Selecting appropriate gastroenteric contrast media for diagnostic fluoroscopic imaging in infants and children: a practical approach.

In our experience, questions about the appropriate use of enteric contrast media for pediatric fluoroscopic studies are common. The purpose of this article is to provide a comprehensive review of enteric contrast media used for pediatric fluoroscopy, highlighting the routine use of these media at a large tertiary care pediatric teaching hospital.

Pediatric thoracic CT angiography at 70 kV: a phantom study to investigate the effects on image quality and radiation dose.

BACKGROUND: Studies have demonstrated that 70-kilovolt (kV) imaging enhances the contrast of iodine, potentially affording a reduction in radiation dose while maintaining the contrast-to-noise ratio (CNR). There is a maximum amount of image noise beyond which increased contrast does not improve structure visualization. Thus, noise should be constrained during protocol optimization. OBJECTIVE: This phantom study investigated the effect of 70-kV imaging for pediatric thoracic CT angiography on image quality and radiation dose in a pediatric population when a noise constraint was considered. MATERIALS AND METHODS: We measured contrast and noise using anthropomorphic thoracic phantoms ranging in size from newborn age equivalent to 10-year-old age equivalent. We inserted contrast rods into the phantoms to simulate injected contrast material used in a CT angiography study. The image-quality metric "iodine CNR with a noise constraint" was used to determine the relative dose factor for each phantom size, kV setting (70-140 kV) and noise constraint (1.00-1.20). A noise constraint of 1.20 indicates that noise should not increase by more than 20% of the noise level in images performed at the reference kV, selected to be 80 kV in this study. The relative dose factor can be applied to the original dose obtained at 80 kV in order to maintain iodine CNR with the noise constraint. A relative dose factor <1.0 indicates potential for dose reduction while a relative dose factor >1.0 indicates a dose penalty. RESULTS: Iodine contrast was highest for 70 kV and decreased with higher kV settings for all phantom sizes. The relative dose factor at 70 kV was <1.0 for all noise constraint >1.0, indicating potential for dose reduction, for the newborn, 1-year-old and 5-year-old age-equivalent phantom sizes. For the 10-year-old age-equivalent phantom, relative dose factor at 70 kV=1.22, 1.11, 1.01, 0.92 and 0.83 for noise constraint=1.00, 1.05, 1.10, 1.15, 1.20, respectively, indicating a dose penalty for noise constraint ≤1.10 and potential for dose reduction for noise constraint >1.10. CONCLUSION: Using 70 kV does allow for radiation dose reduction if the radiologist is willing to accept a higher level of image noise as a trade-off for increased vessel contrast. This increase in noise is small (<5%) for the nominal newborn, 1- and 5-year-old but is >10% for the 10-year-old. Therefore, we recommend limiting 70 kV thoracic CT angiography to newborn through 5-year-old patients.

Size-based protocol optimization using automatic tube current modulation and automatic kV selection in computed tomography.

Size-based diagnostic reference ranges (DRRs) for contrast-enhanced pediatric abdominal computed tomography (CT) have been published in order to establish practical upper and lower limits of CTDI, DLP, and SSDE. Based on these DRRs, guidelines for establishing size-based SSDE target levels from the SSDE of a standard adult by applying a linear correction factor have been published and provide a great reference for dose optimization initiatives. The necessary step of designing manufacturer-specific CT protocols to achieve established SSDE targets is the responsibility of the Qualified Medical Physicist. The task is straightforward if fixed-mA protocols are used, however, more difficult when automatic exposure control (AEC) and automatic kV selection are considered. In such cases, the physicist must deduce the operation of AEC algorithms from technical documentation or through testing, using a wide range of phantom sizes. Our study presents the results of such testing using anthropomorphic phantoms ranging in size from the newborn to the obese adult. The effect of each user-controlled parameter was modeled for a single-manufacturer AEC algorithm (Siemens CARE Dose4D) and automatic kV selection algorithm (Siemens CARE kV). Based on the results presented in this study, a process for designing mA-modulated, pediatric abdominal CT protocols that achieve user-defined SSDE and kV targets is described.

Pediatric CT dose reduction for suspected appendicitis: a practice quality improvement project using artificial Gaussian noise--part 1, computer simulations.

