In vitro stent assessment by MRI: visibility of lumen and artifacts for 27 modern stents

2017 ◽  
Vol 62 (6) ◽  
pp. 565-573 ◽  
Author(s):  
Andreas Heinrich ◽  
Felix V. Güttler ◽  
Florian Schlesies ◽  
René Aschenbach ◽  
Niklas Eckardt ◽  
...  
Keyword(s):  
Standardized Test ◽  
Spin Echo ◽  
Test Method ◽  
Turbo Spin Echo ◽  
Radio Frequency Field ◽  
Nitinol Stents ◽  
Repetition Time ◽  
American Society ◽  
Stent Lumen

AbstractPurpose:The purpose of this study was to measure artifacts and visibility of lumen for modern and most commonly used stents in vascular interventions according to a standardized test method of the American Society for Testing and Materials (ASTM).Materials and methods:Twenty-four peripheral self-expanding nitinol stents and three stainless steel stents with diameters between 5 and 8 mm and lengths between 30 and 250 mm from seven different manufacturers were compared on a 1.5T and a 3T magnetic resonance (MR) scanner. The visualization of lumen and artifacts was measured according to ASTM F2119 for a turbo spin echo (TSE) [repetition time(TR)/echo time (TE) 500/26 ms] and a gradient echo (GRE) (TR/TE 100/15 ms) sequence. The stents were placed parallel and perpendicular to the radio frequency field (BResults:There were large differences in visibility of the lumen for the stent models. The visualization of the lumen varies between 0% and 93% (perpendicular to BConclusion:Reliable stent lumen visualization is possible for Misago, Supera, Tigris, and Viabahn stents, if their axis is perpendicular to B

scholarly journals Development of an in vitro test procedure for the characterization of left atrial appendage occluder devices

2019 ◽  
Vol 5 (1) ◽  
pp. 461-463
Author(s):  
Finja Borowski ◽  
Sebastian Kaule ◽  
Stefan Siewert ◽  
Klaus-Peter Schmitz ◽  
Michael Stiehm ◽  
...  
Keyword(s):  
Left Atrial ◽  
Left Atrial Appendage ◽  
Standardized Test ◽  
Test Procedure ◽  
Test Method ◽  
Atrial Appendage ◽  
In Vitro Test ◽  
Watchman Device ◽  
Vitro Test

AbstractThe implantation of an occluder in the left atrial appendage (LAA) is an emerging therapy for the treatment of patients suffering from atrial fibrillation and with a contraindication to oral anticoagulation. The LAA occluder (LAAO) provides a reduction of the potential risk of strokes by thromboembolism. Currently, only a few CE-approved devices are available on the market and the number of clinical trials is comparatively low. Furthermore, there is currently no standardized test method available for testing functionality of the occluder, especially for testing safe anchorage and permeability. Therefore, the aim of this study is to establish an in vitro test method to prove anchorage mechanism and permeability regarding thromboembolism of the LAAO under physiological conditions. A standardized technical and fully parameterized silicone model of a LAA, based on studies of different morphologies and sizes, was developed. The LAA model was mounted onto the left atrial chamber of a commercial pulse duplicator system to simulate physiological hemodynamic conditions. The test was performed using the Watchman device (Boston Scientific, USA; size: 31 mm). The inner implantation diameter of the LAA model was designed according to a target compression of 10% for the Watchman device in the implanted configuration. Furthermore, thrombus-like particles (n=150, d=1,7±0,05 mm) were added to represent the flushing of thrombi out of the LAA after device implantation. Within several cycles it was confirmed that no particles were washed out of the LAA model with the implanted occluder leading to a full protection against thromboembolism. It could also be shown that the occluder is firmly anchored in the LAA. Pressure measurements with sensors in the left atrium and in the LAA distal to the occluder could also show that the occluder has no influence on the pressure conditions in the LAA.

