ALARA: is there a cause for alarm? Reducing radiation risks from computed tomography scanning in children

CT-abnormalities, bacteriology and symptoms of sinonasal disease in children with Cystic Fibrosis

BACKGROUND

Sinonasal pathology in adults with Cystic Fibrosis (CF) is common but the extent of CT-abnormalities and symptoms of sinonasal disease in children with CF and the age of onset are less frequently studied.

METHODS

In this observational, cross-sectional study 58 children with CF from two CF centres were included. All subjects completed a questionnaire regarding sinonasal symptoms, underwent a CT scan of the paranasal sinuses, and in each subject a culture of the upper airways was performed. Subjects were divided in 6 age cohorts (0-2, 3-5, 6-8, 9-11, 12-14 and 15-17years) and were divided into severe and mild CF based on their CFTR mutation. Opacification of the sinonasal system of the subjects was compared with opacification on MRI-scans of an age-matched control group without CF.

RESULTS

Most frequently reported symptoms were nasal obstruction and posterior/anterior nasal discharge. Opacification was abundant in every age cohort of the study group and was significantly more compared to the control group. In patients with severe CF the opacification was higher than subjects with mild CF. Upper airway cultures showed predominantly Staphylococcus aureus, Haemophilus influenzae and Pseudomonas aeruginosa.

CONCLUSION

CT-abnormalities indicating sinonasal disease and symptoms are present from shortly after birth which may argue for a thorough examination of the upper airways in children with CF.

Radiation Dose Reduction by Indication-Directed Focused z-Direction Coverage for Neck CT

BACKGROUND AND PURPOSE

The American College of Radiology-American Society of Neuroradiology-Society for Pediatric Radiology Practice Parameter for a neck CT suggests that coverage should be from the sella to the aortic arch. It also recommends using CT scans judiciously to achieve the clinical objective. Our purpose was to analyze the potential dose reduction by decreasing the scan length of a neck CT and to assess for any clinically relevant information that might be missed from this modified approach.

MATERIALS AND METHODS

This retrospective study included 126 children who underwent a neck CT between August 1, 2013, and September 30, 2014. Alteration of the scan length for the modified CT was suggested on the topographic image on the basis of the indication of the study, with the reader blinded to the images and the report. The CT dose index volume of the original scan was multiplied by the new scan length to calculate the dose-length product of the modified study. The effective dose was calculated for the original and modified studies by using age-based conversion factors from the American Association of Physicists in Medicine Report No. 96.

RESULTS

Decreasing the scan length resulted in an average estimated dose reduction of 47%. The average reduction in scan length was 10.4 cm, decreasing the overall coverage by 48%. The change in scan length did not result in any missed findings that altered management. Of the 27 abscesses in this study, none extended to the mediastinum. All of the lesions in question were completely covered.

CONCLUSIONS

Decreasing the scan length of a neck CT according to the indication provides a significant savings in radiation dose, while not altering diagnostic ability or management.

Examination of the Increase in Thyroid Cancer Incidence Among Younger Women in the United States by Age, Race, Geography, and Tumor Size, 1999-2007

PURPOSE

Thyroid cancer incidence has been increasing for several decades, but the reasons are not fully understood. Previous surveillance reports have covered less than 26% of the U.S.

POPULATION

More recent, nationwide data are needed. This study examines thyroid cancer incidence among younger women by age, race/ethnicity, geography, and tumor size.

PATIENTS AND METHODS

Our study uses nationwide surveillance data to describe incidence rates and recent trends in thyroid cancer among adults aged 20-39 years in the United States during 1999-2007, with a focus on females.

RESULTS

Incidence rates were more than five times higher among females (16.4 per 100,000; 95% confidence interval [CI]: 16.2-16.6) than among males (3.1 per 100,000; 95% CI: 3.1-3.2). Among females, rates were higher among non-Hispanic whites than among other racial/ethnic groups and higher in the Northeast compared with other regions (p<0.05). During 1999-2007, incidence rates increased 5.3% each year among females (95% CI: 4.7-5.9). This increase was observed across five-year age groups, racial/ethnic groups (except American Indians/Alaska Natives), geographic regions, and tumor sizes.

CONCLUSION

The increase in rates across all tumor sizes suggests that the observed increases cannot be attributed solely to changes in diagnostics or surveillance. In addition, the continued increase in incidence rates in recent years among persons born after 1960 suggests that other, more contemporary factors than those previously proposed may play a contributing role.

Breast Cancer Risk in Childhood Cancer Survivors Without a History of Chest Radiotherapy: A Report From the Childhood Cancer Survivor Study

PURPOSE

Little is known about the breast cancer risk among childhood cancer survivors who did not receive chest radiotherapy. We sought to determine the magnitude of risk and associated risk factors for breast cancer among these women.

PATIENTS AND METHODS

We evaluated cumulative breast cancer risk in 3,768 female childhood cancer survivors without a history of chest radiotherapy who were participants in the Childhood Cancer Survivor Study.

RESULTS

With median follow up of 25.5 years (range, 8 to 39 years), 47 women developed breast cancer at a median age of 38.0 years (range, 22 to 47 years) and median of 24.0 years (range, 10 to 34 years) from primary cancer to breast cancer. A four-fold increased breast cancer risk (standardized incidence ratio [SIR] = 4.0; 95% CI, 3.0 to 5.3) was observed when compared with the general population. Risk was highest among sarcoma and leukemia survivors (SIR = 5.3; 95% CI, 3.6 to 7.8 and SIR = 4.1; 95% CI, 2.4 to 6.9, respectively). By the age of 45 years, the cumulative incidence of breast cancer in sarcoma and leukemia survivors was 5.8% (95% CI, 3.7 to 8.4) and 6.3% (95% CI, 3.0 to 11.3), respectively. No other primary cancer diagnosis was associated with an elevated risk. Alkylators and anthracyclines were associated with an increased breast cancer risk in a dose-dependent manner (P values from test for trend were both < .01).

CONCLUSIONS

Women not exposed to chest radiotherapy who survive childhood sarcoma or leukemia have an increased risk of breast cancer at a young age. The data suggest high-dose alkylator and anthracycline chemotherapy increase the risk of breast cancer. This may suggest a possible underlying gene-environment interaction that warrants further study.

Emergency Department Use of Computed Tomography for Children with Ventricular Shunts

OBJECTIVES

To quantify rates and variation in emergency department (ED) cranial computed tomography (CT) utilization in children with ventricular shunts, estimate radiation exposure, and evaluate the association between CT utilization and shunt revision.

STUDY DESIGN

Retrospective longitudinal cohort study of ED visits from 2003-2013 in children 0-18 years old with initial shunt placement in 2003. Data were examined from 31 hospitals in the Pediatric Health Information System. Main outcomes were cranial CT performed during an ED visit, estimated cumulative effective radiation dose, and shunt revision within 7 days. Multivariable regression modeled the relationship between patient- and hospital-level covariates and CT utilization.

