The Effect of an Automated Mobile Patient Engagement Application on Emergency Department Revisits: Prospective Observational Study

Background

Revisits within 30 days to an emergency department (ED), observation care unit, or inpatient setting following patient discharge continue to be a challenge, especially in urban settings. In addition to the consequences for the patient, these revisits have a negative impact on a health system’s finances in a value-based care or global budget environment. LifeBridge Health, a community health system in Maryland, United States, implemented an automated mobile patient engagement application as part of our enterprise-wide digital health strategy to improve patient engagement and reduce revisits to the ED.

Objective

The aim of this paper was to evaluate the effectiveness of a customized automated digital patient engagement application (GetWell Loop) to reduce 30-day revisits after home discharge from an ED.

Methods

The LifeBridge Health Innovation Department and ED staff from 2 participating health system hospitals collaborated with GetWellNetwork to customize their patient engagement application with automated check-in questions and other on-demand resources (eg, streaming content explaining aspects of self-care during COVID-19). An application link was emailed to adult patients discharged home from the ED. A study of ED visits for patients treated for general medicine and cardiology conditions between August 1, 2018, and July 31, 2019, was conducted using CRISP (Chesapeake Regional Information System for our Patients), Maryland’s state-designated health information exchange. We also used data within GetWell Loop (GetWellNetwork) to track patient activation and engagement. The primary outcome was the number of ED patients who experienced a 30-day revisit and who did or did not activate their GetWell Loop account. Secondary outcomes included the overall activation rate and the rate of engagement as measured by the number of logins, alerts, and comments generated by patients through the application. Bivariate analysis comparing outcomes among patients who activated the GetWell Loop application to patients who did not was conducted using the Fisher exact test. Multivariate logistic regression modeling with elastic net regularization was also performed to account for potential confounders and potential collinearity of covariates.

Results

During this 1-year study, 1062 (27.4%) of 3866 of all emergency patients treated for general medicine or cardiology conditions, who received an invite to use the digital application, activated their account. The patients discharged from the ED, who were treated for general medicine conditions (n=2087) and who activated their GetWell Loop account, experienced a 30-day revisit rate of 17.3% (n=101) compared with 24.6% (n=369) for those who did not activate their account (P<.001). Of the patients treated for cardiology conditions (n=1779), 12.8% (n=61) of those who activated their GetWell account experienced a 30-day revisit compared with 17.7% (n=231) of those who did not activate their account (P=.01). The significance of these findings persisted after adjustment for confounding variables including age, race, sex, and payor in logistic regression modeling (adjusted odds ratio 0.75, 95% CI 0.62-0.92; P=.006).

Conclusions

Our results suggest that a significant percentage of patients are willing to utilize a digital application following ED discharge to better engage in their own care, and that usage of such digital applications may significantly reduce 30-day revisit rates. LifeBridge Health’s experience demonstrates that health care systems can leverage automated mobile apps to improve patient engagement and successfully impact clinical outcomes at scale.

Stratifying Deterioration Risk by Acuity at Admission Offers Triage Insights for Coronavirus Disease 2019 Patients

OBJECTIVES

Triaging patients at admission to determine subsequent deterioration risk can be difficult. This is especially true of coronavirus disease 2019 patients, some of whom experience significant physiologic deterioration due to dysregulated immune response following admission. A well-established acuity measure, the Rothman Index, is evaluated for stratification of patients at admission into high or low risk of subsequent deterioration.

DESIGN

Multicenter retrospective study.

SETTING

One academic medical center in Connecticut, and three community hospitals in Connecticut and Maryland.

PATIENTS

Three thousand four hundred ninety-nine coronavirus disease 2019 and 14,658 noncoronavirus disease 2019 adult patients admitted to a medical service between January 1, 2020, and September 15, 2020.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Performance of the Rothman Index at admission to predict in-hospital mortality or ICU utilization for both general medical and coronavirus disease 2019 populations was evaluated using the area under the curve. Precision and recall for mortality prediction were calculated, high- and low-risk thresholds were determined, and patients meeting threshold criteria were characterized. The Rothman Index at admission has good to excellent discriminatory performance for in-hospital mortality in the coronavirus disease 2019 (area under the curve, 0.81-0.84) and noncoronavirus disease 2019 (area under the curve, 0.90-0.92) populations. We show that for a given admission acuity, the risk of deterioration for coronavirus disease 2019 patients is significantly higher than for noncoronavirus disease 2019 patients. At admission, Rothman Index-based thresholds segregate the majority of patients into either high- or low-risk groups; high-risk groups have mortality rates of 34-45% (coronavirus disease 2019) and 17-25% (noncoronavirus disease 2019), whereas low-risk groups have mortality rates of 2-5% (coronavirus disease 2019) and 0.2-0.4% (noncoronavirus disease 2019). Similarly large differences in ICU utilization are also found.

CONCLUSIONS

Acuity level at admission may support rapid and effective risk triage. Notably, in-hospital mortality risk associated with a given acuity at admission is significantly higher for coronavirus disease 2019 patients than for noncoronavirus disease 2019 patients. This insight may help physicians more effectively triage coronavirus disease 2019 patients, guiding level of care decisions and resource allocation.

Improving Awareness of LGBTQ Patient Preferences Among Radiology Staff Members

BACKGROUND

Our health system set out to improve services to patients from the LGBTQ community as a step towards decreasing disparities in care.

MATERIALS AND METHODS

A pilot education intervention targeting staff knowledge and skills regarding terminology with regards to gender fluidity and sexual orientation was designed and implemented.

RESULTS

81 staff members participated and we found improvements in knowledge but there remain uncertainties that can be addressed in future training sessions.

CONCLUSIONS

LGBTQ staff education in radiology is feasible and effective. Additional education interventions may be necessary to address persistent knowledge gaps. Effects on patient acre are yet unknown.

