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Magnetic Resonance Imaging MRI
 
(MRI) Magnetic resonance imaging is a noninvasive medical imaging technique that uses the interaction between radio frequency pulses, a strong magnetic field and body tissue to obtain images of slices/planes from inside the body. These magnets generate fields from approx. 2000 times up to 30000 times stronger than that of the Earth. The use of nuclear magnetic resonance principles produces extremely detailed pictures of the body tissue without the need for x-ray exposure and gives diagnostic information of various organs.
Measured are mobile hydrogen nuclei (protons are the hydrogen atoms of water, the 'H' in H20), the majority of elements in the body. Only a small part of them contribute to the measured signal, caused by their different alignment in the magnetic field. Protons are capable of absorbing energy if exposed to short radio wave pulses (electromagnetic energy) at their resonance frequency. After the absorption of this energy, the nuclei release this energy so that they return to their initial state of equilibrium.
This transmission of energy by the nuclei as they return to their initial state is what is observed as the MRI signal. The subtle differing characteristic of that signal from different tissues combined with complex mathematical formulas analyzed on modern computers is what enables MRI imaging to distinguish between various organs. Any imaging plane, or slice, can be projected, and then stored or printed.
The measured signal intensity depends jointly on the spin density and the relaxation times (T1 time and T2 time), with their relative importance depending on the particular imaging technique and choice of interpulse times. Any motion such as blood flow, respiration, etc. also affects the image brightness.
Magnetic resonance imaging is particularly sensitive in assessing anatomical structures, organs and soft tissues for the detection and diagnosis of a broad range of pathological conditions. MRI pictures can provide contrast between benign and pathological tissues and may be used to stage cancers as well as to evaluate the response to treatment of malignancies. The need for biopsy or exploratory surgery can be eliminated in some cases, and can result in earlier diagnosis of many diseases.
See also MRI History and Functional Magnetic Resonance Imaging (fMRI).
 
Images, Movies, Sliders:
 CE-MRA of the Carotid Arteries Colored MIP  Open this link in a new window
    
SlidersSliders Overview

 Anatomic Imaging of the Lumbar Spine  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 Normal Dual Inversion Fast Spin-echo  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 Breast MRI Images T2 And T1 Pre - Post Contrast  Open this link in a new window
 Anatomic Imaging of the Shoulder  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 
Radiology-tip.comConventional Radiography,  Computed Tomography
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Radiology-tip.comUltrasound Imaging,  Ultrasound Imaging Procedures
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• Related Searches:
    • MRI Procedure
    • Proton
    • Spine MRI
    • Resonance
    • Contrast Enhanced MRI
 
Further Reading:
  Basics:
A Short History of the Magnetic Resonance Imaging (MRI)
   by www.teslasociety.com    
MRI's inside story
Thursday, 4 December 2003   by www.economist.com    
On the Horizon - Next Generation MRI
Wednesday, 23 October 2013   by thefutureofthings.com    
  News & More:
Metamaterials boost sensitivity of MRI machines
Thursday, 14 January 2016   by www.eurekalert.org    
MRI technique allows study of wrist in motion
Monday, 6 January 2014   by www.healthimaging.com    
New imaging technology promising for several types of cancer
Thursday, 29 August 2013   by medicalxpress.com    
Study Shows MRI Can Be Used for Orthodontic Imaging
Monday, 12 August 2013   by www.sbwire.com    
MRI method for measuring MS progression validated
Thursday, 19 December 2013   by www.eurekalert.org    
The 2003 Nobel Prize in Physiology or Medicine
2003   by www.nobel.se    
Searchterm 'Magnetic Resonance Imaging MRI' was also found in the following services: 
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Radiology  (2) Open this link in a new windowUltrasound  (10) Open this link in a new window
Breast MRIMRI Resource Directory:
 - Breast MRI -
 
(MR mammography) Magnetic resonance imaging of the breast is particularly useful in evaluation of newly diagnosed breast cancer, in women whose breast tissue is mammographically very dense and for screening in women with a high lifetime risk of breast cancer because of their family history or genetic disposition.
Breast MRI can be performed on all standard whole body magnets at a field strength of 0.5 T - 1.5 Tesla. Powerful gradient strengths over 15 mT/m will help to improve the balance between spatial resolution, scanning speed, and volume coverage. The use of a dedicated bilateral breast coil is obligatory.
Malignant lesions release angiogenic factors that increase local vessel density and vessel permeability. Breast cancer is detectable due to the strong enhancement in dynamic breast imaging that peaks early (about 1-2 min.) after contrast medium injection. If breast cancer is suspected, a breast biopsy may be necessary to secure the diagnosis.
See also Magnetic Resonance Imaging MRI, Biopsy and MR Guided Interventions.