RESULTS

The 1319 children with initial shunt placed in 2003 experienced 6636 ED visits during the subsequent decade. A cranial CT was obtained in 49.4% of all ED visits; 19.9% of ED visits with CT were associated with a shunt revision. Approximately 6% of patients received ≥10 CTs, accounting for 37.2% of all ED visits with a CT. The mean number of CTs per patient varied nearly 20-fold across hospitals; the individual hospital accounted for the most variation in CT utilization. The median (IQR) cumulative effective radiation dose was 7.2 millisieverts (3.6-14.0) overall, and 33.4 millisieverts (27.2-43.8) among patients receiving ≥10 CTs.

CONCLUSIONS

A CT scan was obtained in half of ED visits for children with a ventricular shunt, with wide variability in utilization by hospitals. Strategies are needed to identify children at risk of shunt malfunction to reduce variability in CT utilization and radiation exposure in the ED.

A new 2-step risk-stratification clinical score for suspected appendicitis in children

AIM

The aim of this study was to develop a new Children's Appendicitis Score (CAS) by combining 3 inflammatory markers and a set of predictors for suspected appendicitis in children.

METHODS

374 children aged 4-16years with suspicion of appendicitis were prospectively enrolled for the derivation cohort. Demographic characteristics, clinical features, laboratory, and histology data were collected. The outcome measure was the histological presence or absence of appendicitis. Backward logistic regression was employed to select predictors for construction of a score. Diagnostic performance of CAS was compared with the Pediatric Appendicitis Score (PAS) on a separate validation cohort.

RESULTS

The combination of normal white blood cell count (WBC), neutrophil percentage, and C-reactive protein (CRP) had a 100% negative predictive value for appendicitis. We assigned 'coefficient A' as 'zero' when all triple markers were negative and 'one' when any one markers was positive. A second component of 6 predictors was identified for construction of the 'raw score': Localized right-lower-quadrant pain, generalized guarding, constant characteristic of pain, pain on percussion or coughing, WBC≥14000/L and CRP≥24g/L. CAS was generated by multiplying 'coefficient A' by 'raw score'.

CONCLUSION

CAS is superior to PAS in ruling out appendicitis. Risk stratification of equivocal patients could guide the need for further diagnostic imaging examination.

Post-treatment surveillance abdominopelvic computed tomography in children with Wilms tumour: Is it worth the risk?

Background: Wilms tumour is a comparatively common paediatric malignancy with a relatively good prognosis. Routine post-treatment surveillance at our institution currently includes regular abdominopelvic computed tomography (CT) over a two-year period for the early detection of disease recurrence. The rationale is that early salvage therapy may improve overall patient survival, and thus justifies the exposure to potentially harmful ionising radiation. Objective: To critically evaluate the routine use of post-treatment abdominopelvic CT by determining the detection rate of disease recurrence and associated clinical outcomes.Methods: Sixty-four patients in remission following initial treatment for Wilms tumour were included in this retrospective study. Variables obtained from patient records included gender, age, histological grading and tumour stage at presentation, number of abdominopelvic CT scans, site(s) of relapse, method of recurrence detection and confirmation, time to recurrence and clinical outcome. Results: The patients received a total of 334 surveillance abdominopelvic CT scans. Nine (14%) patients developed disease recurrence during the follow-up period. In three cases, the initial detection method was abdominopelvic CT. All three of these patients subsequently died despite salvage therapy (22 months median survival). Five false-positive diagnoses of recurrence occurred, with two being made on abdominopelvic CT. Conclusion: Routine post-treatment abdominopelvic CT showed a low detection rate of disease recurrence in children treated for Wilms tumour, while subjecting patients to a large radiation burden. The recommendation is that current practice be changed in line with the ultrasound-based Société Internationale d’Oncologie Pédiatrique (SIOP) imaging guidelines.

Analysis of radiation dose to pediatric patients during computed tomography examinations

BACKGROUND

Computed tomography (CT) utilization has increased rapidly over the past 15 years. CT is the most common source for radiation exposure.

OBJECTIVES

The objective was to measure the effective dose of radiation delivered during routine head and abdominal CT examinations at a children's hospital.

METHODS

This was a retrospective study of emergency department (ED) patients < 20 years of age who underwent head or abdominal CT scans in 2012 at a single children's hospital. The authors abstracted the dose-length product from the CT scanners and calculated the effective radiation dose delivered. Patient demographics were abstracted from the medical record. The relationship between effective dose and age, patient weight, and reason for examination were evaluated.

RESULTS

A total of 478 subjects were included: 255 underwent head CT, and 223 underwent abdominal CT. The median age was 8.1 years (interquartile range = 2.71 to 14.40 years) and 56.9% were male. The median effective dose for head CT was 2.68 mSv (95% confidence interval [CI] = 2.54 to 2.84 mSv) and decreased as age increased. For abdominal CT, the median effective dose was 5.06 mSv (95% CI = 4.58 to 6.03 mSv) and increased as age increased (3.67 to 11.12 mSv, p < 0.001). For abdominal CT, 8% of 5- to 10-year-olds, 28% of those 10 to 15 years, and 60% of patients over age 15 years received effective doses over 10 mSv.

CONCLUSIONS

The amount of radiation delivered to pediatric patients during routine CT examinations of the head and abdomen was low. Regardless, a large proportion of older patients were exposed to elevated effective doses of radiation during abdominal CT.

Benefits of brain magnetic resonance imaging over computed tomography in children requiring emergency evaluation of ventriculoperitoneal shunt malfunction: reducing lifetime attributable risk of cancer

OBJECTIVES

The rapid growth of computed tomography (CT) has resulted in increased concerns of ionizing radiation exposure and its subsequent risk of cancer development. We evaluated the impact of a new protocol using rapid sequence magnetic resonance imaging (rsMRI) instead of CT in children presenting with possible ventriculoperitoneal shunt (VPS) malfunction to promote patient safety.

METHODS

This is a retrospective case series of pediatric patients who received a neuroimaging study for emergency evaluation of possible VPS malfunction at New York University's Tisch Hospital Emergency Department between January 2010 and July 2011. Radiology Charge Master was queried to identify the patient database. The trend in the use of rsMRI and CT was calculated for 3 patient age groups and compared across 3 chronological intervals. The effective dose of ionizing radiation per CT scan was calculated using the CT dose index and dose-length product for each patient.

RESULTS

Total of 365 patients with the mean age of 8.87 years received either rsMRI or CT study during the study period. One hundred forty-four of these patients required the imaging studies because of VPS malfunction. Overall, 62% of all VPS malfunction cases used rsMRI instead of CT. The ratio of the number of patients receiving rsMRI divided by CT studies has progressively increased from 1.4:1 to 2.1:1 over 3 chronologic periods.

