Associated radiation exposure from medical imaging and excess lifetime risk of developing cancer in pediatric patients with pulmonary hypertension

Pediatric patients with pulmonary hypertension (PH) receive imaging studies that use ionizing radiation (radiation) such as computed tomography (CT) and cardiac catheterization to guide clinical care. Radiation exposure is associated with increased cancer risk. It is unknown how much radiation pediatric PH patients receive. The objective of this study is to quantify radiation received from imaging and compute associated lifetime cancer risks for pediatric patients with PH. Electronic health records between 2012 and 2022 were reviewed and radiation dose data were extracted. Organ doses were estimated using Monte Carlo modeling. Cancer risks for each patient were calculated from accumulated exposures using National Cancer Institute tools. Two hundred and forty-nine patients with PH comprised the study cohort; 97% of patients had pulmonary arterial hypertension, PH due to left heart disease, or PH due to chronic lung disease. Mean age at the time of the first imaging study was 2.5 years (standard deviation [SD] = 4.9 years). Patients underwent a mean of 12 studies per patient per year, SD = 32. Most (90%) exams were done in children <5 years of age. Radiation from CT and cardiac catheterization accounted for 88% of the total radiation dose received. Cumulative mean effective dose was 19 mSv per patient (SD = 30). Radiation dose exposure resulted in a mean increased estimated lifetime cancer risk of 7.6% (90% uncertainty interval 3.0%-14.2%) in females and 2.8% (1.2%-5.3%) in males. Careful consideration for the need of radiation-based imaging studies is warranted, especially in the youngest of children.

Quantifying cancer risk from exposures to medical imaging in the Risk of Pediatric and Adolescent Cancer Associated with Medical Imaging (RIC) Study: research methods and cohort profile

PURPOSE

The Risk of Pediatric and Adolescent Cancer Associated with Medical Imaging (RIC) Study is quantifying the association between cumulative radiation exposure from fetal and/or childhood medical imaging and subsequent cancer risk. This manuscript describes the study cohorts and research methods.

METHODS

The RIC Study is a longitudinal study of children in two retrospective cohorts from 6 U.S. healthcare systems and from Ontario, Canada over the period 1995-2017. The fetal-exposure cohort includes children whose mothers were enrolled in the healthcare system during their entire pregnancy and followed to age 20. The childhood-exposure cohort includes children born into the system and followed while continuously enrolled. Imaging utilization was determined using administrative data. Computed tomography (CT) parameters were collected to estimate individualized patient organ dosimetry. Organ dose libraries for average exposures were constructed for radiography, fluoroscopy, and angiography, while diagnostic radiopharmaceutical biokinetic models were applied to estimate organ doses received in nuclear medicine procedures. Cancers were ascertained from local and state/provincial cancer registry linkages.

RESULTS

The fetal-exposure cohort includes 3,474,000 children among whom 6,606 cancers (2394 leukemias) were diagnosed over 37,659,582 person-years; 0.5% had in utero exposure to CT, 4.0% radiography, 0.5% fluoroscopy, 0.04% angiography, 0.2% nuclear medicine. The childhood-exposure cohort includes 3,724,632 children in whom 6,358 cancers (2,372 leukemias) were diagnosed over 36,190,027 person-years; 5.9% were exposed to CT, 61.1% radiography, 6.0% fluoroscopy, 0.4% angiography, 1.5% nuclear medicine.

CONCLUSION

The RIC Study is poised to be the largest study addressing risk of childhood and adolescent cancer associated with ionizing radiation from medical imaging, estimated with individualized patient organ dosimetry.

Outcome-based comparison of SMFM and ISUOG definitions of fetal growth restriction

OBJECTIVE

The recent international guidelines by the Society for Maternal-Fetal Medicine (SMFM) and the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) differ in their definitions of fetal growth restriction (FGR). Our aim was to compare the performance of the two definitions in predicting neonatal small-for-gestational age (SGA) and composite adverse neonatal outcome (ANO).

METHODS

This was a secondary analysis of data from a prospective study of women referred for fetal growth ultrasound examination between 26 + 0 and 36 + 6 weeks' gestation. The SMFM and ISUOG guidelines were used to define pregnancies with FGR. The SMFM definition of FGR is estimated fetal weight (EFW) or abdominal circumference (AC) < 10^th percentile. The ISUOG-FGR definition follows the Delphi consensus criteria and includes either EFW or AC < 3^rd percentile or EFW or AC < 10^th percentile combined with abnormal Doppler findings or a decrease in growth centiles. The primary outcome was the prediction of neonatal SGA, defined as birth weight < 10^th percentile, and a composite of ANO, which was defined as one or more of: Grade-III or -IV intraventricular hemorrhage, respiratory distress syndrome, neonatal death, cord blood pH < 7.1, seizures and admission to the neonatal intensive care unit. Test characteristics (sensitivity, specificity, positive predictive value (PPV), negative predictive value and positive (LR+) and negative likelihood ratios) and area under the receiver-operating-characteristics curve were determined. The association between FGR detected by each definition and selected adverse outcomes was assessed using logistic regression analysis.