Report of the ACR's Economics Committee on Value-Based Payment Models

A major outcome of the current health care reform process is the move away from unrestricted fee-for-service payment models toward those that are based on the delivery of better patient value and outcomes. The authors' purpose, therefore, is to critically evaluate and define those components of the overall imaging enterprise that deliver meaningful value to both patients and referrers and to determine how these components might be measured and quantified. These metrics might then be used to lobby providers and payers for sustainable payment solutions for radiologists and radiology services. The authors evaluated radiology operations and services using the framework of the imaging value chain, which divides radiology service into a number of discrete value-added activities, which ultimately deliver the primary product, most often the actionable report for diagnostic imaging or an effective outcome for interventional radiology. These value activities include scheduling and imaging appropriateness and stewardship, patient preparation, protocol design, modality operations, reporting, report communication, and clinical follow-up (eg, mammography reminder letters). Two further categories are hospital or health care organization citizenship and examination outcome. Each is discussed in turn, with specific activities highlighted.

Partnering With Your Health System to Select and Implement Clinical Decision Support for Imaging

Recent legislation mandates the documentation of appropriateness criteria consultation when ordering advanced imaging for Medicare patients to remain eligible for reimbursement. Implementation of imaging clinical decision support (CDS) is a solution adopted by many systems to automate compliance with the new requirements. This article is intended to help radiologists who are employed by, contracted with, or otherwise affiliated with systems planning to implement CDS in the near future and ensure that they are able to understand and contribute to the process wherever possible. It includes an in-depth discussion of the legislation, evidence for and against the efficacy of imaging CDS, considerations for selecting a CDS vendor, tips for configuring CDS in a fashion consistent with departmental goals, and pointers for implementation and change management.

Physicians' Perceptions of Radiation Dose Quantity Depend on the Language in Which It Is Expressed

PURPOSE

Radiation dose information is increasingly requested by nonradiology providers, but there are no standard methods for communicating dose. The aim of this study was to compare physicians' perceptions of the amount of radiation associated with similar dose quantities expressed using different dose terms to evaluate the impact of word choice on physicians' understanding of radiation dose.

METHODS

Internal medicine and pediatric residents were surveyed online for 42 days. After obtaining demographics and training levels, respondents were asked to rank five different radiation dose quantities, each corresponding to one of the five ACR relative radiation levels (RRLs) expressed using different dose terms. Respondents ranked the choices from least to greatest (ie, from 1 to 5) or indicated if all five were equal. For the final question, the same dose quantity was expressed five different ways.

RESULTS

Fifty-one medicine and 45 pediatric residents responded (a 44% response rate). Mean differences in rankings were as follows: for chest x-rays, 0.109 (95% confidence interval [CI], -0.018 to 0.236); for cross-country flights, 0.462 (95% CI, 0.338 to 0.585); for natural background radiation, -0.672 (95% CI, -0.793 to -0.551); for cancer risk, -0.294 (95% CI, -0.409 to -0.178); and for ACR RRL, 0.239 (95% CI, 0.148 to 0.329). Statistically significant differences were found in the distributions of rankings (P < .001) and percentage of correct rankings across each radiation dose term (P < .001), with the ACR RRL having the highest percentage of correct rankings (61.2%).

CONCLUSIONS

Adult and pediatric physicians consistently over- or underestimated radiation dose quantities using different terms to express radiation dose. These results suggest that radiation dose information should be communicated using standard terminology such as the ACR RRL scale to foster consistency and improve the accuracy of physicians' radiation risk perceptions.

How to Reduce Head CT Orders in Children with Hydrocephalus Using the Lean Six Sigma Methodology: Experience at a Major Quaternary Care Academic Children's Center

BACKGROUND AND PURPOSE

Lean Six Sigma methodology is increasingly used to drive improvement in patient safety, quality of care, and cost-effectiveness throughout the US health care delivery system. To demonstrate our value as specialists, radiologists can combine lean methodologies along with imaging expertise to optimize imaging elements-of-care pathways. In this article, we describe a Lean Six Sigma project with the goal of reducing the relative use of pediatric head CTs in our population of patients with hydrocephalus by 50% within 6 months.

MATERIALS AND METHODS

We applied a Lean Six Sigma methodology using a multidisciplinary team at a quaternary care academic children's center. The existing baseline imaging practice for hydrocephalus was outlined in a Kaizen session, and potential interventions were discussed. An improved radiation-free workflow with ultrafast MR imaging was created. Baseline data were collected for 3 months by using the departmental radiology information system. Data collection continued postintervention and during the control phase (each for 3 months). The percentage of neuroimaging per technique (head CT, head ultrasound, ultrafast brain MR imaging, and routine brain MR imaging) was recorded during each phase.

RESULTS

The improved workflow resulted in a 75% relative reduction in the percentage of hydrocephalus imaging performed by CT between the pre- and postintervention/control phases (Z-test, P = .0001).

CONCLUSIONS

Our lean interventions in the pediatric hydrocephalus care pathway resulted in a significant reduction in head CT orders and increased use of ultrafast brain MR imaging.

Short-term outcomes after perinatal hypoxic ischemic encephalopathy: a report from the Children's Hospitals Neonatal Consortium HIE focus group

OBJECTIVE

To characterize infants affected with perinatal hypoxic ischemic encephalopathy (HIE) who were referred to regional neonatal intensive care units (NICUs) and their related short-term outcomes.

STUDY DESIGN

This is a descriptive study evaluating the data collected prospectively in the Children's Hospital Neonatal Database, comprised of 27 regional NICUs within their associated children's hospitals. A consecutive sample of 945 referred infants born ⩾36 weeks' gestation with perinatal HIE in the first 3 days of life over approximately 3 years (2010-July 2013) were included. Maternal and infant characteristics are described. Short-term outcomes were evaluated including medical comorbidities, mortality and status of survivors at discharge.