CONCLUSIONS

Children with VPS are subject to multiple neuroimaging studies throughout their lifetime. Rapid sequence MRI is an effective alternative to CT while providing no ionizing radiation exposure or risk of developing radiation-induced cancer.

Risk of cancer incidence before the age of 15 years after exposure to ionising radiation from computed tomography: results from a German cohort study

The aim of this cohort study was to assess the risk of developing cancer, specifically leukaemia, tumours of the central nervous system and lymphoma, before the age of 15 years in children previously exposed to computed tomography (CT) in Germany. Data for children with at least one CT between 1980 and 2010 were abstracted from 20 hospitals. Cancer cases occurring between 1980 and 2010 were identified by stochastic linkage with the German Childhood Cancer Registry (GCCR). For all cases and a sample of non-cases, radiology reports were reviewed to assess the underlying medical conditions at time of the CT. Cases were only included if diagnosis occurred at least 2 years after the first CT and no signs of cancer were recorded in the radiology reports. Standardised incidence ratios (SIR) using incidence rates from the general population were estimated. The cohort included information on 71,073 CT examinations in 44,584 children contributing 161,407 person-years at risk with 46 cases initially identified through linkage with the GCCR. Seven cases had to be excluded due to signs possibly suggestive of cancer at the time of first CT. Overall, more cancer cases were observed (O) than expected (E), but this was mainly driven by unexpected and possibly biased results for lymphomas. For leukaemia, the SIR (SIR = O/E) was 1.72 (95 % CI 0.89-3.01, O = 12), and for CNS tumours, the SIR was 1.35 (95 % CI 0.54-2.78, O = 7). Despite careful examination of the medical information, confounding by indication or reverse causation cannot be ruled out completely and may explain parts of the excess. Furthermore, the CT exposure may have been underestimated as only data from the participating clinics were available. This should be taken into account when interpreting risk estimates.

Imaging assessment of renal injuries in children and adolescents: CT or ultrasound?

BACKGROUND

Since the introduction of the ALARA ("as low as reasonably achievable") concept, ultrasound (US) has been progressively advocated for paediatric diagnostic imaging. This study aimed to analyse the role and accuracy of US in paediatric renal trauma.

METHODS

From 1999 to 2009, the tertiary-care-hospital database was retrospectively evaluated for renal trauma with regards to aetiology, type of injury, diagnostics, management and outcome.

RESULTS

Forty-seven patients (29 males, 18 females; median age=14years, range 1-17 years) were identified. US was initially applied in 45 patients with correct results in 86.6%. Computed tomography (CT) was performed in 16 patients in the acute trauma setting - complementary to US in 14 cases, with a diagnostic accuracy of 93%. Most renal injuries were grade I° (n=30), followed by grade III° (n=8), IV° (n=5), and II°/V° (n=2 each). All patients were initially managed conservatively and followed by US. Clinical deterioration necessitated surgery in four patients (2 nephrectomies, 1 partial nephrectomy, 1 urinoma drainage). The outcome was generally favourable with a renal preservation rate of 95%.

CONCLUSION

With respect to the ALARA principle, US can be safely and reliably applied as the first-line diagnostic imaging technique and for follow-up for suspected traumatic paediatric renal injuries.

Imaging in pediatric urolithiasis-what's the best choice?

The incidence of urolithiasis increased dramatically during the last decades in adults as well as in children. Today, when a urinary stone is suspected, the imaging modality used most frequently is non-contrast enhanced computed tomography (NCCT). Due to the high sensitivity and specifity, NCCT is regarded as the gold standard. Its major drawback is the high dose of radiation administered with this examination. This is of special concern in children. Children with urinary stones are at high risk for multiple recurrences during their life. NCCT increases the risk for abdominal and pelvic cancer in children significantly. With respect to therapeutic success, however, conventional imaging modalities like ultrasound are not inferior and are without any harm. Therefore, ultrasound is recommended as the primary imaging technique in children by several guidelines. Nevertheless, as could be shown by Tasian et al., ultrasound was the first imaging study in only 24% of children with urolithiasis. NCCT was the modality used most frequently (63%) in the USA between 2003 and 2011. There was a wide regional variation within the USA with highest CT use in the Northwestern and Southern and lowest in the New England states. It is hypothesized that engrained practice patterns and specific local medical resources as well as a lower confidence in ultrasound with its operator dependence are potential reasons. Regarding the fact that ultrasonography is highly reliable in the diagnosis of urolithiasis and is without any harm, it is essential to make all efforts to increase the adherence to the guidelines.

Paediatric CT optimisation utilising Catphan® 600 and age-specific anthropomorphic phantoms

The purpose of the study is to perform phantom-based optimisation of paediatric computed tomography (CT) protocols and quantify the impact upon radiation dose and image noise levels. The study involved three Portuguese paediatric centres. Currently employed scanning protocols for head and chest examinations and combinations of exposure parameters were applied to a Catphan(®)600 phantom to review the CT dose impact. Contrast-noise ratio (CNR) was quantified using Radia Diagnostic(®) tool. Imaging parameters, returning similar CNRs (<1) and dose savings were applied to three paediatric anthropomorphic phantoms. OsiriX software based on standard deviation pixel values facilitated image noise analysis. Currently employed protocols and age categorisation varied between centres. Manipulation of exposure parameters facilitated mean dose reductions of 33 and 28 % for paediatric head and chest CT examinations, respectively. The majority of the optimised CT examinations resulted in image noise similar to currently employed protocols. Dose reductions of up to 33 % were achieved with image quality maintained.

Cumulative radiation exposure estimates of hospitalized patients from radiological imaging

PURPOSE

To examine the use of inpatient diagnostic imaging and image-guided procedures to estimate cumulative radiation exposure, radiation exposure based on imaging modality, and compare estimated doses based on patient demographics including age, gender, and diagnoses.

METHODS

Two hundred consecutive hospitalized adult patients who underwent diagnostic imaging studies at 2 large, affiliated hospitals were identified, and every study in each patient's electronic record that took place during a single hospitalization was reviewed. Dose estimates were calculated for each CT, fluoroscopy, nuclear medicine, plain film, and interventional radiology study or procedure based on reported dose length product, published reference values, and conversion factors. Medical records were reviewed to determine patient gender, age, diagnoses, length of stay, admitting service, and time in an intensive care unit (ICU).

RESULTS

Two hundred inpatients (46.5% male; mean age, 60.4 years) underwent 2,751 imaging studies (79.3% radiographs, 9.7% CT, 6.1% ultrasound, 2.5% interventional radiology, 2.2% MRI, 0.4% nuclear medicine). The mean dose estimate per patient was 14.8 milliSieverts (mSv) and the range was 0 mSv to 130.5 mSv. Mean cumulative dose estimates were significantly higher for patients whose hospitalizations included time in an ICU (17.9 mSv versus 11.3 mSv [P = .01]). CT examinations accounted for 82.1% of the total radiation dose estimate. Eleven patients (5.5%) received radiation dose estimates ≥ 50 mSv, including 2 ≥ 100 mSv.

