Radiology resident competency in detecting basilar artery occlusion: a simulation-based assessment.

PURPOSE: Basilar artery strokes are rare but can have characteristic imaging findings that can often be overlooked. This retrospective study aims to assess radiology residents' ability to identify CT imaging findings of basilar artery occlusion in a simulated call environment. METHODS: The Wisdom in Diagnostic Imaging Emergent/Critical Care Radiology Simulation (WIDI SIM)-a tested and reliable computer-aided emergency imaging simulation-was employed to assess resident readiness for independent radiology call. The simulations include 65 cases of varying complexity, including normal studies, with one case specifically assessing basilar artery stroke. Residents were presented with a single, unique case of basilar artery occlusion in two separate years of testing and were only provided with non-contrast CT images. Residents' free text responses were manually scored by faculty members using a standardized grading rubric, with errors subsequently classified by type. RESULTS: A total of 454 radiology residents were tested in two separate years on the imaging findings of basilar artery occlusion using the Wisdom in Diagnostic Imaging simulation web-based testing platform. Basilar artery occlusion was consistently underdiagnosed by radiology residents being tested for call readiness irrespective of the numbers of years in training. On average, only 14% of radiology residents were able to correctly identify basilar artery occlusion on non-contrast CT. CONCLUSIONS: Our findings underscore a potential gap in radiology residency training related to the detection of basilar artery occlusion, highlighting the potential need for increased educational efforts in this area.

An assessment of radiology resident competency in identifying suppurative retropharyngeal lymphadenitis: an examination using the WIDI SIM platform.

BACKGROUND AND PURPOSE: Suppurative retropharyngeal lymphadenitis is a retropharyngeal space infection almost exclusively seen in the young (4-8 years old) pediatric population. It can be misdiagnosed as a retropharyngeal abscess, leading to unnecessary invasive treatment procedures. This retrospective study aims to assess radiology residents' ability to independently identify CT imaging findings and make a definitive diagnosis of suppurative retropharyngeal lymphadenitis in a simulated call environment. MATERIALS AND METHODS: The Wisdom in Diagnostic Imaging Emergent/Critical Care Radiology Simulation (WIDI SIM) is a computer-aided emergency imaging simulation proven to be a reliable method for assessing resident preparedness for independent radiology call. The simulation included 65 cases across various imaging modalities of varying complexity, including normal studies, with one case specifically targeting suppurative retropharyngeal adenitis identification. Residents' free text responses were manually scored by faculty members using a standardized grading rubric, with errors subsequently classified by type. RESULTS: A total of 543 radiology residents were tested in three separate years on the imaging findings of suppurative retropharyngeal lymphadenitis using the Wisdom in Diagnostic Imaging simulation web-based testing platform. Suppurative retropharyngeal lymphadenitis was consistently underdiagnosed by radiology residents being tested for call readiness irrespective of the numbers of years in training. On average, only 3.5% of radiology residents were able to correctly identify suppurative retropharyngeal lymphadenitis on a contrast-enhanced computed tomography (CT). CONCLUSIONS: Our findings underscore a potential gap in radiology residency training related to the accurate identification of suppurative retropharyngeal lymphadenitis, highlighting the potential need for enhanced educational efforts in this area.

Challenges in diagnosis of calcaneal fractures: an examination using the WIDI SIM platform.

INTRODUCTION: The calcaneus is the most commonly fractured tarsal bone. Diagnosis is often challenging due to subtle radiographic changes and requires timely identification to prevent complications, including subtalar arthritis, neurovascular injury, malunion, osteomyelitis, and compartment syndrome. Treatment varies based on fracture type, with non-surgical methods for non-displaced stress fractures and surgical interventions for displaced or intra-articular fractures. METHODS: This study utilized the Wisdom in Diagnostic Imaging Simulation (WIDI SIM) platform, an emergency imaging simulation designed to assess radiology resident preparedness for independent call. During an 8-hour simulation, residents were tested on 65 cases across various imaging modalities of varying complexity, including normal studies. A single, unique case of calcaneal fracture was included within the simulation in four separate years of testing. Cases were assessed using a standardized grading rubric by subspecialty radiology faculty, with errors subsequently classified by type. RESULTS: A total of 1279 residents were tested in five separate years on the findings of calcaneal fractures of 5 different patients. Analysis revealed a consistent pattern of missed diagnoses across all training years, primarily attributed to observational errors. There was limited improvement with training progression as all training years exhibited similar average performance levels. CONCLUSIONS: Calcaneal fractures pose a diagnostic challenge due to their frequent subtle radiographic findings, especially in stress fractures. Simulation-based evaluations using WIDI SIM highlighted challenges in radiology residents' proficiency in diagnosing calcaneal fractures. Addressing these challenges through targeted education and exposure to diverse cases is essential to improve diagnostic accuracy and reduce complications with calcaneal fractures.

