohort data suggest that 1 excess brain malignancy occurred after 4000 brain CTs (40 mSv per scan) and that the estimated risk in the 10 years following CT exposure was 1 brain tumor per 10,000 patients exposed to a 10 mGy scan at less than 10 years of age.

CONCLUSION

Detailed understanding of any potential malignancy risk associated with pediatric imaging of the head and neck furthers our ability to engage in rational, shared, informed decision making with families considering CT scan.

Optimizing the balance between radiation dose and image quality in pediatric head CT: findings before and after intensive radiologic staff training

OBJECTIVE

The purpose of this study was to assess the radiation dose and image quality of pediatric head CT examinations before and after radiologic staff training.

MATERIALS AND METHODS

Outpatients 1 month to 14 years old underwent 215 unenhanced head CT examinations before and after intensive training of staff radiologists and technologists in optimization of CT technique. Patients were divided into three age groups (0-4, 5-9, and 10-14 years), and CT dose index, dose-length product, tube voltage, and tube current-rotation time product values before and after training were retrieved from the hospital PACS. Gray matter conspicuity and contrast-to-noise ratio before and after training were calculated, and subjective image quality in terms of artifacts, gray-white matter differentiation, noise, visualization of posterior fossa structures, and need for repeat CT examination was visually evaluated by three neuroradiologists.

RESULTS

The median CT dose index and dose-length product values were significantly lower after than before training in all age groups (27 mGy and 338 mGy ∙ cm vs 107 mGy and 1444 mGy ∙ cm in the 0- to 4-year-old group, 41 mGy and 483 mGy ∙ cm vs 68 mGy and 976 mGy ∙ cm in the 5- to 9-year-old group, and 51 mGy and 679 mGy ∙ cm vs 107 mGy and 1480 mGy ∙ cm in the 10- to 14-year-old group; p < 0.001). The tube voltage and tube current-time values after training were significantly lower than the levels before training (p < 0.001). Subjective posttraining image quality was not inferior to pretraining levels for any item except noise (p < 0.05), which, however, was never diagnostically unacceptable.

CONCLUSION

Radiologic staff training can be effective in reducing radiation dose while preserving diagnostic image quality in pediatric head CT examinations.

Radiation risks associated with serial imaging in colorectal cancer patients: Should we worry?

To provide an overview of the radiation related cancer risk associated with multiple computed tomographic scans required for follow up in colorectal cancer patients. A literature search of the PubMed and Cochrane Library databases was carried out and limited to the last 10 years from December 2012. Inclusion criteria were studies where computed tomographic scans or radiation from other medical imaging modalities were used and the risks associated with ionizing radiation reported. Thirty-six studies were included for appraisal with no randomized controlled trials. Thirty-four of the thirty-six studies showed a positive association between medical imaging radiation and increased risk of cancer. The radiation dose absorbed and cancer risk was greater in children and young adults than in older patients. Most studies included in the review used a linear, no-threshold model to calculate cancer risks and this may not be applicable at low radiation doses. Many studies are retrospective and ensuring complete follow up on thousands of patients is difficult. There was a minor increased risk of cancer from ionizing radiation in medical imaging studies. The radiation risks of low dose exposure (< 50 milli-Sieverts) are uncertain. A clinically justified scan in the context of colorectal cancer is likely to provide more benefits than harm but current guidelines for patient follow up will need to be revised to accommodate a more aggressive approach to treating metastatic disease.

Diagnostic testing and treatment of pediatric headache in the emergency department

OBJECTIVE

To describe the variability in diagnostic testing and treatment of headaches in children presenting to the emergency department (ED) with use of a nationally representative sample.

STUDY DESIGN

This was a retrospective cohort study using the National Hospital Ambulatory Medical Care Survey during 2005-2009. To assess the use of evidence-based treatment, we analyzed all patients <18 years old in 2 groups: (1) primary discharge diagnosis of headache and (2) discharge diagnosis of migraine.

RESULTS

Four hundred forty-eight sampled ED visits from 2005-2009 represented a national estimate of 1.7 million visits with a discharge diagnosis of headache. A total of 95 visits represented a national estimate of 340 000 visits with a discharge diagnosis of migraine. Median age was 13.1 years and 60% were female with a primary diagnosis of headache. In this group, neuroimaging was performed in 37% of patients and 39% underwent blood tests. Nonsteroidal anti-inflammatory drugs and opioids were most commonly used for treatment. For children with a discharge diagnosis of migraine, approximately 40% of patients received non-evidence-based treatment, most commonly with opioid medications, and >20% of patients underwent computed tomography scanning.

CONCLUSIONS

There is significant variability in the evaluation and treatment of pediatric headache in the ED. Despite evidence-based clinical guidelines for migraine headache, a large number of children continue to receive opioids and ionizing radiation in the ED.

