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Result : Searchterm 'Low Field MRI' found in 1 term [] and 7 definitions [], (+ 17 Boolean[] results
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Low Field MRIForum -
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Advantages of low field imaging are the small-sized 5 Gauss fringe field and therefore the less static magnetic field exposure for the surrounding area, as well as less contraindications causing lower risks for the MRI safety by implemented metal and magnetic devices and equipment.
Low field systems are sometimes for restricted use, e.g. dedicated extremity scanner or open MRI devices. Open MRI devices equipped with permanent magnets are well-suited for MR guided interventions because these machines combine the lower magnetic fields of this type of magnets and the better patient access of open MRI scanner.
In some cases, the contrast of different tissues is better at lower field strength, depending on their T1 or T2 relaxation times. The disadvantage of the lower signal to noise ratio are a poor resolution and a longer scan time for a good image quality.
See also Claustrophobia, Contraindications and MRI Safety.

See also the related poll result: 'In 2010 your scanner will probably work with a field strength of'
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    • Open MRI
    • High Field MRI
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Further Reading:
  News & More:
Low-Field MRI of Laser Polarized Noble Gas
   by xenon.unh.edu    
MRI Resources 
Abdominal Imaging - RIS - MR Guided Interventions - General - Universities - Software
 
BandwidthForum -
related threads
 
(BW) Bandwidth is a measure of frequency range, the range between the highest and lowest frequency allowed in the signal. For analog signals, which can be mathematically viewed as a function of time, bandwidth is the width, measured in Hertz of a frequency range in which the signal's Fourier transform is nonzero.
The receiver (or acquisition) bandwidth (rBW) is the range of frequencies accepted by the receiver to sample the MR signal. The receiver bandwidth is changeable (see also acronyms for 'bandwidth' from different manufacturers) and has a direct relationship to the signal to noise ratio (SNR) (SNR = 1/squareroot (rBW). The bandwidth depends on the readout (or frequency encoding) gradient strength and the data sampling rate (or dwell time).
Bandwidth is defined by BW = Sampling Rate/Number of Samples.
A smaller bandwidth improves SNR, but can cause spatial distortions, also increases the chemical shift. A larger bandwidth reduces SNR (more noise from the outskirts of the spectrum), but allows faster imaging.
The transmit bandwidth refers to the RF excitation pulse required for slice selection in a pulse sequence. The slice thickness is proportional to the bandwidth of the RF pulse (and inversely proportional to the applied gradient strength). Lowering the pulse bandwidth can reduce the slice thickness.



Image Guidance
A higher bandwidth is used for the reduction of chemical shift artifacts (lower bandwidth - more chemical shift - longer dwell time - but better signal to noise ratio). Narrow receive bandwidths accentuate this water fat shift by assigning a smaller number of frequencies across the MRI image. This effect is much more significant on higher field strengths. At 1.5 T, fat and water precess 220 Hz apart, which results in a higher shift than in Low Field MRI.
Lower bandwidth (measured in Hz) = higher water fat shift (measured in pixel shift).
See also Aliasing, Aliasing Artifact, Frequency Encoding, and Chemical Shift Artifact.

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Further Reading:
  Basics:
Bandwidth
   by en.wikipedia.org    
  News & More:
Automated Quality Assurance for Magnetic Resonance Image with Extensions to Diffusion Tensor Imaging(.pdf)
   by scholar.lib.vt.edu    
A Real-Time Navigator Approach to Compensating for Motion Artifacts in Coronary Magnetic Resonance Angiography
   by www.cs.nyu.edu    
MRI Resources 
Shielding - Absorption and Emission - Safety pool - Crystallography - Pediatric and Fetal MRI - Journals
 
C-SCAN™InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.gehealthcare.com/usen/mr/cscan/index.html

Manufactured by Esaote S.p.A.; compact in-office MRI system, fits in a 90 ft² (8.4 m²) space and requires no shielding or special power. This low field MRI magnet is optimized for orthopedic use and imaging of the extremities.
The C-SCAN™ is developed from the ARTOSCAN™ - M with a new computer platform, and is also known as Artoscan C.
Esaote North America and Hologic Inc. are the U.S. distributors of this MRI device.


Device Information and Specification
CLINICAL APPLICATION Dedicated extremity
CONFIGURATION Closed
SURFACE COILS Linear and dual phased array, knee, ankle, wrist (6 total) coils
PULSE SEQUENCES SE, GE, IR, STIR, FSE, 3D CE, GE-STIR, 3D GE, ME, TME, HSE
IMAGING MODES Single, multislice, volume study, fast scan, multi slab
TR 12 - 5,000 msec
TE 5 - 220 msec
SINGLE SLICE 0.8 sec/image
MULTISLICE 0.8 sec/image
FOV 10 - 20 cm
SLICE THICKNESS 2D: 2 mm - 10 mm;
3D: 0.6 mm - 10 mm
DISPLAY MATRIX 512 x 512
MEASURING MATRIX 256 x 256 maximum
PIXEL INTENSITY 4,096 gray lvls, 256 lvls in 3D
SPATIAL RESOLUTION 0.4 mm
MAGNET TYPE Permanent
BORE DIAMETER
or W x H
33.6 x 16 cm
MAGNET WEIGHT 960 kg
H*W*D 124 x 76 x 60 cm
POWER REQUIREMENTS 100/110/200/220/230/240
FIELD STRENGTH 0.2 T
STRENGTH 10 mT/m
5-GAUSS FRINGE FIELD, radial/axial 28 cm/60 cm
SHIMMING Passive