Utilization Management of High-Cost Imaging in an Outpatient Setting in a Large Stable Patient and Provider Cohort over 7 Years.

Purpose To quantify the effect of a comprehensive, long-term, provider-led utilization management (UM) program on high-cost imaging (computed tomography, magnetic resonance imaging, nuclear imaging, and positron emission tomography) performed on an outpatient basis. Materials and Methods This retrospective, 7-year cohort study included all patients regularly seen by primary care physicians (PCPs) at an urban academic medical center. The main outcome was the number of outpatient high-cost imaging examinations per patient per year ordered by the patient's PCP or by any specialist. The authors determined the probability of a patient undergoing any high-cost imaging procedure during a study year and the number of examinations per patient per year (intensity) in patients who underwent high-cost imaging. Risk-adjusted hierarchical models were used to directly quantify the physician component of variation in probability and intensity of high-cost imaging use, and clinicians were provided with regular comparative feedback on the basis of the results. Observed trends in high-cost imaging use and provider variation were compared with the same measures for outpatient laboratory studies because laboratory use was not subject to UM during this period. Finally, per-member per-year high-cost imaging use data were compared with statewide high-cost imaging use data from a major private payer on the basis of the same claim set. Results The patient cohort steadily increased in size from 88 959 in 2007 to 109 823 in 2013. Overall high-cost imaging utilization went from 0.43 examinations per year in 2007 to 0.34 examinations per year in 2013, a decrease of 21.33% (P < .0001). At the same time, similarly adjusted routine laboratory study utilization decreased by less than half that rate (9.4%, P < .0001). On the basis of unadjusted data, outpatient high-cost imaging utilization in this cohort decreased 28%, compared with a 20% decrease in statewide utilization (P = .0023). Conclusion Analysis of high-cost imaging utilization in a stable cohort of patients cared for by PCPs during a 7-year period showed that comprehensive UM can produce a significant and sustained reduction in risk-adjusted per-patient year outpatient high-cost imaging volume. © RSNA, 2017.

Enhancing Radiology Education With a Case-Based Intro to Radiology on the UF WIDI e-Learning Platform.

RATIONALE AND OBJECTIVES: This study explores the implementation and efficacy of an online, interactive, case-based radiology education tool, Wisdom in Diagnostic Imaging (WIDI) Case-Based Intro to Radiology (CBIR). We hypothesize that the WIDI CBIR platform would enhance radiology teaching, foster critical thinking, and provide a comprehensive curriculum in imaging interpretation and utilization. MATERIALS AND METHODS: A focus group consisting of 1 undergraduate, 7 medical students, 9 physician assistant students, and 3 PhD students participated in this study. We tested 3 different teaching methods: a didactic approach without WIDI, a proctored didactic approach using WIDI, and a flipped classroom approach using WIDI. An online survey was conducted to assess student preference and feedback on these methods and the use of WIDI in their curriculum. RESULTS: Most students preferred the proctored didactic approach with WIDI. They reported that the platform complemented their curriculum and encouraged critical thinking. The modules covered adequate clinical and imaging details and enhanced their skills in imaging interpretation. Despite the limitations of a small sample size and reliance on self-reported outcomes, this study indicates that the WIDI platform could be integrated into PA and medical school curricula throughout the US, offering a standardized radiology curriculum. CONCLUSION: The UF WIDI appears to be a promising tool for modernizing radiology education, improving imaging interpretation skills, and enhancing appropriate imaging selection among nonradiologist medical learners. WIDI offers case-based education in imaging use, workflow, search-pattern selection, and interpretation of common radiological findings, potentially bridging the gap in radiology education. Further research and larger studies are required to assess the long-term impact on performance and clinical practice.