Requirements in breast MRI procedures:
Both breasts must be measured without gaps.
Temporal resolution should be sufficient to allow early imaging after contrast agent with dynamic imaging every 60-120 sec.
For the best possible detection of enhancement fat signal should be eliminated either by image subtraction or by spectrally selective fat saturation.
Thin slices are necessary to assure absence of partial volume effects.
Imaging should be performed with a spatial resolution in plane less than 1 mm.


For Ultrasound Imaging (USI) see Breast Ultrasound at US-TIP.com.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'
 
Images, Movies, Sliders:
 Breast MRI Images T2 And T1  Open this link in a new window
      
 Breast MRI Images T2 And T1 Pre - Post Contrast  Open this link in a new window
 Breast MRI Images T1 Pre - Post Contrast  Open this link in a new window
      
 
Radiology-tip.comMammography,  Breast Imaging
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Radiology-tip.comBreast Ultrasound
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• View the DATABASE results for 'Breast MRI' (13).Open this link in a new window


• View the NEWS results for 'Breast MRI' (41).Open this link in a new window.
 
Further Reading:
  Basics:
New Screening Guidelines for Women at High Risk for Breast Cancer
Wednesday, 26 September 2007   by www.newswise.com    
CONTRAST-ENHANCED MRI OF THE BREAST(.pdf)
MRI Improves Breast Cancer Screening in Older BRCA Carriers
Monday, 5 January 2015   by www.cancernetwork.com    
  News & More:
Researchers to develop new hybrid PET/MRI system for improved breast cancer diagnosis
Wednesday, 27 January 2016   by cordis.europa.eu    
Additional Breast Cancer Tumors Found on MRI After Mammography May Be Larger, More Aggressive
Wednesday, 9 December 2015   by www.oncologynurseadvisor.com    
Preoperative MRI May Overdiagnose Contralateral Breast Cancer
Wednesday, 2 December 2015   by www.cancertherapyadvisor.com    
MRI Better Detects Recurrent Breast Cancer
Friday, 15 August 2014   by www.doctorslounge.com    
7-Tesla MRI scanner allows even more accurate diagnosis of breast cancer
Thursday, 6 March 2014   by www.healthcanal.com    
BI-RADS and breast MRI useful in predicting malignancy
Wednesday, 30 May 2012   by www.oncologynurseadvisor.com    
MRI Resources 
Claustrophobia - MR Myelography - Safety Training - Spectroscopy pool - Databases - Jobs pool
 
Cervical Spine MRI
 
Cervical spine MRI is a suitable tool in the assessment of all cervical spine (vertebrae C1 - C7) segments (computed tomography (CT) images may be unsatisfactory close to the thoracic spine due to shoulder artifacts). The cervical spine is particularly susceptible to degenerative problems caused by the complex anatomy and its large range of motion.
Advantages of magnetic resonance imaging MRI are the high soft tissue contrast (particularly important in diagnostics of the spinal cord), the ability to display the entire spine in sagittal views and the capacity of 3D visualization. Magnetic resonance myelography is a useful supplement to conventional MRI examinations in the investigation of cervical stenosis. Myelographic sequences result in MR images with high contrast that are similar in appearance to conventional myelograms. Additionally, open MRI studies provide the possibility of weight-bearing MRI scan to evaluate structural positional and kinetic changes of the cervical spine.
Indications of cervical spine MRI scans include the assessment of soft disc herniations, suspicion of disc hernia recurrence after operation, cervical spondylosis, osteophytes, joint arthrosis, spinal canal lesions (tumors, multiple sclerosis, etc.), bone diseases (infection, inflammation, tumoral infiltration) and paravertebral spaces.
State-of-the-art phased array spine coils and high performance MRI machines provide high image quality and short scan time. Imaging protocols for the cervical spine includes sagittal T1 weighted and T2 weighted sequences with 3-4 mm slice thickness and axial slices; usually contiguous from C2 through T1. Additionally, T2 fat suppressed and T1 post contrast images are often useful in spine imaging.
See also Lumbar Spine MRI.
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• View the DATABASE results for 'Cervical Spine MRI' (2).Open this link in a new window


• View the NEWS results for 'Cervical Spine MRI' (1).Open this link in a new window.
 
Further Reading:
  News & More:
Pre-Op MRI Predicts Outcome of Cervical Spondylotic Myelopathy
Wednesday, 19 June 2013   by www.doctorslounge.com    
Imaging Technique for Spinal Cord Injury Shows Promise
Sunday, 22 December 2013   by www.wauwatosanow.com    
In Vivo 3-D Cervical Spine Kinematics Demonstrated
Thursday, 19 May 2011   by www.doctorslounge.com    
MRI Images at a 45-Degree Angle Through The Cervic al Neural Forami na:A Technique For Improved Visualization(.pdf)
2006   by www.painphysicianjournal.com    
Searchterm 'Magnetic Resonance Imaging MRI' was also found in the following services: 
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Contrast to Noise Ratio
 
(CNR) In Magnetic Resonance Imaging MRI, Contrast to noise ratio is the relationship of signal intensity differences between two regions, scaled to image noise. Improving CNR increases perception of the distinct differences between two clinical areas of interest. A contrast to noise ratio is a summary of SNR and contrast. It is the difference in SNR between two relevant tissue types.
(A and B): CNR = SNRA - SNRB
See also Signal Intensity, Signal to Noise Ratio and Medical Imaging.
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• View the DATABASE results for 'Contrast to Noise Ratio' (2).Open this link in a new window


• View the NEWS results for 'Contrast to Noise Ratio' (1).Open this link in a new window.
 
