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Short T1 Inversion RecoveryInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
(STIR) Also called Short Tau (t) (inversion time) Inversion Recovery. STIR is a fat suppression technique with an inversion time TI = T1 ln2 where the signal of fat is zero (T1 is the spin lattice relaxation time of the component that should be suppressed). To distinguish two tissue components with this technique, the T1 values must be different. Fluid Attenuation Inversion Recovery (FLAIR) is a similar technique to suppress water.
Inversion recovery doubles the distance spins will recover, allowing more time for T1 differences. A 180° preparation pulse inverts the net magnetization to the negative longitudinal magnetization prior to the 90° excitation pulse. This specialized application of the inversion recovery sequence set the inversion time (TI) of the sequence at 0.69 times the T1 of fat. The T1 of fat at 1.5 Tesla is approximately 250 with a null point of 170 ms while at 0.5 Tesla its 215 with a 148 ms null point. At the moment of excitation, about 120 to 170 ms after the 180° inversion pulse (depending of the magnetic field) the magnetization of the fat signal has just risen to zero from its original, negative, value and no fat signal is available to be flipped into the transverse plane.
When deciding on the optimal T1 time, factors to be considered include not only the main field strength, but also the tissue to be suppressed and the anatomy. In comparison to a conventional spin echo where tissues with a short T1 are bright due to faster recovery, fat signal is reversed or darkened. Because body fluids have both a long T1 and a long T2, it is evident that STIR offers the possibility of extremely sensitive detection of body fluid. This is of course, only true for stationary fluid such as edema, as the MRI signal of flowing fluids is governed by other factors.
See also Fat Suppression and Inversion Recovery Sequence.
 
Images, Movies, Sliders:
 Sagittal Knee MRI Images STIR  Open this link in a new window
      

 
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    • Imaging of the Extremities
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    • Chemical Shift Imaging
    • Image Contrast Characteristics
    • Black Blood MRA
 
Further Reading:
  Basics:
Techniques of Fat Suppression(.pdf)
   by cds.ismrm.org    
MRI GLOSSARY
   by fonar.com    
  News & More:
Contrast mechanisms in magnetic resonance imaging
2004   by www.iop.org    
MRI Resources 
MRI Technician and Technologist Schools - Image Quality - Breast MRI - Health - Guidance - Databases
 
Fat SuppressionForum -
related threads
 
Fat suppression is the process of utilizing specific MRI parameters to remove the deleterious effects of fat from the resulting images, e.g. with STIR, FAT SAT sequences, water selective (PROSET WATS - water only selection, also FATS - fat only selection possible) excitation techniques, or pulse sequences based on the Dixon method.
Spin magnetization can be modulated by using special RF pulses. CHESS or its variations like SPIR, SPAIR (Spectral Selection Attenuated Inversion Recovery) and FAT SAT use frequency selective excitation pulses, which produce fat saturation.
Fat suppression techniques are nearly used in all body parts and belong to every standard MRI protocol of joints like knee, shoulder, hips, etc.


Image Guidance
Imaging of, e.g. the foot can induce bad fat suppression with SPIR/FAT SAT due to the asymmetric volume of this body part. The volume of the foot alters the magnetic field to a different degree than the smaller volume of the lower leg affecting the protons there. There is only a small band of tissue where the fat protons are precessing at the frequency expected, resulting in frequency selective fat saturation working only in that area. This can be corrected by volume shimming or creating a more symmetrical volume being imaged with water bags.
Even with their longer scan time and motion sensitivity, STIR (short T1//tau inversion recovery) sequences are often the better choice to suppress fat. STIR images are also preferred because of the decreased sensitivity to field inhomogeneities, permitting larger fields of views when compared to fat suppressed images and the ability to image away from the isocenter.
See also Knee MRI.
Recently introduced Dixon turbo spin echo (fast spin echo) sequences can deliver a significant better fat suppression than conventional TSE//FSE imaging.

 
Images, Movies, Sliders:
 Shoulder Axial T2 FatSat FRFSE  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 MRI Orbita T2 FatSat  Open this link in a new window
    
 Knee MRI Sagittal STIR 001  Open this link in a new window
 MRI - Anatomic Imaging of the Ankle 3  Open this link in a new window
    
SlidersSliders Overview

 
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• View the DATABASE results for 'Fat Suppression' (28).Open this link in a new window

 
Further Reading:
  Basics:
Techniques of Fat Suppression(.pdf)
   by cds.ismrm.org    
  News & More:
Enhanced Fast GRadient Echo 3-Dimensional (efgre3D) or THRIVE
   by www.mri.tju.edu    
Ultrashort echo time (UTE) MRI of the spine in thalassaemia
February 2004   by bjr.birjournals.org    
MRI Resources 
Spine MRI - Sequences - Journals - Directories - Implant and Prosthesis - Research Labs
 
