Determining the normal aorta size in children.

PURPOSE: To establish effective aorta diameter standards at multiple levels of the thoracic aorta, abdominal aorta, and common iliac arteries by using computed tomographic (CT) data in healthy children (infants, children, adolescents) through young adults (hereafter referred to collectively as "children") of a wide range of sizes so that z scores may be calculated. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board. The effective diameter, the average of aortic anteroposterior and lateral diameters, was independently measured at multiple levels of the aorta and common iliac arteries by two radiologists using 1-mm-collimation double-oblique reconstructions. Ordinary least squares regression methods were used to investigate models with various functional forms that related effective diameters at each level to patient body surface area (BSA) and sex. The best model was selected by using R(2), and formulas for deriving the expected diameter and estimates of the mean squared error (MSE) were generated. RESULTS: Results from 88 thoracic and 110 abdominal contrast material-enhanced CT examinations were analyzed in children without known cardiovascular disease who ranged in age from 0 to 20 years (mean, 9.9 years; standard deviation, 5.7), with BSA ranging from 0.19 to 2.52 m(2). Excellent interrater reliability was present (correlation coefficients ranged from 0.95 to 0.98). The best model was a polynomial regression model of the natural log transformation of the effective diameter that included linear, quadratic, and cubic BSA terms and a sex main effect as independent variables. The z scores were calculated by using the observed and expected effective diameters and the MSE. CONCLUSION: The range of normal effective diameters of the aorta at multiple levels and the common iliac arteries was determined for children of different sizes and both sexes. Measurements outside of the normal ranges are consistent with aneurysm or hypoplasia.

Inappropriate and cloned clinical histories on radiology request forms for sick children.

BACKGROUND: An appropriate clinical history improves the perception and interpretation of radiographic examinations in children and adults. However, clinical history provided on radiology request has not been studied for its appropriateness and frequency of cloned clinical history. OBJECTIVE: The purpose of this study was to determine the frequency of inappropriate histories and cloned histories at a tertiary-care children's hospital. MATERIALS AND METHODS: We analyzed radiology request forms of 388 outpatient and inpatient radiographic examinations obtained on 3 days during the same month at a tertiary-care children's hospital. Appropriateness of the clinical history was judged by its relevance to the examination ordered and appropriate associated billable ICD-9 code. Cloning was defined as identical clinical histories appearing on the radiology request on three consecutive days. Cloned histories were further subdivided as being appropriate or inappropriate. RESULTS: A total of 18% (70/388) of the requests for clinical history were either inappropriate, cloned or both. Neonatal intensive care unit (NICU) referrals constituted the majority (82%, 9/11) of combined inappropriate history and cloning. NICU referrals accounted for 52% (28/54) of all inappropriate clinical histories, a significantly higher percentage than other inpatient locations (P = 0.006). The cardiovascular intensive care unit (CVICU) was the second most common patient location for inappropriate clinical histories (11%, 6/54). About one-third of the radiographic requests from the NICU had inappropriate histories (35%, 28/79). Among the outpatient referrals, 50% (4/8) of the inappropriate histories were from the emergency department. The most common cloned histories included "hypoplastic left heart syndrome" (15%, 4/27), "endotracheal tube placement" (11%, 3/27) and "evaluate lung fields and bowel" (11%, 3/27). The most commonly cloned clinical history was seen on referrals from the NICU at 63% (17/27), a significantly higher percentage than other inpatient locations (P = 0.006). The CVICU unit accounted for the second most common patient location for cloned clinical histories (26%, 7/27). The cloned clinical history on the referral request for radiography was unjustified in 48% (13/27) of the cases. NICU referrals had 85% (11/13) of the unjustified cloned histories. CONCLUSION: Inpatient units, particularly the NICU, were most likely to have inappropriate histories and cloning. Cloning was clinically justified in about half of the cases of cloning. The patterns of inappropriate histories and cloning suggest possible corrective measures.

Dynamic pulmonary CT of children.

