Comparison of conventional and simulated reduced-tube current MDCT for evaluation of suspected appendicitis in the pediatric population.

OBJECTIVE: The purpose of this study was to compare CT with conventional and simulated reduced-tube current in the evaluation for acute appendicitis in children. MATERIALS AND METHODS: Validated noise-addition (tube current-reduction) software was used to create 50% and 75% tube current reductions in 60 CT examinations performed for suspected appendicitis, resulting in 180 image sets. Three blinded pediatric radiologists scored the randomized studies for the following factors: presence of the normal appendix or appendicitis (5-point scale; 1=definitely absent and 5=definitely present), presence of alternate diagnoses, and overall image quality (1=nondiagnostic and 5=excellent). Truth was defined by the interpretation of the conventional examination. RESULTS: For conventional examinations, the total number of reviews (60 cases×3 readers=180) in which the normal appendix was identified was 120 of 180 (66.7%), compared with 108 of 180 (60%) in the 50% (p=0.19) and 91 of 180 (50.6%) in the 75% (p=0.002) tube current-reduction groups. Appendicitis was identified in a total of 39 of 180 (21.7%), 38 of 180 (21.1%), and 37 of 180 (20.6%) examinations, respectively (p>0.05). This translates to sensitivities of 97% and 95% for the 50% and 75% tube current-reduction groups, respectively. Alternate diagnoses were detected in 14%, 16%, and 13% of scans, respectively. Compared with conventional-tube current examinations, reader confidence and assessment of image quality were significantly decreased for both tube current-reduction groups. CONCLUSION: Simulated tube current-reduction technology provides for systematic evaluation of diagnostic thresholds. Application of this technology in the setting of suspected appendicitis shows that tube current can be reduced by at least 50% without significantly affecting diagnostic quality, despite a decrease in reader confidence and assessment of image quality.

Lung nodule detection in pediatric chest CT: quantitative relationship between image quality and radiologist performance.

PURPOSE: To determine the quantitative relationship between image quality and radiologist performance in detecting small lung nodules in pediatric CT. METHODS: The study included clinical chest CT images of 30 pediatric patients (0-16 years) scanned at tube currents of 55-180 mA. Calibrated noise addition software was used to simulate cases at three nominal mA settings: 70, 35, and 17.5 mA, resulting in quantum noise of 7-32 Hounsfield Unit (HU). Using a validated nodule simulation technique, lung nodules with diameters of 3-5 mm and peak contrasts of 200-500 HU were inserted into the cases, which were then randomized and rated independently by four experienced pediatric radiologists for nodule presence on a continuous scale from 0 (definitely absent) to 100 (definitely present). The receiver operating characteristic (ROC) data were analyzed to quantify the relationship between diagnostic accuracy (area under the ROC curve, AUC) and image quality (the product of nodule peak contrast and displayed diameter to noise ratio, CDNR display). RESULTS: AUC increased rapidly from 0.70 to 0.87 when CDNR display increased from 60 to 130 mm, followed by a slow increase to 0.94 when CDNR display further increased to 257 mm. For the average nodule diameter (4 mm) and contrast (350 HU), AUC decreased from 0.93 to 0.71 with noise increased from 7 to 28 HU. CONCLUSIONS: We quantified the relationship between image quality and the performance of radiologists in detecting lung nodules in pediatric CT. The relationship can guide CT protocol design to achieve the desired diagnostic performance at the lowest radiation dose.]

The Duke Abdominal Assessment Scale: initial experience.