The ASTM International Standard Test Method for Determining the Superplastic Properties of Metallic Materials

2007 ◽  
Vol 551-552 ◽  
pp. 105-110
Author(s):  
Peter N. Comley
Keyword(s):  
Standardized Test ◽  
Constant Strain Rate ◽  
Standard Test ◽  
Test Method ◽  
Test Machine ◽  
Metallic Materials ◽  
Step Method ◽  
Fine Grain ◽  
American Society ◽  
Superplastic Properties

Over the last 40 years there have been many papers published showing superplastic properties of metallic materials. However there has been no standardized test available to assess and compare material, and researchers and companies in the field have devised a number of different methods to show superplastic properties. The value of these properties can vary dependent on the test method used. ASTM International (formerly The American Society for Testing and Materials ) has developed a standardized test method for superplastic properties. The standard is intended for all to use as a common platform for testing, evaluating and publishing superplastic properties to a uniform format, useful for both academia and industry. The paper outlines the main points of the standard, including:- The coupon geometry and the method of clamping the coupon in the grips. The furnace and test machine requirements. The testing conditions and the method of pulling the coupon. The analysis of the load and extension data from the test, and the standard presentation of superplastic properties. The basic superplastic properties of stress versus strain for any particular constant strain rate. The method to determine ‘m’, using a step method at a particular strain. Some data is presented showing how the properties of fine grain Ti-6Al-4V titanium alloy are derived and presented using the standard.

Standardized Test Methods for Use in Waste Compliance Testing in the Department of Energy'S Waste Acceptance Process

1986 ◽  
Vol 84 ◽  
Author(s):  
George B. Mellinger
Keyword(s):  
Standardized Tests ◽  
Standardized Test ◽  
Test Methods ◽  
Test Method ◽  
Approval Process ◽  
Test Procedures ◽  
Compliance Testing ◽  
American Society

Summary:Standardized test methods that are currently in use or under development appear to adequately cover most of the testing that may be required to demonstrate compliance with the WAPS. It may be important to complete standardization of those tests that are under development, and to develop additional standardized tests for those specifications for which no standardized tests exist. A significant amount of work would be involved in this effort. Therefore, before this effort is undertaken, DOE must decide whether there is a need for a set of standardized test methods that would receive an “official approval” for use in waste compliance testing. If a set of approved tests is needed, DOE would need to determine what types of tests to include in the “approved list”, who should develop these tests, and which organizations should review and approve the test methods. Test method review and approval might be accomplished through the use of the Materials Review Board (MRB), an organization that was created by DOE for the purpose of reviewing and approving key test methods and data related to the repository licensing process. Alternatively, other means of standardizing these tests might be considered, such as processing the tests through the American Society for Testing and Materials for publication as ASTM standards.If a set of approved tests is adopted, producers would not be required to use these tests; however, if a producer wished to propose other tests for compliance testing, it would be reasonable to require that such test procedures undergo a review/approval process similar to that which the officially approved tests had undergone. Once approved, these alternate procedures could be used for compliance testing.

A Novel In Vitro Testing Approach for the Next Generation of Transvenous Cardiac Leads: Buckling Behavior

2018 ◽  
Vol 12 (2) ◽  
Author(s):  
Donna L. Walsh ◽  
Ashok Williams ◽  
Oleg Vesnovsky ◽  
L. D. Timmie Topoleski ◽  
Nandini Duraiswamy
Keyword(s):  
Standardized Test ◽  
Substantial Effect ◽  
Buckling Load ◽  
Test Method ◽  
Test Methodology ◽  
Buckling Behavior ◽  
The Right ◽  
Buckling Test ◽  
High Repeatability