Bubbles in the belly: How well do radiology trainees recognize pneumatosis in pediatric patients on plain film?

OBJECTIVES: Pneumatosis intestinalis is a radiographic finding that refers to the presence of gas within the walls of the small or large bowel. This sign is diagnostic in the setting of premature infants with suspected necrotizing enterocolitis. Earlier detection of NEC on X-ray is vital to improve the overall management in these infants. The identification of pneumatosis intestinalis concerning for necrotizing enterocolitis by the "on-call" trainee is critical in the care of the preterm infant. Our objective was to study trainees' ability to identify pneumatosis on an emergent overnight film. METHODS: The Emergent/Critical Care Imaging SIMulation (WIDI SIM) is a strategically designed computer-aided simulation of an emergency imaging experience that has been rigorously tested and proven to be a reliable means for assessing radiology trainee preparedness to competently and independently cover radiology call. One test case each year included requires the trainee to accurately identify pneumatosis on a plain radiograph of the abdomen in a neonate. RESULTS: A total of 463 radiology trainees from 32 distinct training programs across the country were given a case of pneumatosis using the WIDI simulation web-based testing platform. On average only 28% of radiology trainees were able to correctly identify pneumatosis intestinalis on plain film. Although the sample sizes in the upper-level trainees were smaller, those with greater number years of training performed better. CONCLUSIONS: Further training must be given to radiology trainees to accurately recognize pneumatosis and report concerns for necrotizing enterocolitis. ADVANCES IN KNOWLEDGE: This paper is the first to describe and assess the ability of the "on-call" radiology trainee to accurately recognize pneumatosis and report concerns for necrotizing enterocolitis. Our paper includes the largest cohort of radiology trainees evaluated to this date.

Increasing the appropriateness of outpatient imaging: effects of a barrier to ordering low-yield examinations.

PURPOSE: To determine the effect of a computerized radiology order entry system rule that prevented nonclinician support staff from completing orders for outpatient computed tomographic, magnetic resonance imaging, and nuclear medicine examinations that received initial low-yield decision support scores in the order entry system. MATERIALS AND METHODS: This retrospective HIPAA-compliant study was approved by the institutional review board; the requirement for informed consent was waived. The control group consisted of 42737 consecutive orders for examinations in which decision support was provided that were placed from April to December 2006. The study group consisted of 76238 consecutive orders that were placed from April to December 2007. During the latter time period, a new rule in the order entry system was implemented: Examinations that had low-yield decision support scores could not be scheduled when the orders were placed by nonclinician support staff. To schedule the blocked examinations, the responsible clinician was required to personally log in to complete the process. System event logs and records of outpatient imaging procedures were extracted, counted, and analyzed to determine which ordering sessions resulted in examinations being scheduled and performed and which sessions resulted in modified or cancelled examinations. Results were correlated with user status and decision support scores. The Cochran-Mantel-Haenszel technique was used to control for the status of the order initiator and to allow testing for significance of the effect of the intervention on the "fate" of ordering events. RESULTS: After the intervention, the proportion of total examination requests initiated by clinicians directly logging in almost doubled: from 11,243 (26.31%) of 4,737 to 41,450 (54.37%) of 76238 examinations (P < .001). The fraction of low-yield (decision support score, 1-3) examinations requested through the order entry system that were later scheduled and performed decreased from 2106 (5.43%) of 38,801 to 1261 (1.92%) of 65,765 (P < .001). This is in contrast to requests for examinations with higher initial decision support scores that were not affected by the policy change and were scheduled at the same rate (relative risk, 0.988) before and after the change. CONCLUSION: A simple change in the business logic of the order entry system resulted in a substantially decreased rate of low-yield imaging examinations and a markedly increased percentage of tests personally ordered by clinicians.

A Review of Perceptual Expertise in Radiology-How it develops, How we can test it, and Why humans still matter in the era of Artificial Intelligence.