OBJECTIVE: The purpose of this study was to develop a departmental practice quality improvement project to systematically reduce CT doses for the evaluation of suspected pediatric appendicitis by introducing computer-generated gaussian noise. MATERIALS AND METHODS: Two hundred MDCT abdominopelvic examinations of patients younger than 20 years performed with girth-based scanning parameters for suspected appendicitis were reviewed. Two judges selected 45 examinations in which the diagnosis of appendicitis was excluded (14, appendix not visualized; 31, normal appendix visualized). Gaussian noise was introduced into axial image series, creating five additional series acquired at 25-76% of the original dose. Two readers reviewed 270 image series for appendix visualization (4-point Likert scale and arrow localization). Volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) were calculated by use of patient girth. Confidence ratings and localization accuracy were analyzed with mixed models and nonparametric bootstrap analysis at a 0.05 significance level. RESULTS: The mean baseline SSDE for the 45 patients was 16 mGy (95% CI, 12-20 mGy), and the corresponding CTDIvol was 10 mGy (95% CI, 4-16 mGy). Changes in correct appendix localization frequencies were minor. There was no substantial trend with decreasing simulated dose level (p = 0.46). Confidence ratings decreased with increasing dose reduction (p = 0.007). The average decreases were -0.27 for the 25% simulated dose (p = 0.01), -0.17 for 33% (p = 0.03), and -0.03 for 43% (p = 0.65). CONCLUSION: Pediatric abdominal MDCT can be performed with 43% of the original dose (SSDE, 7 mGy; CTDIvol, 4.3 mGy) without substantially affecting visualization of a normal appendix.

Pediatric CT dose reduction for suspected appendicitis: a practice quality improvement project using artificial gaussian noise--part 2, clinical outcomes.

OBJECTIVE. The purpose of this study was to determine the effect of a nominal 50% reduction in median absorbed radiation dose on sensitivity, specificity, and negative appendectomy rate of CT for acute appendicitis in children. MATERIALS AND METHODS. On the basis of a departmental practice quality improvement initiative using computer-generated gaussian noise for CT dose reduction, we applied a nominal dose reduction of 50% to abdominal CT techniques used for bowel imaging. This retrospective study consisted of 494 children who underwent a CT for suspected acute appendicitis before (n = 244; mean age, 133 months) and after (n = 250; mean age, 145 months) the nominal 50% dose reduction. Test performance characteristics of CT for acute appendicitis and impact on the negative appendectomy rate were compared for both time periods. Primary analyses were performed with histologic diagnosis as the outcome standard. Volume CT dose index and dose-length product were recorded from dose reports and size-specific dose estimates were calculated. RESULTS. The nominal 50% dose reduction resulted in an actual 39% decrease in median absorbed radiation dose. Sensitivity of CT for diagnosis of acute appendicitis was 98% (95% CI, 91-100%) versus 97% (91-100%), and specificity was 93% (88-96%) versus 94% (90-97%) before and after dose reduction, respectively. The negative appendectomy rate was 4.5% (0.8-10.25%) before dose reduction and 4.0% (0.4-7.6%) after dose reduction. CONCLUSION. The negative appendectomy rate and performance characteristics of the CT-based diagnosis of acute appendicitis were not affected by a 39% reduction in median absorbed radiation dose.

An electronic tool for systematic reporting of fractures on skeletal surveys in suspected child abuse: prototype development and physician feedback.

OBJECTIVE: To describe a skeletal survey data entry and compilation tool and assess physician attitudes toward this reporting approach. BACKGROUND: Narrative skeletal survey reports are highly variable and prone to inconsistencies with potential adverse impact on patients. MATERIALS AND METHODS: The prototype skeletal survey data entry and compilation tool was developed and introduced into clinical practice at a large urban children's hospital. Pediatric radiologists and child protection team (CPT) pediatricians completed a survey of reporting preferences. Skeletal survey reports between March 1, 2013, and March 1, 2014, were reviewed to assess use of the tool. RESULTS: The survey response rate was 70% (14/20) for radiologists and 100% (4/4) for CPT pediatricians. Among responding radiologists, 54.5% (6/11) indicated that a skeletal survey data entry and compilation tool was helpful for skeletal surveys with >3 fractures; 80% (8/10) of responding radiologists indicated that tabulated data from prior skeletal survey was helpful when interpreting a follow-up skeletal survey with >3 fractures; 90.9% (10/11) of radiologists thought the tool improved report organization; 72.7% (8/11) thought it improved accuracy. Most radiologists (11/12, 91.7%) and 100% (4/4) of CPT clinicians preferred reports with both free text and a tabulated fracture list for testifying in court when >3 fractures were present. The tool was used in the reporting of 14/23 (61%) skeletal surveys with >3 fractures during a 1-year period. A case example using the application is presented. CONCLUSION: Most radiologists and CPT physicians at our center prefer skeletal survey reports with tabulated data and narrative description; 91.7% (11/12) of radiologists and all CPT clinicians prefer this approach for testifying in court when >3 fractures are present.

