| Info Sheets |
| | | | | | | | | | | | | | | | | | | | | | | | |
| Out- side |
| | | | |
|
| | | | | | | Searchterm 'Display' was also found in the following services: | | | | |
| | |
| |
|
Cine sequences used in cardiovascular MRI are collection of images (usually at the same spatial location) covering of one full period of cardiac cycle or over several periods in order to obtain complete coverage.
The pulse sequence used, is either a standard gradient echo pulse sequence, a segmented data acquisition, a gradient echo EPI sequence or a gradient echo with balanced gradient waveform.
In cardiac gating studies it is possible to assign consecutive lines either to different images, yielding a multiphase sequence with as many images as lines, or the lines are grouped together into segments and assigned to the same image. The overall time to acquire such a segment has to be small compared to the RR-interval of the cardiac cycle, i. e. 50 ms, and hence contains typically 8 to 16 image lines.
This strategy is called segmented data acquisition, and has the advantage of reducing overall imaging time for cardiac images so that they can be acquired within a breath hold, but obviously decreasing the temporal resolution of each individual image.
This method shows dynamic processes, such as the ejection of blood out of the heart into the aorta, by means of fast imaging and displaying the resulting images in a sequential-loop, the impression of a real-time movie is generated. Ejection fractions and stroke volumes calculated from these cine MRI images in different cardiac axes have been shown to be more accurate than any other imaging modality. See also Cardiac Gating. | | | | | | | Further Reading: | News & More:
|
|
| |
| | | | | |
| |
|
Magnetic resonance imaging ( MRI) is based on the magnetic resonance phenomenon, and is used for medical diagnostic imaging since ca. 1977 (see also MRI History).
The first developed MRI devices were constructed as long narrow tunnels. In the meantime the magnets became shorter and wider. In addition to this short bore magnet design, open MRI machines were created. MRI machines with open design have commonly either horizontal or vertical opposite installed magnets and obtain more space and air around the patient during the MRI test.
The basic hardware components of all MRI systems are the magnet, producing a stable and very intense magnetic field, the gradient coils, creating a variable field and radio frequency (RF) coils which are used to transmit energy and to encode spatial positioning. A computer controls the MRI scanning operation and processes the information.
The range of used field strengths for medical imaging is from 0.15 to 3 T. The open MRI magnets have usually field strength in the range 0.2 Tesla to 0.35 Tesla. The higher field MRI devices are commonly solenoid with short bore superconducting magnets, which provide homogeneous fields of high stability.
There are this different types of magnets:
The majority of superconductive magnets are based on niobium-titanium (NbTi) alloys, which are very reliable and require extremely uniform fields and extreme stability over time, but require a liquid helium cryogenic system to keep the conductors at approximately 4.2 Kelvin (-268.8° Celsius). To maintain this temperature the magnet is enclosed and cooled by a cryogen containing liquid helium (sometimes also nitrogen).
The gradient coils are required to produce a linear variation in field along one direction, and to have high efficiency, low inductance and low resistance, in order to minimize the current requirements and heat deposition. A Maxwell coil usually produces linear variation in field along the z-axis; in the other two axes it is best done using a saddle coil, such as the Golay coil.
The radio frequency coils used to excite the nuclei fall into two main categories; surface coils and volume coils.
The essential element for spatial encoding, the gradient coil sub-system of the MRI scanner is responsible for the encoding of specialized contrast such as flow information, diffusion information, and modulation of magnetization for spatial tagging.
An analog to digital converter turns the nuclear magnetic resonance signal to a digital signal. The digital signal is then sent to an image processor for Fourier transformation and the image of the MRI scan is displayed on a monitor.
For Ultrasound Imaging (USI) see Ultrasound Machine at Medical-Ultrasound-Imaging.com.
See also the related poll results: ' In 2010 your scanner will probably work with a field strength of' and ' Most outages of your scanning system are caused by failure of' | | | | | | | | | • View the DATABASE results for 'Device' (141).
| | | • View the NEWS results for 'Device' (29).