CONCLUSIONS

Of imaged inpatients, 62% underwent at least 1 CT and the majority (82.1%) of inpatient radiation exposure was attributable to CT examinations. Mean dose estimate was 14.8 mSv per patient; 5.5% of patients experienced estimated doses ≥ 50 mSv.

Trends in the utilization of computed tomography and cardiac catheterization among children with congenital heart disease

Background/Purpose

Pediatric cardiac computed tomography (CT) is a noninvasive imaging modality used to clearly demonstrate the anatomical detail of congenital heart diseases. We investigated the impact of cardiac CT on the utilization of cardiac catheterization among children with congenital heart disease.

Methods

The study sample consisted of 2648 cardiac CT and 3814 cardiac catheterization from 1999 to 2009 for congenital heart diseases. Diagnoses were categorized into 11 disease groups. The numbers of examination, according to the different modalities, were compared using temporal trend analyses. The estimated effective radiation doses (mSv) of CT and catheterization were calculated and compared.

Results

The number of CT scans and interventional catheterizations had a slight annual increase of 1.2% and 2.7%, respectively, whereas that of diagnostic catheterization decreased by 6.2% per year. Disease groups fell into two categories according to utilization trend differences between CT and diagnostic catheterization. The increased use of CT reduces the need for diagnostic catheterization in patients with atrioventricular connection disorder, coronary arterial disorder, great vessel disorder, septal disorder, tetralogy of Fallot, and ventriculoarterial connection disorder. Clinicians choose either catheterization or CT, or both examinations, depending on clinical conditions, in patients with semilunar valvular disorder, heterotaxy, myocardial disorder, pericardial disorder, and pulmonary vein disorder. The radiation dose of CT was lower than that of diagnostic cardiac catheterization in all age groups.

Conclusion

The use of noninvasive CT in children with selected heart conditions might reduce the use of diagnostic cardiac catheterization. This may release time and facilities within the catheterization laboratory to meet the increasing demand for cardiac interventions.

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.

The prevalence of undiagnosed abnormalities on non-contrast-enhanced computed tomography compared to contrast-enhanced computed tomography of the brain

Background: Even though magnetic resonance imaging (MRI) is the gold standard investigation for intracranial pathology, it is not widely available in developing countries and computed tomography (CT) of the brain remains the first-line investigation for patients with suspected intracranial pathology. It is generally accepted that certain intracranial pathology can be missed on non-contrast-enhanced CT (NECT) of the brain if a contrast-enhanced CT (CECT) is not done. We have to consider on the one hand the risk of delayed or missed diagnosis and on the other hand the cost, increased radiation exposure and contrast-induced reactions. Advances in CT technology have also improved the resolution of CT scan images, making it easier to identify pathology on an NECT of the brain. To date, no study comparing NECT to CECT of the brain, utilising 64-slice CT technology, has been published.Objectives: To determine the prevalence of undiagnosed abnormalities on non-contrast-enhanced computed tomography (NECT) scans of the brain reported as normal, on a 64-slice CT scanner.Method: A descriptive retrospective study was undertaken of CT brain scans done during a 12-month period at a tertiary provincial hospital in the Northern Tshwane district of Gauteng, South Africa. The CT brain scans were evaluated by three reviewers (general radiologists). The NECT and contrast-enhanced computed tomography (CECT) scans of the brain were reviewed independently on separate occasions. Reviewers were blinded to patient history, each other’s interpretation, and to their own interpretation of the NECT when evaluating the CECT and vice versa. Discrepancies in interpretation were resolved during a consensus meeting between all three reviewers. The reviewers also re-evaluated the NECT scans of the cases with undiagnosed abnormal findings during this session. A decision was made pertaining to the visibility of the abnormal findings on the NECT scan.Results: In this study, 3.28% of cases had abnormal findings undiagnosed by three reviewers on the NECT scans. Re-evaluation by the panel reduced this to 1.42%, indicating a reading error of 1.85%.Conclusion: There is a small prevalence of missed abnormal findings on the NECT scan when using only NECT. Omitting unnecessary CECT will reduce the radiation exposure to the patient and reduce the risk of adverse events from the use of intravenous iodinated contrast. Alternatively, doing only a CECT scan would reduce the risk of missing abnormal findings and would also decrease the patient’s exposure to radiation.

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.

Evaluation of acute appendicitis by pediatric emergency physician sonography

STUDY OBJECTIVE

We investigate the accuracy of pediatric emergency physician sonography for acute appendicitis in children.

METHODS

We prospectively enrolled children requiring surgical or radiology consultation for suspected acute appendicitis at an urban pediatric emergency department. Pediatric emergency physicians performed focused right lower-quadrant sonography after didactics and hands-on training with a structured scanning algorithm, including the graded-compression technique. We compared their sonographic interpretations with clinical and radiologic findings, as well as clinical outcomes as defined by follow-up or pathologic findings.

RESULTS

Thirteen pediatric emergency medicine sonographers performed 264 ultrasonographic studies, including 85 (32%) in children with pathology-verified appendicitis. Bedside sonography had a sensitivity of 85% (95% confidence interval [CI] 75% to 95%), specificity of 93% (95% CI 85% to 100%), positive likelihood ratio of 11.7 (95% CI 6.9 to 20), and negative likelihood ratio of 0.17 (95% CI 0.1 to 0.28).

CONCLUSION

With focused ultrasonographic training, pediatric emergency physicians can diagnose acute appendicitis with substantial accuracy.

Radiation dose in the thyroid and the thyroid cancer risk attributable to CT scans for pediatric patients in one general hospital of China

Objective: To quantify the radiation dose in the thyroid attributable to different CT scans and to estimate the thyroid cancer risk in pediatric patients. Methods: The information about pediatric patients who underwent CT scans was abstracted from the radiology information system in one general hospital between 1 January 2012 and 31 December 2012. The radiation doses were calculated using the ImPACT Patient Dosimetry Calculator and the lifetime attributable risk (LAR) of thyroid cancer incidence was estimated based on the National Academies Biologic Effects of Ionizing Radiation VII model. Results: The subjects comprised 922 children, 68% were males, and received 971 CT scans. The range of typical radiation dose to the thyroid was estimated to be 0.61–0.92 mGy for paranasal sinus CT scans, 1.10–2.45 mGy for head CT scans, and 2.63–5.76 mGy for chest CT scans. The LAR of thyroid cancer were as follows: for head CT, 1.1 per 100,000 for boys and 8.7 per 100,000 for girls; for paranasal sinus CT scans, 0.4 per 100,000 for boys and 2.7 per 100,000 for girls; for chest CT scans, 2.1 per 100,000 for boys and 14.1 per 100,000 for girls. The risk of thyroid cancer was substantially higher for girls than for the boys, and from chest CT scans was higher than that from head or paransal sinus CT scans. Conclusions: Chest CT scans caused higher thyroid dose and the LAR of thyroid cancer incidence, compared with paransal sinus or head CT scans. Therefore, physicians should pay more attention to protect the thyroid when children underwent CT scans, especially chest CT scans.