Yield of radiographic skeletal surveys for detection of hand, foot, and spine fractures in suspected child abuse.

OBJECTIVE: Previous studies have found that fractures involving the spine, hands, and feet are rare on skeletal surveys in cases of suspected child abuse, leading some authors to suggest eliminating these regions from the initial skeletal survey protocol. We assessed this recommendation by performing a historical review of these injuries in a pediatric population undergoing film screen-based radiographic skeletal surveys for suspected child abuse. MATERIALS AND METHODS: This cross-sectional retrospective study reviewed reports of initial skeletal surveys of all children younger than 2 years with suspected abuse imaged between April 1988 and December 2001. Radiographic skeletal survey imaging was performed according to American College of Radiology standards. Sixty-two percent (225/365) of all skeletal surveys had positive findings, and 44% (98/225) showed more than one fracture. Surveys with fractures involving the spine, hands, or feet were identified, and the data were tabulated and analyzed. RESULTS: Twenty of 365 studies (5.5%) yielded fractures involving the spine, hands, or feet. Of all positive skeletal surveys, 8.9% (20/225) had fractures involving the spine, hands, or feet. Of all patients with more than one fracture on skeletal survey, 20.4% (20/98) had fractures involving these regions. CONCLUSION: These data, acquired during the film-screen era, suggest that fractures of the spine, hands, and feet may not be rare in infants and toddlers in cases of suspected child abuse. The benefits of eliminating views of these regions from the initial skeletal survey should be carefully weighed against the cost of missing these potentially important injuries in at-risk pediatric populations.

Prevalence of the classic metaphyseal lesion in infants at low versus high risk for abuse.

OBJECTIVE: The purpose of this article is to determine the relative likelihood of encountering a classic metaphyseal lesion in infants at low and high risk for abuse. MATERIALS AND METHODS: This 10-year retrospective study compared the prevalence of the classic metaphyseal lesion on high-detail American College of Radiology-standardized skeletal surveys in infants at low and high risk for abuse. Low-risk infants met all of the following criteria: skull fracture without significant intracranial injury on CT, history of a fall, and no other social risk factors for abuse. High-risk infants met all of the following criteria: significant intracranial injury, retinal hemorrhages, and skeletal injuries (excluding classic metaphyseal lesions and skull fractures). Differences between the two groups were calculated using the Fisher exact test. RESULTS: There were 42 low-risk infants (age range, 0.4-12 months; mean age, 4.4 months) and 18 high-risk infants (age range, 0.8-10.3 months; mean age, 4.6 months). At least one classic metaphyseal lesion was identified in nine infants (50%) in the high-risk category. No classic metaphyseal lesions were identified in the low-risk group. The relative prevalence of classic metaphyseal lesions in the low-risk group (0/42) versus that in the high-risk group (9/18) was statistically significant (p < 0.0001; 95% CI, 0-8% to 29-76%). CONCLUSION: Classic metaphyseal lesions are commonly encountered in infants at high risk for abuse and are rare in infants with skull fractures associated with falls, but no other risk factors. The findings support the view that the classic metaphyseal lesion is a high-specificity indicator of infant abuse.

Patient size measured on CT images as a function of age at a tertiary care children's hospital.

OBJECTIVE: The purpose of our study was to measure patient size on CT images as a function of age at a large tertiary care children's hospital to develop current patient size data for modeling optimal x-ray exposure factors in children. MATERIALS AND METHODS: Anteroposterior and transverse dimensions of the head, thorax, abdomen, and pelvis were measured on CT examinations of pediatric patients less than 21 years old performed between June and November 2007. Patients with diseases that could affect measurements were excluded. From 1,009 patients, 336 examinations of each of four body regions were selected; 2,688 measurements were made and separated into 21 groups. Statistical model building and prediction equations were established for each region and 95% prediction intervals were used for analyses. RESULTS: Rapid growth of the head occurred from birth to approximately 2 years followed by a gradual plateau until 21 years. The thoracic, abdominal, and pelvic regions showed a linear relationship between age and size. Fitted equations showed transverse trunk measurements increased more rapidly than anteroposterior measurements. The anteroposterior trunk size growth rate was relatively region independent; transverse pelvic dimensions grew more rapidly than thoracic or abdominal regions. There was a broad overlap of predicted patient size ranges as a function of age within each region. Excellent interobserver agreement was measured by Pearson's correlation coefficient (r) (all p < 0.0001). CONCLUSION: Fitted average patient sizes are age dependent; however, predicted individual patient size does not correlate well with age. Our study suggests that pediatric patient body size should be determined for individual patients before performing diagnostic imaging procedures that entail radiation risks.