As the first step in image interpretation is detection, an error in perception can prematurely end the diagnostic process leading to missed diagnoses. Because perceptual errors of this sort-"failure to detect"-are the most common interpretive error (and cause of litigation) in radiology, understanding the nature of perceptual expertise is essential in decreasing radiology's long-standing error rates. In this article, we review what constitutes a perceptual error, the existing models of radiologic image perception, the development of perceptual expertise and how it can be tested, perceptual learning methods in training radiologists, and why understanding perceptual expertise is still relevant in the era of artificial intelligence. Adding targeted interventions, such as perceptual learning, to existing teaching practices, has the potential to enhance expertise and reduce medical error.

Predictors of MRI Leakage Among Patients Attributed to an Academic Medical Center Commercial Risk-Shared Insurance Contract.

PURPOSE: For health care organizations engaged in risk-shared insurance contracts, leakage of advanced diagnostic imaging to imaging sites not affiliated with the risk-sharing organization may undermine performance on financial and quality metrics. The goal of this study was to identify factors that are predictive of leakage of MRI examinations among patients attributed to an academic health care organization's risk-shared commercial insurance contract. METHODS: Administrative claims data from 2015 through 2016 for patients attributed to a single risk-shared commercial insurance contract at a large academic medical center (AMC) were analyzed. Primary outcome was MRI leakage: an outpatient MRI study performed at a site not affiliated with the AMC's integrated health care system. Ordering provider alignment with the AMC's risk-shared insurance contract was categorized as strong, weak, or none. Multivariate regression analyses were conducted to evaluate the relationship between provider alignment and MRI leakage, while adjusting for selected covariates. RESULTS: Among 8,215 patients meeting inclusion criteria, there were 13,272 MRI encounters. The overall proportion of leaked MRI studies was 12.7%. MRI studies ordered by providers with weak AMC alignment (odds ratio, 3.16; 95% confidence interval, 2.49-4.02) or no AMC alignment (odds ratio, 3.68; 95% confidence interval, 3.12-4.33) were more likely to leak than MRI studies ordered by providers with strong AMC alignment. CONCLUSIONS: An ordering provider with no alignment with an AMC's commercial risk-shared insurance contract was the strongest predictor of MRI leakage. Population health management initiatives aimed at reducing leakage should consider the impact of provider networks and clinical referral patterns that drive imaging utilization.

The appropriateness of imaging: a comprehensive conceptual framework.

This review seeks to clarify and explicate an elusive concept: the appropriateness of diagnostic imaging. To ensure a common basis for discussion, several key components are articulated and defined. These include the diagnostic imaging procedure (DIP) itself, the subject (a patient), and the setting (a clinical scenario) in which the DIP is being considered. A review of the literature shows that appropriateness is a logical extension of empiric research, which has revealed substantial variation in the type and intensity of health services delivered to otherwise similar populations and communities in the United States. Against this background, the appropriate rate of a service in a population is transformed into appropriateness for an individual patient, which, when defined in terms of expected net health outcome, provides a conceptual link with the denominator of cost-effectiveness analysis. The complementary roles of clinical trials, technology assessment, decision-analytic modeling, and consensus methods in estimating appropriateness are compared and contrasted.

Effect of computerized order entry with integrated decision support on the growth of outpatient procedure volumes: seven-year time series analysis.