Plain abdominal radiographs are the current standard imaging modality of choice in the evaluation of patients with clinically suspected necrotizing enterocolitis. The time interval between radiographic exams varies with the severity of disease and may range from every 6 h to every 24 h. Radiographs are often also obtained at any point of acute clinical deterioration. Evaluation of the abdominal radiographic series is critical as the findings may alter patient management and can be an indication for surgical intervention. For these reasons, it is essential that the radiographic findings are communicated to the referring neonatologist in a clear and consistent manner. Inherent variability and lack of consistency in radiology reporting makes it difficult for the referring clinician to incorporate radiographic reports into his/her treatment algorithm. Assigning abdominal radiographic findings in necrotizing enterocolitis to a numerical scale that increases as the disease progresses provides objective terminology in lieu of subjective descriptors and may facilitate communication to our clinical colleagues. With this task in mind, the Duke Abdominal Assessment Scale was created as a 10-point numerical scale of plain film bowel gas pattern findings designed to reflect progressive disease and increased certainty of the diagnosis of necrotizing enterocolitis.

American Board of Radiology certifying examination: oral versus computer-based format.

OBJECTIVE: This pilot study of a computer-based examination for primary certification by the American Board of Radiology was designed to acquire comparative data on candidates that were measures of individual performance on the oral examination compared with the computer-based examination. MATERIALS AND METHODS: The pilot computer-based pediatric radiology examination was designed by experienced oral board examiners and the pediatric subspecialty trustees. Images were chosen from the examination repository of the American Board of Radiology. The 20-minute examination was designed to include 8-10 cases with 26-31 scorable units covering all aspects of pediatric radiology. RESULTS: Among the 1,317 candidates taking the oral board examination, 1,048 candidates (79.6%) participated in the voluntary pilot examination. The scores of the two examinations were subjected to statistical analysis. The sensitivity and specificity of the pilot examination were 94.5% and 45.7%. The overall accuracy was 92.8%. Seventy-five candidates (7.2%) who participated in this study received different verdicts on the pilot examination and the pediatric radiology category of the oral examination. Fifty-six of these candidates (5.3%) failed the pilot examination but passed in the oral pediatric radiology category; 19 of the candidates (1.8%) passed the pilot examination but failed the oral pediatric radiology test. Pilot examination scores were higher for candidates who passed the oral pediatric radiology category (median score, 80; interquartile range, 74.1-85.2) than for candidates who failed (median score, 65.4; interquartile range, 58.6-71.0) (p < 0.0001). CONCLUSION: The pediatric pilot examination was useful for differentiating passing candidates from failing candidates when the score in the pediatric radiology category of the oral examination was used as the reference standard. The overall accuracy was 92.8%.

Rescue therapy in adult and pediatric patients with pH1N1 influenza infection: a tertiary center intensive care unit experience from April to October 2009.

OBJECTIVE: Severe respiratory failure is a well-recognized complication of pH1N1 influenza infection. Limited data regarding the efficacy of rescue therapies, including high-frequency oscillatory ventilation and extracorporeal membrane oxygenation, have been previously reported in the setting of pH1N1 influenza infection in the United States. DESIGN: Retrospective, single-center cohort study. SETTING: Pediatric, cardiac, surgical, and medical intensive care units in a single tertiary care center in the United States. PATIENTS: One hundred twenty-seven consecutive patients with confirmed influenza A infection requiring hospitalization between April 1, 2009, and October 31, 2009. INTERVENTIONS: Electronic medical records were reviewed for demographic and clinical data. MEASUREMENTS AND MAIN RESULTS: The number of intensive care unit admissions appears inversely related to age with 39% of these admissions <20 yrs of age. Median duration of intensive care unit care was 10.0 days (4.0-24.0), and median duration of mechanical ventilation was 8.0 days (0.0-23.5). Rescue therapy (high-frequency oscillatory ventilation or extracorporeal membrane oxygenation) was used in 36% (12 of 33) of intensive care unit patients. The severity of respiratory impairment was determined by Pao²/Fio² ratio and oxygenation index. High-frequency oscillatory ventilation at 24 hrs resulted in improvements in median Pao²/Fio² ratio (71 [58-93] vs. 145 [126-185]; p < .001), oxygenation index (27 [20-30] vs. 18 [12-25]; p = .016), and Fio2 (100 [70-100] vs. 45 [40-55]; p < .001). Extracorporeal membrane oxygenation resulted in anticipated improvement in parameters of oxygenation at both 2 hrs and 24 hrs after initiation of therapy. Despite the severity of oxygenation impairment, overall survival for both rescue therapies was 75% (nine of 12), 80% (four of five) for high-frequency oscillatory ventilation alone, and 71% (five of seven) for high-frequency oscillatory ventilation + extracorporeal membrane oxygenation. CONCLUSION: In critically ill adult and pediatric patients with pH1N1 infection and severe lung injury, the use of high-frequency oscillatory ventilation and extracorporeal membrane oxygenation can result in significant improvements in Pao²/Fio² ratio, oxygenation index, and Fio². However, the impact on mortality is less certain.