OBJECTIVE: Wide-detector CT allows simultaneous imaging of the entire airway and lungs in small children. Images acquired in multiple phases by continuous scanning during respiration are viewed dynamically, allowing more complete airway and pulmonary evaluation than possible with static protocols. The purpose of this study was to evaluate whether low-dose techniques can be applied to dynamic pulmonary CT of small children. MATERIALS AND METHODS: The study included 24 infants and small children with persistent respiratory difficulty who underwent dynamic pulmonary CT (11 with IV contrast administration, 13 without contrast administration). No significant difference in patient age was present in the two groups. Continuous-mode wide-detector scans were obtained at 350-millisecond gantry rotation for a total of 1.4 seconds at 80 kVp. Some contrast-enhanced studies for simultaneous vascular and airway evaluation were performed at slightly greater tube current. The effective dose for each patient was calculated, and the Student t test was performed to compare effective dose measurements. RESULTS: All studies were of diagnostic quality, frequently yielding critical information not available with other diagnostic tests. The mean effective dose for all patients was 1.7 (SD, 1.1) mSv. In the group who received contrast material, the mean effective dose was greater (1.9 [SD, 1.4] mSv) than in the group who did not receive contrast material (1.5 [SD, 0.7] mSv), but the difference was not significant (p = 0.4). CONCLUSION: Wide-detector dynamic CT is ideal for evaluation of the airway and lungs in infants and small children with persistent respiratory distress. Effective doses are low, typically less than 2 mSv.

MR imaging and CT evaluation of congenital pulmonary vein abnormalities in neonates and infants.

Magnetic resonance (MR) imaging and computed tomography (CT) are increasingly being used in diagnosis and follow-up of congenital pulmonary vein anomalies in neonates and infants. Such anomalies include total or partial anomalous pulmonary venous return, sinus venosus defect, malposition of the septum primum, cor triatriatum, pulmonary vein atresia or stenosis, and abnormal number or course of the pulmonary veins. MR imaging provides a wealth of anatomic and functional data that are valuable in case management and planning intervention. Gadolinium-enhanced MR angiography is the mainstay of anatomic evaluation. Ventricular volumetry with two-dimensional steady-state free-precession sequences and flow analysis with cine phase-contrast imaging provide physiologic information that may be used to calculate the degree of right heart enlargement and the shunt fraction, allowing the cardiologist to determine the functional importance of the lesion. CT provides superior spatial resolution and short imaging times but at the expense of exposure to ionizing radiation.

Limitations of standard echocardiographic methods for quantification of right ventricular size and function in children and young adults.

OBJECTIVES: The aim of this study was to evaluate correlation of 2-dimensional (2D) echocardiographic assessment of right ventricular (RV) and left ventricular (LV) size and function with magnetic resonance imaging (MRI) in children and young adults. METHODS: Patients with repaired tetralogy of Fallot (n = 23) and those who had normal RV volumes (n = 13) and a normal ejection fraction (EF) by MRI constituted the study groups. Echocardiographic indices including the end-diastolic area (EDa), end-systolic area (ESa), fractional area change (FAC), tricuspid annular motion (TAM), RV basal diameter, and RV basal shortening fraction were compared with MRI ventricular volumes and the EF. Two echocardiographers qualitatively graded RV size and function. RESULTS: In both groups, neither the RV EDa nor the ESa correlated with MRI RV volumes. Only TAM correlated with the RV EF. Qualitative assessment of the RV showed poor interobserver agreement. The LV area and FAC correlated well with MRI data. CONCLUSIONS: In contrast to the LV, 2D echocardiographic indices of RV size and function, with the exception of TAM, do not correlate with MRI data.

Advanced imaging improves detection of baffle leaks and stenoses after atrial switch compared with transthoracic echocardiography.