RESULTS

Of the 1054 pregnancies that met the inclusion criteria, 137 (13.0%) and 55 (5.2%) were defined as having FGR by the SMFM and ISUOG definitions, respectively. Composite ANO and SGA neonate each occurred in 139 (13.2%) pregnancies. For the prediction of neonatal SGA, the SMFM-FGR definition had a higher sensitivity (54.7%) than did the ISUOG definition (28.8%). The ISUOG-FGR definition had higher specificity (98.4% vs 93.3%), LR+ (18.0 vs 8.2) and PPV (72.7% vs 55.5%) than did the SMFM definition for the prediction of a SGA neonate. The SMFM- and ISUOG-FGR definitions had similarly poor performance in predicting composite ANO, with sensitivities of 15.1% and 10.1%, respectively.

CONCLUSIONS

The SMFM definition of FGR is associated with a higher detection rate for SGA neonates but at the cost of some reduction in specificity. The ISUOG-FGR definition has a higher specificity, LR+ and PPV for the prediction of neonatal SGA. Both definitions of FGR performed poorly in predicting a composite ANO. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Analyzing Radiation Use during Transjugular Intrahepatic Portosystemic Shunt Creation

Portal vein access during transjugular intrahepatic portosystemic shunt creation was examined in 11 patients. Radiation metrics (kerma area product, reference point air kerma, and fluoroscopy times) during portal vein access were significantly greater for conventional versus intravascular US-guided transjugular intrahepatic portosystemic shunt (54.8 mGy ∙ cm² ± 27.6 vs 8.4 mGy ∙ cm² ± 5.0, P = .009; 210.4 mGy ± 109.1 vs 29.5 mGy ± 18.4, P = .009; 19.1 min ± 8.6 vs 8.9 min ± 4.6, P = .04). Wedged hepatic venography is a major contributor to radiation exposure. Intravascular US guidance is associated with significantly reduced radiation use.

Trends in Use of Medical Imaging in US Health Care Systems and in Ontario, Canada, 2000-2016

Importance

Medical imaging increased rapidly from 2000 to 2006, but trends in recent years have not been analyzed.

Objective

To evaluate recent trends in medical imaging.

Design, Setting, and Participants

Retrospective cohort study of patterns of medical imaging between 2000 and 2016 among 16 million to 21 million patients enrolled annually in 7 US integrated and mixed-model insurance health care systems and for individuals receiving care in Ontario, Canada.

Exposures

Calendar year and country (United States vs Canada).

Main Outcomes and Measures

Use of computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and nuclear medicine imaging. Annual and relative imaging rates by imaging modality, country, and age (children [<18 years], adults [18-64 years], and older adults [≥65 years]).

Results

Overall, 135 774 532 imaging examinations were included; 5 439 874 (4%) in children, 89 635 312 (66%) in adults, and 40 699 346 (30%) in older adults. Among adults and older adults, imaging rates were significantly higher in 2016 vs 2000 for all imaging modalities other than nuclear medicine. For example, among older adults, CT imaging rates were 428 per 1000 person-years in 2016 vs 204 per 1000 in 2000 in US health care systems and 409 per 1000 vs 161 per 1000 in Ontario; for MRI, 139 per 1000 vs 62 per 1000 in the United States and 89 per 1000 vs 13 per 1000 in Ontario; and for ultrasound, 495 per 1000 vs 324 per 1000 in the United States and 580 per 1000 vs 332 per 1000 in Ontario. Annual growth in imaging rates among US adults and older adults slowed over time for CT (from an 11.6% annual percentage increase among adults and 9.5% among older adults in 2000-2006 to 3.7% among adults in 2013-2016 and 5.2% among older adults in 2014-2016) and for MRI (from 11.4% in 2000-2004 in adults and 11.3% in 2000-2005 in older adults to 1.3% in 2007-2016 in adults and 2.2% in 2005-2016 in older adults). Patterns in Ontario were similar. Among children, annual growth for CT stabilized or declined (United States: from 10.1% in 2000-2005 to 0.8% in 2013-2016; Ontario: from 3.3% in 2000-2006 to -5.3% in 2006-2016), but patterns for MRI were similar to adults. Changes in annual growth in ultrasound were smaller among adults and children in the United States and Ontario compared with CT and MRI. Nuclear medicine imaging declined in adults and children after 2006.

Conclusions and Relevance

From 2000 to 2016 in 7 US integrated and mixed-model health care systems and in Ontario, rates of CT and MRI use continued to increase among adults, but at a slower pace in more recent years. In children, imaging rates continued to increase except for CT, which stabilized or declined in more recent periods. Whether the observed imaging utilization was appropriate or was associated with improved patient outcomes is unknown.

Trends in Medical Imaging During Pregnancy in the United States and Ontario, Canada, 1996 to 2016

IMPORTANCE

The use of medical imaging has sharply increased over the last 2 decades. Imaging rates during pregnancy have not been quantified in a large, multisite study setting.

OBJECTIVE

To evaluate patterns of medical imaging during pregnancy.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was performed at 6 US integrated health care systems and in Ontario, Canada. Participants included pregnant women who gave birth to a live neonate of at least 24 weeks' gestation between January 1, 1996, and December 31, 2016, and who were enrolled in the health care system for the entire pregnancy.

