Multivariate phenotype analysis enables genome-wide inference of mammalian gene function.

The function of the majority of genes in the human and mouse genomes is unknown. Investigating and illuminating this dark genome is a major challenge for the biomedical sciences. The International Mouse Phenotyping Consortium (IMPC) is addressing this through the generation and broad-based phenotyping of a knockout (KO) mouse line for every protein-coding gene, producing a multidimensional data set that underlies a genome-wide annotation map from genes to phenotypes. Here, we develop a multivariate (MV) statistical approach and apply it to IMPC data comprising 148 phenotypes measured across 4,548 KO lines. There are 4,256 (1.4% of 302,997 observed data measurements) hits called by the univariate (UV) model analysing each phenotype separately, compared to 31,843 (10.5%) hits in the observed data results of the MV model, corresponding to an estimated 7.5-fold increase in power of the MV model relative to the UV model. One key property of the data set is its 55.0% rate of missingness, resulting from quality control filters and incomplete measurement of some KO lines. This raises the question of whether it is possible to infer perturbations at phenotype-gene pairs at which data are not available, i.e., to infer some in vivo effects using statistical analysis rather than experimentation. We demonstrate that, even at missing phenotypes, the MV model can detect perturbations with power comparable to the single-phenotype analysis, thereby filling in the complete gene-phenotype map with good sensitivity. A factor analysis of the MV model's fitted covariance structure identifies 20 clusters of phenotypes, with each cluster tending to be perturbed collectively. These factors cumulatively explain 75% of the KO-induced variation in the data and facilitate biological interpretation of perturbations. We also demonstrate that the MV approach strengthens the correspondence between IMPC phenotypes and existing gene annotation databases. Analysis of a subset of KO lines measured in replicate across multiple laboratories confirms that the MV model increases power with high replicability.

Outcomes of Neonates Born with Symptomatic Tetralogy of Fallot and Absent Ductus Arteriosus.

OBJECTIVE: To test the hypothesis that neonates with symptomatic tetralogy of Fallot (TOF) and absent ductus arteriosus (ADA) have worse clinical outcomes compared with those with a ductus arteriosus (DA), and that this difference is driven by those born with ADA and with critically deficient pulmonary blood flow (CDPBF). STUDY DESIGN: We performed a retrospective, multicenter cohort study of neonates who underwent intervention for symptomatic TOF comparing death and reintervention between subjects with and without a DA identified on fetal echocardiogram or on echocardiogram performed in the first postnatal day. Exclusion criteria were as follows: inability to define DA status, collaterals supplying pulmonary blood flow, atrioventricular septal defect, and absent pulmonary valve. We defined CDPBF as undergoing a procedure to augment pulmonary blood flow on the date of birth or extracorporeal membrane oxygenation prior to such a procedure. RESULTS: The study cohort included 519 patients, among whom 11% had ADA. Patients with ADA were more likely to have a genetic syndrome and had smaller branch pulmonary artery size. In analyses adjusting for center, interventional treatment strategy, genetic syndrome, and minimum branch pulmonary artery size, ADA was associated with higher mortality risk (adjusted hazard ratio of 2.37 (95% CI: 1.07,5.27; P = .034). Seven patients had CDPBF (1.3% of the entire cohort and 12% of patients with ADA). CONCLUSIONS: A minority of symptomatic TOF neonates have ADA, which is associated with higher adjusted mortality risk compared with those with a DA. CDPBF appears to be a rare but important entity in this population.

Comparing Parent Perception of Neurodevelopment after Primary versus Staged Repair of Neonatal Symptomatic Tetralogy of Fallot.