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Searchterm 'Low Field MRI' was also found in the following services: 
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Imaging of the ExtremitiesMRI Resource Directory:
 - Musculoskeletal and Joint MRI -
 
Knee and shoulder MRI exams are the most commonly requested musculoskeletal MRI scans. Other MR imaging of the extremities includes hips, ankles, elbows, and wrists. Orthopedic imaging requires very high spatial resolution for reliable small structure definition and therefore places extremely high demands on SNR.
Exact presentation of joint pathology expects robust and reliable fat suppression, often under difficult conditions like off-center FOV, imaging at the edge of the field homogeneity or in regions with complex magnetic susceptibility.
MR examinations can evaluate meniscal dislocations, muscle fiber tears, tendon disruptions, tendinitis, and diagnose bone tumors and soft tissue masses. MR can also demonstrate acute fractures that are radiographically impossible to see. Evaluation of articular cartilage for traumatic injury or assessment of degenerative disease represents an imaging challenge, which can be overcome by high field MRI applications. Currently, fat-suppressed 3D spoiled gradient echo sequences and density weighted fast spin echo sequences are the gold-standard techniques used to assess articular cartilage.
Open MRI procedures allow the kinematic imaging of joints, which provides added value to any musculoskeletal MRI practice. This technique demonstrates the actual functional impingements or positional subluxations of joints. In knee MRI examinations, the kinematical patellar study can show patellofemoral joint abnormalities.
See also Open MRI, Knee MRI, Low Field MRI.
 
Images, Movies, Sliders:
 MRI - Anatomic Imaging of the Foot  Open this link in a new window
    
SlidersSliders Overview

 Anatomic Imaging of the Shoulder  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 MRI - Anatomic Imaging of the Ankle 2  Open this link in a new window
    
SlidersSliders Overview

 Anatomic MRI of the Knee 1  Open this link in a new window
    
SlidersSliders Overview

 
Radiology-tip.comJoint Scintigraphy,  Arthrography
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Radiology-tip.comSonography,  Musculoskeletal and Joint Ultrasound
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Further Reading:
  Basics:
Optimizing Musculoskeletal MR
   by rad.usuhs.mil    
VALUE OF 3D T1W & STIR MRI SEQUENCES IN DIAGNOSING EROSIONS IN RHEUMATOID ARTHRITIS
   by www.bocaradiology.com    
Comparison of New Methods for Magnetic Resonance Imaging of Articular Cartilage(.pdf)
2002
  News & More:
MRI technique allows study of wrist in motion
Monday, 6 January 2014   by www.healthimaging.com    
Study: MRA bests MRI in evaluation of wrist tears
Saturday, 12 May 2012   by www.healthimaging.com    
Musculoskeletal MRI at 3.0 T: Relaxation Times and Image Contrast
Sunday, 1 August 2004   by www.ajronline.org    
MRI Resources 
Service and Support - Image Quality - Quality Advice - Corporations - MRI Reimbursement - Equipment
 
Intera 0.5T™InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
From Philips Medical Systems; www.medical.philips.com/de/products/mri/products/ this low field MRI system of the Intera-family is onto diagnostic safety and flexibility aligned - cost effective and with high patient acceptance.

Device Information and Specification
CLINICAL APPLICATION Whole body
CONFIGURATION Short bore compact
SURFACE COILS Standard: head, body, C1, C3; Optional: Small joint, flex-E, flex-R, endocavitary (L and S), dual TMJ, knee, neck, T/L spine, breast; Optional phased array: Spine, pediatric, 3rd party connector, Flex-S-M-L, flex body, flex cardiac, neuro-vascular, head
SPECTROSCOPY No
SYNCHRONIZATION ECG/peripheral: Optional/yes, respiratory gating
PULSE SEQUENCES SE, Modified-SE (TSE), DAVE, STIR, FLAIR, SPIR, MTC, Dynamic, Keyhole, CLEAR, Q Flow, Balanced FFE, Multi Chunk 3D, Multi Stack 3D, FFE-EPI, SE-EPI, IR-EPI, GRASE, Diffusion Imaging, Perfusion Imaging;; Angiography: Inflow MRA, TONE, PCA, CE MRA
IMAGING MODES Single Slice 2D , Multi Single Slice 2D, Multi Slice 2D, 3D, Multi Chunk 3D, Multi Stack 3D
TR Min. 2.9 (Omni) msec
TE Min. 1.0 (Omni) msec
SINGLE/MULTI SLICE RapidView Recon. greater than 500 @ 256 Matrix
FOV Max. 53 cm
SLICE THICKNESS 0.1 mm (Omni)
DISPLAY MATRIX 128 x 128, 256 x 256,512 x 512,1024 x 1024
MEASURING MATRIX Variable in 1% increments
PIXEL INTENSITY Lum.: 120 cd/m2; contrast: 150:1
SPATIAL RESOLUTION Variable (op. param. depend.)
MAGNET TYPE Superconducting
BORE DIAMETER
or W x H
60 x 60 cm
MAGNET WEIGHT 2500 kg
H*W*D 240 x 188 x 157 cm
POWER REQUIREMENTS 380/400 V
COOLING SYSTEM TYPE
CRYOGEN USE 0.03 L/hr helium
FIELD STRENGTH 0.5 T
STRENGTH 23 mT/m (Omni)
5-GAUSS FRINGE FIELD 2.1 m / 2.8 m
SHIMMING Passive and dynamic
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MRI Resources 
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