A novel biallelic loss-of-function variant in DAND5 causes heterotaxy syndrome.

The majority of heterotaxy cases do not obtain a molecular diagnosis, although pathogenic variants in more than 50 genes are known to cause heterotaxy. A heterozygous missense variant in DAND5, a nodal inhibitor, which functions in early development for establishment of right-left patterning, has been implicated in heterotaxy. Recently, the first case was reported of a DAND5 biallelic loss-of-function (LoF) variant in an individual with heterotaxy. Here, we describe a second unrelated individual with heterotaxy syndrome and a homozygous frameshift variant in DAND5 (NM_152654.2:c.197del [p.Leu66ArgfsTer22]). Using an in vitro assay, we demonstrate that the DAND5 c.197del variant is unable to inhibit nodal signaling when compared with the wild-type expression construct. This work strengthens the genetic and functional evidence for biallelic LoF variants in DAND5 causing an autosomal recessive heterotaxy syndrome.

A clinically relevant model of acute respiratory distress syndrome in human-size swine.

Despite over 30 years of intensive research for targeted therapies, treatment of acute respiratory distress syndrome (ARDS) remains supportive in nature. With mortality upwards of 30%, a high-fidelity pre-clinical model of ARDS, on which to test novel therapeutics, is urgently needed. We used the Yorkshire breed of swine to induce a reproducible model of ARDS in human-sized swine to allow the study of new therapeutics, from both mechanistic and clinical standpoints. For this, animals were anesthetized, intubated and mechanically ventilated, and pH-standardized gastric contents were delivered bronchoscopically, followed by intravenous infusion of Escherichia coli-derived lipopolysaccharide. Once the ratio of arterial oxygen partial pressure (PaO2) to fractional inspired oxygen (FIO2) had decreased to <150, the animals received standard ARDS treatment for up to 48 h. All swine developed moderate to severe ARDS. Chest radiographs taken at regular intervals showed significantly worse lung edema after induction of ARDS. Quantitative scoring of lung injury demonstrated time-dependent increases in interstitial and alveolar edema, neutrophil infiltration, and mild to moderate alveolar membrane thickening. This pre-clinical model of ARDS in human-sized swine recapitulates the clinical, radiographic and histopathologic manifestations of ARDS, providing a tool to study therapies for this highly morbid lung disease.

Checkpoint Inhibitor Immune-Related Adverse Events: A Multimodality Pictorial Review.

Cancer immunotherapies are drugs that modulate the body's own immune system as an anticancer strategy. Checkpoint inhibitor immunotherapies interfere with cell surface binding proteins that function to promote self-recognition and tolerance, ultimately leading to upregulation of the immune response. Given the striking success of these agents in early trials in melanoma and lung cancer, they have now been studied in many types of cancer and have become a pillar of anticancer therapy for many tumor types. However, abundant upregulation results in a new class of side effects, known as immune-related adverse events (IRAEs). It is critical for the practicing radiologist to be able to recognize these events to best contribute to care for patients on checkpoint inhibitor immunotherapy. Here, we provide a comprehensive system-based review of immune-related adverse events and associated imaging findings. Further, we detail the best imaging modalities for each as well as describe problem solving modalities. Given that IRAEs can be subclinical before becoming clinically apparent, radiologists may be the first provider to recognize them, providing an opportunity for early treatment. Awareness of IRAEs and how to best image them will prepare radiologists to make a meaningful contribution to patient care as part of the clinical team.

Extracardiac imaging findings in COVID-19-associated multisystem inflammatory syndrome in children.

BACKGROUND: Coronavirus disease 2019 (COVID-19)-associated multisystem inflammatory syndrome in children (MIS-C) is an emerging syndrome that presents with a Kawasaki-like disease and multiorgan damage in children previously exposed to COVID-19. OBJECTIVE: To review the extracardiac radiologic findings of MIS-C in a group of children and young adults with a confirmed diagnosis of MIS-C. MATERIALS AND METHODS: In a retrospective study from April 1, 2020, to July 31, 2020, we reviewed the imaging studies of 47 children and adolescents diagnosed with MIS-C, 25 females (53%) and 22 males (47%), with an average age of 8.4 years (range 1.3-20 years). Forty-five had chest radiographs, 8 had abdominal radiographs, 13 had abdominal US or MRI, 2 had neck US, and 4 had brain MRI. RESULTS: Thirty-seven of 45 (82%) patients with chest radiographs had findings, with pulmonary opacities being the most common finding (n=27, 60%), most often bilateral and diffuse, followed by peribronchial thickening (n=26, 58%). Eight patients had normal chest radiographs. On abdominal imaging, small-volume ascites was the most common finding (n=7, 54%). Other findings included right lower quadrant bowel wall thickening (n=3, 23%), gallbladder wall thickening (n=3, 23%), and cervical (n=2) or abdominal (n=2) lymphadenopathy. Of the four patients with brain MRI, one had bilateral parieto-occipital abnormalities and another papilledema. CONCLUSION: The diagnosis of MIS-C and its distinction from other pathologies should be primarily based on clinical presentation and laboratory evidence of inflammation because imaging findings are nonspecific. However, it should be considered in the setting of bilateral diffuse pulmonary opacities, peribronchial thickening, right lower quadrant bowel inflammation or unexplained ascites in a child presenting with Kawasaki-like symptoms and a history of COVID-19 infection or recent COVID-19 exposure.