Identification of blunt abdominal injuries in children

BACKGROUND

The use of computed tomography (CT) to screen for injuries in pediatric blunt abdominal trauma (BAT) is increasing, concurrent with increasing concern over long-term risk of radiation-associated malignancies. We proposed to determine features that could be identified in the early assessment of these patients, which can predict the likelihood of clinically important intra-abdominal injuries warranting imaging by CT. We further queried if these were discrepant from factors associated with the decision to obtain an abdominal CT.

METHODS

Data of patients admitted with BAT to one of two Level I pediatric trauma centers were reviewed retrospectively. Clinical, laboratory, radiographic, and epidemiologic data were collected. Logistic regression was used to determine associations between pre-CT findings and ultimate diagnoses of "notable" or "clinically important" intra-abdominal injuries. Similar analyses were performed to determine which findings were associated with actually receiving an abdominal CT scan.

RESULTS

Of 571 patients, 37% had a notable intra-abdominal injury and 18% a clinically important intra-abdominal injury. After adjusting for all covariates, hematuria (gross or microscopic), elevated serum alanine aminotransferase, and documentation of clinically concerning abdominal findings upon examination remained significant predictors (odds ratio (OR), 3.5; 95% confidence interval [CI], 1.8-6.8; OR, 10.9; 95% CI, 2.5-47, respectively) of a clinically important injury. Undergoing a CT head and the presence of hematuria were significantly associated with obtaining a CT of the abdomen (OR, 3.4; 95% CI, 1.5-7.7; OR, 2.9; 95% CI, 1.1-7.3, respectively), while concerning abdominal findings and decreased Glasgow Coma Scale (GCS) score were not.

CONCLUSION

Clinical variables may be used to predict intra-abdominal injuries after pediatric BAT that may warrant imaging with CT scanning. Combined with findings from similar studies, it may be possible to derive and validate a decision-making rule both sensitive and specific in predicting the need for abdominal CT scanning in these patients.

LEVEL OF EVIDENCE

Prognostic study, level III.

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.

Radiation from CT scans in paediatric trauma patients: Indications, effective dose, and impact on surgical decisions

OBJECTIVES

The purpose of this study was to determine the effective dose of radiation due to computed tomography (CT) scans in paediatric trauma patients at a level 1 Canadian paediatric trauma centre. We also explored the indications and actions taken as a result of these scans.

PATIENTS AND METHODS

We performed a retrospective review of paediatric trauma patients presenting to our centre from January 1, 2007 to December 31, 2008. All CT scans performed during the initial trauma resuscitation, hospital stay, and 6 months afterwards were included. Effective dose was calculated using the reported dose length product for each scan and conversion factors specific for body region and age of the patient.

RESULTS

157 paediatric trauma patients were identified during the 2-year study period. Mean Injury Severity Score was 22.5 (range 12-75). 133 patients received at least one CT scan. The mean number of scans per patient was 2.6 (range 0-16). Most scans resulted in no further action (56%) or additional imaging (32%). A decision to perform a procedure (2%), surgery (8%), or withdrawal of life support (2%) was less common. The average dose per patient was 13.5mSv, which is 4.5 times the background radiation compared to the general population. CT head was the most commonly performed type of scan and was most likely to be repeated. CT body, defined as a scan of the chest, abdomen, and/or pelvis, was associated with the highest effective dose.

CONCLUSIONS

CT is a significant source of radiation in paediatric trauma patients. Clinicians should carefully consider the indications for each scan, especially when performing non-resuscitation scans. There is a need for evidence-based treatment algorithms to assist clinicians in selecting appropriate imaging for patients with severe multisystem trauma.

The value of radiologic interventions and (18)F-DOPA PET in diagnosing and localizing focal congenital hyperinsulinism: systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to quantify the diagnostic performance of pancreatic venous sampling (PVS), selective pancreatic arterial calcium stimulation with hepatic venous sampling (ASVS), and (18)F-DOPA positron emission tomography (PET) in diagnosing and localizing focal congenital hyperinsulinism (CHI).

PROCEDURES

This systematic review and meta-analysis was conducted according to the PRISMA statement. PubMed, EMBASE, SCOPUS and Web of Science electronic databases were systematically searched from their inception to November 1, 2011. Using predefined inclusion and exclusion criteria, two blinded reviewers selected articles. Critical appraisal ranked the retrieved articles according to relevance and validity by means of the QUADAS-2 criteria. Pooled data of homogeneous study results estimated the sensitivity, specificity, likelihood ratios and diagnostic odds ratio (DOR).

RESULTS

(18)F-DOPA PET was superior in distinguishing focal from diffuse CHI (summary DOR, 73.2) compared to PVS (summary DOR, 23.5) and ASVS (summary DOR, 4.3). Furthermore, it localized focal CHI in the pancreas more accurately than PVS and ASVS (pooled accuracy, 0.82 vs. 0.76, and 0.64, respectively). Important limitations comprised the inclusion of studies with small sample sizes, high probability of bias and heterogeneity among their results. Studies with small sample sizes and high probability of bias tended to overestimate the diagnostic accuracy.

CONCLUSIONS

This systematic review and meta-analysis found evidence for the superiority of (18)F-DOPA PET in diagnosing and localizing focal CHI in patients requiring surgery for this disease.

The establishment of computed tomography diagnostic reference levels in Portugal

The aims of this study were to investigate the frequency of Portuguese computed tomography (CT) examinations, identify protocol application and establish diagnostic reference levels (DRLs). CT departments (n=211) were surveyed nationally (June 2011-January 2012) and CT protocol information and dose data were collected, as were retrospective age-categorised paediatric CT data from three national paediatric centres. The proposed national CT DRLs (CTDIvol) for adults were 75, 18, 14, 18, 17, 36, 22, 27 and 16 mGy for head, neck, chest, abdomen, pelvis, cervical, dorsal, lumbar and joints, respectively. The levels for paediatric head and chest examinations were as follows: 48 and 2 mGy (newborns), 50 and 6 mGy (5 y olds), 70 and 6 mGy (10 y olds) and 72 and 7 mGy (15 y olds). A limited number of current paediatric protocols aligned to recommended international age categorisations. Portuguese DRLs were generally higher than European recommendations, suggesting potential for optimisation. The need for greater standardisation of age-categorised paediatric protocols was identified.