OBJECTIVE: To assess the association between primary (PR) and staged repair (SR) of neonatal symptomatic tetralogy of Fallot (sTOF) and neurodevelopmental outcomes in preschool through school-age children. STUDY DESIGN: Multi-center cohort (n=9 sites) study of sTOF patients who underwent neonatal intervention between 2005 and 2017. The neurodevelopmental outcomes measures included caregivers' ratings of executive function with the Behavior Rating Inventory of Executive Function (BRIEF), and psychosocial functioning with the Behavior Assessment System for Children - 3rd Edition (BASC-3). Results were compared with normative data and by treatment strategy (PR versus SR). A parent survey assessed history of disabilities and access to services related to neurodevelopment. RESULTS: Although the majority of patients (median age 8.3 years, interquartile range 5.7-11.2) had median BRIEF and BASC-3 scores within the normal range, a proportion had clinically elevated (abnormal) scores, especially in the school-age patient subgroup (BRIEF 24-30% and BASC 20-37%). There were no statistically significant differences based on treatment strategy for either the BRIEF or BASC-3. However, lower birth weight, genetic syndrome, and medical complexity were significantly associated with worse executive function, and lower maternal education was associated in school age children with lower executive and psychosocial functioning. Ongoing disabilities were relatively common (learning disability 35%, speech delay 33%, developmental delay 31%), although up to 50% of children were not receiving educational or developmental services. CONCLUSION: Elevated executive and psychosocial concerns are present in the sTOF patient population. Although initial treatment strategy appears unrelated to neurodevelopmental outcomes, lower birth weight, genetic syndrome, and medical complexity, and lower maternal education are risk factors. Early recognition of neurodevelopmental concerns can facilitate access to appropriate neuro-developmental services in this high-risk group.

Assessing the Performance of Machine Learning Methods Trained on Public Health Observational Data: A Case Study From COVID-19.

From early in the coronavirus disease 2019 (COVID-19) pandemic, there was interest in using machine learning methods to predict COVID-19 infection status based on vocal audio signals, for example, cough recordings. However, early studies had limitations in terms of data collection and of how the performances of the proposed predictive models were assessed. This article describes how these limitations have been overcome in a study carried out by the Turing-RSS Health Data Laboratory and the UK Health Security Agency. As part of the study, the UK Health Security Agency collected a dataset of acoustic recordings, SARS-CoV-2 infection status and extensive study participant meta-data. This allowed us to rigorously assess state-of-the-art machine learning techniques to predict SARS-CoV-2 infection status based on vocal audio signals. The lessons learned from this project should inform future studies on statistical evaluation methods to assess the performance of machine learning techniques for public health tasks.

A framework for longitudinal latent factor modelling of treatment response in clinical trials with applications to Psoriatic Arthritis and Rheumatoid Arthritis.

OBJECTIVE: Clinical trials involve the collection of a wealth of data, comprising multiple diverse measurements performed at baseline and follow-up visits over the course of a trial. The most common primary analysis is restricted to a single, potentially composite endpoint at one time point. While such an analytical focus promotes simple and replicable conclusions, it does not necessarily fully capture the multi-faceted effects of a drug in a complex disease setting. Therefore, to complement existing approaches, we set out here to design a longitudinal multivariate analytical framework that accepts as input an entire clinical trial database, comprising all measurements, patients, and time points across multiple trials. METHODS: Our framework composes probabilistic principal component analysis with a longitudinal linear mixed effects model, thereby enabling clinical interpretation of multivariate results, while handling data missing at random, and incorporating covariates and covariance structure in a computationally efficient and principled way. RESULTS: We illustrate our approach by applying it to four phase III clinical trials of secukinumab in Psoriatic Arthritis (PsA) and Rheumatoid Arthritis (RA). We identify three clinically plausible latent factors that collectively explain 74.5% of empirical variation in the longitudinal patient database. We estimate longitudinal trajectories of these factors, thereby enabling joint characterisation of disease progression and drug effect. We perform benchmarking experiments demonstrating our method's competitive performance at estimating average treatment effects compared to existing statistical and machine learning methods, and showing that our modular approach leads to relatively computationally efficient model fitting. CONCLUSION: Our multivariate longitudinal framework has the potential to illuminate the properties of existing composite endpoint methods, and to enable the development of novel clinical endpoints that provide enhanced and complementary perspectives on treatment response.

Health-Related Quality of Life After Neonatal Treatment of Symptomatic Tetralogy of Fallot: Insights from the Congenital Cardiac Research Collaborative.

