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 'Gradient Echo Multi Slice' 
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Gradient Echo Multi SliceInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
(GEMS) This pulse sequence uses a changeable flip angle instead of a 90° pulse and a gradient instead of a RF pulse to rephase the FID.
T2*, T1 weighted and proton density images can be acquired. The flip angle in combination with the TR determines the T1 weighting and the TE controls the amount of dephasing. To minimize T2* the echo time should be short.

See also Gradient Echo Sequence.
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Spin Echo SequenceInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
Spin Echo Timing Diagram (SE) The most common pulse sequence used in MR imaging is based of the detection of a spin or Hahn echo. It uses 90° radio frequency pulses to excite the magnetization and one or more 180° pulses to refocus the spins to generate signal echoes named spin echoes (SE).
In the pulse sequence timing diagram, the simplest form of a spin echo sequence is illustrated.
The 90° excitation pulse rotates the longitudinal magnetization (Mz) into the xy-plane and the dephasing of the transverse magnetization (Mxy) starts.
The following application of a 180° refocusing pulse (rotates the magnetization in the x-plane) generates signal echoes. The purpose of the 180° pulse is to rephase the spins, causing them to regain coherence and thereby to recover transverse magnetization, producing a spin echo.
The recovery of the z-magnetization occurs with the T1 relaxation time and typically at a much slower rate than the T2-decay, because in general T1 is greater than T2 for living tissues and is in the range of 100-2000 ms.
The SE pulse sequence was devised in the early days of NMR days by Carr and Purcell and exists now in many forms: the multi echo pulse sequence using single or multislice acquisition, the fast spin echo (FSE/TSE) pulse sequence, echo planar imaging (EPI) pulse sequence and the gradient and spin echo (GRASE) pulse sequence;; all are basically spin echo sequences.
In the simplest form of SE imaging, the pulse sequence has to be repeated as many times as the image has lines.
Contrast values:
PD weighted: Short TE (20 ms) and long TR.
T1 weighted: Short TE (10-20 ms) and short TR (300-600 ms)
T2 weighted: Long TE (greater than 60 ms) and long TR (greater than 1600 ms)
With spin echo imaging no T2* occurs, caused by the 180° refocusing pulse. For this reason, spin echo sequences are more robust against e.g., susceptibility artifacts than gradient echo sequences.

See also Pulse Sequence Timing Diagram to find a description of the components.
 
Images, Movies, Sliders:
 Shoulder Coronal T1 SE  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 Shoulder Axial T1 SE  Open this link in a new window
 MRI Orbita T1  Open this link in a new window
    
 
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Further Reading:
  Basics:
Fast Spin Echo(.pdf)
Tuesday, 24 January 2006   by www.81bones.net    
Magnetic resonance imaging
   by www.scholarpedia.org    
FUNDAMENTALS OF MRI: Part I
   by www.e-radiography.net    
  News & More:
New MR sequence helps radiologists more accurately evaluate abnormalities of the uterus and ovaries
Thursday, 23 April 2009   by www.eurekalert.org    
MRI techniques improve pulmonary embolism detection
Monday, 19 March 2012   by medicalxpress.com    
MRI Resources 
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Aurora® 1.5T Dedicated Breast MRI SystemInfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.
 
www.auroramri.com/mri/product/ From Aurora Imaging Technology, Inc.;
The Aurora® 1.5T Dedicated Breast MRI System with Bilateral SpiralRODEO™ is the first and only FDA approved MRI device designed specifically for breast imaging. The Aurora System, which is already in clinical use at a growing number of leading breast care centers in the US, Europe, got in December 2006 also the approval from the State Food and Drug Administration of the People's Republic of China (SFDA).
'Some of the proprietary and distinguishing features of the Aurora System include: 1) an ellipsoid magnetic shim that provides coverage of both breasts, the chest wall and bilateral axillary lymph nodes; 2) a precision gradient coil with the high linearity required for high resolution spiral reconstruction;; 3) a patient-handling table that provides patient comfort and procedural utility; 4) a fully integrated Interventional System for MRI guided biopsy and localization; and 5) the user-friendly AuroraCAD™ computer-aided image display system designed to improve the accuracy and efficiency of diagnostic interpretations.'
Device Information and Specification
CLINICAL APPLICATION
CONFIGURATION
Short bore compact
IMAGING MODES
Bi-lateral RODEO fat suppression, high resolution Rotating Delivery of Excitation Offresonance Spiral, integrated targeting SW compatible with major MR guided intervention equipment
TR
10 ms for gradient echo and less than 2,500 ms for T2 weighted spin echo
TE
From 5 ms for RODEO Plus to over 80 ms, 120 ms for T2 sequences
SINGLE/MULTI SLICE
Around 0.02 sec for a 256x256 image, 12.4 sec for a 512 x 512 x 32 multislice set
FOV
20 - 36 cm, max. elliptical 36 x 44 cm
MEASURING MATRIX
512 x 512
BORE DIAMETER
or W x H
64 cm diameter (gantry)
MAGNET WEIGHT
8,500 lbs
H*W*D
240 x 188 x 163 cm
POWER REQUIREMENTS
150A/120V-208Y/3 Phase//60 Hz/5 Wire
COOLING SYSTEM
Helium for magnet, distilled/de-ionized water for coil;
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• View the DATABASE results for 'Aurora® 1.5T Dedicated Breast MRI System' (2).Open this link in a new window


