P5282Comparison of cardiovascular magnetic resonance ejection fraction and left ventricular volumes by long axis feature tracking strain analysis versus standard short axis stack contour tracing

Introduction

Cardiovascular magnetic resonance (CMR) feature tracking (FT) is based on the recognition of endocardial features obtained during standard CMR cine imaging to be tracked and followed throughout the cardiac cycle. Global longitudinal strain (GLS) has been proposed as a superior measure for diagnosis and prognosis than ejection fraction (EF). However, EF remains an important primary parameter to describe cardiac function. A rapid determination of GLS based on three long axis views (LAX) allows for a simultaneous calculation of EF without additional imaging or post-processing promising a significant reduction of scan and post-processing time.

Purpose

The purpose of this work is to compare the LV volumes and EF obtained during assessment of GLS based on CMR feature tracking with standard analysis of a short axis (SAX) stack used as the reference standard.

Methods

75 consecutive patients underwent a routine clinical scan obtaining a full SAX stack as well as 3 standard LAX views using either 3-Tesla or 1,5-Tesla clinical scanners. We determined LV volumes and EF based on the reference standard as well as feature tracking analysis with additional GLS. A p value <0.01 was considered statistically significant.

Results

Mean EF was 45.9% using standard SAX (range, 13%-72%) and 51.1% using triplanar feature tracking (r=0.950; p<0.0001, figure 1A). Bland-Altman analysis showed a systematic bias of 5,27%; without proportional bias (figure 1B). End-diastolic volumes (r=0,975; p<0.0001) and end-systolic volumes (r=0.985; p<0.0001) demonstrated similar results. Mean GLS was −17.3% (range: −30,7% to −3,3%) and was significantly correlated with standard EF (r=−0,884; p<0.0001). Classification of EF into categories: reduced, mid-range or preserved (<40%, 40–49%, ≥50%) remain unchanged in 79% of patients when using EF by feature tracking analysis. Twelve of 16 reclassifications occurred in the mid-range category.

Figure 1

Conclusion

There is a good correlation between EF obtained by rapid post-processing of GLS with EF based on a full SAX stack resulting in an identical categorization in 79% of patients. Reduction of EF within the mid-range might be best assesses by the standard SAX stack.

P606High intermodality variability in ejection fraction measured by echocardiography, cardiac magnetic resonance and single photon emission computed tomography in chronic coronary artery disease patients

Background

Clinical treatment strategies are often based on measurement of left ventricular ejection fraction (LVEF). There is limited evidence about variations in LVEF when measured by different imaging modalities.

Purpose

To investigate the intermodality variability of LVEF measured by two-dimensional echocardiography (2DE), three-dimensional echocardiography (3DE), cardiac magnetic resonance (CMR), and single photon emission computed tomography (SPECT) in patients with chronic coronary artery disease (CAD).

Methods

Patients from a multicenter study (DOPPLER-CIP – Determining optimal noninvasive parameters for the prediction of left ventricular remodeling in chronic ischemic patients) with chronic CAD were included. LVEF was measured by CMR and at least one additional modality. In each modality, LVEF was measured by a core laboratory independently of the other modalities. Measurements of LVEF by CMR were compared to 2DE, 3DE and SPECT using correlation and Bland-Altman plots.

Results

A total of 343 patients were included. Mean age was 63.9±8.3 years and 253 (74%) were males. Mean LVEF by CMR was 61.8±11.6%. Correlations between CMR LVEF and other modalities were moderate for 2DE and 3DE, and good for SPECT (Figure A-C). CMR had significantly greater correlation to SPECT, compared to 2DE and 3DE. Bland-Altman plots indicated relatively wide limits of agreement between all modalities, ranging from 31% to 42% (Figure, D-F). Mean absolute difference of LVEF between CMR and other modalities were 8.5% for 2DE, 9.0% for 3DE, and 8.3% for SPECT. The percentage of measurements that fell within a range of 5% difference compared to CMR LVEF was 41% for 2DE, 34% for 3DE and 37% for SPECT (all p>0.05).

Conclusions

In a multicenter study with chronic CAD patients, LVEF assessed by CMR had better correlation to SPECT, compared to 2DE and 3DE. However, there was considerable variability among all three modalities that were compared to CMR. Awareness of these variations are important in clinical management.

A giant exoplanet orbiting a very-low-mass star challenges planet formation models

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.

Guidelines for training in cardiovascular magnetic resonance (CMR)

These "Guidelines for training in Cardiovascular Magnetic Resonance" were developed by the Certification Committee of the Society for Cardiovascular Magnetic Resonance (SCMR) and approved by the SCMR Board of Trustees.