Current guidelines for adults with atrial switch repair recommend baseline cardiovascular magnetic resonance (CMR) for assessment of ventricular size and function, systemic and venous baffle obstruction and leaks, and valvular function. It also recommends transthoracic echocardiography (TTE) for outpatient follow up. Many such patients with implanted cardiac devices may need cardiac computed tomography (CCT) when CMR is not feasible. This study reviews and compares CMR, transesophageal echocardiography (TEE), CCT, cardiac catheterization with angiography and TTE in detection of baffle problems in patients after atrial switch operation. The medical records of patients who had at least one imaging study performed after atrial switch operation at our center from 2010 to 2020 were retrospectively reviewed. Results are reported as descriptive statistics for demographics and imaging findings. The principal outcome measure was detection of baffle leak and/or baffle stenosis. Fifty-seven patients had at least one cardiac imaging study after atrial switch operation (36 Senning and 21 Mustard operations) during the study period. Nearly 33% (19/57) had baffle complications of stenosis and/or baffle leaks identified. All 57 patients had TTE performed but baffle problems were noted by TTE in only 8 (14%) patients (7 baffle stenosis and 1 baffle leak). Of the 49 patients without known baffle problems by TTE, 24 had advanced imaging (TEE/CCT/CMR/angiography). Advanced imaging identified baffle problems in nearly half (11/24, 46%) of them (7 baffle leaks and 4 baffle stenosis). Baffle problems were present in (8/23) patients with transvenous cardiac devices. Baffle complications are common after atrial switch operations and in our study occur in 1/3rd of the patients. However, TTE is not sensitive enough to recognize these complications. Advanced imaging for detection of baffle complications should be considered in all patients after atrial switch operation.

Pediatric chest MDCT using tube current modulation: effect on radiation dose with breast shielding.

OBJECTIVE: The purpose of our study was to assess the effect on radiation dose and image noise during pediatric chest 16-MDCT using automatic tube current modulation and bismuth breast shields. MATERIALS AND METHODS: Age-based chest 16-MDCT was performed on an anthropomorphic phantom representing a 5-year-old child. Two scans were obtained in each of four sequences: first, without a shield; second, with a 2-ply bismuth shield; third, using automatic tube current modulation with a scout image obtained after placement of the shield; and fourth, using automatic tube current modulation with a scout image obtained before placement of the shield. Metal oxide semiconductor field effect transistor technology was used to measure the radiation dose in 20 organ locations. Effective dose was estimated using the console dose-length product. Noise was measured by recording the SD of Hounsfield units in identical regions of interest. RESULTS: The bismuth breast shield reduced the dose to the breast by 26%. Shielding and automatic tube current modulation reduced the breast dose by 52%. Multiple organ doses were lowest when the shield was placed after the scout radiograph had been obtained. When the shield was placed after the scout image was obtained, the mean noise in the range of shielding increased from 11.4 to 13.1 H (superior mediastinum) and from 10.0 to 12.8 H (heart) (p < 0.01). Increased noise, however, was near the target noise index (measured in SD of Hounsfield units) of 12.0 H (SD). Using automatic tube current modulation, the effective dose was reduced by 35% when the shield was placed after the scout and by 20% when the shield was present in the scout. CONCLUSION: The greatest dose reduction is achieved by placing the shield after obtaining the scout image to avoid Auto mA compensation due to density of shield. With this technique, image noise increased but remained close to the target noise index.

Normal pulmonary artery and branch pulmonary artery sizes in children.

To establish standards for pulmonary artery and branch pulmonary artery (PA and BPA) effective diameter (ED) and cross-sectional area (CSA) by using computed tomography (CT) data in children of a wide range of sizes and investigate the roundness of arteries. The ED (average of short and long axes) and CSA for the PA and BPA were measured using 1-mm collimation double-oblique reconstructions. Ordinary least squares regression was used to investigate models with various functional forms that related ED and CSA to patient size. Aspect ratio (AR), the short axis divided by long axis, was measured to evaluate roundness. The ideal diameter derived from CSA measurements was compared to ED, short axis, and long axis measurements. 108 CT examinations were analyzed in children without reason for abnormal PA size who ranged in age from 0 to 18 years (mean, 10.9 years; SD, 5.9 years). Interrater reliability was excellent. Data were modeled using a natural log-transformed response variable and a linear term for height as the independent variable. AR for the PA, right pulmonary artery, and left pulmonary artery measured < 0.9 for 38, 55, and 37%, respectively, indicating that many arteries are not round. Ideal diameter was not significantly different than ED but was for short- and long-axis diameter measurements. Normal ED and CSA for PA and BPA were determined for children of different sizes. Measurements outside of the normal range are consistent with dilatation or stenosis. Single diameter techniques are likely to introduce error.