EXPOSURES

Computed tomography (CT), magnetic resonance imaging, conventional radiography, angiography and fluoroscopy, and nuclear medicine.

MAIN OUTCOMES AND MEASURES

Imaging rates per pregnancy stratified by country and year of child's birth.

RESULTS

A total of 3 497 603 pregnancies in 2 211 789 women were included. Overall, 26% of pregnancies were from US sites. Most (92%) were in women aged 20 to 39 years, and 85% resulted in full-term births. Computed tomography imaging rates in the United States increased from 2.0 examinations/1000 pregnancies in 1996 to 11.4/1000 pregnancies in 2007, remained stable through 2010, and decreased to 9.3/1000 pregnancies by 2016, for an overall increase of 3.7-fold. Computed tomography rates in Ontario, Canada, increased more gradually by 2.0-fold, from 2.0/1000 pregnancies in 1996 to 6.2/1000 pregnancies in 2016, which was 33% lower than in the United States. Overall, 5.3% of pregnant women in US sites and 3.6% in Ontario underwent imaging with ionizing radiation, and 0.8% of women at US sites and 0.4% in Ontario underwent CT. Magnetic resonance imaging rates increased steadily from 1.0/1000 pregnancies in 1996 to 11.9/1000 pregnancies in 2016 in the United States and from 0.5/1000 pregnancies in 1996 to 9.8/1000 pregnancies in 2016 in Ontario, surpassing CT rates in 2013 in the United States and in 2007 in Ontario. In the United States, radiography rates doubled from 34.5/1000 pregnancies in 1996 to 72.6/1000 pregnancies in 1999 and then decreased to 47.6/1000 pregnancies in 2016; rates in Ontario slowly increased from 36.2/1000 pregnancies in 1996 to 44.7/1000 pregnancies in 2016. Angiography and fluoroscopy and nuclear medicine use rates were low (5.2/1000 pregnancies), but in most years, higher in Ontario than the United States. Imaging rates were highest for women who were younger than 20 years or aged 40 years or older, gave birth preterm, or were black, Native American, or Hispanic (US data only). Considering advanced imaging only, chest imaging of pregnant women was more likely to use CT in the United States and nuclear medicine imaging in Ontario.

CONCLUSIONS AND RELEVANCE

The use of CT during pregnancy substantially increased in the United States and Ontario over the past 2 decades. Imaging rates during pregnancy should be monitored to avoid unnecessary exposure of women and fetuses to ionizing radiation.

Information overload: when less is more in medical imaging

In medicine, data collection and analysis provide the information needed to reduce diagnostic uncertainty. An examination of how medical imaging data is collected and then transformed into diagnostic information provides testable ideas for better managing this dynamic process. In other fields, process data is systematically assessed for differences between observed and predicted values. For studies that expose patients to the potentially harmful effects of ionizing radiation, monitoring imaging studies/illness, images/imaging study and radiation exposure/image would be steps towards developing radiation dose budgets for the diagnosis and treatment of common conditions. Random variation within the expected range would signal a high quality process. Conversely, single outlying cases or nonrandom variation within the expected range would trigger an investigation for a possible underlying cause. Such investigations would provide insights into how to continually improve this important aspect of healthcare.

Overnight Resident versus 24-hour Attending Radiologist Coverage in Academic Medical Centers

Academic medical centers have long relied on radiology residents to provide after-hours coverage, which means that they essentially function with autonomy. In this approach, attending radiologist review of resident interpretations occurs the following morning, often by subspecialist faculty. In recent years, however, this traditional coverage model in academic radiology departments has been challenged by an alternative model, the 24-hour attending radiologist coverage. Proponents of this new model seek to improve patient care after hours by increasing report accuracy and the speed with which the report is finalized. In this article, we review the traditional and the 24-hour attending radiologist coverage models. We summarize previous studies that indicate that resident overnight error rates are sufficiently low so that changing to an overnight attending model may not necessarily provide a meaningful increase in report accuracy. Whereas some centers completely replaced overnight residents, we note that most centers use a hybrid model, and overnight residents work alongside supervising attending radiologists, much as they do during the day. Even in this hybrid model, universal double reading and subspecialist final review, typical features of the traditional autonomous resident coverage model, are generally sacrificed. Because of this, changing from resident coverage to coverage by an attending radiologist that is 24 hours/day, 7 days/week may actually have detrimental effects to patient safety and quality of care provided. Changing to an overnight attending radiologist model may also have negative effects on the quality of radiology resident training, and it significantly increases cost.