Synchronous occurrence of metastatic Wilms tumor and ganglioneuroma.

We describe a 4-year-old female patient with a persistent paraspinal mass following chemotherapy for Wilms tumor. A discordant response to chemotherapy prompted biopsy of the persistent mass, which revealed a ganglioneuroma. This report highlights the synchronous occurrence of different tumors in the same patient, and suggests that repeat biopsies should be considered when contiguous tumor masses do not respond as expected.

Reversible cardiac dysfunction associated with pandemic 2009 influenza A(H1N1).

Historical influenza A epidemics have carried elevated rates of cardiovascular disease, including transient cardiac dysfunction. Whether such an association holds for the novel influenza A strain, pandemic 2009 influenza A(H1N1) [A(H1N1)], remains unknown. We report an index case of transient cardiac dysfunction associated with A(H1N1) infection. Next, we reviewed 123 sequential cases of patients hospitalized with pandemic A(H1N1) at a single academic medical center in the United States from April 1, 2009, through October 31, 2009. We identified that 4.9% (6/123) of patients had either new or worsened left ventricular dysfunction. These cases ranged in age from 23 to 51 years, and all had preexisting medical conditions. ICU level care was required in 83% (5/6) of the cases. Sixty-seven percent (4/6) of the cases had follow-up echocardiograms, and left ventricular function improved in all four. We conclude that potentially reversible cardiac dysfunction is a relatively common complication associated with hospitalized pandemic A(H1N1) influenza.

Hereditary spherocytosis and partial splenectomy in children: review of surgical technique and the role of imaging.

The risks associated with total splenectomy, including overwhelming postsplenectomy infection, have led to an interest in the use of partial splenectomy as an alternative surgical option for children with congenital hemolytic anemias and hypersplenism. Partial splenectomy, a procedure designed to remove enough spleen to improve anemia and avoid complications of splenic sequestration while preserving splenic function, has shown promise in children. Radiologic imaging is essential for the preoperative evaluation and postoperative care for children undergoing partial splenectomy and offers a broad range of critical clinical information essential for care of these complex children. It is imperative for radiologists involved in the care of these children to be familiar with the surgical technique and imaging options for these procedures. This article reviews the surgical technique as well as the current status of various diagnostic imaging options used for children undergoing partial splenectomy, highlighting technical aspects and specific clinical information obtained by each modality.

Prospective double-blinded study of abdominal-pelvic computed tomography guided by the region of tenderness: estimation of detection of acute pathology and radiation exposure reduction.

