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Result : Searchterm 'Magnetic Resonance' found in 21 terms [] and 109 definitions []
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Searchterm 'Magnetic Resonance' was also found in the following services: 
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News  (787)  Resources  (181)  Forum  (1)  
 
Phase Contrast AngiographyMRI Resource Directory:
 - MRA -
 
(PCA) With this method images of the blood flow-velocity (or any other movement of tissue) are produced. The MRI signal contains both amplitude and phase information. The phase information can be used with subtraction of images with and without a velocity encoding gradient. The signal will be directly proportional to the velocity because of the relation between blood flow-velocity and signal intensity.
This is the strength of PCA, complete suppression of stationary tissue (no velocity - no signal), the direct velocity of flow is being imaged, while in TOF (Inflow) angiography, tissue with short T1 (fat or methaemoglobin) might be visualized.
The strength of the gradient determines the sensitivity to flow. It is set by setting the aliasing or encoding velocity (VENC). Unfortunately, phase sensitization can only be acquired along one axis at a time. Therefore, phase contrast angiographic techniques tend to be 4 times slower than TOF techniques with the same matrix.

See also Phase Contrast Sequence, Magnetic Resonance Angiography, Contrast Enhanced Magnetic Resonance Angiography, Flow Effects and Flow Quantification.
 
Images, Movies, Sliders:
 PCA-MRA 3D Brain Venography Colored MIP  Open this link in a new window
    

 
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• Related Searches:
    • Velocity Encoding
    • Velocity
    • 3 Dimensional Magnetic Resonance Angiography
    • Angiography
    • Contrast Enhanced MR Venography
 
Further Reading:
  Basics:
Magnetic resonance angiography: current status and future directions
Wednesday, 9 March 2011   by www.jcmr-online.com    
  News & More:
MR–ANGIOGRAPHY(.pdf)
Searchterm 'Magnetic Resonance' was also found in the following services: 
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Radiology  (14) Open this link in a new windowUltrasound  (27) Open this link in a new window
Sensitivity EncodingInfoSheet: - Sequences - 
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Overview, 
Types of, 
etc.
 
(SENSE) A MRI technique for relevant scan time reduction. The spatial information related to the coils of a receiver array are utilized for reducing conventional Fourier encoding. In principle, SENSE can be applied to any imaging sequence and k-space trajectories. However, it is particularly feasible for Cartesian sampling schemes. In 2D Fourier imaging with common Cartesian sampling of k-space sensitivity encoding by means of a receiver array enables to reduce the number of Fourier encoding steps.
SENSE reconstruction without artifacts relies on accurate knowledge of the individual coil sensitivities. For sensitivity assessment, low-resolution, fully Fourier-encoded reference images are required, obtained with each array element and with a body coil.
The major negative point of parallel imaging techniques is that they diminish SNR in proportion to the numbers of reduction factors. R is the factor by which the number of k-space samples is reduced. In standard Fourier imaging reducing the sampling density results in the reduction of the FOV, causing aliasing. In fact, SENSE reconstruction in the Cartesian case is efficiently performed by first creating one such aliased image for each array element using discrete Fourier transformation (DFT).
The next step then is to create a full-FOV image from the set of intermediate images. To achieve this one must undo the signal superposition underlying the fold-over effect. That is, for each pixel in the reduced FOV the signal contributions from a number of positions in the full FOV need to be separated. These positions form a Cartesian grid corresponding to the size of the reduced FOV.
The advantages are especially true for contrast-enhanced MR imaging such as dynamic liver MRI (liver imaging) , 3 dimensional magnetic resonance angiography (3D MRA), and magnetic resonance cholangiopancreaticography (MRCP).
The excellent scan speed of SENSE allows for acquisition of two separate sets of hepatic MR images within the time regarded as the hepatic arterial-phase (double arterial-phase technique) as well as that of multidetector CT.
SENSE can also increase the time efficiency of spatial signal encoding in 3D MRA. With SENSE, even ultrafast (sub second) 4D MRA can be realized.
For MRCP acquisition, high-resolution 3D MRCP images can be constantly provided by SENSE. This is because SENSE resolves the presence of the severe motion artifacts due to longer acquisition time. Longer acquisition time, which results in diminishing image quality, is the greatest problem for 3D MRCP imaging.
In addition, SENSE reduces the train of gradient echoes in combination with a faster k-space traversal per unit time, thereby dramatically improving the image quality of single shot echo planar imaging (i.e. T2 weighted, diffusion weighted imaging).
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• View the DATABASE results for 'Sensitivity Encoding' (12).Open this link in a new window