Evaluation of Ventricle Size Measurements in Infants by Pediatric Emergency Medicine Physicians.

OBJECTIVES: The identification of hydrocephalus in infants by pediatric emergency medicine (PEM) physicians using cranial point-of-care ultrasound (POCUS) has not been evaluated. We aimed to conduct a pilot/proof-of-concept study to evaluate whether PEM physicians can identify hydrocephalus (anterior horn width >5 mm) in 15 infants (mean 69 ± 42 days old) from the neonatal intensive care unit using POCUS. Our exploratory aims were to determine the test characteristics of cranial POCUS performed by PEM physicians for diagnosing hydrocephalus and the interrater reliability between measurements made by the PEM physicians and the radiologist. METHODS: Depending on the availability, 1 or 2 PEM physicians performed a cranial POCUS through the open anterior fontanel for each infant after a 30-minute didactic lecture to determine the size of the left and right ventricles by measuring the anterior horn width at the foramen of Monroe in coronal view. Within 1 week, an ultrasound (US) technologist performed a cranial US and a radiologist determined the ventricle sizes from the US images; these measurements were the criterion standard. RESULTS: A radiologist determined 12 of the 30 ventricles as hydrocephalic. The sensitivity and specificity of the PEM physicians performed cranial POCUS was 66.7% (95% confidence interval [CI], 34.9%-90.1%) and 94.4% (95% CI, 72.7%-99.9%), whereas the positive and negative predictive values were 88.9% (95% CI, 53.3%-98.2%) and 81.0% (95% CI, 65.5%-90.5%), respectively. The interrater reliability between the PEM physician's and radiologist's measurements was r = 0.91. The entire POCUS examinations performed by the PEM physicians took an average of 1.5 minutes. The time between the cranial POCUS and the radiology US was, on average, 4 days. CONCLUSIONS: While the PEM physicians in our study were able to determine the absence of hydrocephalus in infants with high specificity using cranial POCUS, there was insufficient evidence to support the use of this modality for identifying hydrocephalus. Future studies with more participants are warranted to accurately determine test characteristics.

Rethinking Greulich and Pyle: A Deep Learning Approach to Pediatric Bone Age Assessment Using Pediatric Trauma Hand Radiographs.

PURPOSE: To develop a deep learning approach to bone age assessment based on a training set of developmentally normal pediatric hand radiographs and to compare this approach with automated and manual bone age assessment methods based on Greulich and Pyle (GP). METHODS: In this retrospective study, a convolutional neural network (trauma hand radiograph-trained deep learning bone age assessment method [TDL-BAAM]) was trained on 15 129 frontal view pediatric trauma hand radiographs obtained between December 14, 2009, and May 31, 2017, from Children's Hospital of New York, to predict chronological age. A total of 214 trauma hand radiographs from Hasbro Children's Hospital were used as an independent test set. The test set was rated by the TDL-BAAM model as well as a GP-based deep learning model (GPDL-BAAM) and two pediatric radiologists (radiologists 1 and 2) using the GP method. All ratings were compared with chronological age using mean absolute error (MAE), and standard concordance analyses were performed. RESULTS: The MAE of the TDL-BAAM model was 11.1 months, compared with 12.9 months for GPDL-BAAM (P = .0005), 14.6 months for radiologist 1 (P < .0001), and 16.0 for radiologist 2 (P < .0001). For TDL-BAAM, 95.3% of predictions were within 24 months of chronological age compared with 91.6% for GPDL-BAAM (P = .096), 86.0% for radiologist 1 (P < .0001), and 84.6% for radiologist 2 (P < .0001). Concordance was high between all methods and chronological age (intraclass coefficient > 0.93). Deep learning models demonstrated a systematic bias with a tendency to overpredict age for younger children versus radiologists who showed a consistent mean bias. CONCLUSION: A deep learning model trained on pediatric trauma hand radiographs is on par with automated and manual GP-based methods for bone age assessment and provides a foundation for developing population-specific deep learning algorithms for bone age assessment in modern pediatric populations.Supplemental material is available for this article.© RSNA, 2020See also the commentary by Halabi in this issue.