Estimating organ doses from tube current modulated CT examinations using a generalized linear model.

PURPOSE: Currently, available Computed Tomography dose metrics are mostly based on fixed tube current Monte Carlo (MC) simulations and/or physical measurements such as the size specific dose estimate (SSDE). In addition to not being able to account for Tube Current Modulation (TCM), these dose metrics do not represent actual patient dose. The purpose of this study was to generate and evaluate a dose estimation model based on the Generalized Linear Model (GLM), which extends the ability to estimate organ dose from tube current modulated examinations by incorporating regional descriptors of patient size, scanner output, and other scan-specific variables as needed. METHODS: The collection of a total of 332 patient CT scans at four different institutions was approved by each institution's IRB and used to generate and test organ dose estimation models. The patient population consisted of pediatric and adult patients and included thoracic and abdomen/pelvis scans. The scans were performed on three different CT scanner systems. Manual segmentation of organs, depending on the examined anatomy, was performed on each patient's image series. In addition to the collected images, detailed TCM data were collected for all patients scanned on Siemens CT scanners, while for all GE and Toshiba patients, data representing z-axis-only TCM, extracted from the DICOM header of the images, were used for TCM simulations. A validated MC dosimetry package was used to perform detailed simulation of CT examinations on all 332 patient models to estimate dose to each segmented organ (lungs, breasts, liver, spleen, and kidneys), denoted as reference organ dose values. Approximately 60% of the data were used to train a dose estimation model, while the remaining 40% was used to evaluate performance. Two different methodologies were explored using GLM to generate a dose estimation model: (a) using the conventional exponential relationship between normalized organ dose and size with regional water equivalent diameter (WED) and regional CTDIvol as variables and (b) using the same exponential relationship with the addition of categorical variables such as scanner model and organ to provide a more complete estimate of factors that may affect organ dose. Finally, estimates from generated models were compared to those obtained from SSDE and ImPACT. RESULTS: The Generalized Linear Model yielded organ dose estimates that were significantly closer to the MC reference organ dose values than were organ doses estimated via SSDE or ImPACT. Moreover, the GLM estimates were better than those of SSDE or ImPACT irrespective of whether or not categorical variables were used in the model. While the improvement associated with a categorical variable was substantial in estimating breast dose, the improvement was minor for other organs. CONCLUSIONS: The GLM approach extends the current CT dose estimation methods by allowing the use of additional variables to more accurately estimate organ dose from TCM scans. Thus, this approach may be able to overcome the limitations of current CT dose metrics to provide more accurate estimates of patient dose, in particular, dose to organs with considerable variability across the population.

ACR Appropriateness Criteria® Known or Suspected Congenital Heart Disease in the Adult.

The incidence of congenital heart disease (CHD) has been increasing in the adult patient population in part as a result of better patient survival. Patients with more severe CHD are living longer. Nearly all adults with known CHD require periodic imaging as a means of monitoring their disease process. Furthermore, adult patients with suspected CHD require imaging as a means of definitive diagnosis. As a result, it is important for both the referring clinician and the imager to be aware of the most appropriate imaging modality needed to obtain the data most needed to direct the next steps in patient care. Imaging procedures for the diagnosis of known or suspected CHD in the adult include chest radiography, fluoroscopy, echocardiography, nuclear scintigraphy, cardiac-gated CT, MRI, and cardiac catheterization/angiography. The physician trying to diagnose these often complex conditions needs complete and reliable information that includes details about intracardiac and vascular anatomy, hemodynamics, and function. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Chronic Chest Pain-High Probability of Coronary Artery Disease.