Analysis of limited-sequence head computed tomography for children with shunted hydrocephalus: potential to reduce diagnostic radiation exposure

OBJECT

Despite its diagnostic utility, head CT scanning imparts risks of radiation exposure. Children with shunt-treated hydrocephalus exhibit increased risks of radiation toxicity due to the higher vulnerability of developing, immature tissues and frequent scanning. Several methods have been used to achieve dose reduction, including modifications of CT scanner tube current and potential. This retrospective study explores the use of a newly defined limited sequence of axial head CT slices to evaluate children with shunted hydrocephalus and decrease radiation exposure from diagnostic CT scans.

METHODS

Consistent sequences of 7 axial slices were extracted from previously performed standard head CT scans in children with shunted hydrocephalus. Chronologically distinct limited sequences of each patient were blindly, retrospectively reviewed by 2 pediatric neuroradiologists and 1 pediatric neurosurgeon. Limited-sequence CT evaluation focused on the adequacy of portraying the ventricular system, changes in ventricular size, and visualization of the proximal catheter. Reviewers assessed all original full series head CT scans at least 4 months later for comparison. Adequacy and accuracy of the limited-sequence CT compared with the gold standard head CT was investigated using descriptive statistics. Effective dose (ED) estimates of the limited-sequence and standard head CT scans were compared using descriptive statistics and the Mann-Whitney test.

RESULTS

Two serial head CT scans from each of 50 patients (age range 0-17 years; mean age 5.5 years) were reviewed both in standard and limited-sequence forms. The limited-sequence CT adequately portrayed the ventricular system in all cases. The inaccuracy rate for assessing changes in ventricular size by majority assessment (2 of 3 reviewers evaluating inaccurately) was 3 (6%) of 50. In 1 case, the inaccurate assessment would not have altered clinical management, corresponding to a 2 (4%) of 50 clinically relevant inaccuracy rate. As compared with the gold standard complete head CT series, the limited-sequence CT exhibited high sensitivity (100%) and specificity (91%) for portraying changes in ventricular caliber. Additionally, the limited-sequence CT displayed the ventricular catheter in 91.7% of scans averaged across 3 observers. Among all scans reviewed, 97 pairs of standard head CT and complementary limited-sequence CT scans contained adequate dosing information to calculate the effective dose (ED). The ED50 of the limited-sequence CT (0.284 mSv) differed significantly from the ED50 of the standard head CT (4.27 mSv) (p < 0.0001). The limited-sequence CT reflected a median absolute reduction of 4.10 mSv and a mean percent reduction of 91.8% in ED compared with standard head CT.

CONCLUSIONS

Limited-sequence head CT scanning provided adequate and accurate diagnostic information in children with shunted hydrocephalus. Techniques including minimization of axial slice quantity and modification of CT scanner parameters can achieve significant dose reduction, maintaining a balance between diagnostic utility and patient safety.

Neuroimaging in childhood headache: a systematic review

Headache is a common complaint in children, one that gives rise to considerable parental concern and fear of the presence of a space-occupying lesion. The evaluation and diagnosis of headache is very challenging for paediatricians, and neuroimaging by means of CT or MRI is often requested as part of the investigation. CT exposes children to radiation, while MRI is costly and sometimes requires sedation or general anaesthesia, especially in children younger than 6 years. This review of the literature on the value of neuroimaging in children with headache showed that the rate of pathological findings is generally low. Imaging findings that led to a change in patient management were in almost all cases reported in children with abnormal signs on neurological examination. Neuroimaging should be limited to children with a suspicious clinical history, abnormal neurological findings or other physical signs suggestive of intracranial pathology. Well-designed prospective studies are needed to better define the clinical findings that warrant neuroimaging in children with headache.

Parental knowledge of radiation exposure in medical imaging used in the pediatric emergency department

OBJECTIVES

We sought to quantify the knowledge base among parents and legal guardians presenting to our pediatric emergency department regarding radiation exposure during medical imaging and potential risks to children resulting from ionizing radiation. We sought to examine if a child's previous exposure to medical imaging changed caregiver knowledge base and discern caregivers' preference for future education on this topic.

METHODS

A prospective convenience sample survey was performed of caregivers who presented with their child to our tertiary pediatric emergency department. Parents or legal guardians (18-89 years) who accompanied a child (0-17 years) were eligible for inclusion and approached for enrollment. A structured questionnaire was administered by trained interviewers, and a chart review was conducted to ascertain if their child had a history of previous imaging.