STUDY OBJECTIVE: Computed tomography (CT) is increasingly used for emergency department (ED) patients with abdominal tenderness. CT-related radiation contributes to 2% of US cancers. We hypothesized that in the ED patient with nontraumatic abdominal tenderness, the tender region accurately delineates acute pathology. z axis-restricted CT guided by this region could detect pathology while reducing radiation dose. METHODS: This was a prospective double-blinded observational trial with informed consent and was institutional review board-approved and registered with ClinicalTrials.gov. A convenience sample of ED patients undergoing abdominal CT was recruited, excluding pregnant women, patients with altered mental status or abdominal sensation, preverbal children, and patients with abdominal trauma or surgery in the previous month. Before standard CT, physicians demarcated the tender region with labels invisible to radiologists on abdominal windows. Radiologists blinded to the tender region recorded cephalad-caudad limits of pathology on CT. Personnel blinded to pathology location recorded label positions on lung windows. Two hypothetical CT strategies were then explored: CT restricted to the tender region and CT from the cephalad skin marker to the lower caudad limit of the usual CT. The percentage of the pathologic region contained within the extent of the 2 hypothetical z axis restricted CTs was calculated. z axis reduction, which is linearly related to radiation reduction, from the restricted CTs was determined. RESULTS: One hundred two subjects were enrolled, 93 with complete data for analysis. Fifty-one subjects had acute pathology on CT. CT limited to the tender region would reduce z axis (radiation exposure) by 69% (95% confidence interval [CI] 60% to 78%). All acute pathology was included within these boundaries in 17 of the 51 abnormal cases (33%; 95% CI 22% to 47%). CT from the cephalad marker through the caudad abdomen and pelvis would reduce z axis (radiation exposure) by 38% (95% CI 29% to 48%). All acute pathology was included within these boundaries in 36 of 51 abnormal cases (71%; 95% CI 57% to 81%). With both strategies 1 and 2, the pathologic region was at least partially included within the CT region in the majority of cases (84% and 92%, respectively). CONCLUSION: CT with z axis restriction based on abdominal tenderness could reduce radiation exposure but with a potentially unacceptably high rate of misdiagnosis, using our current methods. Further prospective study may be warranted to determine the diagnostic utility of partially visualized pathology.

Radiographic predictors of disease severity in neonates and infants with necrotizing enterocolitis.

OBJECTIVE: The objective of our study was to validate a radiographic scale, the Duke abdominal assessment scale (DAAS), as a tool for predicting the severity of disease in neonates and infants with suspected necrotizing enterocolitis (NEC). MATERIALS AND METHODS: Study group patients (n = 43) underwent at least two two-view abdominal radiographic series within 48 hours of surgical intervention for suspected NEC complications. Control group patients (n = 86) were patients with suspected NEC who did not undergo surgery for suspected NEC complications. DAAS scores were assigned by two pediatric radiologists with 20 and 6 years' experience. RESULTS: The initial radiographs of 26 of 43 (60.5%) patients in the study group showed fixed bowel loops (10/43, 23.3%), highly probable or definite pneumatosis (9/43, 20.9%), or portal venous gas (7/43, 16.3%). These findings had progressed to pneumoperitoneum on the follow-up series in 20 (46.5%) study group patients. Among the control group, three patients (3.5%) had highly probable or definite pneumatosis, and none had fixed bowel loops, portal venous gas, or pneumoperitoneum. Patients with higher DAAS scores were more likely to undergo surgical intervention than patients with lower scores (odds ratio, 1.69; 95% CI, 1.40-2.03). A receiver operating characteristic curve analysis showed good overall performance (c statistic = 0.83) for predicting eventual surgical intervention in the study group with higher DAAS scores. CONCLUSION: The DAAS provides a standardized 10-point radiographic scale that increases with disease severity when using need for surgical intervention as a surrogate for severe NEC. For every 1-point increase in the DAAS score, patients were statistically significantly more likely to have severe disease as measured by need for surgical intervention.