To evaluate the association between initial management strategy of neonatal symptomatic Tetralogy of Fallot (sTOF) and later health-related quality of life (HRQOL) outcomes. We performed a multicenter, cross-sectional evaluation of a previously assembled cohort of infants with sTOF who underwent initial intervention at ≤ 30 days of age, between 2005 and 2017. Eligible patients' parents/guardians completed an age-appropriate Pediatric Quality of Life Inventory, a Pediatric Quality of Life Inventory Cardiac Module Heart Disease Symptoms Scale, and a parental survey. The association between treatment strategy and HRQOL was evaluated, and the entire sTOF cohort was compared to published values for the healthy pediatric population and to children with complex congenital heart disease and other chronic illness. The study cohort included 143 sTOF subjects, of which 59 underwent a primary repair, and 84 had a staged repair approach. There was no association between initial management strategy and lower HRQOL. For the entire cohort, in general, individual domain scores decreased as age sequentially increased. Across domain measurements, mean scores for the sTOF cohort were significantly lower than the healthy pediatric population and comparable to those with other forms of complex CHD and other chronic health conditions. The presence of a genetic syndrome was significantly associated with a poor HRQOL (p = 0.003). Initial treatment strategy for sTOF was not associated with differences in late HRQOL outcomes, though the overall HRQOL in this sTOF cohort was significantly lower than the general population, and comparable to others with chronic illness.

Impact of Management Strategy on Feeding and Somatic Growth in Neonates with Symptomatic Tetralogy of Fallot: Results from the Congenital Cardiac Research Collaborative.

OBJECTIVE: To evaluate early growth following primary or staged repair of neonatal symptomatic tetralogy of Fallot (sTOF). STUDY DESIGN: We performed a retrospective, multicenter cohort study of consecutive infants with sTOF who underwent initial intervention at age ≤30 days, from 2005 to 2017. Management strategies were either primary repair or staged repair (ie, initial palliation followed by complete repair). The primary outcome was change in weight-for-age z-score (ΔWAZ) from the initial intervention to age 6 ± 2 months. Secondary outcomes included method and mode of feeding, feeding-related medications, and feeding-related readmissions. Propensity score adjustment was used to account for baseline differences between groups. A secondary analysis was performed comparing patients stratified by the presence of adequate growth (6-month ΔWAZ > -0.5) or inadequate growth (6-month ΔWAZ ≤ -0.5), independent of treatment strategy. RESULTS: The study cohort included 143 primary repair subjects and 240 staged repair subjects. Prematurity was more common in the staged repair group. After adjustment, median ΔWAZ did not differ between treatment groups over the first 6 months of life (primary: -0.43 [IQR, -1.17 to 0.50]; staged: -0.31 [IQR, -1.31 to 0.71]; P = .55). For the entire cohort, ΔWAZ was negative (-0.36; IQR, -1.21 to 0.63). There were no between-group differences in the secondary outcomes. Secondary analysis revealed that the subjects with adequate growth were more likely to be orally fed at initial hospital discharge (P = .04). CONCLUSIONS: In neonates with sTOF, growth trajectory over the first 6 months of life was substandard, irrespective of treatment strategy. Those patients with adequate growth were more likely to be discharged from the index procedure on oral feeds.

Interoperability of statistical models in pandemic preparedness: principles and reality.

We present interoperability as a guiding framework for statistical modelling to assist policy makers asking multiple questions using diverse datasets in the face of an evolving pandemic response. Interoperability provides an important set of principles for future pandemic preparedness, through the joint design and deployment of adaptable systems of statistical models for disease surveillance using probabilistic reasoning. We illustrate this through case studies for inferring and characterising spatial-temporal prevalence and reproduction numbers of SARS-CoV-2 infections in England.

Palliation Strategy to Achieve Complete Repair in Symptomatic Neonates with Tetralogy of Fallot.

