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Open MRIForum -
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Open MRI scanners have been developed for people who are anxious or obese or for examination of small parts of the body, such as the extremities (knee, shoulder). In addition, some systems offer imaging in different positions and sequences of movements. The basic technology of an open MRI machine is similar to that of a traditional MRI device. The major difference for the patient is that instead of lying in a narrow tunnel, the imaging table has more space around the body so that the magnet does not completely surround the person being tested.
Types of constructions:
Semi open high field MRI scanners provide an ultra short bore (tunnel) and widely flared ends. In this type of MRI systems, patients lie with the head in the space outside the bore, if for example the hips are examined.
Open low field MRI machines have often a wide open design, e.g. an open C-arm scanner is shaped like two large discs separated by a large pillar. Patients have an open sided feeling and more space around them allows a wider range of positions.
Advanced open MRI scanners combine the advantages of both, the high field strength, newest gradient technology and wide open design. Even scans of patients in upright, weight-bearing positions are possible (e.g. Upright™ MRI formerly Stand-Up MRI).

Difficulties with a traditional MRI scan include claustrophobia and patient size or, for health related reasons, patients who are not able to receive this type of diagnostic test. The MRI unit is a limited space, and some patients may be too large to fit in a narrow tunnel. In addition, weight limits can restrict the use of some scanners. The open MRI magnet has become the best option for those patients.
All of the highest resolution MRI scanners are tunnels and tend to accentuate the claustrophobic reaction. While patients may find the open MRI scanners easier to tolerate, some machines use a lower field magnet and generates lower image quality or have longer scan time. The better performance of an advanced open MRI scanner allows good image quality caused by the higher signal to noise ratio with maximum patient comfort.
See also Claustrophobia, MRI scan and Knee MRI.
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Searchterm 'Open MRI' was also found in the following services: 
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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'

• View the DATABASE results for 'Low Field MRI' (8).Open this link in a new window

• View the NEWS results for 'Low Field MRI' (5).Open this link in a new window.
Further Reading:
Low-Field MRI of Laser Polarized Noble Gas
  News & More:
Portable MRI could aid wounded soldiers and children in the third world
Thursday, 23 April 2015   by    
Portable 'battlefield MRI' comes out of the lab
Thursday, 30 April 2015   by    
MRI Resources 
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ClaustrophobiaForum -
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A psychological reaction to being confined in a relatively small area.
This is a very real psychological danger for some individuals during the MRI procedure. A small percentage of patients is claustrophobic and cannot tolerate the confined space within a closed MRI magnet. Claustrophobia, panic attacks and other psychological stress situations have been reported in about 1-4% of cases as a reason to interrupt the MRI examination. Principally short and wide open MRI devices are advantageous because the percentage of claustrophobic incidents drops significantly.
Detailed explanation of the MRI procedure, careful attention and special equipment (mirrors to look outside the machine, emergency bells) help to reduce claustrophobia significantly. The majority of claustrophobic patients will be sufficiently relaxed with orally or intravenous sedatives.
See also Open MRI.


• View the DATABASE results for 'Claustrophobia' (16).Open this link in a new window

Further Reading:
Open MRI scanners reduce anxiety in patients
Thursday, 8 September 2011   by    
  News & More:
The MRI is a source of anxiety — and musical inspiration
Tuesday, 10 December 2013   by    
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DeviceForum -
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Types of Magnets, 
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:
Resistive Magnet
Permanent Magnet
Superconducting Magnet
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

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'
Radiology-tip.comGamma Camera,  Linear Accelerator
Radiology-tip.comUltrasound Machine,  Real-Time Scanner

• View the DATABASE results for 'Device' (141).Open this link in a new window

• View the NEWS results for 'Device' (29).Open this link in a new window.
Further Reading:
  News & More:
Kyoto University and Canon reduce cost of MRI scanner to one tenth
Monday, 11 January 2016   by    
A transportable MRI machine to speed up the diagnosis and treatment of stroke patients
Wednesday, 22 April 2015   by    
Portable 'battlefield MRI' comes out of the lab
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Friday, 1 August 2014   by    
New devices doubles down to detect and map brain signals
Monday, 23 July 2012   by    
Searchterm 'Open MRI' was also found in the following services: 
Radiology  (2) Open this link in a new windowUltrasound  (1) Open this link in a new window
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
Radiology-tip.comSonography,  Musculoskeletal and Joint Ultrasound

• View the DATABASE results for 'Imaging of the Extremities' (5).Open this link in a new window

Further Reading:
Study: Ultrashort echo-time MRI helps to find changes in deep tissue health
Wednesday, 20 August 2014   by    
Musculoskeletal MRI at 3.0 T: Relaxation Times and Image Contrast
Sunday, 1 August 2004   by    
Optimizing Musculoskeletal MR
Comparison of New Methods for Magnetic Resonance Imaging of Articular Cartilage(.pdf)
  News & More:
3D 'bone maps' could spot early signs of osteoporosis
Monday, 27 February 2017   by    
Is magnetic resonance imaging necessary in isolated greater trochanter fracture? A systemic review and pooled analysis
Thursday, 24 December 2015   by    
MRI technique allows study of wrist in motion
Monday, 6 January 2014   by    
Researcher uses MRI to measure joint's geometry and role in severe knee injury
Tuesday, 23 September 2014   by    
Advancing Clinical Trials with Medical Imaging: Spotlight on Immunologic Diseases
Tuesday, 28 April 2015   by    
Study: MRA bests MRI in evaluation of wrist tears
Saturday, 12 May 2012   by    
MRI Resources 
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