RESULT

High relative frequencies of maternal predisposing conditions, cesarean and operative vaginal deliveries were observed. Low Apgar scores, profound metabolic acidosis, extensive resuscitation in the delivery room, clinical and electroencephalographic (EEG) seizures, abnormal EEG background and brain imaging directly correlated with the severity of HIE. Therapeutic hypothermia was provided to 85% of infants, 15% of whom were classified as having mild HIE. Electrographic seizures were observed in 26% of the infants. Rates of complications and morbidities were similar to those reported in prior clinical trials and overall mortality was 15%.

CONCLUSION

Within this large contemporary cohort of newborns with perinatal HIE, the application of therapeutic hypothermia and associated neurodiagnostic studies appear to have expanded relative to reported clinical trials. Although seizure incidence and mortality were lower compared with those reported in the trials, it is unclear whether this represented improved outcomes or therapeutic drift with the treatment of milder disease.

The Children's Hospitals Neonatal Database: an overview of patient complexity, outcomes and variation in care

The Children's Hospitals Neonatal Consortium is a multicenter collaboration of leaders from 27 regional neonatal intensive care units (NICUs) who partnered with the Children's Hospital Association to develop the Children's Hospitals Neonatal Database (CHND), launched in 2010. The purpose of this report is to provide a first summary of the population of infants cared for in these NICUs, including representative diagnoses and short-term outcomes, as well as to characterize the participating NICUs and institutions. During the first 2 1/2 years of data collection, 40910 infants were eligible. Few were born inside these hospitals (2.8%) and the median gestational age at birth was 36 weeks. Surgical intervention (32%) was common; however, mortality (5.6%) was infrequent. Initial queries into diagnosis-specific inter-center variation in care practices and short-term outcomes, including length of stay, showed striking differences. The CHND provides a contemporary, national benchmark of short-term outcomes for infants with uncommon neonatal illnesses. These data will be valuable in counseling families and for conducting observational studies, clinical trials and collaborative quality improvement initiatives.

Expert witness blinding strategies to mitigate bias in radiology malpractice cases: a comprehensive review of the literature

Like all physicians, radiologists in the United States are subject to frequent and costly medical malpractice claims. Legal scholars and physicians concur that the US civil justice system is neither precise nor accurate in determining whether malpractice has truly occurred in cases in which claims are made. Sometimes, this inaccuracy is driven by biases inherent in medical expert-witness opinions. For example, expert-witness testimony involving "missed" radiology findings can be negatively affected by several cognitive biases, such as contextual bias, hindsight bias, and outcome bias. Biases inherent in the US legal system, such as selection bias, compensation bias, and affiliation bias, also play important roles. Fortunately, many of these biases can be significantly mitigated or eliminated through the use of appropriate blinding techniques. This paper reviews the major works on expert-witness blinding in the legal scholarship and the radiology professional literature. Its purpose is to acquaint the reader with the evidence that unblinded expert-witness testimony is tainted by multiple sources of bias and to examine proposed strategies for addressing these biases through blinding.

Predicting death or tracheostomy placement in infants with severe bronchopulmonary dysplasia

OBJECTIVE

To estimate the risk of death or tracheostomy placement (D/T) in infants with severe bronchopulmonary dysplasia (sBPD) born < 32 weeks' gestation referred to regional neonatal intensive care units.

STUDY DESIGN

We conducted a retrospective cohort study in infants born < 32 weeks' gestation with sBPD in 2010-2011, using the Children's Hospital Neonatal Database. sBPD was defined as the need for FiO2 ⩾ 0.3, nasal cannula support >2 l min(-1) or positive pressure at 36 weeks' post menstrual age. The primary outcome was D/T before discharge. Predictors associated with D/T in bivariable analyses (P < 0.2) were used to develop a multivariable logistic regression equation using 80% of the cohort. This equation was validated in the remaining 20% of infants.

RESULT

Of 793 eligible patients, the mean gestational age was 26 weeks' and the median age at referral was 6.4 weeks. D/T occurred in 20% of infants. Multivariable analysis showed that later gestational age at birth, later age at referral along with pulmonary management as the primary reason for referral, mechanical ventilation at the time of referral, clinically diagnosed pulmonary hypertension, systemic corticosteroids after referral and occurrence of a bloodstream infection after referral were each associated with D/T. The model performed well with validation (area under curve 0.86, goodness-of-fit χ(2), P = 0.66).

CONCLUSION

Seven clinical variables predicted D/T in this large, contemporary cohort with sBPD. These results can be used to inform clinicians who counsel families of affected infants and to assist in the design of future prospective trials.

Characterization of peripheral nerve sheath tumors with 3T proton MR spectroscopy

BACKGROUND AND PURPOSE

The characterization of peripheral nerve sheath tumors is challenging. The purpose here was to investigate the diagnostic value of quantitative proton MR spectroscopy at 3T for the characterization of peripheral nerve sheath tumors as benign or malignant, compared with PET.

MATERIALS AND METHODS

Twenty participants with 24 peripheral nerve sheath tumors underwent MR spectroscopy by use of a point-resolved sequence (TE, 135 ms). Six voxels were placed in 4 histologically proven malignant peripheral nerve sheath tumors and 22 voxels in 20 benign peripheral nerve sheath tumors (9 histologically proven, 11 with documented stability). The presence or absence of a trimethylamine signal was evaluated, the trimethylamine concentration estimated by use of phantom replacement methodology, and the trimethylamine fraction relative to Cr measured. MR spectroscopy results for benign and malignant peripheral nerve sheath tumors were compared by use of a Mann-Whitney test, and concordance or discordance with PET findings was recorded.

RESULTS

In all malignant tumors and in 9 of 18 benign peripheral nerve sheath tumors, a trimethylamine peak was detected, offering the presence of trimethylamine as a sensitive (100%), but not specific (50%), marker of malignant disease. Trimethylamine concentrations (2.2 ± 2.8 vs 6.6 ± 5.8 institutional units; P < .049) and the trimethylamine fraction (27 ± 42 vs 88 ± 22%; P < .012) were lower in benign than malignant peripheral nerve sheath tumors. A trimethylamine fraction threshold of 50% resulted in 100% sensitivity (95% CI, 58.0%-100%) and 72.2% (95% CI, 59.5%-75%) specificity for distinguishing benign from malignant disease. MR spectroscopy and PET results were concordant in 12 of 16 cases, (2 false-positive results for MR spectroscopy and PET each).