Pediatric MDCT: towards assessing the diagnostic influence of dose reduction on the detection of small lung nodules.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the effect of reduced tube current (dose) on lung nodule detection in pediatric multidetector array computed tomography (MDCT). MATERIALS AND METHODS: The study included normal clinical chest MDCT images of 13 patients (aged 1-7 years) scanned at tube currents of 70 to 180 mA. Calibrated noise addition software was used to simulate cases as they would have been acquired at 70 mA (the lowest original tube current), 35 mA (50% reduction), and 17.5 mA (75% reduction). Using a validated nodule simulation technique, small lung nodules of 3 to 5 mm in diameter were inserted into the cases, which were then randomized and rated independently by three experienced pediatric radiologists for nodule presence on a continuous scale ranging from zero (definitely absent) to 100 (definitely present). The observer data were analyzed to assess the influence of dose on detection accuracy using the Dorfman-Berbaum-Mets method for multiobserver, multitreatment receiver-operating characteristic (ROC) analysis and the Williams trend test. RESULTS: The areas under the ROC curves were 0.95, 0.91, and 0.92 at 70, 35, and 17.5 mA, respectively, with standard errors of 0.02 and interobserver variability of 0.02. The Dorfman-Berbaum-Mets method and the Williams trend test yielded P values for the effect of dose of .09 and .05, respectively. CONCLUSION: Tube current (dose) has a weak effect on the detection accuracy of small lung nodules in pediatric MDCT. The effect on detection accuracy of a 75% dose reduction was comparable to interobserver variability, suggesting a potential for dose reduction.

Pediatric hematopoietic stem cell transplantation and the role of imaging.

The use of hematopoietic stem cell transplantation (HSCT) in the treatment of children afflicted with many potentially fatal malignant and nonmalignant diseases is well recognized. Although outcomes continue to improve and the utility of HSCT is increasing, HSCT remains a complicated process necessitating support from many medical disciplines, including radiology. Importantly, children who undergo HSCT are at risk for the development of specific complications that are linked to the timeline of transplantation, as well as to the relationship between the underlying diagnoses, severe immune deficiency, cytoreductive regimen, and graft-versus-host reactions. An understanding of the complex interplay of the immune status, therapeutic regimen, and disease allows increased diagnostic accuracy. Successful treatment of these high-risk children requires that radiologists who are involved with their care be familiar with broad concepts, as well as with specific problems that frequently occur following HSCT. In this article, the clinical aspects of pediatric HSCT are summarized, including common complications, and imaging features of these complications are described.

Radiologists' agreement when using a 10-point scale to report abdominal radiographic findings of necrotizing enterocolitis in neonates and infants.

OBJECTIVE: The purpose of this study was to evaluate radiologists' agreement when using a 10-point scale of abnormal findings designed to standardize reporting of abdominal radiographs in neonates or infants with suspected necrotizing enterocolitis. MATERIALS AND METHODS: A 10-point scale of radiographic findings was devised at our institution and was in use for approximately 18 months before the initiation of this study. After institutional review board approval, 88 abdominal radiographs (anteroposterior and cross-table lateral) were randomly selected for review, allowing for an equal distribution of examinations throughout the scale according to the original examination report. The mean age of the patients in the total study population was 24.9 days (range, 0-56 days); 61 patients (47.3%) were girls and 68 (52.7%) were boys. Four pediatric radiologists having 20, 13, 7, and 5 years of experience scored images twice at least 4 weeks apart according to the scale, which was designed to characterize certainty and severity of disease in neonates and infants with possible necrotizing enterocolitis. Interobserver and intraobserver agreement was assessed by applying weighted kappa statistics. Operative and pathology reports were reviewed. RESULTS: The average intraobserver weighted kappa value was 0.792 (SD, 0.025; range, 0.635-0.946). The average interobserver weighted kappa value was 0.665 (SD, 0.035, range, 0.574-0.898). CONCLUSION: Substantial intraobserver and interobserver agreement was found when radiologists used a 10-point scale to report abnormal findings on abdominal radiographs in neonates or infants with suspected necrotizing enterocolitis. This scale warrants further evaluation as a potentially useful clinical tool.

Pediatric cardiac-gated CT angiography: assessment of radiation dose.