PURPOSE: To determine the effect of a computerized radiology order entry (ROE) and decision support (DS) system on growth rate of outpatient computed tomography (CT), magnetic resonance (MR) imaging, and ultrasonography (US) procedure volumes over time at a large metropolitan academic medical center. MATERIALS AND METHODS: Institutional review board approval was obtained for this study of deidentified aggregate administrative data. The research was compliant with HIPAA; informed consent was waived. This was a retrospective study of outpatient advanced imaging utilization before, during, and after implementation of a Web-based ROE and DS system. Dependent variables were the quarterly volumes of outpatient CT, MR imaging, and US examinations from quarter 4 of 2000 through quarter 4 of 2007. Outpatient visits during each quarter were included as control variables. These data were analyzed as three separate time series with piecewise linear regression for simultaneous estimation of quarterly examination volume trends before and after ROE and DS system implementation. This procedure was repeated with log-transformed quarterly volumes to estimate percentage growth rates. RESULTS: There was a significant decrease in CT volume growth (274 per quarter) and growth rate (2.75% per quarter) after ROE and DS system implementation (P < .001). For MR imaging, growth rate decreased significantly (1.2%, P = .016) after ROE and DS system implementation; however, there was no significant change in quarterly volume growth. With US, quarterly volume growth (n = 98, P = .014) and growth rate (1.3%, P = .001) decreased significantly after ROE implementation. These changes occurred during a steady growth in clinic visit volumes in the associated referral practices. CONCLUSION: Substantial decreases in the growth of outpatient CT and US procedure volume coincident with ROE implementation (supplemented by DS for CT) were observed. The utilization of outpatient MR imaging decreased less impressively, with only the rate of growth being significantly lower after interventions were in effect.

Recommendations for additional imaging in radiology reports: multifactorial analysis of 5.9 million examinations.

PURPOSE: To quantify the rates of recommendation for additional imaging (RAI) in a large number of radiology reports of different modalities and to estimate the effects of 11 clinically relevant factors. MATERIALS AND METHODS: This HIPAA compliant research was approved by the institutional review board under an expedited protocol for analyzing anonymous aggregated radiology data. All diagnostic imaging examinations (n = 5 948 342) interpreted by radiologists between 1995 and 2008 were studied. A natural language processing technique specifically designed to extract information about any recommendations from radiology report texts was used. The analytic data set included three quantitative variables: the interpreting radiologist's experience, the year of study, and patient age. Categoric variables described patient location (inpatient, outpatient, emergency department), whether a resident dictated the case, patient sex, modality, body area studied, ordering service, radiologist's specialty division, and whether the examination result was positive. A multivariable logistic regression model was used to determine the effect of each of these factors on likelihood of RAI while holding all others equal. RESULTS: Recommendations increased during the 13 years of study, with the unadjusted rate rising from roughly 6% to 12%. After accounting for all other factors, the odds of any one examination resulting in an RAI increased by 2.16 times (95% confidence interval: 2.12, 2.21) from 1995 to 2008. As radiologist experience increased, the odds of an RAI decreased by about 15% per decade. Studies that had positive findings were more likely (odds ratio = 5.03; 95% confidence interval: 4.98, 5.07) to have an RAI. The remaining factors also had significant effects on the tendency for an RAI. CONCLUSION: The likelihood of RAI increased by 15% for each decade of radiologist experience and roughly doubled over 13 years of study.

Evidence-based imaging guidelines and Medicare payment policy.

OBJECTIVE: This study examines the relationship between evidence-based appropriateness criteria for neurologic imaging procedures and Medicare payment determinations. The primary research question is whether Medicare is more likely to pay for imaging procedures as the level of appropriateness increases. DATA SOURCES: The American College of Radiology Appropriateness Criteria (ACRAC) for neurological imaging, ICD-9-CM codes, CPT codes, and payment determinations by the Medicare Part B carrier for Florida and Connecticut. STUDY DESIGN: Cross-sectional study of appropriateness criteria and Medicare Part B payment policy for neurological imaging. In addition to descriptive and bivariate statistics, multivariate logistic regression on payment determination (yes or no) was performed. DATA COLLECTION METHODS: The American College of Radiology Appropriateness Criteria (ACRAC) documents specific to neurological imaging, ICD-9-CM codes, and CPT codes were used to create 2,510 medical condition/imaging procedure combinations, with associated appropriateness scores (coded as low/middle/high). PRINCIPAL FINDINGS: As the level of appropriateness increased, more medical condition/imaging procedure combinations were payable (low = 61 percent, middle = 70 percent, and high = 74 percent). Logistic regression indicated that the odds of a medical condition/imaging procedure combination with a middle level of appropriateness being payable was 48 percent higher than for an otherwise similar combination with a low appropriateness score (95 percent CI on odds ratio=1.19-1.84). The odds ratio for being payable between high and low levels of appropriateness was 2.25 (95 percent CI: 1.66-3.04). CONCLUSIONS: Medicare could improve its payment determinations by taking advantage of existing clinical guidelines, appropriateness criteria, and other authoritative resources for evidence-based practice. Such an approach would give providers a financial incentive that is aligned with best-practice medicine. In particular, Medicare should review and update its payment policies to reflect current information on the appropriateness of alternative imaging procedures for the same medical condition.