Stressors contributing to burnout amongst pediatric radiologists: results from a survey of the Society for Pediatric Radiology.

BACKGROUND: A recent study showed a high prevalence of burnout in pediatric radiology. OBJECTIVE: The purpose of this study is to evaluate potential stressors contributing to burnout in pediatric radiology. MATERIALS AND METHODS: Society for Pediatric Radiology members received an invitation for an anonymous survey evaluating stressors contributing to burnout. Stressors evaluated included call burden, financial stress, work-life balance, health care evolution and job market changes, and radiology as a career choice. Additional questions regarding demographics were obtained. RESULTS: The response rate was 460/1,453 (32%). The prevalence of emotional exhaustion was 66% (286/435), depersonalization was 61% (265/433) and perceived lack of personal accomplishment was 15% (67/436). In a backward selective logistic regression model, work-life imbalance and call burden were the only significant factors predicting higher emotional exhaustion (P<0.001). Using a similar model, work-life imbalance, call burden and decreased rate of reimbursement were significantly associated with higher probability of depersonalization (P=0.033, 0.0002 and 0.015, respectively). Emotional exhaustion and depersonalization were significantly associated with higher odds of a radiologist's wish to work in another medical specialty (P=0.011 and 0.002, respectively). CONCLUSION: Key stressors contributing to burnout in pediatric radiology include work-life imbalance, pediatric call burden and a decreased rate of reimbursement. Burnout in pediatric radiology is a serious issue that needs to be addressed and prioritized on the individual and departmental/institutional levels and further investigated to develop effective interventions to mitigate it.

Is Intussusception a Middle-of-the-Night Emergency?

OBJECTIVES: Intussusception is the most common abdominal emergency in pediatric patients aged 6 months to 3 years. There is often a delay in diagnosis, as the presentation can be confused for viral gastroenteritis. Given this scenario, we questioned the practice of performing emergency reductions in children during the night when minimal support staff are available. Pneumatic reduction is not a benign procedure, with the most significant risk being bowel perforation. We performed this analysis to determine whether it would be safe to delay reduction in these patients until normal working hours when more support staff are available. METHODS: We performed a retrospective review of intussusceptions occurring between January 2010 and May 2015 at 2 tertiary care institutions. The medical record for each patient was evaluated for age at presentation, sex, time of presentation to clinician or the emergency department, and time to reduction. The outcomes of attempted reduction were documented, as well as time to surgery and surgical findings in applicable cases. A Wilcoxon rank test was used to compare the median time with nonsurgical intervention among those who did not undergo surgery to the median time to nonsurgical intervention among those who ultimately underwent surgery for reduction. Multivariable logistic regression was used to test the association between surgical intervention and time to nonsurgical reduction, adjusting for the age of patients. RESULTS: The median time to nonsurgical intervention was higher among patients who ultimately underwent surgery than among those who did not require surgery (17.9 vs 7.0 hours; P < 0.0001). The time to nonsurgical intervention was positively associated with a higher probability of surgical intervention (P = 0.002). CONCLUSIONS: Intussusception should continue to be considered an emergency, with nonsurgical reduction attempted promptly as standard of care.

MABAL: a Novel Deep-Learning Architecture for Machine-Assisted Bone Age Labeling.