Growth changes after inhalant abuse and toluene exposure: A systematic review and meta-analysis of human and animal studies

Inhalant abuse is a significant public health issue, particularly for adolescents, the predominant group of inhalant users. Adolescence is a critical growth period, and inhalant abuse has been associated with growth impairments, including reduced body weight and height. However, the extent to which inhalant abuse affects growth remains unquantified, and potential moderators remain unknown. To address this knowledge gap, a systematic review and meta-analysis of clinical human and preclinical animal studies utilizing toluene exposure (the primary solvent in abused products) was conducted. Five-hundred and sixty-nine studies were screened; 31 met inclusion criteria, yielding 64 toluene-control comparisons for body weight and 6 comparisons for height. Toluene exposure was negatively associated with body weight ( d = -0.73) and height ( d = -0.69). Concentration of inhaled toluene, but not duration, moderated the effect of toluene exposure on body weight, with more severe impairments at higher concentrations. Differences in effect size for body weight were observed for study characteristic subgroups including sex, age at first exposure, administration route and species. However, these findings should be interpreted cautiously due to low study numbers. Growth impairments, particularly during adolescence, can cause long-term health consequences. These effects on growth are therefore an important clinical outcome for individuals with a history of inhalant abuse.

Pharmacomechanical Catheter-Directed Thrombolysis for Deep-Vein Thrombosis

BACKGROUND

The post-thrombotic syndrome frequently develops in patients with proximal deep-vein thrombosis despite treatment with anticoagulant therapy. Pharmacomechanical catheter-directed thrombolysis (hereafter "pharmacomechanical thrombolysis") rapidly removes thrombus and is hypothesized to reduce the risk of the post-thrombotic syndrome.

METHODS

We randomly assigned 692 patients with acute proximal deep-vein thrombosis to receive either anticoagulation alone (control group) or anticoagulation plus pharmacomechanical thrombolysis (catheter-mediated or device-mediated intrathrombus delivery of recombinant tissue plasminogen activator and thrombus aspiration or maceration, with or without stenting). The primary outcome was development of the post-thrombotic syndrome between 6 and 24 months of follow-up.

RESULTS

Between 6 and 24 months, there was no significant between-group difference in the percentage of patients with the post-thrombotic syndrome (47% in the pharmacomechanical-thrombolysis group and 48% in the control group; risk ratio, 0.96; 95% confidence interval [CI], 0.82 to 1.11; P=0.56). Pharmacomechanical thrombolysis led to more major bleeding events within 10 days (1.7% vs. 0.3% of patients, P=0.049), but no significant difference in recurrent venous thromboembolism was seen over the 24-month follow-up period (12% in the pharmacomechanical-thrombolysis group and 8% in the control group, P=0.09). Moderate-to-severe post-thrombotic syndrome occurred in 18% of patients in the pharmacomechanical-thrombolysis group versus 24% of those in the control group (risk ratio, 0.73; 95% CI, 0.54 to 0.98; P=0.04). Severity scores for the post-thrombotic syndrome were lower in the pharmacomechanical-thrombolysis group than in the control group at 6, 12, 18, and 24 months of follow-up (P<0.01 for the comparison of the Villalta scores at each time point), but the improvement in quality of life from baseline to 24 months did not differ significantly between the treatment groups.

CONCLUSIONS

Among patients with acute proximal deep-vein thrombosis, the addition of pharmacomechanical catheter-directed thrombolysis to anticoagulation did not result in a lower risk of the post-thrombotic syndrome but did result in a higher risk of major bleeding. (Funded by the National Heart, Lung, and Blood Institute and others; ATTRACT ClinicalTrials.gov number, NCT00790335 .).

Endothelial chimerism in chronic sclerotic-type chronic graft-versus-host disease (GVHD) and GVHD-associated angiomatosis

Graft-versus-host disease-associated angiomatosis (GVHD-AA) is an uncommon manifestation of chronic GVHD consisting of friable vascular proliferations. Using fluorescence in situ hybridization, we demonstrate the presence of donor-derived endothelial cells within areas of GVHD-AA. This is the first documented occurrence of a benign neoplastic growth in relationship to a form of chronic GVHD.

Improving Performance During Image-Guided Procedures

OBJECTIVE

Image-guided procedures have become a mainstay of modern health care. This article reviews how human operators process imaging data and use it to plan procedures and make intraprocedural decisions.

METHODS

A series of models from human factors research, communication theory, and organizational learning were applied to the human-machine interface that occupies the center stage during image-guided procedures.

RESULTS

Together, these models suggest several opportunities for improving performance as follows: 1. Performance will depend not only on the operator's skill but also on the knowledge embedded in the imaging technology, available tools, and existing protocols. 2. Voluntary movements consist of planning and execution phases. Performance subscores should be developed that assess quality and efficiency during each phase. For procedures involving ionizing radiation (fluoroscopy and computed tomography), radiation metrics can be used to assess performance. 3. At a basic level, these procedures consist of advancing a tool to a specific location within a patient and using the tool. Paradigms from mapping and navigation should be applied to image-guided procedures. 4. Recording the content of the imaging system allows one to reconstruct the stimulus/response cycles that occur during image-guided procedures.

CONCLUSIONS

When compared with traditional "open" procedures, the technology used during image-guided procedures places an imaging system and long thin tools between the operator and the patient. Taking a step back and reexamining how information flows through an imaging system and how actions are conveyed through human-machine interfaces suggest that much can be learned from studying system failures. In the same way that flight data recorders revolutionized accident investigations in aviation, much could be learned from recording video data during image-guided procedures.