Neonates with symptomatic tetralogy of Fallot (sTOF) may undergo palliations with varying physiology, namely systemic to pulmonary artery connections (SPC) or right ventricular outflow tract interventions (RVOTI). A comparison of palliative strategies based on the physiology created is lacking. Consecutive sTOF neonates undergoing SPC or RVOTI from 2005-2017 were reviewed from the Congenital Cardiac Research Collaborative. The primary outcome was survival with successful complete repair (CR) by 18 months. A variety of secondary outcomes were assessed including overall survival, hospitalization-related comorbidities, and interstage reinterventions. Propensity score adjustment was utilized to compare treatment strategies. The cohort included 252 SPC (surgical shunt = 226, ductus arteriosus stent = 26) and 68 RVOTI (balloon pulmonary valvuloplasty = 48, RVOT stent = 11, RVOT patch = 9) patients. Genetic syndrome (29 [42.6%] v 75 [29.8%], p = 0.04), weight < 2.5 kg (28 [41.2%] v 68 [27.0%], p = 0.023), bilateral pulmonary artery Z-score < - 2 (19 [28.0%] v 36 [14.3%], p = 0.008), and pre-intervention antegrade flow (48 [70.6%] v 104 [41.3%], p < 0.001) were more common in RVOTI. Significant center differences were noted (p < 0.001). Adjusted survival to CR by 18 months (HR = 0.87, 95% CI = 0.63-1.21, p = 0.41) and overall survival (HR = 2.08, 95% CI = 0.93-4.65, p = 0.074) were similar. RVOTI had increased interstage reintervention (HR = 2.15, 95% CI = 1.36-3.99, p = 0.001). Total anesthesia (243 [213, 277] v 328 [308, 351] minutes, p < 0.001) and cardiopulmonary bypass times (117 [103, 132] v 151 [143, 160] minutes, p < 0.001) favored RVOTI. In this multicenter comparison of physiologic palliation strategies for sTOF, survival to successful CR and overall survival were similar; however, reintervention burden was significantly higher in RVOTI.

Interpreting Quality Improvement When Introducing New Technology: A Collaborative Experience in ASD Device Closures.

The objective of this study was to evaluate the impact of the regular introduction of new technologies into interventional cardiac catheterization procedures, in this case new atrial septal defect (ASD) closure devices, while conducting a multi-center collaborative initiative to reduce radiation usage during all procedures. Data were collected prospectively by 8 C3PO institutions between January 1, 2014 and December 31, 2017 for ASD device closure procedures in the cardiac catheterization lab during a quality improvement (QI) initiative aimed at reducing patient radiation exposure. Radiation exposure was measured in dose area product per body weight (µGy*m2/kg). Use of proposed practice change strategies at the beginning and end of the QI intervention period was assessed. Radiation exposure was summarized by institution and by initial type of device used for closure. This study included 602 ASD device closures. Without changes in patient characteristics, total fluoroscopy duration, or number of digital acquisitions, median radiation exposure decreased from 37 DAP/kg to 14 DAP/kg from 2014 to 2017. While all individual centers decreased overall median DAP/kg, the use of novel devices for ASD closure correlated with a temporary period of worsening institutional radiation exposure and increased fluoroscopy time. The introduction of new ASD closure devices resulted in increased radiation exposure during a QI project designed to reduce radiation exposure. Therefore, outcome assessment must be contextualized in QI projects, hospital evaluation, and public reporting, to acknowledge the expected variation during innovation and introduction of novel therapies.

Impact of Treatment Strategy on Outcomes in Isolated Pulmonary Artery of Ductal Origin.

Isolated pulmonary artery (PA) of ductal origin (IPADO) is a rare cardiac defect which requires surgical repair, with or without preceding palliation. We sought to determine the impact of treatment strategy on outcomes. Retrospective study of consecutive patients with IPADO that underwent staged or primary repair from 1/05 to 9/16 at 6 Congenital Cardiac Research Collaborative centers. Patients with single ventricle physiology, major aortopulmonary collaterals, or bilateral IPADO were excluded. Primary outcome was isolated PA z-score at late follow-up. Secondary outcomes included PA symmetry index (isolated:confluent PA diameter) and reintervention burden. Propensity score adjustment was used to account for baseline differences. Of 60 patients in the study cohort, 26 (43%) underwent staged and 34 (57%) primary repair. The staged and primary repair groups differed in weight at diagnosis and presence of other heart disease but not in baseline PA dimensions. Staged patients underwent ductal stent (n = 16) or surgical shunt (n = 10) placement followed by repair at 210 vs. 21 days in the primary repair group (p < 0.001). At median follow-up of 4.5 years post-repair, after adjustment, isolated PA z-score (- 0.74 [- 1.75, - 0.26] vs. - 1.95 [- 2.91, - 1.59], p = 0.012) and PA symmetry index (0.81 [0.49, 1.0] vs. 0.55 [0.48, 0.69], p = 0.042) significantly favored the staged repair group. Freedom from PA reintervention was not different between groups (adjusted HR 0.78 [0.41, 1.48]; p = 0.445). A staged approach to repair of IPADO is associated with superior isolated PA size and symmetry at late follow-up. Consideration should be given to initial palliation in IPADO patients, when feasible.

