Magnetic Resonance - Technology Information Portal Welcome to MRI Technology
Info
  Sheets

Out-
      side
 



 
 'high field' 
SEARCH FOR    
 
  2 3 5 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Result : Searchterm 'high field' found in 1 term [] and 35 definitions []
previous     6 - 10 (of 36)     next
Result Pages : [1]  [2 3 4 5 6 7 8]
Searchterm 'high field' was also found in the following services: 
spacer
News  (60)  Resources  (13)  Forum  (11)  
 
B0
 
[B0] A conventional symbol for the main magnetic field strength (magnetic flux density or induction) in a MRI system. Although historically used, H0 (units of magnetic field strength, ampere//meter) should be distinguished from the more appropriate B0 [units of magnetic induction, tesla].
In current MR systems it has a constant value over time varying from 0.02 to 4 T. Field strengths of 0.5 T and above are generated with superconductive magnets. High field strengths have a better signal to noise ratio (SNR). The optimal imaging field strength for clinical imaging is between 0.5 and 2.0 T.

See also the related poll result: 'In 2010 your scanner will probably work with a field strength of'
spacer
 
Further Reading:
  Basics:
Factors influencing flip angle mapping in MRI: RF pulse shape, slice-select gradients, off-resonance excitation, and B0 inhomogeneities.
Tuesday, 1 August 2006   by www.ncbi.nlm.nih.gov    
Magnetic Field
   by hyperphysics.phy-astr.gsu.edu    
  News & More:
Turbo-FLASH Based Arterial Spin Labeled Perfusion MRI at 7 T
Thursday, 20 June 2013   by www.plosone.org    
Penn researchers to get 7 Tesla whole-body MRI system
Monday, 28 August 2006   by www.eurekalert.org    
Optimizing SPIR and SPAIR fat suppression
Tuesday, 30 November 2004   by clinical.netforum.healthcare.philips.com    
MRI Resources 
Pathology - Nerve Stimulator - Liver Imaging - Education pool - Contrast Enhanced MRI - MRA
 
Brain MRIForum -
related threadsMRI Resource Directory:
 - Brain MRI -
 
Brain imaging, magnetic resonance imaging of the head or skull, cranial magnetic resonance tomography (MRT), neurological MRI - they describe all the same radiological imaging technique for medical diagnostic.
Magnetic resonance imaging of the human brain includes the anatomic description and the detection of lesions. Special techniques like diffusion weighted imaging, functional magnetic resonance imaging (fMRI) and spectroscopy provide also information about the function and chemical metabolites of the brain. MRI provides detailed pictures of brain and nerve tissues in multiple planes without obstruction by overlying bones. Brain MRI is the procedure of choice for most brain disorders. It provides clear images of the brainstem and posterior brain, which are difficult to view on a CT scan. It is also useful for the diagnosis of demyelinating disorders (disorders such as multiple sclerosis (MS) that cause destruction of the myelin sheath of the nerve).
With this noninvasive procedure also the evaluation of blood flow and the flow of cerebrospinal fluid (CSF) is possible. Different MRA methods, also without contrast agents can show a venous or arterial angiogram. MRI can distinguish tumors, inflammatory lesions, and other pathologies from the normal brain anatomy. However, MRI scans are also used instead other methods to avoid the dangers of interventional procedures like angiography (DSA - digital subtraction angiography) as well as of repeated exposure to radiation as required for computed tomography (CT) and other X-ray examinations.
A (birdcage) bird cage coil achieves uniform excitation and reception and is commonly used to study the brain. Usually a brain MRI procedure includes FLAIR, T2 weighted and T1 weighted sequences in two or three planes.

See also Fetal MRI, Fluid Attenuation Inversion Recovery (FLAIR), Perfusion Imaging and High Field MRI.
See also Arterial Spin Labeling.
 