Chronic intermittent toluene inhalation in adolescent rats results in metabolic dysfunction with altered glucose homeostasis

BACKGROUND AND PURPOSE

Abuse of toluene-containing inhalants is an increasing public health problem, especially among adolescents. Abuse during adolescence is associated with emaciation, while industrial exposure leads to altered glycaemic control suggesting metabolic instability. However, the relationship between adolescent inhalant abuse and metabolic dysfunction remains unknown.

EXPERIMENTAL APPROACH

To model human abuse patterns, we exposed male adolescent Wistar rats [postnatal day (PND) 27] to chronic intermittent inhaled toluene (CIT, 10,000 ppm) or air (control) for 1 h·day(-1) , three times a week for 4 weeks. Feeding and body composition were monitored. After 4 weeks, circulating metabolic hormone concentrations and responses to a glucose tolerance test (GTT) were measured. Dietary preference was measured by giving animals access to either a 'western diet' plus standard chow (WC + SC) or standard chow alone during 4 weeks of abstinence. Metabolic hormones and GTT were subsequently measured.

KEY RESULTS

Adolescent CIT exposure significantly retarded weight gain, altered body composition, circulating metabolic hormones and responses to a GTT. While reduced body weight persisted, responses to a GTT and circulating hormones appeared to normalize for animals on standard chow following abstinence. In CIT-exposed WC + SC rats, we observed impaired glucose tolerance associated with altered metabolic hormones. Analysis of hypothalamic genes revealed differential expression profiles in CIT-exposed rats following both the exposure period and abstinence, suggesting a central contribution to inhalant-induced metabolic dysfunction.

CONCLUSION AND IMPLICATIONS

CIT exposure during adolescence has long-term effects on metabolic function, which may increase the risk of disorders related to energy balance and glycaemic control.

Optimizing radiation use during fluoroscopic procedures: a quality and safety improvement project

PURPOSE

The ionizing radiation used during fluoroscopically guided medical interventions carries risk. The teams performing these procedures seek to minimize those risks while preserving each procedure's benefits. This report describes a data-driven optimization strategy.

METHODS

Manual and automated data capture systems were used to collect a series of different metrics, including fluoroscopy time, kerma area product, and reference point air kerma, from both adult and pediatric interventional radiologic procedures. Tools from statistical process control were used to identify opportunities for improvement and assess which changes led to improvement.

RESULTS

Initial efforts focused on creating a system capable of reliably capturing fluoroscopy time from all interventional radiologic procedures. Ongoing data analysis and feedback to frontline teams led to the development of a manual workflow that reliably captured fluoroscopy time. Data capture was later supplemented by automatic capture of electronic records. This process exploited the standardized format (DICOM Structured Reporting) that newer fluoroscopy units use to record the radiation metrics. Data analysis found marked differences between the imaging protocols used for adults and children. Revision of the adult protocols led to a stable twofold reduction in average exposure per adult procedure. Analysis of balancing measures found no impact on workflow.

CONCLUSIONS

A systematic approach to improving radiation use during procedures led to a substantial and sustained reduction in risk with no reduction in benefits. Data were readily captured by both manual and automated processes. Concepts from cognitive psychology and information theory provided a theoretical basis for both data analysis and improvement opportunities.

Improving team performance during the preprocedure time-out in pediatric interventional radiology

BACKGROUND

The preprocedure time-out is a high-profile safety measure, and compliance is coming under increasing scrutiny. A checklist-based scoring system was developed to rigorously assess compliance, and a system of video monitoring and feedback was used to track performance and improve the time-out process in pediatric interventional radiology.

METHODS

A time-out "script" containing a series of observable behaviors to be performed collectively by the physician, nurse, and technologist before each interventional procedure was used to create a checklist. A procedure room equipped with an audio/video recording system allowed capture of time-outs for later review. The reviewer scored one or two time-outs each week, and the results were posted to provide feedback.

RESULTS

The process of continual feedback and modification led to substantial improvements in time-out performance during a three-year period. Analysis of subscores revealed common failure modes that were subsequently addressed. The scoring checklist was also modified after analysis suggested redundant or unnecessary items. Gains were noted in the efficiency of the time-out protocol, which took more than 1 minute in the initial stages but soon shortened to 30-45 seconds as the team gained experience. Assessment of scoring consistency across three independent observers revealed 93% interobserver agreement and 95% intraobserver agreement. Clarification of the scoring criteria led to improved consistency (97% and 98% inter- and intraobserver agreement, respectively).

CONCLUSIONS

The combination of a time-out checklist, recorded procedures, review, and feedback produced not only improvements in time-out performance but also improvements in the scoring system and time-out process.

Flight data recorder for interventional radiology

To test process improvement strategies, a recording system in a new pediatric interventional radiology suite was installed modeled after the flight data recorders found in modern aviation. Using the resulting data from these recordings, a variety of quality and safety improvement projects were planned including improving timeout performance and optimizing radiation use. There were several challenges, including balancing the need to protect patients during efforts to improve teamwork. However, the flight data recorder drove home the notion that interventional radiology is a team sport and that improvements can be measured by keeping score.