Data quality methods through remote source data verification auditing: results from the Congenital Cardiac Research Collaborative.

BACKGROUND: Multicentre research databases can provide insights into healthcare processes to improve outcomes and make practice recommendations for novel approaches. Effective audits can establish a framework for reporting research efforts, ensuring accurate reporting, and spearheading quality improvement. Although a variety of data auditing models and standards exist, barriers to effective auditing including costs, regulatory requirements, travel, and design complexity must be considered. MATERIALS AND METHODS: The Congenital Cardiac Research Collaborative conducted a virtual data training initiative and remote source data verification audit on a retrospective multicentre dataset. CCRC investigators across nine institutions were trained to extract and enter data into a robust dataset on patients with tetralogy of Fallot who required neonatal intervention. Centres provided de-identified source files for a randomised 10% patient sample audit. Key auditing variables, discrepancy types, and severity levels were analysed across two study groups, primary repair and staged repair. RESULTS: Of the total 572 study patients, data from 58 patients (31 staged repairs and 27 primary repairs) were source data verified. Amongst the 1790 variables audited, 45 discrepancies were discovered, resulting in an overall accuracy rate of 97.5%. High accuracy rates were consistent across all CCRC institutions ranging from 94.6% to 99.4% and were reported for both minor (1.5%) and major discrepancies type classifications (1.1%). CONCLUSION: Findings indicate that implementing a virtual multicentre training initiative and remote source data verification audit can identify data quality concerns and produce a reliable, high-quality dataset. Remote auditing capacity is especially important during the current COVID-19 pandemic.

Use of carotid and axillary artery approach for stenting the patent ductus arteriosus in infants with ductal-dependent pulmonary blood flow: A multicenter study from the congenital catheterization research collaborative.

BACKGROUND: Carotid artery (CA) and axillary artery (AA) access are increasingly used for transcatheter stenting of the patent ductus arteriosus (PDA), although reports are limited. METHODS: The Congenital Catheterization Research Collaborative (CCRC) reviewed multicenter data from infants who underwent PDA stenting via the CA or AA approach from 2008 to 2017, and compared outcomes to those of infants undergoing PDA stenting via the femoral artery (FA) approach. Post-procedure ultrasound (US) imaging was reviewed. RESULTS: Forty-nine infants underwent PDA stenting from the CA (n = 43) or AA (n = 6) approach, compared with 55 infants who underwent PDA stenting from the FA approach. The PDA was the sole pulmonary blood flow (PBF) source in 61% of infants in the CA/AA cohort, compared with 33% of the FA cohort (p < .01). Ductal tortuosity for CA/AA cohort was Type I (straight) in 10 (20%), Type II (one turn) in 17 (35%), and Type III (multiple turns) in 22 (45%) infants and reflected a greater degree of tortuosity when compared to the FA cohort (p < .01). In 17 infants with CA/AA approach, the "flip technique" was used, and was associated with shorter procedure times for highly tortuous PDA (Type III) patients. Rates of procedural complications were similar across access sites. Most common complications were access site injury (thrombus or bleeding) and stent malposition. No complications were specifically related to the "flip technique." CONCLUSIONS: Use of CA and AA approach for PDA stenting was found to be more commonly employed in sole source PBF and highly tortuous PDAs. Procedural modifications such as the "flip technique" may lead to shorter procedure times. CA and AA approaches are associated with a similar burden of procedural or late complications. Post-procedural surveillance of the CA and AA is suggested, given the incidence of vascular findings on US.