Images, Movies, Sliders:
 Brain MRI Images Axial T2  Open this link in a new window
      

 MRI of the Skull Base  Open this link in a new window
    
SlidersSliders Overview

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

 Brain MRI Images T1  Open this link in a new window
 MRI of the Brain Stem with Temoral Bone and Auditory System  Open this link in a new window
    
SlidersSliders Overview

 TOF-MRA Circle of Willis Inverted MIP  Open this link in a new window
    

 PCA-MRA 3D Brain Venography Colored MIP  Open this link in a new window
    

 
Medical-Ultrasound-Imaging.comA-Mode
spacer

• View the DATABASE results for 'Brain MRI' (14).Open this link in a new window


• View the NEWS results for 'Brain MRI' (32).Open this link in a new window.
 
Further Reading:
  Basics:
New MRI technique offers faster diagnosis of multiple sclerosis
Monday, 1 February 2016   by medicalxpress.com    
Ultra-high-field MRI reveals language centres in the brain in much more detail
Tuesday, 28 October 2014   by medicalxpress.com    
A Dutch study has revealed that as many as 13% of healthy adults may have some type of undiagnosed abnormality in the brain.
Sunday, 4 November 2007   by www.news-medical.net:80    
  News & More:
MRI Reveals Significant Brain Abnormalities Post-COVID
Monday, 21 November 2022   by neurosciencenews.com    
Combining genetics and brain MRI can aid in predicting chances of Alzheimer's disease
Wednesday, 29 June 2022   by www.sciencedaily.com    
Roundup: How Even Mild COVID Can Affect the Brain; This Many Daily Steps Improves Longevity; and More
Friday, 11 March 2022   by baptisthealth.net    
A low-cost and shielding-free ultra-low-field brain MRI scanner
Tuesday, 14 December 2021   by www.nature.com    
Large International Study Reveals Spectrum of COVID-19 Brain Complications
Tuesday, 9 November 2021   by www.itnonline.com    
Brain MRI-Based Subtypes of MS Predict Disability Progression, Treatment Response
Thursday, 13 May 2021   by www.neurologyadvisor.com    
New MRI method improves detection of disease changes in the brain's network
Thursday, 11 June 2020   by www.compute.dtu.dk    
New NeuroCOVID Classification System Uses MRI to Categorize Patients
Friday, 12 June 2020   by www.diagnosticimaging.com    
New MRI technique can 'see' molecular changes in the brain
Thursday, 5 September 2019   by medicalxpress.com    
Talking therapy or medication for depression: Brain scan may help suggest better treatment
Monday, 27 March 2017   by www.newsnation.in    
MRI identifies brain abnormalities in chronic fatigue syndrome patients
Wednesday, 29 October 2014   by www.eurekalert.org    
MRIs Useful in Tracking Depression in MS Patients
Tuesday, 1 July 2014   by www.hcplive.com    
Contrast agent linked with brain abnormalities on MRI
Tuesday, 17 December 2013   by www.sciencecodex.com    
MRIs Reveal Signs of Brain Injuries Not Seen in CT Scans
Tuesday, 18 December 2012   by www.sciencedaily.com    
Iron Deposits in the Brain May Be Early Indicator of MS
Wednesday, 13 November 2013   by www.healthline.com    
Migraine Sufferers Have Thicker Brain Cortex
Tuesday, 20 November 2007   by www.medicalnewstoday.com    
MRI Resources 
Societies - Supplies - Jobs pool - Spectroscopy pool - Directories - DICOM
 