Detection of simulated inflicted metaphyseal fractures in a fetal pig model: image optimization and dose reduction with computed radiography.

PURPOSE: To prospectively determine in a fetal pig model whether diagnostic performance comparable to that of high-detail screen-film imaging can be achieved with computed radiography for the detection of simulated classic metaphyseal lesions (CMLs), by using Faxitron digital images as the reference standard, and whether radiation dose reduction is possible. MATERIALS AND METHODS: This study was granted exempt status by the institutional review board and the animal care and use committee. Fractures simulating the CML were produced in distal femurs of 20 deceased fetal pigs. Twenty normal femurs served as control femurs. Femurs were imaged with a standard single-side-read 100-microm pixel sampling imaging plate (IP), a high-resolution dual-side-read 50-microm pixel sampling IP, and a high-detail screen-film imaging system. Eight tube current-time product settings (0.5-10.0 mAs) and two tube voltage selections (56 and 70 kVp) were employed. Two pediatric radiologists evaluated 920 images for fracture by using a five-point Likert scale. Area under the receiver operating characteristic curve (A(z)) values for the imaging systems were compared by using nonparametric chi(2) tests (all P < .05). RESULTS: For pooled rater data, performance of computed radiography was comparable to that of screen-film imaging, and superior performance (P = .04) was achieved with the more experienced rater. The A(z) value tended to increase as the tube current-time product setting was increased. Within each system, there was no significant difference in A(z) values for all images obtained at 56 and 70 kVp (dual-side-read IP, P = .63; single-side-read IP, P = .25; screen-film imaging system, P = .5). At 56 kVp, a dose reduction of up to 69% was achieved, and accuracy of computed radiography was comparable to that of screen-film imaging. CONCLUSION: Findings in this study suggest that computed radiography can replace screen-film imaging in the detection of CMLs and may permit dose reduction.

Suspected infant abuse: radiographic skeletal survey practices in pediatric health care facilities.

PURPOSE: To determine current national radiographic skeletal survey imaging practices, including migration to digital technologies, for evaluation of suspected infant abuse. MATERIALS AND METHODS: Of 155 children's health care facilities in the United States in which radiographic skeletal surveys are performed for suspected infant (<1 year old) abuse, 137 (88.4%) agreed to complete a questionnaire. Questions included facility type, imaging department volume, radiographic equipment, and details of skeletal survey imaging practices. Statistical analysis was performed with chi(2), Fisher exact, Pearson correlation, Spearman rank correlation, and Student t tests. RESULTS: One hundred seven completed questionnaires were returned. Forty-seven (43.9%) facilities used screen-film imaging; 60 (56.1%) used digital. Of screen-film users, 25 (53.2%) had already migrated or planned to migrate to digital within 1 year. Of screen-film users, 27 (60.0%) reported use of a high-detail imaging system, while 13 (21.7%) digital users employed a high-resolution technique (P < .001). Eighty-four (78.5%) facilities reported more than 10 images in their protocol, and 45 (42.0%) specified more than 15 images. Only one (0.9%) facility obtained fewer than three images. Upper extremities were imaged separately with at least two exposures in 81 (75.7%) facilities. Lower extremities were imaged separately with at least two exposures in 82 (76.6%) facilities. One hundred five (98.1%) facilities reported acquisition of lateral spinal views. CONCLUSION: Within U.S. pediatric health care facilities, most skeletal surveys in cases of suspected infant abuse include separate frontal views of the appendicular skeleton and frontal and lateral views of the axial skeleton. Imaging protocols and other image quality determinants vary widely, and as U.S. pediatric health care facilities migrate from film-based to digital imaging technology, imaging practices directly applicable to the digital environment are being retained; however, less attention is being paid to technical elements specific to digital imaging that affect high-detail image quality.