Echocardiographic versus angiographic measurement of the aortic valve annulus in children undergoing balloon aortic valvuloplasty: method affects outcomes.

OBJECTIVE: Operators are mindful of the balloon-to-aortic annulus ratio when performing balloon aortic valvuloplasty. The method of measurement of the aortic valve annulus has not been standardised. METHODS AND RESULTS: Patients who underwent aortic valvuloplasty at two paediatric centres between 2007 and 2014 were included. The valve annulus measured by echocardiography and angiography was used to calculate the balloon-to-aortic annulus ratio and measurements were compared. The primary endpoint was an increase in aortic insufficiency by ≥2 degrees. Ninety-eight patients with a median age at valvuloplasty of 2.1 months (Interquartile range (IQR): 0.2-105.5) were included. The angiographic-based annulus was 8.2 mm (IQR: 6.8-16.0), which was greater than echocardiogram-based annulus of 7.5 mm (IQR: 6.1-14.8) (p < 0.001). This corresponded to a significantly lower angiographic balloon-to-aortic annulus ratio of 0.9 (IQR: 0.9-1.0), compared to an echocardiographic ratio of 1.1 (IQR: 1.0-1.1) (p < 0.001). The degree of discrepancy in measured diameter increased with smaller valve diameters (p = 0.041) and in neonates (p = 0.044). There was significant disagreement between angiographic and echocardiographic balloon-to-aortic annulus ratio measures regarding "High" ratio of >1.2, with angiographic ratio flagging only 2/12 (16.7%) of patients flagged by echocardiographic ratio as "High" (p = 0.012). Patients who had an increase in the degree of aortic insufficiency post valvuloplasty, only 3 (5.5%) had angiographic ratio > 1.1, while 21 (38%) had echocardiographic ratio >1.1 (p < 0.001). Patients with resultant ≥ moderate insufficiency more often had an echocardiographic ratio of >1.1 than angiographic ratio of >1.1 There was no association between increase in balloon-to-aortic annulus ratio and gradient reduction. CONCLUSIONS: Angiographic measurement is associated with a greater measured aortic valve annulus and the development of aortic insufficiency. Operators should use caution when relying solely on angiographic measurement when performing balloon aortic valvuloplasty.

Tumour-infiltrating CD8+ lymphocytes and colorectal cancer recurrence by tumour and nodal stage.

BACKGROUND: Intratumoural T-cell infiltrate intensity cortes wrelaith clinical outcome in stage II/III colorectal cancer (CRC). We aimed to determine whether this association varies across this heterogeneous group. METHODS: We performed a pooled analysis of 1804 CRCs from the QUASAR2 and VICTOR trials. Intratumoural CD8+ and CD3+ densities were quantified by immunohistochemistry in tissue microarray (TMA) cores, and their association with clinical outcome analysed by Cox regression. We validated our results using publicly available gene expression data in a pooled analysis of 1375 CRCs from seven independent series. RESULTS: In QUASAR2, intratumoural CD8+ was a stronger predictor of CRC recurrence than CD3+ and showed similar discriminative ability to both markers in combination. Pooled multivariable analysis of both trials showed increasing CD8+ density was associated with reduced recurrence risk independent of confounders including DNA mismatch repair deficiency, POLE mutation and chromosomal instability (multivariable hazard ratio [HR] for each two-fold increase = 0.92, 95%CI = 0.87-0.97, P = 3.6 × 10-3). This association was not uniform across risk strata defined by tumour and nodal stage: absent in low-risk (pT3,N0) cases (HR = 1.03, 95%CI = 0.87-1.21, P = 0.75), modest in intermediate-risk (pT4,N0 or pT1-3,N1-2) cases (HR = 0.92, 95%CI = 0.86-1.0, P = 0.046) and strong in high-risk (pT4,N1-2) cases (HR = 0.87, 95%CI = 0.79-0.97, P = 9.4 × 10-3); PINTERACTION = 0.090. Analysis of tumour CD8A expression in the independent validation cohort revealed similar variation in prognostic value across risk strata (PINTERACTION = 0.048). CONCLUSIONS: The prognostic value of intratumoural CD8+ cell infiltration in stage II/III CRC varies across tumour and nodal risk strata.