| | | | Further Reading: | News & More:
|
|
small-steps-can-yield-big-energy-savings-and-cut-emissions-mris Thursday, 27 April 2023 by www.itnonline.com | | |
Portable MRI can detect brain abnormalities at bedside Tuesday, 8 September 2020 by news.yale.edu | | |
Point-of-Care MRI Secures FDA 510(k) Clearance Thursday, 30 April 2020 by www.diagnosticimaging.com | | |
World's First Portable MRI Cleared by FDA Monday, 17 February 2020 by www.medgadget.com | | |
Low Power MRI Helps Image Lungs, Brings Costs Down Thursday, 10 October 2019 by www.medgadget.com | | |
Cheap, portable scanners could transform brain imaging. But how will scientists deliver the data? Tuesday, 16 April 2019 by www.sciencemag.org | | |
The world's strongest MRI machines are pushing human imaging to new limits Wednesday, 31 October 2018 by www.nature.com | | |
Kyoto University and Canon reduce cost of MRI scanner to one tenth Monday, 11 January 2016 by www.electronicsweekly.com | | |
A transportable MRI machine to speed up the diagnosis and treatment of stroke patients Wednesday, 22 April 2015 by medicalxpress.com | | |
Portable 'battlefield MRI' comes out of the lab Thursday, 30 April 2015 by physicsworld.com | | |
Chemists develop MRI technique for peeking inside battery-like devices Friday, 1 August 2014 by www.eurekalert.org | | |
New devices doubles down to detect and map brain signals Monday, 23 July 2012 by scienceblog.com |
|
| |
| | | | | |
| |
|
(DWI) Magnetic resonance imaging is sensitive to diffusion, because the diffusion of water molecules along a field gradient reduces the MR signal. In areas of lower diffusion the signal loss is less intense and the display from this areas is brighter. The use of a bipolar gradient pulse and suitable pulse sequences permits the acquisition of diffusion weighted images (images in which areas of rapid proton diffusion can be distinguished from areas with slow diffusion).
Based on echo planar imaging, multislice DWI is today a standard for imaging brain infarction. With enhanced gradients, the whole brain can be scanned within seconds. The degree of diffusion weighting correlates with the strength of the diffusion gradients, characterized by the b-value, which is a function of the gradient related parameters: strength, duration, and the period between diffusion gradients.
Certain illnesses show restrictions of diffusion, for example demyelinization and cytotoxic edema. Areas of cerebral infarction have decreased apparent diffusion, which results in increased signal intensity on diffusion weighted MRI scans. DWI has been demonstrated to be more sensitive for the early detection of stroke than standard pulse sequences and is closely related to temperature mapping.
DWIBS is a new diffusion weighted imaging technique for the whole body that produces PET-like images. The DWIBS sequence has been developed with the aim to detect lymph nodes and to differentiate normal and hyperplastic from metastatic lymph nodes. This may be possible caused by alterations in microcirculation and water diffusivity within cancer metastases in lymph nodes.
See also Diffusion Weighted Sequence, Perfusion Imaging, ADC Map, Apparent Diffusion Coefficient, and Diffusion Tensor Imaging. | | | | • View the DATABASE results for 'Diffusion Weighted Imaging' (11).
| | | • View the NEWS results for 'Diffusion Weighted Imaging' (4).
| | | | Further Reading: | | Basics:
|
|
News & More:
| |
| |
| | | Searchterm 'Display' was also found in the following services: | | | | |
| | |
| |
|
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Cylindrical Wide Short Bore
Opt. (WIP) Single and Multi Voxel
SE, FE, IR, FastSE, FastIR, FastFLAIR, Fast STIR, FastFE, FASE, Hybrid EPI, Multi Shot EPI; Angiography: 2D(gate/non-gate)/3D TOF, SORS-STC
IMAGING MODES
Single, multislice, volume study
TE
8 msec min. SE; 1.2 msec min. FE
less than 0.015 (256x256)
1.0 min. 2-DFT: 0.2 min. 3-DFT
32-1024, phase;; 64-1024, freq.
65.5 cm, patient aperture
4050 kg (bare magnet incl. L-He)
COOLING SYSTEM TYPE
Closed-loop water-cooled
Liquid helium: approx. less than 0.05 L/hr
Passive, active, auto-active
| | | | • View the DATABASE results for 'Excelart AG™ with Pianissimo' (2).
| | | | |
| | | | | |
| |
|
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Cylindrical Wide Short Bore
SE, FE, IR, FastSE, FastIR, FastFLAIR, Fast STIR, FastFE, FASE, Hybrid EPI, Multi Shot EPI; Angiography: 2D(gate/non-gate)/3D TOF, SORS-STC
IMAGING MODES
Single, multislice, volume study
TE
8 msec min. SE; 0.9 msec min. FE
less than 0.011 (256x256)
1.0 min. 2-DFT: 0.2 min. 3-DFT
32-1024, phase;; 64-1024, freq.
65.5 cm, patient aperture
4050 kg (bare magnet incl. L-He)
POWER REQUIREMENTS
380/400/415/440/480 V
COOLING SYSTEM TYPE
Closed-loop water-cooled
Liquid helium: approx. less than 0.05 L/hr
Passive, active, auto-active
| | | | • View the DATABASE results for 'Excelart XG™ with Pianissimo' (2).
| | | | Further Reading: | News & More:
|
|
| |
| | | | |
| | | |
|
| |
| Look Ups |
| |