Bone age assessment (BAA) is a commonly performed diagnostic study in pediatric radiology to assess skeletal maturity. The most commonly utilized method for assessment of BAA is the Greulich and Pyle method (Pediatr Radiol 46.9:1269-1274, 2016; Arch Dis Child 81.2:172-173, 1999) atlas. The evaluation of BAA can be a tedious and time-consuming process for the radiologist. As such, several computer-assisted detection/diagnosis (CAD) methods have been proposed for automation of BAA. Classical CAD tools have traditionally relied on hard-coded algorithmic features for BAA which suffer from a variety of drawbacks. Recently, the advent and proliferation of convolutional neural networks (CNNs) has shown promise in a variety of medical imaging applications. There have been at least two published applications of using deep learning for evaluation of bone age (Med Image Anal 36:41-51, 2017; JDI 1-5, 2017). However, current implementations are limited by a combination of both architecture design and relatively small datasets. The purpose of this study is to demonstrate the benefits of a customized neural network algorithm carefully calibrated to the evaluation of bone age utilizing a relatively large institutional dataset. In doing so, this study will aim to show that advanced architectures can be successfully trained from scratch in the medical imaging domain and can generate results that outperform any existing proposed algorithm. The training data consisted of 10,289 images of different skeletal age examinations, 8909 from the hospital Picture Archiving and Communication System at our institution and 1383 from the public Digital Hand Atlas Database. The data was separated into four cohorts, one each for male and female children above the age of 8, and one each for male and female children below the age of 10. The testing set consisted of 20 radiographs of each 1-year-age cohort from 0 to 1 years to 14-15+ years, half male and half female. The testing set included left-hand radiographs done for bone age assessment, trauma evaluation without significant findings, and skeletal surveys. A 14 hidden layer-customized neural network was designed for this study. The network included several state of the art techniques including residual-style connections, inception layers, and spatial transformer layers. Data augmentation was applied to the network inputs to prevent overfitting. A linear regression output was utilized. Mean square error was used as the network loss function and mean absolute error (MAE) was utilized as the primary performance metric. MAE accuracies on the validation and test sets for young females were 0.654 and 0.561 respectively. For older females, validation and test accuracies were 0.662 and 0.497 respectively. For young males, validation and test accuracies were 0.649 and 0.585 respectively. Finally, for older males, validation and test set accuracies were 0.581 and 0.501 respectively. The female cohorts were trained for 900 epochs each and the male cohorts were trained for 600 epochs. An eightfold cross-validation set was employed for hyperparameter tuning. Test error was obtained after training on a full data set with the selected hyperparameters. Using our proposed customized neural network architecture on our large available data, we achieved an aggregate validation and test set mean absolute errors of 0.637 and 0.536 respectively. To date, this is the best published performance on utilizing deep learning for bone age assessment. Our results support our initial hypothesis that customized, purpose-built neural networks provide improved performance over networks derived from pre-trained imaging data sets. We build on that initial work by showing that the addition of state-of-the-art techniques such as residual connections and inception architecture further improves prediction accuracy. This is important because the current assumption for use of residual and/or inception architectures is that a large pre-trained network is required for successful implementation given the relatively small datasets in medical imaging. Instead we show that a small, customized architecture incorporating advanced CNN strategies can indeed be trained from scratch, yielding significant improvements in algorithm accuracy. It should be noted that for all four cohorts, testing error outperformed validation error. One reason for this is that our ground truth for our test set was obtained by averaging two pediatric radiologist reads compared to our training data for which only a single read was used. This suggests that despite relatively noisy training data, the algorithm could successfully model the variation between observers and generate estimates that are close to the expected ground truth.

Estimating Effective Dose of Radiation From Pediatric Cardiac CT Angiography Using a 64-MDCT Scanner: New Conversion Factors Relating Dose-Length Product to Effective Dose.

OBJECTIVE: The purpose of this study is to determine the conversion factors that enable accurate estimation of the effective dose (ED) used for cardiac 64-MDCT angiography performed for children. MATERIALS AND METHODS: Anthropomorphic phantoms representative of 1- and 10-year-old children, with 50 metal oxide semiconductor field-effect transistor dosimeters placed in organs, underwent scanning performed using a 64-MDCT scanner with different routine clinical cardiac scan modes and x-ray tube potentials. Organ doses were used to calculate the ED on the basis of weighting factors published in 1991 in International Commission on Radiological Protection (ICRP) publication 60 and in 2007 in ICRP publication 103. The EDs and the scanner-reported dose-length products were used to determine conversion factors for each scan mode. The effect of infant heart rate on the ED and the conversion factors was also assessed. RESULTS: The mean conversion factors calculated using the current definition of ED that appeared in ICRP publication 103 were as follows: 0.099 mSv · mGy-1 · cm-1, for the 1-year-old phantom, and 0.049 mSv · mGy-1 · cm-1, for the 10-year-old phantom. These conversion factors were a mean of 37% higher than the corresponding conversion factors calculated using the older definition of ED that appeared in ICRP publication 60. Varying the heart rate did not influence the ED or the conversion factors. CONCLUSION: Conversion factors determined using the definition of ED in ICRP publication 103 and cardiac, rather than chest, scan coverage suggest that the radiation doses that children receive from cardiac CT performed using a contemporary 64-MDCT scanner are higher than the radiation doses previously reported when older chest conversion factors were used. Additional up-to-date pediatric cardiac CT conversion factors are required for use with other contemporary CT scanners and patients of different age ranges.