Circle of WillisForum -
related threadsMRI Resource Directory:
 - Anatomy -
 
A large network of interconnecting blood vessels at the base of the brain that when visualized resembles a circle, the arteries effectively act as anastomoses for each other. This means that if any one of the communicating arteries becomes blocked, blood can flow from another part of the circle to ensure that blood flow is not compromised.
The circle of Willis is formed by both the internal carotid arteries, entering the brain from each side and the basilar artery, entering posteriorly. The connection of the vertebral arteries forms the basilar artery. The basilar artery divides into the right and left posterior cerebral arteries. The internal carotid arteries trifurcate into the anterior cerebral artery, middle cerebral artery, and posterior communicating artery. The two anterior cerebral arteries are joined together anteriorly by the anterior communicating artery. The posterior communicating arteries join the posterior cerebral arteries, completing the circle of Willis.
The time of flight angiography MRI technique allows imaging of the circle of Willis without the need of a contrast medium (best results with high field MRI). A cerebrovasular contrast enhanced magnetic resonance angiography (MRA) depicts the circle of Willis in addition to the vessels of the neck (carotid and vertebral arteries) with one bolus injection of a contrast agent.

For Ultrasound Imaging (USI) see Cerebrovascular Ultrasonography at Medical-Ultrasound-Imaging.com.
 
Images, Movies, Sliders:
 CE-MRA of the Carotid Arteries  Open this link in a new window
    
SlidersSliders Overview

 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

 
spacer

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

 
Further Reading:
  News & More:
Magnetic resonance angiography: current status and future directions
Wednesday, 9 March 2011   by www.jcmr-online.com    
Searchterm 'high field' was also found in the following services: 
spacer
News  (60)  Resources  (13)  Forum  (11)  
 
ContraindicationsForum -
related threadsMRI Resource Directory:
 - Safety -
 
The principal contraindications of the MRI procedure are mostly related to the presence of metallic implants in a patient. The risks of MRI scans increase with the used field strength. In general, implants are becoming increasingly MR safe and an individual evaluation is carried out for each case.
mri safety guidance
MRI Safety Guidance
Some patients should not be examined in MRI machines, or come closer than the 5 Gauss line to the system.

Absolute Contraindications for the MRI scan:
electronically, magnetically, and mechanically activated implants
ferromagnetic or electronically operated active devices like automatic cardioverter defibrillators
metallic splinters in the eye
ferromagnetic haemostatic clips in the central nervous system (CNS)

Patients with absolute contraindications should not be examined or only with special MRI safety precautions. Patients with an implanted cardiac pacemaker have been scanned on rare occasions, but pacemakers are generally considered an absolute contraindication. Relative contraindications may pose a relative hazard, and the type and location of an implant should be assessed prior to the MRI examination.

Relative Contraindications for the MRI scan:
other pacemakers, e.g. for the carotid sinus
lead wires or similar wires (MRI Safety risk)
prosthetic heart valves (in high fields, if dehiscence is suspected)
haemostatic clips (body)

Osteosynthesis material is usually anchored so well in the patients that no untoward effect will result. Another effect on metal parts in the patient's body is the heating of these parts through induction. In addition, image quality may be severely degraded. The presence of other metallic implants such as surgical clips etc. should be made known to the MRI operators. Most of these materials are non-magnetic, but if magnetic, they can pose a hazard.

See also MRI safety, Pregnancy, Claustrophobia and Tattoos.
Radiology-tip.comradRadiation Safety,  As Low As Reasonably Achievable
spacer
Medical-Ultrasound-Imaging.comUltrasound Safety
spacer

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

 
Further Reading:
  Basics:
MRI in Patients with Implanted Devices: Current Controversies
Monday, 1 August 2016   by www.acc.org    
Newer Heart Devices Safe During MRI
Monday, 23 August 2004   by www.hospimedica.com    
Physics of MRI Safety
   by www.aapm.org    
FDA Releases New Guidance On Establishing Safety, Compatibility Of Passive Implants In MR Environments
Tuesday, 16 December 2014   by www.meddeviceonline.com    
  News & More:
Women with permanent make-up tattoos suffer horrific facial burns after going in for MRI scans - which create an electric current in the ink
Monday, 4 July 2016   by www.dailymail.co.uk    
Positive diagnosis for neural therapeutic implants
Tuesday, 19 April 2016   by medicalxpress.com    
Codman Neuro develops new MRI-resistant programmable valve for treatment of hydrocephalus
Tuesday, 22 September 2015   by www.news-medical.net    
MRI Resources 
Nerve Stimulator - Absorption and Emission - Stimulator pool - - Pathology - Anatomy
 