Avoiding errors in reasoning: an introduction to logical fallacies.

OBJECTIVE: The objective of this article is to provide all students of radiology, from novices to experts, a framework for understanding common errors in reasoning. CONCLUSION: By familiarizing ourselves with common fallacies, we can take steps to reduce the probability that we will commit such errors or fail to recognize and respond appropriately to them when they occur.

Intrapartum antibiotic prophylaxis 1: relative effects of recommended antibiotics on gram-negative pathogens.

OBJECTIVE: To assess whether the antibiotic chosen for intrapartum antibiotic prophylaxis affects the subsequent exposure of the neonate to ampicillin-resistant gram-negative bacteria. METHODS: We performed a randomized clinical trial of ampicillin versus penicillin for intrapartum antibiotic prophylaxis. Genital tract cultures for Enterobacteriaceae were obtained at study entry and 8-36 hours postpartum. Organisms were isolated, identified, and tested for ampicillin susceptibility. RESULTS: The ampicillin (n = 175) and penicillin (n = 177) groups, respectively, did not differ in rates of ampicillin-resistant Escherichia coli at entry (25% versus 22%, P =.57) or postpartum (36% versus 38%, P =.64). Similarly, groups did not differ in rates of ampicillin-resistant Enterobacteriaceae at entry (38% versus 32%, P =.23) or postpartum (51% versus 55%, P =.46). However, postpartum culture rates of resistant Escherichia coli were higher than entry culture rates for both the ampicillin (36% versus 25%, P =.026) and penicillin (38% versus 22%, P <.001) groups. Postpartum culture rates of resistant Enterobacteriaceae were also higher than entry culture rates for both the ampicillin (51% versus 38%, P <.001) and penicillin (55% versus 32%, P <.001) groups. Results were similar when considering only women who received two or more doses and no additional antibiotics. CONCLUSION: Intrapartum antibiotic prophylaxis with either ampicillin or penicillin increases exposure of neonates to ampicillin-resistant Enterobacteriaceae.

MR imaging of the trigeminal ganglion, nerve, and the perineural vascular plexus: normal appearance and variants with correlation to cadaver specimens.

BACKGROUND AND PURPOSE: MR imaging is the method of choice for evaluating the trigeminal nerve. Detection of abnormalities such as perineural tumor spread requires detailed knowledge of the normal MR appearance of the trigeminal nerve and surrounding structures. The purpose of this study was to clarify the normal MR appearance and variations of the trigeminal ganglion, maxillary nerve (V2), and mandibular nerve (V3) with their corresponding perineural vascular plexus. METHOD: S: MR images obtained in 32 patients without symptoms referable to the trigeminal nerve were retrospectively reviewed. The trigeminal ganglion in Meckel's cave, V2 within the foramen rotundum, and V3 at the level of foramen ovale were assessed for visualization and enhancement. The configuration of the perineural vascular plexus was recorded. Correlation to cadaver specimens was made. RESULTS: The trigeminal ganglion and V3 were observed to enhance in 3-4% of patients unilaterally. V2 and V3 were well visualized 93% of the time. The perineural vascular plexus of V2 was observed 91% of the time, and that of V3 in 97% of instances. CONCLUSION: This study characterizes the normal MR appearance of the trigeminal ganglion and its proximal branches. The trigeminal ganglion, V2, and, V3 are almost always reliably seen on thin-section MR studies of the skull base. Enhancement of the perivascular plexus is routinely seen; however, enhancement of the trigeminal ganglion, V2, or V3 alone is seen only on occasion as supported by the avascular appearance of these anatomic structures in cadaver specimens.

In support of the ACR Appropriateness Criteria.