CONCLUSIONS

Quantitative measurement of trimethylamine concentration by use of MR spectroscopy is feasible in peripheral nerve sheath tumors and shows promise as a method for the differentiation of benign and malignant lesions. Trimethylamine presence within a peripheral nerve sheath tumor is a sensitive marker of malignant disease, but quantitative measurement of trimethylamine content is required to improve specificity.

Therapeutic interventions and short-term outcomes for infants with severe bronchopulmonary dysplasia born at <32 weeks' gestation

OBJECTIVE

To characterize the treatments and short-term outcomes in infants with severe bronchopulmonary dysplasia (sBPD) referred to regional neonatal intensive care units.

STUDY DESIGN

Infants born <32 weeks' gestation with sBPD were identified using the Children's Hospital Neonatal Database. Descriptive outcomes are reported.

RESULT

A total of 867 patients were eligible. On average, infants were born at 26 weeks' gestation and referred 43 days after birth. Infants frequently experienced lung injury (pneumonia: 24.1%; air leak: 9%) and received systemic corticosteroids (61%) and mechanical ventilation (median duration 37 days). Although 91% survived to discharge, the mean post-menstrual age was 47 weeks. Ongoing care such as supplemental oxygen (66%) and tracheostomy (5%) were frequently needed.

CONCLUSION

Referred infants with sBPD sustain multiple insults to lung function and development. Because affected infants have no proven, safe or efficacious therapy and endure an exceptional burden of care even after referral, urgent work is required to observe and improve their outcomes.

Characterization of soft tissue masses: can quantitative diffusion weighted imaging reliably distinguish cysts from solid masses?

OBJECTIVE

To investigate the accuracy of quantitative diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping for characterizing soft tissue masses (STMs) as cysts or solid masses.

MATERIALS AND METHODS

This IRB-approved retrospective study included 36 subjects with 37 STMs imaged by conventional MRI (T1-weighted, T2-weighted, contrast-enhanced T1-weighted sequences) and DWI (b-values 50, 400, 800 s/mm(2)) with ADC mapping. STMs were defined as non-solid cysts by histology or clinical follow-up, and as solid by histology. For each STM, ADC values (range, mean) were recorded by two observers. Differences between ADC values in cysts and solid STMs were compared using Wilcoxon rank-sum and receiver-operating characteristic (ROC) analysis.

RESULTS

There were higher minimum (1.65 vs 0.68, p = 0.003) and mean (2.31 vs 1.45, p = 0.005) ADC values in cysts than solid STMs respectively. Areas under the ROC for minimum and mean ADC values were 0.82 and 0.81 respectively. Using threshold ADC values of 1.8 (minimum) or 2.5 (mean) yielded a sensitivity of 60 % and 80 % respectively, and a specificity of 100 % for classifying a STM as a cyst; for tumors with high fluid-signal intensity, the performance of these threshold values was maintained.

CONCLUSION

Diffusion-weighted imaging with ADC mapping provides a non-contrast MRI alternative for the characterization of STMs as cysts or solid masses. Threshold ADC values exist that provide 100 % specificity for differentiating cysts and solid STMs, even for tumors of high fluid-signal intensity on T2-weighted images.

Detection of cytomegalovirus DNA in plasma as an adjunct diagnostic for gastrointestinal tract disease in kidney and liver transplant recipients

BACKGROUND

Cytomegalovirus (CMV) disease is the most common infectious complication after solid organ transplantation, frequently affecting the gastrointestinal (GI) tract. There are limited data on quantitative polymerase chain reaction (qPCR) for plasma CMV DNA as an adjunct diagnostic method for GI tract disease in kidney and liver transplant recipients.

METHODS

We reviewed all records of adult kidney and liver transplant recipients with a GI tract biopsy and plasma CMV qPCR result within 15 days of biopsy during a 6.5-year period at our center. CMV GI tract disease was defined as histopathologic evidence of CMV on biopsy by immunohistochemistry or visualization of inclusion bodies.

RESULTS

GI tract biopsy and qPCR results were available for 81 kidney and liver transplant recipients; 20 cases of confirmed CMV GI tract disease were identified. Overall, the sensitivity of qPCR for diagnosing CMV GI tract disease was 85% (95% confidence interval [CI], 61%-96%), and the specificity was 95% (95% CI, 85%-99%). For CMV-seronegative recipients (R(-)) with CMV-seropositive donors (D(+)), the sensitivity of qPCR was 100% (95% CI, 59%-99%), and the specificity was 80% (95% CI, 30%-99%). The lowest sensitivity was observed in CMV D(+)/R(+) cases (72.7%; 95% CI, 39%-93%). The mean plasma CMV copy number in patients with GI tract disease was 3.84 log10 (38 334 copies/mL).

CONCLUSIONS

Plasma CMV qPCR had good sensitivity and excellent specificity for CMV GI tract disease in kidney and liver transplant recipients. Its sensitivity was 100% in CMV D(+)/R(-) cases but 72.7% in CMV D(+)/R(+) cases. This variation in assay performance according to host serostatus may reflect differences in disease pathogenesis.

Increased error rates in preliminary reports issued by radiology residents working more than 10 consecutive hours overnight

RATIONALE AND OBJECTIVES

To determine if the rate of major discrepancies between resident preliminary reports and faculty final reports increases during the final hours of consecutive 12-hour overnight call shifts.