Manufacturers are constantly seeking to design new, better performing transvenous cardiac leads to prevent perforation of the heart by the lead tip. Currently, there is no standardized test method to measure the buckling load of leads, a major factor in the propensity of the lead to perforate the heart. This study further investigates the effect of boundary conditions on buckling loads at the lead tip of different transvenous cardiac leads achieved using different variations of our initial physiologically relevant test method. The goals of the test are to create the maximum buckling load with high repeatability and the simplest possible design. A buckling test was performed to capture maximum buckling load using three leads of each model (five currently available cardiac lead models) and were tested in each of six test setups. The buckling test methodology had a substantial effect on the load-displacement profiles, regardless of whether the lead was a pacemaker or defibrillator lead. By adding the right ventricular (RV) constraint, the buckling load more than doubled for most leads. The use of a lubricant reduced friction between the lead body and the RV surface, and thereby subsequently lowered the buckling load in those setups that used the RV constraint. In addition, the use of the lubricant reduced the variability in the results. The addition of both the RV constraint and the lubricant substantially influences the mechanical behavior of transvenous cardiac leads and is recommended for buckling testing of transvenous cardiac leads.

Contrast-Enhanced Turbo Spin-Echo(TSE) T1-weighted Imaging: Improved Contrast of Enhancing Lesions

1997 ◽  
Vol 37 (3) ◽  
pp. 379
Author(s):  
Sung Wook Choi ◽  
Ghi Jai Lee ◽  
Jae Chan Shim ◽  
Young Ju Lee ◽  
Se Hyung Jeong ◽  
...  
Keyword(s):  
Spin Echo ◽  
Turbo Spin Echo ◽  
Turbo Spin ◽  
Contrast Enhanced

scholarly journals Laboratory Test to Evaluate the Resistance of Cementitious Materials to Biodeterioration in Sewer Network Conditions

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 686
Author(s):  
Amr Aboulela ◽  
Matthieu Peyre Lavigne ◽  
Amaury Buvignier ◽  
Marlène Fourré ◽  
Maud Schiettekatte ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Standardized Test ◽  
Performance Indicator ◽  
Cementitious Materials ◽  
Test Method ◽  
Sustainable Construction ◽  
Public Health Issue ◽  
Sulfur Source ◽  
Test Protocol ◽  
Wide Range

The biodeterioration of cementitious materials in sewer networks has become a major economic, ecological, and public health issue. Establishing a suitable standardized test is essential if sustainable construction materials are to be developed and qualified for sewerage environments. Since purely chemical tests are proven to not be representative of the actual deterioration phenomena in real sewer conditions, a biological test–named the Biogenic Acid Concrete (BAC) test–was developed at the University of Toulouse to reproduce the biological reactions involved in the process of concrete biodeterioration in sewers. The test consists in trickling a solution containing a safe reduced sulfur source onto the surface of cementitious substrates previously covered with a high diversity microbial consortium. In these conditions, a sulfur-oxidizing metabolism naturally develops in the biofilm and leads to the production of biogenic sulfuric acid on the surface of the material. The representativeness of the test in terms of deterioration mechanisms has been validated in previous studies. A wide range of cementitious materials have been exposed to the biodeterioration test during half a decade. On the basis of this large database and the expertise gained, the purpose of this paper is (i) to propose a simple and robust performance criterion for the test (standardized leached calcium as a function of sulfate produced by the biofilm), and (ii) to demonstrate the repeatability, reproducibility, and discriminability of the test method. In only a 3-month period, the test was able to highlight the differences in the performances of common cement-based materials (CEM I, CEM III, and CEM V) and special calcium aluminate cement (CAC) binders with different nature of aggregates (natural silica and synthetic calcium aluminate). The proposed performance indicator (relative standardized leached calcium) allowed the materials to be classified according to their resistance to biogenic acid attack in sewer conditions. The repeatability of the test was confirmed using three different specimens of the same material within the same experiment and the reproducibility of the results was demonstrated by standardizing the results using a reference material from 5 different test campaigns. Furthermore, developing post-testing processing and calculation methods constituted a first step toward a standardized test protocol.

Sign in / Sign up

Export Citation Format

Share Document