Management of excluded bile ducts in paediatric orthotopic liver transplant recipients of technical variant allografts

BACKGROUND

A strategy to increase the number of size- and weight-appropriate organs and decrease the paediatric waiting list mortality is wider application of sectional orthotopic liver transplantation (OLT). These technical variants consist of living donor, deceased donor reduced and split allografts. However, these grafts have an increased risk of biliary complications. An unusual and complex biliary complication which can lead to graft loss is inadvertent exclusion of a major segmental bile duct. We present four cases and describe an algorithm to correct these complications.

METHODS

A retrospective review of the paediatric orthotopic liver transplantation database (2000-2010) at Washington University in St. Louis/St. Louis Children's Hospital was conducted.

RESULTS

Sixty-eight patients (55%) received technical variant allografts. Four complications of excluded segmental bile ducts were identified. Percutaneous cholangiography provided diagnostic confirmation and stabilization with external biliary drainage. All patients required interval surgical revision of their hepaticojejunostomy for definitive drainage. Indwelling biliary stents aided intra-operative localization of the excluded ducts. All allografts were salvaged.

DISCUSSION

Aggressive diagnosis, percutaneous decompression and interval revision hepaticojejunostomy are the main tenets of management of an excluded bile duct. Careful revision hepaticojejunostomy over a percutaneous biliary stent can result in restoration of biliary continuity and allograft survival.

Objective assessment of operator performance during ultrasound-guided procedures

PURPOSE

Simulation permits objective assessment of operator performance in a controlled and safe environment. Image-guided procedures often require accurate needle placement, and we designed a system to monitor how ultrasound guidance is used to monitor needle advancement toward a target. The results were correlated with other estimates of operator skill.

METHODS

The simulator consisted of a tissue phantom, ultrasound unit, and electromagnetic tracking system. Operators were asked to guide a needle toward a visible point target. Performance was video-recorded and synchronized with the electromagnetic tracking data. A series of algorithms based on motor control theory and human information processing were used to convert raw tracking data into different performance indices. Scoring algorithms converted the tracking data into efficiency, quality, task difficulty, and targeting scores that were aggregated to create performance indices. After initial feasibility testing, a standardized assessment was developed. Operators (N = 12) with a broad spectrum of skill and experience were enrolled and tested. Overall scores were based on performance during ten simulated procedures. Prior clinical experience was used to independently estimate operator skill.

RESULTS

When summed, the performance indices correlated well with estimated skill. Operators with minimal or no prior experience scored markedly lower than experienced operators. The overall score tended to increase according to operator's clinical experience. Operator experience was linked to decreased variation in multiple aspects of performance. The aggregated results of multiple trials provided the best correlation between estimated skill and performance. A metric for the operator's ability to maintain the needle aimed at the target discriminated between operators with different levels of experience.

CONCLUSIONS

This study used a highly focused task model, standardized assessment, and objective data analysis to assess performance during simulated ultrasound-guided needle placement. The performance indices were closely related to operator experience.

Biosorptive recovery of platinum from platinum group metal refining wastewaters by immobilised Saccharomyces cerevisiae

The process of platinum group metal (PGM) refining can be up to 99.99% efficient at best, and although it may seem small, the amount of valuable metal lost to waste streams is appreciable enough to warrant recovery. The method currently used to remove entrained metal ions from refinery wastewaters, chemical precipitation, is not effective for selective recovery of PGMs. The yeast Saccharomyces cerevisiae has been found capable of sorbing numerous precious and base metals, and is a cheap and abundant source of biomass. In this investigation, S. cerevisiae was immobilised using polyethyleneimine and glutaraldehyde to produce a suitable sorbent, capable of high platinum uptake (150-170 mg/g) at low pH (<2). The sorption mechanism was found to be a chemical reaction, which made effective desorption impossible. When applied to PGM refinery wastewater, two key wastewater characteristics limited the success of the sorption process; high inorganic ion content and complex speciation of the platinum ions. The results proved the concept principle of platinum recovery by immobilised yeast biosorption and indicated that a more detailed understanding of the platinum speciation within the wastewater is required before biosorption can be applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to be highly effective in principle, but the complexity of the wastewater requires that pretreatment steps be taken before the successful application of this process to industrial wastewater.

The biodistribution of [153Gd]Gd-labeled magnetic resonance contrast agents in a transgenic mouse model of renal failure differs greatly from control mice

Nephrogenic systemic fibrosis occurs in renally impaired patients who have undergone contrast enhanced MR examination using intravenous gadolinium-based contrast agents. The effect of impaired kidney function on the biodistribution of gadolinium-based contrast agents was investigated using radiolabeled (153/Nat) gadolinium-DOTA, (153/Nat) gadolinium-DTPA, and (153/Nat) gadolinium-DTPA-BMA in a transgenic mouse model of renal impairment. Renally impaired animals had more activity associated with their tissues than did control mice, and this increase varied according to the radiotracer injected. For example, after 7 days, renally impaired animals that received (153/Nat) Gd-DOTA had 3-fold (P < 0.037) more activity in their bone tissue, whereas renally impaired animals receiving (153/Nat) Gd-DTPA and (153/Nat) Gd-DTPA-BMA had 8-fold (P < 0.0001) and 24-fold (P < 0.0001) more activity in their bone tissue, respectively. These findings demonstrate that renal impairment dramatically alters the tissue distribution of Gd(3+) ions in vivo, which are likely a critical factor in the development of nephrogenic systemic fibrosis.