The American College of Radiology Appropriateness Criteria were recently revised and translated into a new electronic format searchable online. They are also now being used as the basis for decision support logic underlying computerized radiology order entry. This article addresses some previous criticisms of the structure and output of the American College of Radiology expert panel process. Although there is certainly room for improvement, the conceptual framework and methodology underlying the appropriateness criteria are sound and do not need to be drastically altered.

Comparison of N-butyl cyanoacrylate and onyx for the embolization of intracranial arteriovenous malformations: analysis of fluoroscopy and procedure times.

OBJECTIVE: Intracranial arteriovenous malformations (AVM) may be managed through staged preoperative embolization and resection. Two commonly used liquid embolics are N-butyl cyanoacrylate (nBCA; Cordis Microvascular, Inc., New Brunswick, NJ) and Onyx (ev3, Inc., Irvine, CA). We sought to compare the utility of these agents in terms of fluoroscopy and procedure times. METHODS: All intracranial AVMs embolized from 2002 to 2006 at the University of Florida were included in this study. Patients were stratified into three treatment groups: nBCA, Onyx, and patients who received both nBCA and Onyx during separate embolizations. Cohorts were compared by sex, age, Spetzler-Martin grade, AVM volume, fluoroscopy time, procedure time, surgical blood loss, and complications. RESULTS: A total of 182 embolizations were performed on 88 patients (nBCA, 60 patients and 106 procedures; Onyx, 20 patients and 43 procedures; and nBCA/Onyx, eight patients and 16 nBCA and 17 Onyx procedures). There were no significant differences in patient demographics, AVM volumes, and Spetzler-Martin grades. Mean fluoroscopy and procedure times were increased for Onyx (57 min; 2.6 h) compared with nBCA (37 min; 2.1 h) embolizations (P < 0.0001 and P = 0.001, respectively). Cumulative mean fluoroscopy time was increased for Onyx (135 min) and nBCA/Onyx (180 min) cohorts relative to nBCA (64 min; P < 0.0001). Cumulative mean procedure time was increased in the nBCA/Onyx group (10.4 h) compared with nBCA (3.7 h) and Onyx (5.4 h; P < 0.0001). Seventy patients (80%) underwent AVM resection. No significant differences in surgical blood loss or complication rates were observed among the cohorts. CONCLUSION: Onyx AVM embolization requires increased fluoroscopy and procedure times compared with nBCA. Further investigation is necessary to justify increased radiation exposure and procedure time associated with Onyx.

Bottleneck factor and height-width ratio: association with ruptured aneurysms in patients with multiple cerebral aneurysms.

OBJECTIVE: Determining factors predictive of the natural risk of rupture of cerebral aneurysms is difficult because of the need to control for confounding variables. We studied factors associated with rupture in a study model of patients with multiple cerebral aneurysms, one aneurysm that had ruptured and one or more that had not, in which each patient served as their own internal control. METHODS: We collected aneurysm location, one-dimensional measurements, and two-dimensional indices from the computed tomographic angiograms of patients in the proposed study model and compared ruptured versus unruptured aneurysms. Bivariate statistics were supplemented with multivariable logistic regression analysis to model ruptured status. A total of 40 candidate models were evaluated for predictive power and fit with Wald scoring, Cox and Snell R2, Hosmer and Lemeshow tests, case classification counting, and residual analysis to determine which of the computed tomographic angiographic measurements or indices were jointly associated with and predictive of aneurysm rupture. RESULTS: Thirty patients with 67 aneurysms (30 ruptured, 37 unruptured) were studied. Maximum diameter, height, maximum width, bulge height, parent artery diameter, aspect ratio, bottleneck factor, and aneurysm/parent artery ratio were significantly (P < 0.05) associated with ruptured aneurysms on bivariate analysis. When best subsets and stepwise multivariable logistic regression was performed, bottleneck factor (odds ratio = 1.25, confidence interval = 1.11-1.41 for every 0.1 increase) and height-width ratio (odds ratio = 1.23, confidence interval = 1.03-1.47 for every 0.1 increase) were the only measures that were significantly predictive of rupture. CONCLUSION: In a case-control study of patients with multiple cerebral aneurysms, increased bottleneck factor and height-width ratio were consistently associated with rupture.