Estimation of organ and effective doses from newborn radiography of the chest and abdomen

Neonatal intensive care patients undergo frequent chest and abdomen radiographic imaging. In this study, the organ doses and the effective dose resulting from combined chest-abdomen radiography of the newborn child are determined. These values are calculated using the Monte Carlo simulation software PCXCM 2.0 and compared with direct dose measurements obtained from thermoluminescent detectors (TLDs) in a physical phantom. The effective dose obtained from PCXMC is 21.2 ± 0.7 μSv and that obtained from TLD measurements is 22.0 ± 0.5 μSv. While the two methods are in close agreement with regard to the effective dose, there is a wide range of variation in organ doses, ranging from 85 % difference for the testes to 1.4 % for the lungs. Large organ dose variations are attributed to organs at the edge of the field of view, or organs with large experimental error or simulation uncertainty. This study suggests that PCXMC can be used to estimate organ and effective doses for newborn patients.

The use of computed tomography in pediatrics and the associated radiation exposure and estimated cancer risk

IMPORTANCE

Increased use of computed tomography (CT) in pediatrics raises concerns about cancer risk from exposure to ionizing radiation.

OBJECTIVES

To quantify trends in the use of CT in pediatrics and the associated radiation exposure and cancer risk.

DESIGN

Retrospective observational study.

SETTING

Seven US health care systems.

PARTICIPANTS

The use of CT was evaluated for children younger than 15 years of age from 1996 to 2010, including 4 857 736 child-years of observation. Radiation doses were calculated for 744 CT scans performed between 2001 and 2011.

MAIN OUTCOMES AND MEASURES

Rates of CT use, organ and effective doses, and projected lifetime attributable risks of cancer. RESULTS The use of CT doubled for children younger than 5 years of age and tripled for children 5 to 14 years of age between 1996 and 2005, remained stable between 2006 and 2007, and then began to decline. Effective doses varied from 0.03 to 69.2 mSv per scan. An effective dose of 20 mSv or higher was delivered by 14% to 25% of abdomen/pelvis scans, 6% to 14% of spine scans, and 3% to 8% of chest scans. Projected lifetime attributable risks of solid cancer were higher for younger patients and girls than for older patients and boys, and they were also higher for patients who underwent CT scans of the abdomen/pelvis or spine than for patients who underwent other types of CT scans. For girls, a radiation-induced solid cancer is projected to result from every 300 to 390 abdomen/pelvis scans, 330 to 480 chest scans, and 270 to 800 spine scans, depending on age. The risk of leukemia was highest from head scans for children younger than 5 years of age at a rate of 1.9 cases per 10 000 CT scans. Nationally, 4 million pediatric CT scans of the head, abdomen/pelvis, chest, or spine performed each year are projected to cause 4870 future cancers. Reducing the highest 25% of doses to the median might prevent 43% of these cancers.

CONCLUSIONS AND RELEVANCE

The increased use of CT in pediatrics, combined with the wide variability in radiation doses, has resulted in many children receiving a high-dose examination. Dose-reduction strategies targeted to the highest quartile of doses could dramatically reduce the number of radiation-induced cancers.

Analysis of radiation exposure among pediatric trauma patients at national trauma centers

BACKGROUND

Injured children undergo radiologic studies as part of trauma evaluations. Children are more sensitive than adult patients to the effects of ionizing radiation. Few studies have described the radiation exposure to pediatric patients during trauma evaluations. We sought to describe the rate of use of radiology studies and to estimate the effective dose of radiation delivered to pediatric trauma patients presenting to trauma centers within the United States.

METHODS

We performed an analysis of pediatric patients younger than 19 years who presented to an American College of Surgery-verified trauma center in 2010 (National Trauma Data Bank). We excluded patients who were transferred from another facility, patients who died at the scene or those who presented to the emergency department dead on arrival. We examined the use of computed tomography (CT) and standard radiographs (x-ray). Radiologic studies were identified through common procedure codes (CPT). Using published criteria, we estimated the effective radiation dose per trauma patient.

RESULTS

Among the 84,863 eligible pediatric trauma patients, 26,360 (31.1%) underwent imaging with x-ray or CT. Of these patients, 17,321 (65.7%) were male, median age was 13.0 years (interquartile range, 6.0-17.0), and 20,965 (79.5%) had an Injury Severity Score (ISS) of less than 16. A total of 23,148 (27.4%) underwent CT. X-ray studies accounted for a small amount of exposure to radiation as compared with CT. Mean (SD) effective radiation exposure of patients imaged with CT was 12.0 (8.2) mSv. Younger children and those with increasing injury severity were exposed to higher doses of radiation (β = -0.04, p < 0.001).

CONCLUSION

The majority of radiation exposure to pediatric trauma patients is secondary to CT. Younger children and those with more severe injuries are exposed to higher doses of radiation. Pediatric trauma patients are exposed to levels of radiation, which could potentially lead to long-term harm.

LEVEL OF EVIDENCE

Epidemiologic study, level III.

Emergency department visits in children with hemophilia

BACKGROUND

The pediatric emergency department (ED) management of bleeding and other complications of hemophilia constitutes an increasingly important component of hemophilia therapy. This retrospective study examined the overall ED use by children with hemophilia in a single center, with a particular aim to investigate visits related to injury or bleeding, and those related to blood stream infection in patients with a central venous catheter (CVC).

METHODS

Electronic medical records of patients with hemophilia presenting to Children's Hospital of Michigan ED were reviewed. Different categories of ED visits over a 5-year period (January 2006-December 2010) were examined.

RESULTS

There were 536 ED visits from 84 male patients (median age 4 years, range 0-21) with hemophilia over the 5-year period. The reasons for ED visits were: injury or bleeding (61.2%); suspected CVC-related infection (11.8%); causes unrelated to hemophilia (19.2%); and routine clotting factor infusion (7.8%). Eighteen visits from six patients were secondary to injury or bleeding in a patient not yet diagnosed with hemophilia. An intracranial hemorrhage was detected in five visits. Overall, 5.4% of all visits represented distinct episodes of bloodstream infection.

CONCLUSION

The pediatric ED is an indispensable component of the overall hemophilia care, because: (1) patients with potentially lethal problems such as ICH or CVC-related infection may present to the ED for their initial management; (2) previously undiagnosed patients with hemophilia may also present to the ED for their first bleeding episodes, initiating the diagnostic investigations; (3) the ED provides after-hours treatment service for many episodes of injury or bleeding, and also for clotting factor infusion.

Patient dose and image quality in low-dose abdominal CT: a comparison between iterative reconstruction and filtered back projection

BACKGROUND

In computed tomography (CT), there is increasing concern for potential CT radiation hazards. Several raw-data-based iterative reconstruction techniques attempt to facilitate low-dose imaging without compromising image quality, which raises the question whether these techniques may allow further dose reduction.