• View the NEWS results for 'Aurora® 1.5T Dedicated Breast MRI System' (3).Open this link in a new window.
 
Further Reading:
  News & More:
Aurora Imaging Technology Announces Approval in China
   by salesandmarketingnetwork.com    
Aurora Imaging Technology, Inc. Release: Results of a Multi-Center Trial Demonstrates Superior Diagnostic Performance of the Aurora® 1.5T Dedicated Breast MRI System Over Whole-Body Breast MRI
Monday, 1 October 2012   by www.biospace.com    
MRI Resources 
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Echelon™ 1.5TInfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.
 
www.hitachimed.com/contentindex.asp?ID=971 From Hitachi Medical Systems America Inc.;
Hitachi expanded its portfolio with the Echelon™ 1.5T. The MRI scanner combines a compact magnet and a scalable 8-channel RF system with high-performance gradients and slew rate to select short echo times, small field of views, high matrices and thin slices. Standard features of the Echelon MRI system include higher-order active shim, RAPID (parallel imaging for use on brain MRI, body, cardiovascular imaging, and orthopedic coils), multiple coil ports, and an advanced reconstruction engine.
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
Short bore
Head, body coil, spine, breast, knee, shoulder, vascular multiple array coils.
SYNCHRONIZATION
Cardiac gating, ECG/peripheral, respiratory gating
PULSE SEQUENCES
SE, IR, FSE, FIR, GE, SG, BASG, PBSG, PCIR, DWI, Radial, Angiography: TOF, FLUTE (Fluoro-triggered bolus MRA), Time-resolved MRA
IMAGING MODES
Single, multislice, volume study
PIXEL INTENSITY
Level Range: -2,000 to +4,000
Sub millimeter
POWER REQUIREMENTS
208/220/240 V, single phase
CRYOGEN USE
Low cryogen boil-off
STRENGTH
30 mT/m
150 T/m/sec
Higher-order active shim
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• View the DATABASE results for 'Echelon™ 1.5T' (2).Open this link in a new window


• View the NEWS results for 'Echelon™ 1.5T' (3).Open this link in a new window.
 
Further Reading:
  Basics:
Echelon 1.5T
   by www.hitachimed.com    
MRI Resources 
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Virgo™InfoSheet: - Devices -
Intro, 
Types of Magnets, 
Overview, 
etc.MRI Resource Directory:
 - Devices -
 
www.canamglobal.com/mri/virgomri.html From Millennium Technology Inc. This open C-shaped MRI system eases patient comfort and technologist maneuverability. This low cost scanner is build for a wide range of applications. The Virgo™ patient table is detachable and moves on easy rolling castors. Able to accommodate patient weights up to 160 kg, the tabletop has a range of motion of 30 cm in the lateral direction and 90cm in the longitudinal direction. Images generated with this scanner can only be viewed (without data loss) on Millennium's proprietary viewing software.
Device Information and Specification
CLINICAL APPLICATION
Whole body
CONFIGURATION
C shaped
SYNCHRONIZATION
Standard cardiac gating, ECG/peripheral, respiratory gating
PULSE SEQUENCES
2D Spin Echo (single and multi-echo), 2D Inversion Recovery, 2D Sequential and 3D Volume Gradient Echo, 2D and 3D Spoiled Gradient Echo
IMAGING MODES
Localizer, single slice, multislice, volume, fast, POMP, multi slab, cine, slice and frequency zip, extended dynamic range, tailored RF
TR
steps of 1 msec
TE
steps of 1 msec
SINGLE/MULTI SLICE
Simultaneous scan and reconstruction;; 100 images/second reconstruction
400 mm
2D : 2 mm; 3D : 0.5 mm
MEASURING MATRIX
512x512
PIXEL INTENSITY
256 gray levels
MAGNET TYPE
Permanent
BORE DIAMETER
or Vertical Gap
44 cm
STRENGTH
15 mT/m
5-GAUSS FRINGE FIELD
3 m/3 m
Passive
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