Diffusion Weighted SequenceInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Diffusion Weighted Imaging -
 
Diffusion weighted imaging can be performed similar to the phase contrast angiography sequence. The gradients must be increased in amplitude to depict the much slower motions of molecular diffusion in the body.
While a T1 weighted MRI pulse sequence is diffusion sensitive, a quantitative diffusion pulse sequence was introduced by Steijskal and Tanner. Its characteristic features are two strong symmetrical gradient lobes placed on either side of the 180° refocusing pulse in a spin echo sequence. These symmetrical gradient lobes have the sole purpose of enhancing dephasing of spins, thereby accelerating intravoxel incoherent motion (IVIM) signal loss.
Dephasing is proportional to the square of the time (diffusion time) during which the gradients are switched on and the strength of the applied gradient field. Therefore, the use of high field gradient systems with faster and more sensitive sequences, make diffusion weighting more feasible.
Areas in which the protons diffuse rapidly (swollen cells in early stroke, less restriction to diffusion) will show an increased signal when the echo is measured relative to areas in which diffusion is restricted. For increased accuracy of diffusion measurement and image enhancement, useful motion correction techniques such as navigator echo and other methods should be used. In addition to this, applying the b-value calculated by the strength and duration of motion probing gradients with a high rate of accuracy is very important.

See also Apparent Diffusion Coefficient, ADC Map, Lattice Index Map.
spacer

• View the DATABASE results for 'Diffusion Weighted Sequence' (6).Open this link in a new window

 
Further Reading:
  Basics:
Diffusion-Weighted Imaging
   by spinwarp.ucsd.edu    
A Comparison of Methods for High-Spatial-Resolution Diffusion-weighted Imaging in Breast MRI
Tuesday, 25 August 2020   by pubs.rsna.org    
Diffusion Imaging: From Basic Physics to Practical Imaging
1999   by ej.rsna.org    
  News & More:
DWI-MRI helps breast cancer patients' chemotherapy response
Friday, 20 January 2023   by www.auntminnieeurope.com    
Effect of gadolinium-based contrast agent on breast diffusion-tensor imaging
Thursday, 6 August 2020   by www.eurekalert.org    
Hopkins researchers use diffusion MRI technique to monitor ultrasound uterine fibroid treatment
Monday, 8 August 2005   by www.eurekalert.org    
Diffusion-weighted MRI sensitive for metastasis in pelvic lymph nodes
Sunday, 15 June 2014   by www.2minutemedicine.com    
EVALUATION OF HUMAN STROKE BY MR IMAGING
2000
MRI Resources 
Developers - Musculoskeletal and Joint MRI - PACS - MRI Technician and Technologist Jobs - Stent - Sequences
 
previous      6 - 10 (of 36)     next
Result Pages : [1]  [2 3 4 5 6 7 8]
 Random Page
 
Share This Page
FacebookTwitterLinkedIn

MR-TIP    
Community   
User
Pass
Forgot your UserID/Password ?    



How AI will impact MRI :
only diagnostics 
saving time 
reducing cost 
makes planning obsolete 
reduce human knowledge 
not at all 

Look
      Ups





MR-TIP.com uses cookies! By browsing MR-TIP.com, you agree to our use of cookies.

Magnetic Resonance - Technology Information Portal
Member of SoftWays' Medical Imaging Group - MR-TIP • Radiology-TIP • Medical-Ultrasound-Imaging • 
Copyright © 2003 - 2024 SoftWays. All rights reserved. [ 31 October 2024]
Terms of Use | Privacy Policy | Advertising
 [last update: 2024-02-26 03:41:00]