PURPOSE

To compare image quality of iterative reconstruction and filtered back projection in low-dose abdominal CT and study the potential for further dose reduction.

MATERIAL AND METHODS

Forty-five patients underwent CT of the abdomen twice: with standard low-dose technique and with 30% reduced dose, using both iterative reconstruction and filtered back projection. Four radiologists made pair-wise image quality assessment using five visual criteria. Visual grading regression (VGR) and weighted kappa (κ w) were used to analyze the data.

RESULTS

There were significant effects of log(mAs) (P <0.001) and reconstruction algorithm (P <0.01) on all image quality criteria with an estimated potential dose reduction of 5-9%. Inter-observer agreement ranged from 70% to 91% and κ w from -0.01 to 0.57.

CONCLUSION

An iterative reconstruction algorithm improved image quality in abdominal CT, but the estimated dose reduction was rather small. The full potential of the algorithm remains unclear.

Implantable continuous Doppler monitoring device for detection of hepatic artery thrombosis after liver transplantation

BACKGROUND

Early hepatic artery thrombosis (eHAT) after liver transplantation occurs in 3% of adults and 8% of children and often results in retransplantation. eHAT is initially asymptomatic and arterial patency is monitored with percutaneous Doppler ultrasound screening (pDUS). The aim of the study is to analyze the diagnostic accuracy of "continuous" Doppler registration (CONDOR) using an implantable miniature Doppler.

METHODS

This prospective observational study was conducted in 102 liver transplant recipients. Hepatic arterial signal is checked by CONDOR at least six times per day for the first 10 days after transplantation with comparison of diagnostic accuracy of CONDOR versus pDUS.

RESULTS

Extra investigations were performed after 48 (11%) regular pDUS where arterial patency was questioned: 32 extra pDUS, 14 computed tomography (CT) angiographies, and 2 reoperations. CT scan confirmed eHAT in 4 cases. In 10 cases of pDUS-suspected eHAT, where subsequent CT showed an open artery, the CONDOR signal was clearly pulsatile. In 2 of 4 patients with five eHATs, a weak arterial signal was inadvertently interpreted as an open artery (sensitivity of 60%). The accuracy for detection of eHAT increased from 93% (pDUS) to 99% (CONDOR). Using CONDOR, additional CT angiographies may be prevented in 10% of cases.

CONCLUSION

CONDOR is a useful adjunct to pDUS because it reduces the false-positive rate of pDUS. Further development of the technique and analysis of the signal generated by CONDOR are needed to improve the sensitivity before CONDOR can replace pDUS as a reliable screening method for detection of eHAT.

Neuroblastoma: the impact of biology and cooperation leading to personalized treatments

Neuroblastoma is the most common extra-cranial solid tumor in children. It is a heterogeneous disease, consisting of neural crest-derived tumors with remarkably different clinical behaviors. It can present in a wide variety of ways, including lesions which have the potential to spontaneously regress, or as an extremely aggressive form of metastatic cancer which is resistant to all forms of modern therapy. They can arise anywhere along the sympathetic nervous system. The median age of presentation is approximately 18 months of age. Urinary catecholamines (HVA and VMA) are extremely sensitive and specific tumor markers and are used in diagnosis, treatment response assessment and post-treatment surveillance. The largest national treatment groups from North America, Europe and Japan have formed the International Neuroblastoma Risk Group Task Force (INRG) to identify prognostic factors, to understand the mechanisms of tumorigenesis in this rare disease and to develop multi-modality therapies to improve outcomes and decrease treatment-related toxicities. This international cooperation has resulted in a significant leap in our understanding of the molecular pathogenesis of neuroblastoma. Lower staged disease can be cured if the lesion is resectable. Treatment of unresectable disease (loco-regional and metastatic) is stratified depending on clinical features (age at presentation, staging investigations) and specific tumor biological markers that include histopathological analyses, chromosomal abnormalities and the quantification of expression of an oncogene (MYCN). Modern treatment of high-risk neuroblastoma is the paradigm for the evolution of therapy in pediatric oncology. Outcomes have improved substantially with multi-modality therapy, including chemotherapy, surgery, radiation therapy, myeloablative therapy with stem cell transplant, immunotherapy and differentiation therapy; these comprise the standard of care worldwide. In addition, newer targeted therapies are being tested in phase I/II trials. If successful these agents will be incorporated into mainstream treatment programs.

Childhood osteomyelitis: imaging characteristics

Background

The purpose of this review is to illustrate the imaging findings of childhood osteomyelitis. The diagnosis of childhood osteomyelitis can be challenging. Clinical presentation and laboratory results can differ and are relatively unreliable. To date, its role in the assessment of treatment efficacy is not yet clear.

Methods

This review article provides an overview of the different imaging modalities and imaging characteristics of childhood osteomyelitis. Levels of evidence for different modalities are presented.

Results

Paediatric radiology plays a pivotal role in the diagnosis of childhood osteomyelitis and can also be used to guide therapy and intervention.

Conclusion

Although imaging is essential in the diagnostic process, cooperation between the physician and radiologist remains the cornerstone in accurately diagnosing childhood osteomyelitis.

Main Messages

• Imaging plays a pivotal role in the diagnosis of childhood osteomyelitis.

• Cooperation between the clinician and radiologist is a very important aspect of making the diagnosis.

• The initial imaging modality in childhood osteomyelitis is conventional imaging.

• Normal conventional imaging does not exclude osteomyelitis.

Multi-detector CT in the paediatric urinary tract

The use of paediatric multi-slice CT (MSCT) is rapidly increasing worldwide. As technology advances its application in paediatric care is constantly expanding with an increasing need for radiation dose control and appropriate utilization. Recommendations on how and when to use CT for assessment of the paediatric urinary tract appear to be an important issue. Therefore the European Society of Paediatric Radiology (ESPR) uroradiology task force and European Society of Urogenital Radiology (ESUR) paediatric working groups created a proposal for performing renal CT in children that has recently been published. The objective of this paper is to discuss paediatric urinary tract CT (uro-CT) in more detail and depth. The specific aim is not only to offer general recommendations on clinical indications and optimization processes of paediatric CT examination, but also to address various childhood characteristics and phenomena that facilitate understanding the different approach and use of uro-CT in children compared to adults. According to ALARA principles, paediatric uro-CT should only be considered for selected indications provided high-level comprehensive US is not conclusive and alternative non-ionizing techniques such as MR are not available or appropriate. Optimization of paediatric uro-CT protocols (considering lower age-adapted kV and mAs) is mandatory, and the number of phases and acquisition series should be kept as few as possible.