Creating and evaluating a data-driven curriculum for central venous catheter placement

BACKGROUND

Central venous catheter placement is a common procedure with a high incidence of error. Other fields requiring high reliability have used Failure Mode and Effects Analysis (FMEA) to prioritize quality and safety improvement efforts.

OBJECTIVE

To use FMEA in the development of a formal, standardized curriculum for central venous catheter training.

METHODS

We surveyed interns regarding their prior experience with central venous catheter placement. A multidisciplinary team used FMEA to identify high-priority failure modes and to develop online and hands-on training modules to decrease the frequency, diminish the severity, and improve the early detection of these failure modes. We required new interns to complete the modules and tracked their progress using multiple assessments.

RESULTS

Survey results showed new interns had little prior experience with central venous catheter placement. Using FMEA, we created a curriculum that focused on planning and execution skills and identified 3 priority topics: (1) retained guidewires, which led to training on handling catheters and guidewires; (2) improved needle access, which prompted the development of an ultrasound training module; and (3) catheter-associated bloodstream infections, which were addressed through training on maximum sterile barriers. Each module included assessments that measured progress toward recognition and avoidance of common failure modes. Since introducing this curriculum, the number of retained guidewires has fallen more than 4-fold. Rates of catheter-associated infections have not yet declined, and it will take time before ultrasound training will have a measurable effect.

CONCLUSION

The FMEA provided a process for curriculum development. Precise definitions of failure modes for retained guidewires facilitated development of a curriculum that contributed to a dramatic decrease in the frequency of this complication. Although infections and access complications have not yet declined, failure mode identification, curriculum development, and monitored implementation show substantial promise for improving patient safety during placement of central venous catheters.

Improving quality and patient safety by minimizing unnecessary variation

Quality and safety in health care have proven difficult to precisely define and measure. In other fields, quality is defined as the absence of unnecessary variation and process improvement efforts are gauged by their ability to reduce variation. This article explores how this definition can be applied to various attributes of image-guided procedures.

Assessing system performance

Measuring system performance during image-guided procedures is difficult but necessary if the safety, quality, and efficiency of interventional radiology are to be improved. Because overall performance during these procedures is directly related to the operator's skill, this article will focus on how observable manifestations of skill can be elicited and analyzed. The discussion includes issues encountered when the results of "high-stakes" tests such as board certification are used to predict future system performance. The underlying theme is that process improvement uses the scientific method to gain knowledge of a system. The successive cycles of "predict-test-analyze-decide" found in any training program generate an expanding knowledge base that leads to measurable improvements in system performance.

Malignant disease in peptic ulcer surgery patients after long term follow-up: A cohort study of 1992 patients

AIMS

To assess the effect of previous peptic ulcer surgery on subsequent malignant events, in particular in relation to previous vagotomy, a historical cohort study was conducted.

METHODS

All patients undergoing surgery for peptic ulcer disease with accurate follow-up data at a large peptic ulcer clinic in the Western Infirmary, Glasgow, from 1965 to 1983 were assessed. All cancer events and specific cancer events (gastric, bronchial, laryngeal, colorectal, bladder, breast, prostate, pancreas, kidney, oesophageal cancers) were determined as outcome measures and expressed as standardised incidence ratio (SIR).

RESULTS

Vagotomy and drainage accounted for 67% of all procedures for peptic ulcer disease. Eighty-three percent were habitual smokers. For all peptic ulcer surgery patients, the SIR for all cancer events was 0.86. For specific cancers, the SIRs were bronchial cancer (SIR 1.13); laryngeal cancer (SIR 2.17), colorectal cancer (SIR 0.67). For vagotomised patients the risk of gastric cancer was significantly elevated (SIR 1.50).

CONCLUSIONS

An excess of cancers attributable to smoking have been found in peptic ulcer surgery patients. Vagotomised patients have a higher risk of gastric cancer after long term follow-up. This finding may have implications for screening and the safety of long term acid suppression with agents such as proton pump inhibitors.

Biosorption of precious metals

Biosorption has emerged as a low-cost and often low-tech option for removal or recovery of base metals from aqueous wastes. The conditions under which precious metals such as gold, platinum and palladium are sorbed by biomass are often very different to those under which base metals are sorbed. This, coupled with the increasingly high demand for precious metals, drives the increase in research into efficient recovery of precious metal ions from all waste material, especially refining wastewaters. Common biosorbents for precious metal ions include various derivatives of chitosan, as well as other compounds with relatively high surface amine functional group content. This is generally due to the ability of the positively charged amine groups to attract anionic precious metal ions at low pH. Recent research regarding the biosorption of some precious metals is reviewed here, with emphasis on the effects of the biosorption environment and the biosorption mechanisms identified.