OBJECTIVE: The purpose of our study was to determine a dose range for cardiac-gated CT angiography (CTA) in children. MATERIALS AND METHODS: ECG-gated cardiac CTA simulating scanning of the heart was performed on an anthropomorphic phantom of a 5-year-old child on a 16-MDCT scanner using variable parameters (small field of view; 16 x 0.625 mm configuration; 0.5-second gantry cycle time; 0.275 pitch; 120 kVp at 110, 220, and 330 mA; and 80 kVp at 385 mA). Metal oxide semiconductor field effect transistor (MOSFET) technology measured 20 organ doses. Effective dose calculated using the dose-length product (DLP) was compared with effective dose determined from measured absorbed organ doses. RESULTS: Highest organ doses included breast (3.5-12.6 cGy), lung (3.3-12.1 cGy), and bone marrow (1.7-7.6 cGy). The 80 kVp/385 mA examination produced lower radiation doses to all organs than the 120 kVp/220 mA examination. MOSFET effective doses (+/- SD) were as follows: 110 mA: 7.4 mSv (+/- 0.6 mSv), 220 mA: 17.2 mSv (+/- 0.3 mSv), 330 mA: 25.7 mSv (+/- 0.3 mSv), 80 kVp/385 mA: 10.6 mSv (+/- 0.2 mSv). DLP effective doses for diagnostic runs were as follows: 110 mA: 8.7 mSv, 220 mA: 19 mSv, 330 mA: 28 mSv, 80 kVp/385 mA: 12 mSv. DLP effective doses exceeded MOSFET effective doses by 9.7-17.2%. CONCLUSION: Radiation doses for a 5-year-old during cardiac-gated CTA vary greatly depending on parameters. Organ doses can be high; the effective dose may reach 28.4 mSv. Further work, including determination of size-appropriate mA and image quality, is important before routine use of this technique in children.

Thoracic disorders in the immunocompromised child.

Immunodeficiencies in children may be caused by primary immunodeficiency syndromes or can result from secondary disorders of immune regulation. Thoracic complications in immunocompromised children are frequent and may vary according to the type of the immunodeficiency. Imaging plays a pivotal role in detection and distinction of the variety of sequelae. It is important for the radiologist to understand both the spectrum of pediatric immune disorders, and the mechanisms underlying these disorders.

Computer-simulated radiation dose reduction for abdominal multidetector CT of pediatric patients.

OBJECTIVE: Limiting CT radiation dose is especially critical when imaging children. The purpose of our study was to modify and test an accurate and safe tool for evaluating systematic dose reduction for abdominal multidetector CT (MDCT) in pediatric patients. MATERIALS AND METHODS: After validating the computer-simulation technique with a water phantom, we subjected the original digital scanning data for 26 contrast-enhanced abdominal MDCT scans (120 mA) obtained in infants and children (age range, 1 month-9 years; mean age, 3.1 years) to simulated tube current reduction (100, 80, 60, and 40 mA) by adding noise. this procedure created four additional examinations per child that were identical to the originals except for image noise. The 130 examinations were scored randomly, independently, and without prior knowledge of the children's diagnoses by three radiologists for depiction of high-visibility structures, such as adrenal glands and fat in the intrahepatic falciform ligament, and low-visibility structures, such as the extrahepatic hepatic artery, small intrahepatic vessels, and common bile duct. Aligned rank and Wilcoxon's signed rank tests were used for statistical analyses. RESULTS: Simulated tube current reduction significantly affected the detection of low-visibility structures (p < 0.001). Reduced detection in low-visibility structures was evident at a level less than or equal to 80 mA. No loss of detection in high-visibility structures was found at any tube current level (p > 0.5). CONCLUSION: The results of this computer simulation suggest that accurate abdominal MDCT can be performed in pediatric patients using substantially reduced radiation, depending on the indication for imaging. (In our case, the reduction was between 33% and 67%, depending on whether a high-visibility or low-visibility structure was being assessed.) This simulation technology can be applied to MDCT of other organ systems for systematic evaluation of radiation dose reduction.