The ultrasound frequency determines the degree of intrinsic coagulation activation

Diagnostic ultrasound activates intrinsic coagulation. The aim of the present work was to quantify the action of different ultrasound frequencies on the contact phase of human blood coagulation. Pooled normal citrated platelet-poor plasma in 2 ml aliquots in polypropylene monovettes was exposed to diagnostic ultrasound, changing the ultrasound frequency from 17 to 15 to 12 to 8 to 7 MHz (at an intensity of 1.1 MI). After 0-2 min (23°C), 400 μl samples were withdrawn and placed into polypropylene Eppendorf cups. Forty microliters of plasma sample was pipetted into U-wells polystyrene microtiter plates of high purity (Brand781600). Immediately thereafter, the recalcified coagulation activity assay (RECA) was performed. Seventeen megahertz ultrasound exposure was the weakest activator of intrinsic coagulation of all frequencies tested: even 2 min of exposure at 23°C enhanced F2a generation by only about three-fold. The shorter the ultrasound exposure, the better the action against intrinsic hemostasis: 0.5 min of ultrasound exposure at 23°C induced less than two-fold thrombin generation in all frequencies tested. One minute ultrasound exposure (23°C) triggered intrinsic coagulation strongest at 8 MHz, showing an approximately four-fold increase in F2a generation. A 1.5 min of ultrasound exposure (23°C) triggered coagulation strongest at 7 MHz, showing an approximately 14-fold increase in F2a generation. Two minute of ultrasound exposure (23°C) triggered coagulation strongest at 15 MHz, showing an approximately 18-fold increase in F2a generation. Ultrasound has to be considered as a potential inducer of pathologic systemic coagulation. Patients at risk for increased coagulation activation and/or liver insufficiency should be protected with low molecular weight heparin, if a prolonged ultrasound diagnostic is planned. Ultrasound frequencies of about 17 MHz are the weakest activators of intrinsic coagulation. Ultrasound frequencies of about 7 MHz might be used for therapeutic induction of coagulation activation, such as in patients with severe cerebral or hepatic hemorrhages.

Emergent pediatric US: what every radiologist should know

Appendicitis, intussusception, and hypertrophic pyloric stenosis (HPS) are three of the most common reasons for emergent abdominal imaging in pediatric patients. Although the use of computed tomography has risen dramatically over the past 2 decades, children are particularly at risk for the adverse effects of ionizing radiation, and even low-dose radiation is associated with a small but significant increase in lifetime risk of fatal cancer. In most emergency departments, the use of magnetic resonance (MR) imaging as a primary modality for the evaluation of a child with abdominal pain remains impractical due to its high cost, its limited availability, and the frequent need for sedation. Ultrasonography (US) does not involve ionizing radiation and, unlike MR imaging, is relatively inexpensive, is widely available, and does not require sedation. Another major advantage of US in abdominal imaging is that it allows dynamic assessment of bowel peristalsis and compressibility. Delayed diagnosis of any of the aforementioned disease processes can lead to serious morbidity and, in some cases, death. The ability to diagnose or exclude disease with US should be part of a core radiology skill set for any practice that includes a pediatric population.

Reduction of radiation exposure in pediatric patients with trauma: cephalic stabilization improves adequacy of lateral cervical spine radiographs

INTRODUCTION

Plain radiographs continue to play a role in cervical spine clearance. Inadequate radiographs commonly necessitate repeat x-rays or computed tomography imaging (10 × radiation dose). We have used the technique of cephalic stabilization (CS) to improve the results of plain radiographs. Cephalic stabilization lateral radiographs are obtained, with one assistant applying traction to the arms while another placing fingers in the patient's ears and stabilizing the head. This study tests the hypothesis that CS improves visualization of the cervicothoracic junction during lateral cervical spine radiographs.

METHODS

A 2-year review of institutional pediatric trauma registry identified 46 patients with CS, matched 1:3 with controls. Randomized lateral radiographs were evaluated independently by 2 pediatric radiologists to determine adequate visualization of the craniocervical and cervicothoracic junctions. Reviewers were blinded to CS through image cropping.

RESULTS

The proportion of adequate visualization of the cervicothoracic junction was 0.85 for cases with stabilization and 0.60 for controls. Odds of obtaining adequate visualization with stabilization are 3.8 times those without stabilization (P = .001) and were even greater for patients younger than 13 years.

CONCLUSIONS

Cephalic stabilization improves visualization of the cervicothoracic junction in lateral cervical spine radiographs and can reduce radiation exposure in patients who would otherwise require further imaging.

Diagnostic value of routine chest radiography in febrile, neutropenic children for early detection of pneumonia and mould infections

BACKGROUND

Despite recent studies failing to demonstrate the value of routine chest radiography (CXR) in the initial evaluation of the febrile neutropenic patient with cancer, this screening test is advocated by some experts. We evaluated the benefits of CXR for early diagnosis of pulmonary infection at St. Jude Children's Research Hospital (SJCRH) with emphasis on early recognition of mould infections.

PATIENTS AND METHODS

We reviewed the courses of 200 consecutive febrile neutropenic pediatric patients to determine if routine CXR at initial evaluation was useful in the identification of clinically occult pneumonia. We also reviewed all cases of proven or probable mould infections from the opening of SJCRH in 1962 until 1998 when routine CXR was no longer practiced in our institution to identify cases that were first recognized by routine CXR.

RESULTS

Of 200 febrile neutropenic patients, pulmonary abnormalities consistent with pneumonia were detected by routine CXR in only five patients without pulmonary signs or symptoms. In only one case was a change in management considered. Of the 70 patients with pulmonary mould infection identified from 1962 to 1998, routine CXR was performed in 45 patients at the onset of a febrile, neutropenic episode in which a mould infection was diagnosed. Routine CXR was pivotal in the recognition of the mould infection in only two cases over this 36-year period.

CONCLUSION

CXR is warranted in the evaluation of the newly febrile neutropenic pediatric oncology patient only when respiratory signs or symptoms are present.

CT in children--dose protection and general considerations when planning a CT in a child

Today CT represents about 10% of all ionizing radiation based imaging modalities, but delivers more than 50% of the total collective dose for diagnostic imaging. Compared to adults the radiation sensitivity of children is considerable higher than in adults. Additionally children differ from adults--factors like body size, mass, density, proportions as well as metabolism have to be mentioned. Children grow and mature--all this components have to be mapped in examination protocols by Pediatric Radiology. The total dose of a CT examination depends on the settings of several factors such as the scout view, the scan length, exposure settings including automated exposure control, type of scanning (single slice, helical, volume mode), slice thickness, pitch values as well as on image reconstruction parameters. If intravenous contrast media injection is needed bolus tracking or timing represents another source of radiation. The aim of the paper is to present and discuss all aspects of defining a pediatric age and query adapted CT protocol particularly concerning all dose relevant factors in pediatric CT and their adjustment in children. Moreover hints are given concerning optimization of intravenous contrast media injection as well as special (low dose) imaging protocols.