MATERIALS AND METHODS

Institutional review board exemption status was obtained for this study. All overnight radiology reports interpreted by residents on-call between January 2010 and June 2010 were reviewed by board-certified faculty and categorized as major discrepancies if they contained a change in interpretation with the potential to impact patient management or outcome. Initial determination of a major discrepancy was at the discretion of individual faculty radiologists based on this general definition. Studies categorized as major discrepancies were secondarily reviewed by the residency program director (M.H.S.) to ensure consistent application of the major discrepancy designation. Multiple variables associated with each report were collected and analyzed, including the time of preliminary interpretation, time into shift study was interpreted, volume of studies interpreted during each shift, day of the week, patient location (inpatient or emergency department), block of shift (2-hour blocks for 12-hour shifts), imaging modality, patient age and gender, resident identification, and faculty identification. Univariate risk factor analysis was performed to determine the optimal data format of each variable (ie, continuous versus categorical). A multivariate logistic regression model was then constructed to account for confounding between variables and identify independent risk factors for major discrepancies.

RESULTS

We analyzed 8062 preliminary resident reports with 79 major discrepancies (1.0%). There was a statistically significant increase in major discrepancy rate during the final 2 hours of consecutive 12-hour call shifts. Multivariate analysis confirmed that interpretation during the last 2 hours of 12-hour call shifts (odds ratio (OR) 1.94, 95% confidence interval (CI) 1.18-3.21), cross-sectional imaging modality (OR 5.38, 95% CI 3.22-8.98), and inpatient location (OR 1.81, 95% CI 1.02-3.20) were independent risk factors for major discrepancy.

CONCLUSIONS

In a single academic medical center, major discrepancies in resident preliminary reports increased significantly during the final 2 hours of consecutive 12-hour overnight call shifts. This finding could be related to either fatigue or circadian desynchronization. Discrimination of these two potential etiologies requires additional investigation as major discrepancies in resident reports have the potential to negatively impact patient care/outcome. Cross-sectional imaging modalities including computed tomography and ultrasound (versus conventional radiography), as well as inpatient location (versus Emergency Department location), were also associated with significantly higher major discrepancy rates.

MRI pyschophysics: an experimental framework relating image quality to diagnostic performance metrics

PURPOSE

To determine the minimal image quality needed to preserve diagnostic performance relative to arthroscopy in the knee.

MATERIALS AND METHODS

Synthetic noise was added to images from clinical MRI scans (three-dimensional SPACE pulse sequence; Siemens) from five patients who had undergone knee MRI with arthroscopic follow-up, resulting in 25 simulated sets of images with standardized signal-to-noise ratios (SNRs) of 1, 2, 5, 10, or 20. All cases were scored by four musculoskeletal radiologists progressing from low to high SNR and grading all cartilage surfaces, major ligaments and menisci on a 5-point scale. Receiver operator characteristic (ROC) curves were constructed for the detection of meniscal tears and cartilage abnormalities. The area under the ROC curve (AUC) was determined for each structure at each SNR level. In addition, reader confidence was measured and pairwise comparisons across SNR levels were performed. Results were compared with arthroscopy as the reference standard.

RESULTS

ROC AUC was maximized for meniscal tears at SNR = 5 (structure specific CNR = 3.2) and for cartilage abnormalities at SNR = 10 (CNR = 4.2). Observer confidence was maximized for menisci at SNR = 5 (CNR = 8.0), for ligaments at SNR = 10 (CNR = 13.6) and cartilage at SNR = 10 (CNR = 8.2).

CONCLUSION

For 3D isotropic imaging in the knee, images with SNR < 10 or CNR < 10 should be rejected as nondiagnostic.

The role of magnetic resonance imaging in the diagnostic evaluation of malignant peripheral nerve sheath tumors

BACKGROUND AND AIMS

Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of mortality in patients with neurofibromatosis type-1 (NF1)); however, they may also arise sporadically. Differences in magnetic resonance imaging (MRI) features between MPNSTs arising in NF1 subjects versus non-NF1 subjects have not been studied before. The accuracy of MRI in distinguishing MPNSTs from benign peripheral nerve sheath tumors (BPNSTs) has also been debated. The objective of this study was to determine the potential differentiating MRI features between (a) NF1-related and non-NF1-related MPNSTs and (b) MPNSTs and BPNSTs.

MATERIALS AND METHODS

We retrospectively evaluated the MRI studies of 21 patients (12 NF1 subjects and nine non-NF1 subjects) with MPNSTs and 35 patients with BPNSTs. In all studies, the lesions were assessed in terms of size, margins, T1 and T2 signal characteristics, internal architecture, pattern of contrast enhancement, invasion of adjacent structures and necrosis/cystic degeneration as well as for the presence of tail-, target- and split-fat signs.

RESULTS

MPNSTs of NF1 subjects occurred at an earlier age and displayed a higher incidence of necrosis/cystic degeneration compared with MPNSTs of non-NF1 subjects. Compared with BPNSTs, MPNSTs were significantly larger at the time of diagnosis and demonstrated a higher incidence of ill-defined margins (specificity 91%, sensitivity 52%) and invasion of adjacent structures (specificity 100%, sensitivity 43%).

CONCLUSIONS

Differences exist between NF1-related and non-NF1-related MPNSTs regarding the age of occurrence and MRI appearance. In the MRI evaluation of peripheral nerve sheath tumors, the presence of ill-defined tumor margins and/or invasion of adjacent structures are highly specific for malignancy.

MR imaging features of common variant spinal anatomy

The spine is one of the most commonly imaged body parts for all age groups, with indications ranging from congenital abnormalities at birth to degenerative pathology toward the end of life. Because of the importance of softtissue contrast when imaging the spine, MR imaging has become the most important modality in its evaluation. One of the key challenges in the clinical analysis of spinal MR imaging lies in the wide range of so-called normal variability. The goal of this article is not to provide the reader with an exhaustive atlas detailing the appearance of every known variant. Instead, the authors review the MR appearance of the most important variants and provide a logical and, they hope, memorable framework for assimilating this information into practice. To understand why these variations occur, the authors examine the aberrant pathways of embryology, growth, and development that lead to their formation.

