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 'Imaging of the Extremities' 
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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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• Related Searches:
    • MRI Procedure
    • High Field MRI
    • Short T1 Inversion Recovery
    • Single Turn Solenoid
    • Knee MRI
 
Further Reading:
  Basics:
Study: Ultrashort echo-time MRI helps to find changes in deep tissue health
Wednesday, 20 August 2014   by www.healio.com    
Musculoskeletal MRI at 3.0 T: Relaxation Times and Image Contrast
Sunday, 1 August 2004   by www.ajronline.org    
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:
3D 'bone maps' could spot early signs of osteoporosis
Monday, 27 February 2017   by www.gmanetwork.com    
Is magnetic resonance imaging necessary in isolated greater trochanter fracture? A systemic review and pooled analysis
Thursday, 24 December 2015   by www.ncbi.nlm.nih.gov    
MRI technique allows study of wrist in motion
Monday, 6 January 2014   by www.healthimaging.com    
Researcher uses MRI to measure joint's geometry and role in severe knee injury
Tuesday, 23 September 2014   by medicalxpress.com    
Advancing Clinical Trials with Medical Imaging: Spotlight on Immunologic Diseases
Tuesday, 28 April 2015   by www.clinicalleader.com    
Study: MRA bests MRI in evaluation of wrist tears
Saturday, 12 May 2012   by www.healthimaging.com    
MRI Resources 
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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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DixonInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
The Dixon technique is a MRI method used for fat suppression and/or fat quantification. The difference in magnetic resonance frequencies between fat and water-bound protons allows the separation of water and fat images based on the chemical shift effect.
This imaging technique is named after Dixon, who published in 1984 the basic idea to use phase differences to calculate water and fat components in postprocessing. Dixon's method relies on acquiring an image when fat and water are 'in phase', and another in 'opposed phase' (out of phase). These images are then added together to get water-only images, and subtracted to get fat-only images. Therefore, this sequence type can deliver up to 4 contrasts in one measurement: in phase, opposed phase, water and fat images. An additional benefit of Dixon imaging is that source images and fat images are also available to the diagnosing physician.
The original two point Dixon sequence (number of points means the number of images acquired at different TE) had limited possibilities to optimize the echo time, spatial resolution, slice thickness, and scan time; but Dixon based fat suppression can be very effective in areas of high magnetic susceptibility, where other techniques fail. This insensitivity to magnetic field inhomogeneity and the possibility of direct image-based water and fat quantification have currently generated high research interests and improvements to the basic method (three point Dixon).
The combination of Dixon with gradient echo sequences allows for example liver imaging with 4 image types in one breath hold. With Dixon TSE/FSE an excellent fat suppression with high resolution can be achieved, particularly useful in imaging of the extremities.
For low bandwidth imaging, chemical shift correction of fat images can be made before recombination with water images to produce images free of chemical shift displacement artifacts. The need to acquire more echoes lengthens the minimum scan time, but the lack of fat saturation pulses extends the maximum slice coverage resulting in comparable scan time.
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Further Reading:
  Basics:
Separation of fat and water signal in magnetic resonanace imaging
2011   by www.diva-portal.org    
Direct Water and Fat Determination in Two-Point Dixon Imaging
April 2013   by scholarship.rice.edu    
MRI evaluation of fatty liver in day to day practice: Quantitative and qualitative methods
Wednesday, 3 September 2014   by www.sciencedirect.com    
Measurement of Fat/Water Ratios in Rat Liver Using 3DThree-Point Dixon MRI
2004   by www.civm.duhs.duke.edu    
  News & More:
Liver Imaging Today
February 2013   by www.healthcare.siemens.it    
mDIXON being developed to simplify and accelerate liver MRI
September 2010   by incenter.medical.philips.com    
MRI Resources 
Health - Pregnancy - Education - Stent - Diffusion Weighted Imaging - Used and Refurbished MRI Equipment
 
Knee MRI
 
Knee MRI, with its high soft tissue contrast is one of the main imaging tools to depict knee joint pathology. MRI allows accurate imaging of intra-articular structures such as ligaments, cartilage, menisci, bone marrow, synovium, and adjacent soft tissue.
Knee exams require a dedicated extremity coil, providing a homogenous imaging volume and high SNR to ensure best signal coverage. A complete knee MR examination includes for example sagittal and coronal T1 weighted, and proton density weighted pulse sequences +/- fat saturation, or STIR sequences. For high spatial resolution, maximal 4 mm thick slices with at least an in plane resolution of 0.75 mm and small gap are recommended. To depict the anterior cruciate ligament clearly, the sagittal plane has to be rotated 10 - 20° externally (parallel to the medial border of the femoral condyle). Retropatellar cartilage can bee seen for example in axial T2 weighted gradient echo sequences with Fatsat. However, the choice of the pulse sequences is depended of the diagnostic question, the used scanner, and preference of the operator.
Diagnostic quality in knee imaging is possible with field strengths ranging from 0.2 to 3T. With low field strengths more signal averages must be measured, resulting in increased scan times to provide equivalent quality as high field strengths.
More diagnostic information of meniscal tears and chondral defects can be obtained by direct magnetic resonance arthrography, which is done by introducing a dilute solution of gadolinium in saline (1:1000) into the joint capsule. The knee is then scanned in all three planes using T1W sequences with fat suppression. For indirect arthrography, the contrast is given i.v. and similar scans are started 20 min. after injection and exercise of the knee.
Frequent indications of MRI scans in musculoskeletal knee diseases are:
e.g., meniscal degeneration and tears, ligament injuries, osteochondral fractures, osteochondritis dissecans, avascular bone necrosis and rheumatoid arthritis.
See also Imaging of the Extremities and STIR.
 