RESULTS

Sixty percent of caregivers interviewed (n = 205 of 340) did not associate any long-term negative effects with medical imaging. Among participants who did express a perceived risk from medical imaging radiation exposure, only 50% could indicate a known negative effect from exposure. We found no significant association between a child having had documented imaging studies and awareness of long-term negative effects (P = 0.22). Participants preferred to learn more about this topic from an Internet-based resource (50%), informational pamphlet (38%), or via treating physician (33%).

CONCLUSIONS

Parents and legal guardians are largely unaware that exposure to radiation during medical imaging carries an inherent risk for their child. Health care providers wishing to educate caregivers should utilize reliable Internet sources, educational pamphlets, and direct communication.

Low-dose protocol for head CT in evaluation of hydrocephalus in children

Background:

A suspicion of ventriculo–peritoneal shunt failure is classified as the most common indication for CT in children with hydrocephalus. The main target of the study was to evaluate the diagnostic value of a low-dose protocol and to compare a total DLP received by patients in compared protocols.

Material/Methods:

Our retrospective analysis included 256 examinations performed in patients aged from 1 month to 18 years, with body mass ranging from 3 to 100 kg. The examinations were conducted in the years 2009–2011. A total number of 128 examinations were performed on the basis of the low-dose protocol and 128 according to a standard protocol using the Siemens SOMATOM Definition AS 128-slice scanner.

Results/Conlusions:

The analysis showed a full value of the diagnostic low-dose protocol with a simultaneous decrease of the total dose of DLP to the average of 40%.

Application protocol with lower mAs in assessing the causes of ventriculo-peritoneal shunt failure in children with hydrocephalus is coherent with the valid principles of radiation protection in pediatrics and reduces the total DLP while maintaining a very good diagnostic value.

Odontoma-associated tooth impaction: accurate diagnosis with simple methods? Case report and literature review

Odontomas account for the largest fraction of odontogenic tumors and are frequent causes of tooth impaction. A case of a 13-year-old female patient with an odontoma-associated impaction of a mandibular molar is presented with a review of the literature. Preoperative planning involved simple and convenient methods such as clinical examination and panoramic radiography, which led to a diagnosis of complex odontoma and warranted surgical removal. The clinical diagnosis was confirmed histologically. Multidisciplinary consultation may enable the clinician to find the accurate diagnosis and appropriate therapy based on the clinical and radiographic appearance. Modern radiologic methods such as cone-beam computed tomography or computed tomography should be applied only for special cases, to decrease radiation.

The pediatric cervical spine instability study. A pilot study assessing the prognostic value of four imaging modalities in clearing the cervical spine for children with severe traumatic injuries

PURPOSE

Cervical spine clearance in severely injured children after trauma is often difficult because of unique injury patterns, concerns about radiation exposure to growing tissue, and unfamiliarity with unstable cervical injuries. We prospectively assessed the utility of four radiographic modalities to clear the cervical spine in children after severe trauma.

METHODS

Twenty-four comatose, intubated children with severe traumatic injuries underwent radiographic evaluation to clear the cervical spine. Each patient had plain radiographs, flexion-extension radiographs under fluoroscopy, computed tomography (CT), and magnetic resonance (MR) imaging within 10 days of admission. Patients underwent cervical spine flexion-extension radiographs 2-3 months after trauma to detect late instability. Sensitivity and specificity for each radiographic modality was determined.

RESULTS

Plain cervical spine radiographs demonstrated sensitivity of 100% and specificity of 95%; flexion-extension radiographs had “indeterminate” sensitivity and specificity of 100%. For CT, sensitivity was 100% and specificity was 95%, and for MR imaging, sensitivity was 100% and specificity was 74%.

CONCLUSIONS

There was a low prevalence of cervical instability in this high-risk group. Plain radiographs, flexion-extension radiographs, and CT all had high sensitivities and specificities. MR imaging had a high false-positive rate, making it sensitive but not specific. The data support using either CT or plain radiographs as the initial cervical spine screening study, but CT is recommended because of its superior ability to detect critical injuries. To definitively rule out ligamentous instability after a negative screening CT scan or cervical spine X-ray, these data support using flexion-extension X-rays with fluoroscopy and not MR imaging.

Vertigo in children and adolescents: characteristics and outcome

Objectives. To describe the characteristics and outcome of vertigo in a pediatric population. Patients. All children and adolescents presenting with vertigo to a tertiary otoneurology clinic between the years 2003–2010 were included in the study. Results. Thirty-seven patients with a mean age of 14 years were evaluated. The most common etiology was migraine-associated vertigo (MAV) followed by acute labyrinthitis/neuritis and psychogenic dizziness. Ten patients (27%) had pathological findings on the otoneurological examination. Abnormal findings were documented in sixteen of the twenty-three (70%) completed electronystagmography evaluations. Twenty patients (54%) were referred to treatment by other disciplines than otology/otoneurology. A follow-up questionnaire was filled by twenty six (70%) of the study participants. While all patients diagnosed with MAV had continuous symptoms, most other patients had complete resolution. Conclusions. Various etiologies of vertigo may present with similar symptoms and signs in the pediatric patient. Yet, variable clinical courses should be anticipated, depending on the specific etiology. This is the reason why treatment and follow up should be specifically tailored for each case according to the diagnosis. Close collaboration with other medical disciplines is often required to reach the correct diagnosis and treatment while avoiding unnecessary laboratory examinations.