Aging impairs the beneficial effect of granulocyte colony-stimulating factor and stem cell factor on post-myocardial infarction remodeling

Granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) are potential new therapies to ameliorate post-myocardial infarction (post-MI) remodeling, as they enhance endogenous cardiac repair mechanisms and decrease cardiomyocyte apoptosis. Because both of these pathways undergo alterations with increasing age, we hypothesized that therapeutic efficacy of G-CSF and SCF is impaired in old versus young adult rats. MI was induced in 6- and 20-month-old rats by permanent ligation of the left coronary artery. In young animals, G-CSF/SCF therapy stabilized and reversed a decline in cardiac function, attenuated left ventricular dilation, decreased infarct size, and reduced cardiomyocyte hypertrophy. Remarkably, these effects on cardiac structure and function were absent in aged rodents. This could not be attributed to ineffective mobilization of bone marrow cells or decreased quantity of c-Kit(+) cells within the myocardium with aging. However, whereas the G-CSF/SCF cocktail reduced cardiac myocyte apoptosis in old as well as in young hearts, the degree of reduction was substantially less with age and the rate of cardiomyocyte apoptosis in old animals remained high despite cytokine treatment. These findings demonstrate that G-CSF/SCF lacks therapeutic efficacy in old animals by failing to offset periinfarct apoptosis and therefore raise important concerns regarding the efficacy of novel cytokine therapies in elderly individuals at greatest risk for adverse consequences of MI.

Cardiac repair with intramyocardial injection of allogeneic mesenchymal stem cells after myocardial infarction

Although clinical trials of autologous whole bone marrow for cardiac repair demonstrate promising results, many practical and mechanistic issues regarding this therapy remain highly controversial. Here, we report the results of a randomized study of bone-marrow-derived mesenchymal stem cells, administered to pigs, which offer several new insights regarding cellular cardiomyoplasty. First, cells were safely injected by using a percutaneous-injection catheter 3 d after myocardial infarction. Second, cellular transplantation resulted in long-term engraftment, profound reduction in scar formation, and near-normalization of cardiac function. Third, transplanted cells were pre-prepared from an allogeneic donor and were not rejected, a major practical advance for widespread application of this therapy. Together, these findings demonstrate that the direct injection of cellular grafts into damaged myocardium is safe and effective in the perii-nfarct period. The direct delivery of cells to necrotic myocardium offers a valuable alternative to intracoronary cell injections, and the use of allogeneic mesenchymal stem cells provides a valuable strategy for cardiac regenerative therapy that avoids the need for preparing autologous cells from the recipient.

Computed tomography appearance of an intra-aortic balloon pump: a potential pitfall in diagnosis

The case of a patient with an indwelling intra-aortic balloon pump (IABP) who underwent computed tomography (CT) to rule out mesenteric ischemia is reported. Three-dimensional reconstruction revealed regularly spaced air-fluid levels within the aorta. Intra-aortic balloon pump function is reviewed, and it is shown that its artifactual appearance on CT results from the phase difference between the cardiac cycle and gantry speed. Recognizing and understanding the appearance of an IABP is important so as not confuse it with intra-aortic air, which suggests ischemia.

Mandatory versus selective preoperative carotid screening: a retrospective analysis

BACKGROUND

Extracranial internal carotid artery stenosis is a risk factor for perioperative stroke in coronary artery bypass (CAB) surgery. Although both selective and nonselective methods of preoperative carotid screening have been advocated, it is unclear which approach is most clinically efficacious.

METHODS

Hospital records for 1421 consecutive CAB patients from January 2000 through April 2002 were reviewed. Univariate and multivariate analyses were performed across selected parameters to identify risk factors for significant carotid stenosis (> or = 70%). Patients were retrospectively stratified into high- or low-risk groups based on risk factors common to carotid stenosis and perioperative stroke. The prevalence of carotid stenosis, surgical management, and perioperative stroke rates were determined for each group.

RESULTS

One-thousand one-hundred thirty-eight patients out of 1421 patients (80.1%) underwent preoperative carotid screening. The prevalence of significant carotid stenosis was 13.4%. Univariate risk factors for stenosis included an age of more than 65 years, peripheral vascular disease, prior cerebrovascular accident, history of cerebrovascular disease, left main coronary disease, carotid bruit, female gender, and hypertension. Carotid stenosis was a risk factor for stroke, neurologic injury, in-hospital mortality, and longer hospitalization. Prevalence of carotid stenosis was greater in high-risk patients (17.8%, N = 708) versus low-risk patients (6.1%, N = 426). Concomitant or staged carotid endarterectomy (CEA)/CAB was more commonly performed in the high-risk group (5.8% vs. 1%, p < 0.001). All nine patients with significant carotid stenosis who suffered perioperative strokes were in the high-risk group (9 out of 708 vs 0 out of 426, p = 0.016).

CONCLUSIONS

In our cohort, selectively screening only patients with either an age of more than 65, carotid bruit, or cerebrovascular disease would have reduced the screening load by nearly 40% with negligible impact on surgical management or neurologic outcomes.

Generation of molecular chiral asymmetry through stirred crystallization

In our earlier work we established that stirred crystallization of achiral compounds that crystallize in enantiomeric forms result in spontaneous chiral symmetry breaking. The asymmetry thus spontaneously generated is confined to the solid state. In this article, we present a case in which the crystal enantiomeric excess (CEE) can be converted to molecular enantiomeric excess (EE) through a solid state reaction which relates the enantiomeric form of the crystal to the enantiomeric form of the product. Such a process not only provides a means of detecting the CEE generated in stirred crystallization but it is also a means through which chiral asymmetry generated spontaneously is "propagated" to generate chiral compounds with enantiomeric excess.