Further Reading:
  Basics:
Vascular Filters of Functional MRI: Spatial Localization Using BOLD and CBV Contrast
Contrast mechanisms in magnetic resonance imaging
2004   by www.iop.org    
Optimal k-Space Sampling for Dynamic Contrast-Enhanced MRI with an Application to MR Renography
Thursday, 5 November 2009   by www.ncbi.nlm.nih.gov    
Searchterm 'Magnetic Resonance Imaging MRI' was also found in the following services: 
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Radiology  (2) Open this link in a new windowUltrasound  (10) Open this link in a new window
MRI Procedure
 
The MRI device is located within a specially shielded room (Faraday cage) to avoid outside interference, caused by the use of radio waves very close in frequency to those of ordinary FM radio stations.
The MRI procedure can easily be performed through clothing and bones, but attention must be paid to ferromagnetic items, because they will be attracted from the magnetic field. A hospital gown is appropriate, or the patient should wear clothing without metal fasteners and remove any metallic objects like hairpins, jewelry, eyeglasses, clocks, hearing aids, any removable dental work, lighters, coins etc., not only for MRI safety reasons. Metal in or around the scanned area can also cause errors in the reconstructed images (artifacts). Because the strong magnetic field can displace, or disrupt metallic objects, people with an implanted active device like a cardiac pacemaker cannot be scanned under normal circumstances and should not enter the MRI area.
The MRI machine can look like a short tunnel or has an open MRI design and the magnet does not completely surround the patient. Usually the patient lies on a comfortable motorized table, which slides into the scanner, depending on the MRI device, patients may be also able to sit up. If a contrast agent is to be administered, intravenous access will be placed. A technologist will operate the MRI machine and observe the patient during the examination from an adjacent room. Several sets of images are usually required, each taking some minutes. A typical MRI scan includes three to nine imaging sequences and may take up to one hour. Improved MRI devices with powerful magnets, newer software, and advanced sequences may complete the process in less time and better image quality.
Before and after the most MRI procedures no special preparation, diet, reduced activity, and extra medication is necessary. The magnetic field and radio waves are not felt and no pain is to expect.
Movement can blur MRI images and cause certain artifacts. A possible problem is the claustrophobia that some patients experience from being inside a tunnel-like scanner. If someone is very anxious or has difficulty to lie still, a sedative agent may be given. Earplugs and/or headphones are usually given to the patient to reduce the loud acoustic noise, which the machine produces during normal operation. A technologist observes the patient during the test. Some MRI scanners are equipped with televisions and music to help the examination time pass.
MRI is not a cheap examination, however cost effective by eliminating the need for invasive radiographic procedures, biopsies, and exploratory surgery. MRI scans can also save money while minimizing patient risk and discomfort. For example, MRI can reduce the need for X-ray angiography and myelography, and can eliminate unnecessary diagnostic procedures that miss occult disease.
See also Magnetic Resonance Imaging MRI, Medical Imaging, Cervical Spine MRI, Claustrophobia, MRI Risks and Pregnancy.
For Ultrasound Imaging (USI) see Ultrasound Imaging Procedures at US-TIP.com.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'
 
Images, Movies, Sliders:
 Brain MRI Images Axial T2  Open this link in a new window
      

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

 CE-MRA of the Carotid Arteries  Open this link in a new window
    
SlidersSliders Overview

 Breast MRI Images T2 And T1 Pre - Post Contrast  Open this link in a new window
 Sagittal Knee MRI Images T1 Weighted  Open this link in a new window
      

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


• View the NEWS results for 'MRI Procedure' (6).Open this link in a new window.
 
Further Reading:
  News & More:
Metamaterials boost sensitivity of MRI machines
Thursday, 14 January 2016   by www.eurekalert.org    
Casting patterns make MRI safer
Tuesday, 13 January 2015   by www.engineeringcapacity.com    
Working with MRI machines may cause vertigo: Study
Wednesday, 25 June 2014   by www.cos-mag.com    
Novel Imaging Technique Improves Prostate Cancer Detection
Tuesday, 6 January 2015   by health.ucsd.edu    
MRI Improves Breast Cancer Screening in Older BRCA Carriers
Monday, 5 January 2015   by www.cancernetwork.com    
MRI Resources 
Non-English - Homepages - Safety pool - Crystallography - Libraries - Shielding
 
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