Protein in the Hospital: Gaining Perspective and Moving Forward

Provision of adequate protein is crucial for optimizing outcomes in hospitalized patients. However, the methodologies upon which current recommendations are based have limitations, and little is known about true requirements in any clinical population. In this tutorial, we aim to give clinicians an understanding of how current protein recommendations were developed, an appreciation for the limitations of these recommendations, and an overview of more sophisticated approaches that can be applied to better define protein requirements. A broader perspective of the challenges and opportunities in determining clinical protein requirements can help clinicians think critically about the individualized nutrition care they provide to their patients with the goal of administering adequate protein to optimize outcomes.

Blood Pressure Effects on Retinal Vessel Diameter and Flicker Response: A 1.5-Year Follow-Up

PURPOSE

The study examined the influence of individual blood pressure changes overtime on retinal vessel diameter and the latter's response to flicker light.

METHODS

The diameter of a retinal arterial and venous segment was measured continuously on-line with a Dynamic Vessel Analyzer in 20 patients twice (mean interval between examinations of 24 months). Eleven patients had no cardiovascular disease. Nine patients had arterial hypertension and were untreated at the time of the first measurement; at the time of the second measurement they were undergoing various antihypertensive therapies. Each test consisted of a 50-s baseline plus three 20-s periods of flicker stimulation followed by an 80-s period of observation. During the examinations the blood pressure was measured at 1-minute intervals.

RESULTS

In the hypertension group changes in the mean arterial blood pressure (MAP) correlated significantly with changes in the arterial baseline diameter (y = -0.1 - 0.37x, r =0.74, p (increase) <0.03). A comparison of the two measurements showed no such relationship in the group of cardiovascularly healthy subjects. The venous baseline and the arterial and venous flicker response did not change significantly in either group between the two measurements and showed no relationship to blood pressure changes.

CONCLUSIONS

In hypertensive subjects, long-term therapy-related changes in blood pressure induced a change in the arterial baseline by approximately +3.7 microm/-10 mmHg MAP. An influence of lowering MAP to the arterial flicker response could not be detected.

Retinal Vessel Reaction to Short-Term IOP Elevation in Ocular Hypertensive and Glaucoma Patients

PURPOSE

Regulation of ocular blood flow might be impaired in glaucoma patients. We compared the reaction of retinal vessels to a short-term increase of intraocular pressure (IOP), using a retinal vessel analyzer (RVA), in normal volunteers, ocular hypertensive patients (OH) and primary open angle glaucoma patients (POAG).

METHODS

Ten healthy subjects (56+/-8 years, IOP 13.7+/-1.6 mmHg), 10 OH patients (55+/-12 years, IOD 23.4+/-4.1 mmHg) and 11 POAG patients (60+/-11 years, IOP 23.3+/-1.95 mmHg) were evaluated. Arterial and venous retinal vessel diameter was measured continuously before, during and after raising IOP to suprasystolic values by the suction cup method, described as ocular oscillo-dynamography.

RESULTS

The change in vessel diameter after the IOP rise differed in its temporal sequence and in absolute values depending on the group examined. In the retinal branch veins the reduction of vessel diameter during the IOP rise was significantly different in POAG (0%+/-6.7) and volunteers (-6.7%+/-8.5; p = 0.06) and in POAG and OH (-6.7%+/-7.0; p = 0.04). At 70-130 sec after IOP increase a dilatation occurred, again differing significantly in POAG (+5.8%+/-3.9) and volunteers (+9.7%+/-4.3; p = 0.03). Systemic blood pressure did not show any significant differences between groups or during the course of the examination.

DISCUSSION

At short-term rise in IOP leads to less retinal vessel reaction in POAG patients than in volunteers and OH. This might be due to impaired autoregulation to ocular perfusion changes in POAG patients.

Survey of Nutrition Management Practices in Centers for Pediatric Intestinal Rehabilitation

BACKGROUND

Nutrition management of pediatric intestinal failure (IF) requires interdisciplinary coordination of parenteral nutrition (PN) and enteral nutrition (EN) support. Nutrition strategies used by specialists in pediatric intestinal rehabilitation to promote gut adaptation and manage complications have not been previously summarized.

METHODS

A practice survey was distributed to members of the dietitian subgroup of the American Society for Parenteral and Enteral Nutrition Pediatric Intestinal Failure Section. The survey included 24 open-ended questions related to PN and enteral feeding strategies, nutrition management of PN-associated liver disease, and laboratory monitoring.

RESULTS

Dietitians from 14 centers completed the survey. Management components for patients at risk for cholestasis were consistent and included fat minimization, trace element modification, avoiding PN overfeeding, and providing EN. Parenteral amino acid solutions designed for infants/young children are used in patients <1 or 2 years of age. Trace minerals are dosed individually in 10 of 14 centers. Eleven centers prescribe a continuous infusion of breast milk or elemental formula 1-2 weeks after resection while 3 centers determine the formula type by the extent of resection. Most (86%) centers do not have a protocol for initiating oral/motor therapy. Laboratory panel composition varied widely by center. The selection and frequency of use depended on clinical variables, including cholestatic status, exclusive vs partial PN dependence, postrepletion verification vs routine monitoring, intestinal anatomy, and acuity of care.