Feed and Wrap MRI Technique in Infants.

The feed and wrap technique refers to the use of feeding and swaddling to induce natural sleep in infants. It can be used prior to an magnetic resonance imaging (MRI) scan, avoiding sedation or anesthesia. We performed a retrospective review of feed and wrap MRI scans in infants 3 months or younger over a 2-year period at our center (279 scans) to evaluate the efficacy of this technique. Of scan results reviewed, 79% addressed the clinical question, 20% partially addressed the clinical question, and 1% were technically inadequate. History of preterm birth (odds ratio [OR] = 2.368; P = .032) and spine MRI (OR = 2.821; P = .001) were associated with a less-successful scan outcome. The feed and wrap technique can be used successfully in infants undergoing MRI; however, it may be less successful in preterm infants and those requiring spinal MRI. A standardized technique performed by experienced personnel may avoid anesthesia and sedation in infants who require MRI.

Interpretation difficulty of normal versus abnormal radiographs using a pediatric example.

BACKGROUND: Radiograph teaching files are usually dominated by abnormal cases, implying that normal radiographs are easier to interpret. Our main objective was to compare the interpretation difficulty of normal versus abnormal radiographs of a set of common pediatric radiographs. METHODS: We developed a 234-item digital case bank of pediatric ankle radiographs, recruited a convenience sample of participants, and presented the cases to each participant who then classified the cases as normal or abnormal. We determined and contrasted the interpretation difficulty of the normal and abnormal x-rays items using Rasch Measurement Theory. We also identified case features that were associated with item difficulty. RESULTS: 139 participants (86 medical students, 7 residents, 29 fellows, 5 emergency physicians, and 3 radiologists) rated a minimum of 50 cases each, which resulted in 16,535 total ratings. Abnormal cases were more difficult (+0.99 logits) than were normal ones (-0.58 logits), difference 1.57 logits (95% CI 1.2, 2.0), but there was considerable overlap in difficulty scores. Patient variables associated with a more difficult normal radiograph included younger patient age (ß = -0.16, 95% CI -0.22, -0.10), history of distal fibular tenderness (ß = 0.55, 95% CI 0.17, 0.93), and presence of a secondary ossification centre (ß = 0.84, 95% CI 0.27, 1.41). CONCLUSIONS: While abnormal images were more difficult to interpret, normal images did show a range of interpretation difficulties. Including a significant proportion of normal cases may be of benefit to learners.

Postoperative imaging findings in children with auxiliary partial orthotopic liver transplant (APOLT).

Auxiliary partial orthotopic liver transplant (APOLT) is a treatment technique for people who have acute hepatic failure secondary to fulminant hepatic failure and might ultimately recover normal liver function. This surgical procedure is complicated, involving the placement of a liver graft while maintaining viability of the remaining native portion of the liver. This method allows the native liver to recover hepatic function, therefore eliminating the need for long-term immunosuppression, as is typically needed in post-transplant settings. Postoperative imaging in these cases can be challenging given the complex anatomy, specifically the vascular anastomosis. Therefore it is important for radiologists and clinicians to be aware of the anatomy as well as the variable imaging appearances of the liver. We review the imaging findings in children who have undergone auxiliary partial orthotopic liver transplant (APOLT).

Value of gadolinium-enhanced MRI in detection of acute appendicitis in children and adolescents.

OBJECTIVE: The aim of this study was to determine both the value of gadolinium-enhanced MRI in children with suspected acute appendicitis and the best sequences for detecting acute appendicitis, to thereby decrease imaging time. MATERIALS AND METHODS: This was a retrospective review of pediatric patients with suspected appendicitis who had undergone MRI at our institution between 2010 and 2011 after an indeterminate ultrasound examination. MRI examinations included T1-weighted unenhanced and contrast-enhanced, T2-weighted, and balanced steady-state free precession (SSFP) sequences in axial and coronal planes. Sequences were reviewed together and individually by five radiologists who were blinded to the final diagnosis. Radiologists were asked to score their confidence of appendicitis diagnosis using a 5-point scale. The diagnostic performance of each MR sequence was obtained by comparing the mean area under the curve (AUC) using receiver operating characteristic (ROC) analysis. RESULTS: A total of 49 patients with clinically suspected appendicitis were included, of whom 16 received a diagnosis of appendicitis. The mean AUCs for reviewing all sequences together, contrast-enhanced sequences alone, T2-weighted sequences alone, and balanced SSFP alone were 0.984, 0.979, 0.944, and 0.910, respectively. No significant difference was observed between reviewing all sequences together versus contrast-enhanced sequences alone (p = 0.90) and T2-weighted sequences alone (p = 0.23). A significant difference was observed between contrast-enhanced sequences and balanced SSFP (p < 0.03). CONCLUSION: Gadolinium-enhanced images and T2-weighted images are most helpful in the assessment of acute appendicitis in the pediatric population. These findings have led to protocol modifications that have reduced imaging time.