 
Further Reading:
  News & More:
Image Characteristics and Quality
   by www.sprawls.org    
MRI Resources 
Jobs pool - Developers - Pacemaker - Mobile MRI - Nerve Stimulator - Health
 
Spectroscopic Imaging Techniques
 
For the wide uses of NMR spectroscopy (from mineralogy to medicine) there is a variety of different spectroscopic imaging techniques available.
A short listing of the most frequent variations:
'One-dimensional NMR Spectroscopy (1D NMR) is attended to the spectra of (1H) Proton, 13Carbon etc., which in general is divided in continuous wave and pulse spectroscopy. General used to determine chemical structures. Proton nuclear magnetic resonance (1H-NMR) spectroscopy and carbon nuclear magnetic resonance (13C-NMR) spectroscopy are the most prominent techniques here.
'Two-dimensional NMR Spectroscopy' (2D NMR) is based on pulse spectroscopy. This technique is mostly used for the study of chemical interactions accompanied by magnetization transfer. Examples for more diversified spectroscopy techniques are based on homonuclear (COSY, TOCSY, 2D-INADEQUATE, NOESY, ROESY) or heteronuclear correlation (HSQC, HMQC, HMBC).
'Solid State NMR Spectroscopy' analyzes samples with little or no molecular mobility. Dipolar coupling and chemical shift anisotropy are the dominating nuclear physical effects here. Used for example in pharmaceutical analysis.
'Solution State NMR Spectroscopy' is a technique to analyze the structure of samples with a high degree of molecular mobility as polymers, proteins, nucleic acids etc.
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• View the DATABASE results for 'Spectroscopic Imaging Techniques' (2).Open this link in a new window

 
Further Reading:
  Basics:
Chemical Applications of NMR
   by hyperphysics.phy-astr.gsu.edu    
  News & More:
Automated analysis of the total choline resonance peak in breast proton magnetic resonance spectroscopy
Wednesday, 4 October 2023   by analyticalsciencejournals.onlinelibrary.wiley.com    
New Brain Imaging Technique Identifies Previously Undetected Epileptic Seizure Sites
Friday, 13 November 2015   by www.newswise.com    
Proton MR Spectroscopic Imaging without Water Suppression1
2000   by radiology.rsnajnls.org    
Searchterm 'Magnetic Resonance' was also found in the following services: 
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News  (787)  Resources  (181)  Forum  (1)  
 
Spine MRIMRI Resource Directory:
 - Spine MRI -
 
Magnetic resonance imaging (MRI) of the spine is a noninvasive procedure to evaluate different types of tissue, including the spinal cord, vertebral disks and spaces between the vertebrae through which the nerves travel, as well as distinguish healthy tissue from diseased tissue.
The cervical, thoracic and lumbar spine MRI should be scanned in individual sections. The scan protocol parameter like e.g. the field of view (FOV), slice thickness and matrix are usually different for cervical, thoracic and lumbar spine MRI, but the method is similar. The standard views in the basic spinal MRI scan to create detailed slices (cross sections) are sagittal T1 weighted and T2 weighted images over the whole body part, and transverse (e.g. multi angle oblique) over the region of interest with different pulse sequences according to the result of the sagittal slices. Additional views or different types of pulse sequences like fat suppression, fluid attenuation inversion recovery (FLAIR) or diffusion weighted imaging are created dependent on the indication.

Indications:
•
Neurological deficit, evidence of radiculopathy, cauda equina compression
•
Primary tumors or drop metastases
•
Infection/inflammatory disease, multiple sclerosis
•
Postoperative evaluation of lumbar spine: disk vs. scar
•
Evaluation of syrinx
•
Localized back pain with no radiculopathy (leg pain)

Contrast enhanced MRI techniques delineate infections vs. malignancies, show a syrinx cavity and support to differentiate the postoperative conditions. After surgery for disk disease, significant fibrosis can occur in the spine. This scarring can mimic residual disk herniation. Magnetic resonance myelography evaluates spinal stenosis and various intervertebral discs can be imaged with multi angle oblique techniques. Cine series can be used to show true range of motion studies of parts of the spine. Advanced open MRI devices are developed to perform positional scans in the position of pain or symptom (e.g. Upright™ MRI formerly Stand-Up MRI).
 