Analysis of Simulated Angiographic Procedures. Part 2: Extracting Efficiency Data from Audio and Video Recordings

PURPOSE

To create and test methods of extracting efficiency data from recordings of simulated renal stent procedures.

MATERIALS AND METHODS

Task analysis was performed and used to design a standardized testing protocol. Five experienced angiographers then performed 16 renal stent simulations using the Simbionix AngioMentor angiographic simulator. Audio and video recordings of these simulations were captured from multiple vantage points. The recordings were synchronized and compiled. A series of efficiency metrics (procedure time, contrast volume, and tool use) were then extracted from the recordings. The intraobserver and interobserver variability of these individual metrics was also assessed. The metrics were converted to costs and aggregated to determine the fixed and variable costs of a procedure segment or the entire procedure.

RESULTS

Task analysis and pilot testing led to a standardized testing protocol suitable for performance assessment. Task analysis also identified seven checkpoints that divided the renal stent simulations into six segments. Efficiency metrics for these different segments were extracted from the recordings and showed excellent intra- and interobserver correlations. Analysis of the individual and aggregated efficiency metrics demonstrated large differences between segments as well as between different angiographers. These differences persisted when efficiency was expressed as either total or variable costs.

CONCLUSIONS

Task analysis facilitated both protocol development and data analysis. Efficiency metrics were readily extracted from recordings of simulated procedures. Aggregating the metrics and dividing the procedure into segments revealed potential insights that could be easily overlooked because the simulator currently does not attempt to aggregate the metrics and only provides data derived from the entire procedure. The data indicate that analysis of simulated angiographic procedures will be a powerful method of assessing performance in interventional radiology.

Analysis of Simulated Angiographic Procedures: Part 1—Capture and Presentation of Audio and Video Recordings

PURPOSE

To assess different methods of recording angiographic simulations and to determine how such recordings might be used for training and research.

MATERIALS AND METHODS

Two commercially available high-fidelity angiography simulations, the Mentice Vascular Interventional Simulation Trainer and the Simbionix AngioMentor, were used for data collection. Video and audio records of simulated procedures were created by different methods, including software-based screen capture, video splitters and converters, and external cameras. Recording parameters were varied, and the recordings were transferred to computer workstations for postprocessing and presentation.

RESULTS

The information displayed on the simulators' computer screens could be captured by each method. Although screen-capture software provided the highest resolution, workflow considerations favored a hardware-based solution that duplicated the video signal and recorded the data stream(s) at lower resolutions. Additional video and audio recording devices were used to monitor the angiographer's actions during the simulated procedures. The multiple audio and video files were synchronized and composited with personal computers equipped with commercially available video editing software. Depending on the needs of the intended audience, the resulting files could be distributed and displayed at full or reduced resolutions.

CONCLUSIONS

The capture, editing, presentation, and distribution of synchronized multichannel audio and video recordings holds great promise for angiography training and simulation research. To achieve this potential, technical challenges will need to be met, and content will need to be tailored to suit the needs of trainees and researchers.

Performance of Dead Azolla filiculoides Biomass in Biosorption of Au from Wastewater

Dried milled biomass of Azolla filiculoides removed up to 98.2% of gold from wastewater from a gold plating factory containing 5 mg gold/l in solution in batch biosorption. The gold uptake capacity of the biomass was 98 mg/g. Whole dried biomass used in a continuous flow column removed up to 100% of gold from diluted wastewater. A similar column was linked to a sulphide precipitation process to provide a two-step system which was able to remove 98% of gold from undiluted wastewater containing 41 mg Au/l. The lifetime of the column was five days.

Measurement of Blood Flow Before and After Embolization with Use of Fluorescent Microspheres in an Animal Model

PURPOSE

Catheter-directed embolization has become a widespread technique for the treatment of benign and malignant neoplasms. The mechanism whereby embolization leads to selective atrophy of these neoplasms is largely speculative. As a potential model for the large regional perfusion differences between normal and neoplastic tissues, renal perfusion was studied before and after catheter-directed embolization. The working hypothesis was that embolization would create measurable changes in blood flow in the renal cortex and medulla.

MATERIALS AND METHODS

Microspheres (l0 microm in diameter) containing a series of different fluorophores were injected into the arterial system before and after the renal arteries were embolized with a series of larger (100-300 microm) particulate embolic agents. The distribution of the microspheres in the renal cortex, renal medulla, and liver was analyzed by fluorescence microscopy as well as by extraction of the fluorophores.

RESULTS

The distribution of the fluorescent microspheres was readily assessed by fluorescence microscopy or extraction of the fluorophores. Before embolization, the renal cortex received approximately three times more flow than the medulla. After embolization, perfusion of the renal cortex and medulla decreased in parallel.

CONCLUSIONS

Fluorescent microspheres are a powerful tool for measuring the changes in flow that occur after catheter-directed embolization. The fact that parallel decreases in flow were found in the renal cortex and medulla indicates that the distribution of each embolic agent was flow-directed. These results might provide insight into the mechanism of tumor atrophy after uterine artery embolization or hepatic chemoembolization.