FORTE 3.0T™InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.isoltech.co.kr/english/product/30t.htm From ISOL Technology
'Ultra high field MR system , it's right close to you. FORTE 3.0T is the new standard for the future ultra high field MR system. If you are pushing the limits of your existing clinical MR scanner, the FORTE will surely take you to the next level of diagnostic imaging. FORTE is the core leader of the medical technology in the 21st century. Proving effects of fMRI that cannot be measured with MRI less than 2.0T.'
Device Information and Specification
CLINICAL APPLICATION Whole body
CONFIGURATION Short bore compact
SURFACE COILS Head, C-spine, L-spine, TMJ, Knee, Shoulder, General purpose
SPECTROSCOPY Yes
SYNCHRONIZATION ECG/peripheral: Optional/yes, external trigger, respiratory gating
PULSE SEQUENCES Spin echo, Gradient echo, Fast spin echo, Inversion recovery, 2D/3D Fast gradient echo sequences FLAIR/STIR, 2D/3D TOF
IMAGING MODES 2D/3D, T1, T2 and Diffusion//Perfusion imaging, MR Angiography package, Advanced EPI package, Multi-nuclei MR Spectroscopy package
FOV 40 cm
DISPLAY MATRIX 128 x 128, 256 x 256, 512 x 512, 1024 x 1024
MAGNET TYPE Superconducting
BORE DIAMETER
or W x H
61 cm without body coil
MAGNET WEIGHT 12000 kg
H*W*D 260 x 220 x 235 cm
COOLING SYSTEM TYPE Water-cooled coil and air-cooled amplifier
CRYOGEN USE 0.15 L/hr helium
FIELD STRENGTH 3.0T
STRENGTH 38 mT/m
5-GAUSS FRINGE FIELD 3.3 m / 5.2 m
SHIMMING Passive and active
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• View the DATABASE results for 'FORTE 3.0T™' (2).Open this link in a new window

MagneVu 1000InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.mri4ra.com/isis.html From MagneVu; The MagneVu 1000 is a compact, robust, and portable, permanent magnet MRI system and operates without special shielding or costly site preparation.
This MRI device utilizes a patented non-homogeneous magnetic field image acquisition method to achieve high performance imaging. The MagneVu 1000 MRI scanner is designed for MRI of the extremities with the current specialty areas in diabetes and rheumatoid arthritis. Easy access is afforded for claustrophobic, pediatric, or limited mobility patients.
In August 1998 FDA marketing clearance and other regulatory approvals have been received.
Until 2008, over 130 devices in the US are in use. Some further developments of MagneVu's extremity scanner are: 'truly Plug n' Play MRI™' and iSiS ( which adds wireless capability to the second generation MV1000-XL).

Device Information and Specification
CLINICAL APPLICATION Dedicated extremity
CONFIGURATION Portable open MRI
PULSE SEQUENCES T1 and T2 weighted SE, STIR
IMAGING MODES 3-dimensional multi-echo data acquisition
SLICE THICKNESS 3D: 0.6–1 mm
SPATIAL RESOLUTION 0.5–1 mm
MAGNET TYPE Permanent
MAGNET WEIGHT about 50 kg
POWER REQUIREMENTS 110 V
FIELD STRENGTH 0.2 T
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• View the DATABASE results for 'MagneVu 1000' (3).Open this link in a new window

 
Further Reading:
  News & More:
VALUE OF 3D T1W & STIR MRI SEQUENCES IN DIAGNOSING EROSIONS IN RHEUMATOID ARTHRITIS
   by www.bocaradiology.com    
MRI Resources 
Mobile MRI Rental - Equipment - Crystallography - Education - Implant and Prosthesis - Diffusion Weighted Imaging
 
Intera Achieva 3.0T™InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
From Philips Medical Systems;
www.medical.philips.com/main/products/mri/products/intera_achieva3.0t/ Philips continues to expand the frontiers of utra high field MRI with the introduction of the new Intera Achieva 3.0T™. Its powerful future-safe platform shares all the advantages of the Achieva family and covers applications throughout the whole body.


Device Information and Specification
CLINICAL APPLICATION Whole body
CONFIGURATION Short bore compact
SURFACE COILS Standard: T/R-head, Body, Optional phased array: CTL spine; Optional SENSE coils: Torso, Cardiac, Head, Knee, Breast, Neurovascular, Flex M, Flex L
SPECTROSCOPY Optional
SYNCHRONIZATION ECG/peripheral: Optional/yes, respiratory gating
PULSE SEQUENCES SE, Modified-SE, IR (T1, T2, PD), STIR, FLAIR, SPIR, FFE, T1-FFE, T2-FFE, Balanced FFE, TFE, Balanced TFE, Dynamic, Keyhole, 3D, Multi Chunk 3D, Multi Stack 3D, K Space Shutter, MTC, TSE, Dual IR, DRIVE, EPI, Cine, 2DMSS, DAVE, Mixed Mode; Angiography: Inflow MRA, TONE, PCA, CE MRA
IMAGING MODES Single Slice 2D , Multi Single Slice 2D, Multi Slice 2D, 3D, Multi Chunk 3D, Multi Stack 3D
Minimum TR 1.1 msec
FOV Over 40 cm
SLICE THICKNESS 0.05 mm
DISPLAY MATRIX 128 x 128, 256 x 256,512 x 512,1024 x 1024 (64 for Bold img)
MEASURING MATRIX Variable in 1% increments
PIXEL INTENSITY Lum.: 120 cd/m2; contrast: 150:1
SPATIAL RESOLUTION Variable (op. param. depend.)
MAGNET TYPE Superconducting
BORE DIAMETER
or W x H
35 x 35 cm
MAGNET WEIGHT 5500 kg
H*W*D 206 x 200 x 167 cm
POWER REQUIREMENTS 380/400 V
CRYOGEN USE 0.15 L/hr helium
FIELD STRENGTH 3 tesla (3T)
STRENGTH up to 80 mT/m
5-GAUSS FRINGE FIELD 3.0 m / 5.2 m
SHIMMING Passive and dynamic, 1st order std./2nd opt.
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• View the DATABASE results for 'Intera Achieva 3.0T™' (2).Open this link in a new window

 
Further Reading:
  News & More:
Faster speed, better spatial resolution lead 3T benefits
   by sipi.usc.edu    
MRI Resources 
Contrast Agents - PACS - Calculation - Colonography - Portals - Directories
 
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