Binding of correolide to the K(v)1.3 potassium channel: characterization of the binding domain by site-directed mutagenesis

Correolide is a novel immunosuppressant that inhibits the voltage-gated potassium channel K(v)1.3 [Felix et al. (1999) Biochemistry 38, 4922-4930]. [(3)H]Dihydrocorreolide (diTC) binds with high affinity to membranes expressing homotetrameric K(v)1.3 channels, and high affinity diTC binding can be conferred to the diTC-insensitive channel, K(v)3.2, after substitution of three nonconserved residues in S(5) and S(6) with the corresponding amino acids present in K(v)1.3 [Hanner et al. (1999) J. Biol. Chem. 274, 25237-25244]. Site-directed mutagenesis along S(5) and S(6) of K(v)1.3 was employed to identify those residues that contribute to high affinity binding of diTC. Binding of monoiodotyrosine-HgTX(1)A19Y/Y37F ([(125)I]HgTX(1)A19Y/Y37F) in the external vestibule of the channel was used to characterize each mutant for both tetrameric channel formation and levels of channel expression. Substitutions at Leu(346) and Leu(353) in S(5), and Ala(413), Val(417), Ala(421), Pro(423), and Val(424) in S(6), cause the most dramatic effect on diTC binding to K(v)1.3. Some of the critical residues in S(6) appear to be present in a region of the protein that alters its conformation during channel gating. Molecular modeling of the S(5)-S(6) region of K(v)1.3 using the X-ray coordinates of the KcsA channel, and other experimental constraints, yield a template that can be used to dock diTC in the channel. DiTC appears to bind in the water-filled cavity below the selectivity filter to a hydrophobic pocket contributed by the side chains of specific residues. High affinity binding is predicted to be determined by the complementary shape between the bowl-shape of the cavity and the shape of the ligand. The conformational change that occurs in this region of the protein during channel gating may explain the state-dependent interaction of diTC with K(v)1.3.

Neonatal high-frequency ventilation. Past, present, and future

High-frequency ventilation has become established as an effective treatment modality in a variety of clinical situations. The laboratory and clinical investigations of these techniques have contributed tremendously to our understanding of the pathophysiology of respiratory failure and the important concept of maintaining adequate lung volume. Clinicians have come to appreciate better the factors involved in lung injury and the potential for damage to distant organs. The place of HFV in the therapeutic armamentarium will undoubtedly continue to evolve in the years to come. Of particular interest is the advent of advanced modes of fully synchronized and volume-targeted conventional mechanical ventilatory modes, along with the trend to use smaller tidal volumes and higher levels of PEEP with conventional ventilation. With these developments there seems to be a certain convergence of HFV and tidal ventilation that is the logical result of our improved understanding of respiratory pathophysiology. The available controlled trials of HFV versus tidal ventilation do not clearly differentiate whether improved outcomes are the result of HFV per se, or a reflection of the effects of optimizing lung volume, a benefit that may not be unique to HFV.

Thrombolytic therapy for adhesion of percutaneous central venous catheters to vein intima associated with Malassezia furfur Infection

OBJECTIVE

To report our experience with thrombolytic agents in the management of two infants with silicone central venous catheters that had adhered to the vein wall as a result of infection with Malassezia furfur.

STUDY DESIGN

Case review of two very low birth weight infants with adherent central venous catheters.

RESULTS

Treatment with urokinase and tissue plasminogen activator facilitated the removal of these catheters without breakage or surgical intervention.

CONCLUSIONS

Thrombolytic agents should be considered as a treatment of adhered catheters, as well as of occluded catheters.

Chiral asymmetry in spiral galaxies?

Spiral galaxies are chiral entities when coupled with the direction of their recession velocity. As viewed from the Earth, the S-shaped and Z-shaped spiral galaxies are two chiral forms. What is the nature of chiral symmetry in spiral galaxies? In the Carnegie Atlas of Galaxies that lists photographs of a total of 1,168 galaxies, we found 540 galaxies, classified as normal or barred spirals, that are clearly identifiable as S- or Z- type. The recession velocities for 538 of these galaxies could be obtained from this atlas and other sources. A statistical analysis of this sample reveals no overall asymmetry but there is a significant asymmetry in certain subclasses: dominance of S-type galaxies in the Sb class of normal spiral galaxies and a dominance of Z-type in the SBb class of barred spiral galaxies. Both S- and Z-type galaxies seem to have similar velocity distribution, indicating no spatial segregation of the two chiral forms.

Early high-frequency oscillatory ventilation versus synchronized intermittent mandatory ventilation in very low birth weight infants: a pilot study of two ventilation protocols

OBJECTIVE

To evaluate the feasibility of conducting a prospective, randomized trial comparing early high-frequency oscillatory ventilation (HFOV) to synchronized intermittent mandatory ventilation (SIMV) in very low birth weight (VLBW) premature infants. This pilot study evaluated two ventilator management protocols to determine how well they could be implemented in a multicenter clinical trial. Although this pilot study was not powered to detect differences in outcome, we also collected outcome data.

DESIGN

Prospective, multicenter, randomized pilot study.

SETTING

Seven tertiary-level intensive care nurseries with previous experience with both HFOV and flow-triggered SIMV.

PATIENTS

Fifty infants weighing 501 to 1200 g, less than 4 hours of age, who had received one dose of surfactant and required ventilation with mean airway pressure > or =6 cm H2O and F(I)O2 > or =0.25, and had an anticipated duration of ventilation greater than 24 hours.

INTERVENTIONS

Patients were stratified by birth weight and prenatal steroid status, then randomized to either HFOV or SIMV with tidal volume monitoring. Ventilator management for patients in both study arms was strictly governed by protocols that included optimizing lung inflation and blood gases, weaning strategies, and extubation criteria.

MEASUREMENTS

Data were collected using the tools planned for the larger collaborative study. Protocol compliance was closely monitored, with successive changes in the protocol made as necessary to improve clarity and increase compliance. The incidence of major neonatal adverse outcomes was recorded.