Pediatric head trauma

Head injury in children accounts for a large number of emergency department visits and hospital admissions. Falls are the most common type of injury, followed by motor-vehicle-related accidents. In the present study, we discuss the evaluation, neuroimaging and management of children with head trauma. Furthermore, we present the specific characteristics of each type of pediatric head injury.

Imaging pediatric bone sarcomas

Primary malignant bone tumors are rare and account for about 6% of all new pediatric cancer cases per year in the United States. Identification of the lesion not uncommonly occurs as a result of imaging performed for trauma. Clinical and standard imaging characteristics of the various tumor types are evolving in concert with treatment advancements and clinical trial regimens. This article reviews the 3 most common pediatric bone sarcomas-osteosarcoma, Ewing sarcoma, and chondrosarcoma-and their imaging as applicable to contemporary disease staging and monitoring, and explores the roles of evolving imaging techniques.

Clinical indications and utilization of 320-detector row CT in 2500 outpatients

Clinical indications and utilization patterns for 3963 CT scans on 2500 consecutive patents on a 320-detector row CT in an outpatient setting were retrospectively analyzed and compared with previously reported CT studies. The impact of the latest generation CT technology, including whole organ perfusion, on indications and utilization patterns during the study period was also assessed. The top five requested CT scan types were abdomen/pelvis, chest, head, sinuses, and coronary CT angiography. Indication and utilization rates were similar to prior studies for abdomen/pelvis, non-cardiac chest, and head CT scans. Abdominal pain and headaches were the most frequent indications for abdomen/pelvis and head CTs, respectively. The 7.3% cardiac CT scan utilization rate was not comparable to rates of up to 72% in self-referral outpatient settings. Whole organ volume CT imaging was utilized in 100% of coronary CT angiography and 22.7% of head CTs. The 320-row CT had fewer negative head and body CT findings as compared to prior reports. The availability of new technology, such as whole organ dynamic scans, appears to have influenced CT indications, utilization and finding rates with a decrease in negative brain and body results. Comparisons with previous outpatient CT studies were similar for multiple categories with the exception of cardiac CT utilization, which is heavily influenced by self-referral. Further study of outpatient imaging indications and utilization rates from multiple centers may benefit from a standardized categorization to improve understanding of the disparate outpatient imaging environment.

Managing radiation risk in the evaluation of the pediatric trauma patient

Pediatric trauma is usually a nonoperative experience for the pediatric general surgeon. The pediatric trauma surgeon resuscitates the child and then evaluates and triages the identified injuries. A common diagnostic tool is the computed tomography (CT) scan. Most children who require evaluation for significant trauma will get a CT scan, but there are no national guidelines directing the assessment. Injuries to the head, cervical spine, chest, and abdomen can all be imaged with a CT scan; the question is whether the liberal approach to imaging children is appropriate. Over the past decade, concern has arisen about the radiation dose delivered by CT. This concern has generated a national campaign to "image gently." This article reviews the data involving the risk of medical radiation exposure and discusses strategies for managing the risk.

Minor head injury in children

PURPOSE OF REVIEW

This review will examine mild closed head injury (CHI) and the current evidence on head computed tomography (CT) imaging risks in children, prediction rules to guide decisions on CT scan use, and issues of concussion after initial evaluation.

RECENT FINDINGS

The current literature offers preliminary evidence on the risks of radiation exposure from CT scans in children. A recent study introduces a validated prediction rule for use in mild CHI, to limit the number of CT scans performed. Concurrent with this progress, fast (or short sequence) MRI represents an emerging technology that may prove to be a viable alternative to CT scan use in certain cases of mild CHI where imaging is desired. The initial emergency department evaluation for mild CHI is the start point for a sequence of follow-up to assure that postconcussive symptoms fully resolve. The literature on sports-related concussion offers some information that may be used for patients with non-sports-related concussion.

SUMMARY

It is clear that CT scan use should be as safe and limited in scope as possible for children. Common decisions on the use of CT imaging for mild head injury can now be guided by a prediction rule for clinically important traumatic brain injury. Parameters for the follow-up care of patients with mild CHI after emergency department discharge are needed in the future to assure that postconcussive symptoms are adequately screened for full resolution.