Correction: Tumour-infiltrating CD8+ lymphocytes and colorectal cancer recurrence by tumour and nodal stage.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Variability in radiation dose and image quality: A comparison across fluoroscopy-system vendors, generations of equipment and institutions.

OBJECTIVES: To evaluate differences in radiation dose and image quality across institutions, fluoroscope vendors and generations of fluoroscopes for pediatric cardiac catheterization. BACKGROUND: Increased recognition of the potentially harmful effects of ionizing radiation has spurred technological advances in fluoroscopes, as well as increased focus on optimizing fluoroscope performance. There is currently little understanding of variability in the dose-image quality relationship across institutions, fluoroscope vendor and/or generation of equipment. METHODS: We evaluated latest generation fluoroscopes from Phillips, Siemens, GE, and Toshiba, and an older generation Phillips fluoroscope (release date 2003) at three different institutions. Radiation dose was measured using an anthropomorphic dose-assessment phantom with effective dose in mSv estimated from Monte Carlo simulations. Image quality phantom images were scored on a 12-point scale by three blinded reviewers. RESULTS: Fluoroscope effective doses ranged from 0.04 to 0.14 mSv/1,000 pulses for fluoroscopy with associated composite image quality scores ranging from 8.0 ± 0.6 to 10.4 ± 1.3. For cineangiography, effective doses ranged from 0.17 to 0.57 mSv/1,000 frames with image quality scores ranging from 10.1 ± 0.3 to 11.1 ± 0.3. There was modest correlation between effective dose and image quality (r = 0.67, P = 0.006). The older generation fluoroscope delivered consistently higher doses than the newer generation systems (2.3- to 3.5-fold higher for fluoroscopy; 1.1- to 3.4-fold higher for cineangiography) without appreciable differences in image quality. CONCLUSION: Technological advances have markedly improved fluoroscope performance. Comparing latest generation systems across vendors and institutions, we found variability in the dose-IQ relationship and speculate that this reflects both equipment and institutional optimization practices.

Percutaneous Removal of Intravascular Pellet Following Penetrating Cardiac Trauma.

There is controversy regarding the management of projectile embolization, a rare complication of penetrating trauma. We present the case of a 5-year-old, 20 kg male with retrograde venous projectile embolization following traumatic injury with a pellet gun. The projectile was successfully removed utilizing a novel, percutaneous approach.

Abstract 12670: Variability in Radiation Dose and Image Quality: A Comparison Across Fluoroscopy-system Vendors and Generations of Equipment.

INTRODUCTION: Increased recognition of the potentially harmful effects of ionizing radiation has spurred technological advances to reduce exposure during fluoroscopy. However there is currently little understanding of the dose-image quality (IQ) relationship between fluoroscopy vendors and across generations of equipment used for imaging during pediatric catheterization. METHODS: We evaluated latest generation fluoroscopy systems from Phillips, Siemens, GE and Toshiba, and an older generation Phillips system (2004 release). Fluoroscopy and cineangiography were performed on a tissue simulation anthropomorphic phantom using a standardized imaging approach. Phantom surface exposures were used for Monte Carlo simulations to calculate radiation effective dose, accounting for differences in beam parameters. We also imaged a fluoroscopy IQ phantom to assess contrast-detail and line-per-inch visualization. IQ images were scored by 3 blinded reviewers with scores averaged to produce a composite rating (scale 0-18). To assess the impact of imaging approach we then simulated a neonatal cardiac catheterization incorporating "typical" imaging protocols provided by institutions using the various systems. RESULTS: Effective doses and IQ scores are summarized in the table. Effective doses varied by >400% with the older generation system consistently delivering markedly higher doses. The associated figure summarizes dose and IQ for a simulated neonatal cardiac catheterization which accounts for measured doses as well as the reported institutional imaging parameters summarized in the figure legend. CONCLUSION: These data demonstrate substantial technological improvements in fluoroscopy equipment and may be useful to justify institutional "upgrades". Comparing latest generation systems across vendors and institutions, we found variability in the dose-IQ relationship that reflects both equipment and imaging approach.