CONCLUSION

EN and PN management strategies are relatively consistent among U.S. centers. Collaborative initiatives are necessary to define better practices and establish laboratory monitoring guidelines.

Evaluation of Advanced Bioimpedance Spectroscopy Models for Measuring Body Composition in Healthy Adults (NHANES 1999-2004) and Those Undergoing Massive Weight Loss Following Roux-en-Y Gastric Bypass Surgery

INTRODUCTION

Bioimpedance spectroscopy (BIS) devices utilize biophysical modeling to generate body composition data. The addition of body mass index (BMI) to modified Xitron-Hanai-based mixture equations improved BIS estimates of intracellular water (ICW), particularly at the extremes of BMI. A 3-compartment model for distinguishing excess fluid (ExF) from normally hydrated lean (NHLT) and adipose tissue may further improve BIS estimates.

OBJECTIVE

We aimed to validate a BIS approach based on the Chamney model for determining fat mass (FM) in healthy individuals (NHANES) and for measuring FM changes in individuals undergoing massive weight loss.

METHODS

Using adult NHANES 1999-2004 (2821 female, 3063 male) and longitudinal pre-to-post-RYGB (15F) data, we compared dual-energy-X-ray absorptiometry (DXA) and BIS for FM. We applied BIS adiposity-corrected values to Chamney equations for normally hydrated lean and adipose tissue (NHLT, NHAT) and FM. Method agreement was evaluated by correlations, paired t-tests, root mean square error (RMSE), Bland-Altman (B-A) analysis, and concordance correlation coefficients (CCC).

RESULTS

Method agreement between BIS and DXAFM was good in healthy adults (r=0.96, CCC=0.93, p<.0001), and pre-to-post-RYGB (r=0.93-0.98, CCC=0.81-0.86, p<.001). Although cross-sectional FM measures differed, FM change measures post-RYGB did not (35.6±8.9 vs. 35.2±9.2 kg, BIS vs. DXA) and agreed well (r=0.84, p<.0001). The 15 subjects with follow-up measurements at 1 year lost 11.5±9.8 kg FFM by DXA, but only 1.3±2.5 kg of NHLT by BIS, suggesting that the FFM loss may have been mostly adipose tissue water.

CONCLUSIONS

Incorporation of the Chamney model into BIS algorithms is a major conceptual advancement for assessing and monitoring body composition. Its ability to differentiate ICW and extracellular water (ECW) in NHLT and NHAT, as well as excess ECW is promising, and would facilitate lean tissue monitoring in obesity and acute/chronic disease.

[The Trade-Off between Chance of Success and Urgency in Organ Allocation: A Discrete Choice Experiment to Elicit Public Preferences]

OBJECTIVE

According to the German Organ Transplantation Act, donor organs must be allocated with particular regard to chance of success and urgency. However, the objectives of these guiding criteria - the efficient use of available organs and meeting the most urgent need - are in conflict with each other, as success rate of transplantation (TX) ordinarily diminishes when urgency increases. Current allocation guidelines balance these criteria differently depending on the organ. This is only justified in part by medical reasons. Thus, further considerations are essential to develop consistent allocation rules. Therefore, a discussion on the stated trade-off considering the far-reaching consequences of such allocation decisions is indispensable. This also implies taking account of public preferences.

METHODS

In this pilot study, preferences of 250 participants were assessed using a Discrete Choice Experiment. Choice-sets for the allocation of a donor organ included 2 patients, who were characterized by 3 success- and 2 urgency-based attributes. Data analysis was performed by Counting Analysis and Hierarchical Bayes estimation as well as Student's t-tests for subgroup analysis.

RESULTS

All attributes influenced allocation decisions significantly (p≤0.01). Both, patients with greater chance of success and higher urgency were preferred. As a whole, chance of success and urgency were equally important for the allocation of organs (53 and 47%, respectively). The importance of the success- and urgency-based criteria was quantified as follows: The post-TX 5-year probability of survival was weighted with 31%, the expected post-TX quality of life and the surgery survival rate with 11% each, the pre-TX 3-month mortality with 35% and the pre-TX quality of life with 12%. Subgroup analysis revealed significant differences.

CONCLUSION

The pilot study was successful in analyzing the balance of the guiding criteria chance of success and urgency without referring to a specific kind of organ. This type of results allows comparing current allocation rules and public preferences. These results could help decision makers to take into account public preferences developing organ-specific guidelines. A stronger involvement of citizens in decision making could gain confidence in transplantation medicine, increase the willingness to donate and potentially counteract the scarcity of organs and thereby the tragedy of the distributional conflict. Therefore the continuation of this project is advisable.