MAIN RESULTS

Data are presented for 24 HFOV and 24 SIMV infants (two infants, twins, were withdrawn from the study at parent's request). Nineteen of the 24 HFOV infants and 20 of the 24 SIMV infants survived to 36 weeks corrected age. Age at final extubation for survivors was 16+/-16 (mean+/-SD) days for HFOV infants and 24+/-24 days for SIMV infants. At 36 weeks corrected age, 14 of the 19 HFOV survivors were extubated and in room air, whereas 5 required supplemental oxygen. In comparison, 6 of the 20 SIMV survivors were extubated and in room air, whereas 14 required supplemental oxygen. Grade III/IV IVH and/or periventricular leukomalacia occurred in 2 HFOV and 2 SIMV patients. Overall compliance with the ventilator protocols was 82% for the SIMV protocol, and 88% for the HFOV protocol.

CONCLUSIONS

The preliminary outcome data supports conducting the large randomized trial, which began in July of 1998. The protocols for the ventilator management of VLBW infants, both with HFOV and with SIMV were easily implemented and consistently followed, and are presented here.

Large enhancement of the sub-barrier fusion probability for a halo nucleus

The fusion-fission cross sections of the 4He+238U and 6He+238U systems have been measured, at Louvain-la-Neuve, for energies around and below the Coulomb barrier, using an array of Si detectors surrounding a UF4 target. The data taken with 4He are in good agreement with previous data and with the coupled channel fusion calculation performed with ECIS. The 6He data show a regular trend with a large enhancement below the barrier which is attributed to the halo structure of the 6He nucleus.

Peptide aldehyde inhibitors of bacterial peptide deformylases

Bacterial peptide deformylases (PDF, EC 3.5.1.27) are metalloenzymes that cleave the N-formyl groups from N-blocked methionine polypeptides. Peptide aldehydes containing a methional or norleucinal inhibited recombinant peptide deformylase from gram-negative Escherichia coli and gram-positive Bacillus subtilis. The most potent inhibitor was calpeptin, N-CBZ-Leu-norleucinal, which was a competitive inhibitor of the zinc-containing metalloenzymes, E. coli and B. subtilis PDF with Ki values of 26.0 and 55.6 microM, respectively. Cobalt-substituted E. coli and B. subtilis deformylases were also inhibited by these aldehydes with Ki values for calpeptin of 9.5 and 12.4 microM, respectively. Distinct spectral changes were observed upon binding of calpeptin to the Co(II)-deformylases, consistent with the noncovalent binding of the inhibitor rather than the formation of a covalent complex. In contrast, the chelator 1,10-phenanthroline caused the time-dependent inhibition of B. subtilis Co(II)-PDF activity with the loss of the active site metal. The fact that calpeptin was nearly equipotent against deformylases from both gram-negative and gram-positive bacterial sources lends further support to the idea that a single deformylase inhibitor might have broad-spectrum antibacterial activity.

Response of premature infants with severe respiratory failure to inhaled nitric oxide. Preemie NO Collaborative Group

Elevated pulmonary vascular resistance is seen in premature infants with severe respiratory distress syndrome (RDS). Inhaled nitric oxide (NO) has been shown to decrease pulmonary vascular resistance and to improve oxygenation in some patients with respiratory failure. The purpose of this study was to determine whether premature infants with severe RDS would respond to inhaled NO with an improvement in oxygenation. Eleven premature infants (mean gestational age 29.8 weeks) with severe respiratory failure caused by RDS were treated with NO in four concentrations [1, 5, 10, 20 parts per million (ppm) NO] and with placebo (0 ppm NO). Arterial blood gas measurements were drawn immediately before and at the end of each of the 15-minute treatments and were used to determine the arterial/alveolar oxygen ratio (PaO2/PAO2). Ten of the 11 infants had a greater than 25% increase in PaO2/PAO2. Five of the 11 had a greater than 50% increase in PaO2/PAO2. Despite normal cranial ultrasound imaging prior to NO, 3 infants had intracranial hemorrhage (ICH) noted on their first ultrasound scan after this brief period of NO treatment, and 4 additional infants developed ICH later during their hospitalization. No infant had significant elevations of methemoglobin concentrations after the total 60-minute exposure to NO. NO may be an effective method of improving oxygenation in infants with severe RDS. The disturbing incidence of ICH in this small group of infants needs to be carefully evaluated before considering routine use or NO for preterm infants.

Disruption of barrier function in neonatal skin associated with adhesive removal

OBJECTIVE

Patients in the neonatal intensive care unit require life support and monitoring equipment that must be securely attached to the skin; removal or replacement often causes skin trauma. In this study, we compared the effects of application and removal of three different adhesives on the skin barrier function of premature neonates. The effects were measured by transepidermal water loss (TEWL), colorimetric measurements, and visual inspection.

DESIGN

Thirty neonates, between 26 and 40 weeks of gestational age and with birth weights ranging from 690 to 3000 gm, were enrolled in the study during the first week of life. Pieces of plastic tape (1 cm2), pectin barrier, and hydrophilic gel were applied to previously undisturbed sites on the back. A fourth site was used as a control. We measured TEWL, colorimetric readings, and visual inspection scores of skin irritation and stripping at each of the four sites serially: before adhesive application, 30 minutes after adhesive removal, and 24 hours later.

RESULTS

Thirty minutes after adhesive removal, TEWL, colorimetric measurements, and visual inspection scores were all significantly higher at the sites of plastic tape and pectin barrier removal than at the control and gel adhesive sites (p < 0.01), demonstrating greater disruption of skin barrier function with removal of the plastic tape and pectin barrier. When the neonates were divided into three groups on the basis of birth weight (< 1000 gm [n = 10], 1000 to 1500 gm [n = 11], and > 1500 gm [n = 9], the same pattern of greater disruption in skin barrier function, as measured by TEWL, was observed in each birth weight group. Twenty-four hours after adhesive removal, TEWL of the plastic tape and pectin barrier sites were not significantly different from the control site, indicating recovery of skin barrier function.

CONCLUSIONS

This study demonstrates that a single application and removal of two commonly used adhesives, plastic tape and pectin barrier, disrupts skin barrier function in neonates of varying gestational ages.