Images, Movies, Sliders:
 Anatomic Imaging of the Lumbar Spine  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 
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• View the DATABASE results for 'Spine MRI' (11).Open this link in a new window


• View the NEWS results for 'Spine MRI' (4).Open this link in a new window.
 
Further Reading:
  Basics:
Newer Sequences for Spinal MR Imaging: Smorgasbord or Succotash of Acronyms?
   by www.ajnr.org    
Cutting Edge Imaging of THE Spine
February 2007   by www.pubmedcentral.nih.gov    
Landmark Independent Study by UCLA School of Medicine Reports Comparison of Dynamic™ Upright® MRI With Static Upright MRI in More Than 1,000 Patients (1,302):
Thursday, 15 November 2007   by www.fonar.com    
  News & More:
Recommendations for MRI Assessment in Managing Axial Spondyloarthritis
Wednesday, 8 January 2020   by www.rheumatologyadvisor.com    
MRI Of The Spine Identifies Smoldering Myeloma Patients At High Risk Of Progressing To Multiple Myeloma
Tuesday, 26 August 2014   by www.myelomabeacon.com    
Intensive training of young tennis players causes spinal damage
Wednesday, 18 July 2007   by www.eurekalert.org    
Searchterm 'Magnetic Resonance' was also found in the following services: 
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Time of Flight AngiographyInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - MRA -
 
(TOF) The time of flight angiography is used for the imaging of vessels. Usually the sequence type is a gradient echo sequences with short TR, acquired with slices perpendicular to the direction of blood flow.
The source of diverse flow effects is the difference between the unsaturated and presaturated spins and creates a bright vascular image without the invasive use of contrast media. Flowing blood moves unsaturated spins from outside the slice into the imaging plane. These completely relaxed spins have full equilibrium magnetization and produce (when entering the imaging plane) a much higher signal than stationary spins if a gradient echo sequence is generated. This flow related enhancement is also referred to as entry slice phenomenon, or inflow enhancement.
Performing a presaturation slab on one side parallel to the slice can selectively destroy the MR signal from the in-flowing blood from this side of the slice. This allows the technique to be flow direction sensitive and to separate arteriograms or venograms. When the local magnetization of moving blood is selectively altered in a region, e.g. by selective excitation, it carries the altered magnetization with it when it moves, thus tagging the selected region for times on the order of the relaxation times.
For maximum flow signal, a complete new part of blood has to enter the slice every repetition (TR) period, which makes time of flight angiography sensitive to flow-velocity. The choice of TR and slice thickness should be appropriate to the expected flow-velocities because even small changes in slice thickness influences the performance of the TOF sequence. The use of sequential 2 dimensional Fourier transformation (2DFT) slices, 3DFT slabs, or multiple 3D slabs (chunks) are depending on the coverage required and the range of flow-velocities.
3D TOF MRA is routinely used for evaluating the Circle of Willis.

See also Magnetic Resonance Angiography and Contrast Enhanced Magnetic Resonance Angiography.
 
Images, Movies, Sliders:
 TOF-MRA Circle of Willis Inverted MIP  Open this link in a new window
    

 Circle of Willis, Time of Flight, MIP  Open this link in a new window
    
SlidersSliders Overview

 
Radiology-tip.comradCT Angiography,  Coronary Angiogram
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Medical-Ultrasound-Imaging.comColor Power Angio,  Doppler Ultrasound
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• View the DATABASE results for 'Time of Flight Angiography' (11).Open this link in a new window

 
Further Reading:
  Basics:
MR–ANGIOGRAPHY(.pdf)
  News & More:
Magnetic resonance angiography: current status and future directions
Wednesday, 9 March 2011   by www.jcmr-online.com    
MRI Resources 
Directories - PACS - Guidance - Education pool - Anatomy - Research Labs
 
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