Ultrasonography/MRI versus CT for diagnosing appendicitis.

BACKGROUND: Cross-sectional imaging increases accuracy in diagnosing appendicitis. We hypothesized that a radiation-free imaging pathway of ultrasonography selectively followed by MRI would not change clinical end points compared with computed tomography (CT) for diagnosis of acute appendicitis in children. METHODS: We retrospectively reviewed children (<18 years old) who had diagnostic imaging for suspected acute appendicitis between November 2008 and October 2012. Before November 2010 CT was used as the primary imaging modality (group A); subsequently, ultrasonography was the primary imaging modality followed by MRI for equivocal findings (group B). Data collected included time from triage to imaging and treatment and results of imaging and pathology. RESULTS: Six hundred sixty-two patients had imaging for suspected appendicitis (group A = 265; group B = 397, of which 136 [51%] and 161 [41%], respectively, had positive imaging for appendicitis). Negative appendectomy rate was 2.5% for group A and 1.4% for group B. Perforation rate was similar for both groups. Time from triage to antibiotic administration and operation did not differ between groups A and B. There was higher proportion of positive imaging and appendectomies in group A and thus more negative imaging tests in group B (ultrasonography and MRI), but diagnostic accuracy of the 2 imaging pathways was similar. CONCLUSIONS: In children with suspected acute appendicitis, a radiation-free diagnostic imaging of ultrasonography selectively followed by MRI is feasible and comparable to CT, with no difference in time to antibiotic administration, time to appendectomy, negative appendectomy rate, perforation rate, or length of stay.

Computed tomography with intravenous contrast alone: the role of intra-abdominal fat on the ability to visualize the normal appendix in children.

BACKGROUND: Computed tomography (CT) with enteric contrast is frequently used to evaluate children with suspected appendicitis. The use of CT with intravenous (IV) contrast alone (CT IV) may be sufficient, however, particularly in patients with adequate intra-abdominal fat (IAF). OBJECTIVES: The authors aimed 1) to determine the ability of radiologists to visualize the normal (nondiseased) appendix with CT IV in children and to assess whether IAF adequacy affects this ability and 2) to assess the association between IAF adequacy and patient characteristics. METHODS: This was a retrospective 16-center study using a preexisting database of abdominal CT scans. Children 3 to 18 years who had CT IV scan and measured weights and for whom appendectomy history was known from medical record review were included. The sample was chosen based on age to yield a sample with and without adequate IAF. Radiologists at each center reread their site's CT IV scans to assess appendix visualization and IAF adequacy. IAF was categorized as "adequate" if there was any amount of fat completely surrounding the cecum and "inadequate" if otherwise. RESULTS: A total of 280 patients were included, with mean age of 10.6 years (range = 3.1 to 17.9 years). All 280 had no history of prior appendectomy; therefore, each patient had a presumed normal appendix. A total of 102 patients (36.4%) had adequate IAF. The proportion of normal appendices visualized with CT IV was 72.9% (95% confidence interval [CI] = 67.2% to 78.0%); the proportions were 89% (95% CI = 81.5% to 94.5%) and 63% (95% CI = 56.0% to 70.6%) in those with and without adequate IAF (95% CI for difference of proportions = 16% to 36%). Greater weight and older age were strongly associated with IAF adequacy (p < 0.001), with weight appearing to be a stronger predictor, particularly in females. Although statistically associated, there was noted overlap in the weights and ages of those with and without adequate IAF. CONCLUSIONS: Protocols using CT with IV contrast alone to visualize the appendix can reasonably include weight, age, or both as considerations for determining when this approach is appropriate. However, although IAF will more frequently be adequate in older, heavier patients, highly accurate prediction of IAF adequacy appears challenging solely based on age and weight.