In patients with chronic chest pain in the setting of high probability of coronary artery disease (CAD), imaging has major and diverse roles. First, imaging is valuable in determining and documenting the presence, extent, and severity of myocardial ischemia, hibernation, scarring, and/or the presence, site, and severity of obstructive coronary lesions. Second, imaging findings are important in determining the course of management of patients with suspected chronic myocardial ischemia and better defining those patients best suited for medical therapy, angioplasty/stenting, or surgery. Third, imaging is also necessary to determine the long-term prognosis and likely benefit from various therapeutic options by evaluating ventricular function, diastolic relaxation, and end-systolic volume. Imaging studies are also required to demonstrate other abnormalities, such as congenital/acquired coronary anomalies and severe left ventricular hypertrophy, that can produce angina in the absence of symptomatic coronary obstructive disease due to atherosclerosis. Clinical risk assessment is necessary to determine the pretest probability of CAD. Multiple methods are available to categorize patients as low, medium, or high risk for developing CAD. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Radiation Safety in Children With Congenital and Acquired Heart Disease: A Scientific Position Statement on Multimodality Dose Optimization From the Image Gently Alliance.

There is a need for consensus recommendations for ionizing radiation dose optimization during multimodality medical imaging in children with congenital and acquired heart disease (CAHD). These children often have complex diseases and may be exposed to a relatively high cumulative burden of ionizing radiation from medical imaging procedures, including cardiac computed tomography, nuclear cardiology studies, and fluoroscopically guided diagnostic and interventional catheterization and electrophysiology procedures. Although these imaging procedures are all essential to the care of children with CAHD and have contributed to meaningfully improved outcomes in these patients, exposure to ionizing radiation is associated with potential risks, including an increased lifetime attributable risk of cancer. The goal of these recommendations is to encourage informed imaging to achieve appropriate study quality at the lowest achievable dose. Other strategies to improve care include a patient-centered approach to imaging, emphasizing education and informed decision making and programmatic approaches to ensure appropriate dose monitoring. Looking ahead, there is a need for standardization of dose metrics across imaging modalities, so as to encourage comparative effectiveness studies across the spectrum of CAHD in children.

Spine bone densitometry in asthmatic children treated with high dose corticosteroids: correcting for racial discrepancies.

PURPOSE: Our hypothesis is that the use of standards based on Caucasian children will under-estimate the incidence of abnormal bone density in African American children. MATERIALS AND METHODS: Eighty-two African American and 80 Caucasian asthmatic children classified as high-dose inhaled corticosteroid users comprised the study population. Bone mineral density measurements were compared to reference standards, based on Caucasians, to calculate Z-values. Regression analysis was used to compare Z-values derived from the race-specific and Caucasian standards for 32 African American children. The derived regression analysis equation was then applied to the entire African American population to determine the incidence of abnormal bone density. RESULTS: The asthmatic Caucasian mean spine bone density was significantly less than the normal standards (p < .001), but the African American mean spine bone density was not, despite the high-dose steroid use. Using the Caucasian standards, Caucasians were significantly more likely to have abnormal bone density detected (p < 0.015). Regression analysis of the 32 children with available race specific standards resulted in the following equation: Z African American= Z Caucasian-0.86. The number of African Americans with abnormal bone density detected using the regression equation was not significantly different than the Caucasian children (p > 0.12). CONCLUSIONS: Asthmatic African Americans treated with high-dose inhaled corticosteroids had denser bones than Caucasians. Caucasian standards can be adjusted using a regression equation.

Big help for small hearts.

The ACH Heart Center is a comprehensive, full-service resource for infants and children with congenital and acquired heart disease. UAMS physicians and nurses and ACH nurses and staff are here to care for these children both directly and by providing support to pediatricians and primary care physicians within Arkansas and the surrounding states.