Images, Movies, Sliders:
 Sagittal Knee MRI Images T1 Weighted  Open this link in a new window
      

 Anatomic MRI of the Knee 2  Open this link in a new window
    
SlidersSliders Overview

 Knee MRI Coronal Pd Spir 001  Open this link in a new window
 Sagittal Knee MRI Images STIR  Open this link in a new window
      

 Axial Knee MRI Images T2 Weighted  Open this link in a new window
 Anatomic MRI of the Knee 1  Open this link in a new window
    
SlidersSliders Overview

 
Radiology-tip.comArthrography,  Bone Scintigraphy
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Radiology-tip.comMusculoskeletal and Joint Ultrasound,  Sonography
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• View the DATABASE results for 'Knee MRI' (4).Open this link in a new window


• View the NEWS results for 'Knee MRI' (4).Open this link in a new window.
 
Further Reading:
  Basics:
Musculoskeletal MRI at 3.0 T: Relaxation Times and Image Contrast
Sunday, 1 August 2004   by www.ajronline.org    
Knee, Anterior Cruciate Ligament Injuries (MRI)
Tuesday, 28 March 2006   by www.emedicine.com    
Empirical evaluation of the inter-relationship of articular elements involved in the pathoanatomy of knee osteoarthritis using Magnetic Resonance Imaging
Friday, 30 October 2009   by 7thspace.com    
  News & More:
Researcher uses MRI to measure joint's geometry and role in severe knee injury
Tuesday, 23 September 2014   by medicalxpress.com    
Abnormalities on MRI predict knee replacement
Monday, 9 March 2015   by medicalxpress.com    
Financial Interest May Motivate Higher Knee MRI Referral
Wednesday, 4 December 2013   by www.doctorslounge.com    
Study: MRI scans of knees can be used for biometric identification
Wednesday, 23 January 2013   by www.wired.co.uk    
MRI Resources 
MRA - Contrast Enhanced MRI - PACS - MRI Technician and Technologist Career - Collections - Mobile MRI
 
Shoulder MRI
 
MRI of the shoulder with its excellent soft tissue discrimination, and high spatial resolution offers the best noninvasive way to study the shoulder. MRI images of the bone, muscles and tendons of the glenohumeral joint can be obtained in any oblique planes and projections. MRI gives excellent depiction of rotator cuff tears, injuries to the biceps tendon and damage to the glenoid labrum. Shoulder MRI is better than ultrasound imaging at depicting structural changes such as osteophytic spurs, ligament thickening, and acromial shape that may have predisposed to tendon degeneration.
A dedicated shoulder coil and careful patient positioning in external rotation with the shoulder as close as reasonably possible to the center of the magnet is necessary for a good image quality. If possible, the opposite shoulder should be lifted up, so that the patient lies on the imaged shoulder in order to rotate and fix this shoulder to reduce motion during breathing.
Axial, coronal oblique, and sagittal oblique proton density with fat suppression, T2 and T1 provide an assessment of the rotator cuff, biceps, deltoid, acromio-clavicular joint, the glenohumeral joint and surrounding large structures. If a labral injury is suspected, a Fat Sat gradient echo sequence is recommended. In some cases, a direct MR shoulder arthrogram with intra-articular injection of dilute gadolinium or an indirect arthrogram with imaging 20 min. after intravenous injection may be helpful.
See also Imaging of the Extremities.
 
Images, Movies, Sliders:
 Anatomic Imaging of the Shoulder  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 
Radiology-tip.comArthrography
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Radiology-tip.comLow Intensity Pulsed Ultrasound,  Musculoskeletal and Joint Ultrasound
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• View the DATABASE results for 'Shoulder MRI' (3).Open this link in a new window


• View the NEWS results for 'Shoulder MRI' (1).Open this link in a new window.
 
Further Reading:
  Basics:
Palpation-directed rotator interval anterior approach technique demonstrates high accuracy
Wednesday, 8 April 2015   by www.healio.com    
MRI of little value in shoulder pain
Tuesday, 29 October 2013   by www.rheumatologyupdate.com.au    
  News & More:
MRI likely useful for detection of full-thickness rotator cuff tears, bicep instability
Tuesday, 2 February 2016   by www.healio.com    
Shoulder pain? Don't rush to get an MRI
Thursday, 10 October 2013   by bangordailynews.com    
MRI costs wide-ranging
Thursday, 14 April 2011   by www.chieftain.com    
MRE Could Provide A Definitive Diagnosis For People With Muscle Pain, Study Shows
Friday, 30 November 2007   by www.sciencedaily.com    
Peer-Reviewed Study Concludes The FONAR UPRIGHT™ MRI Could Serve as the “Standard Procedure of Care” for Pediatric Shoulder Malady
Wednesday, 30 May 2007   by www.fonar.com    
MRI Resources 
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