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Echo Train
 
A series of 180° RF rephasing pulses and their corresponding echoes for a fast or turbo spin echo pulse sequence.

See Fast Spin Echo and Turbo Spin Echo Turbo Factor.
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• Related Searches:
    • Asymmetrical Echoes
    • Slew Rate
    • Radio Frequency Pulse
    • Echo Train Length
    • Fast Spin Echo Optimization
 
Further Reading:
  Basics:
RARE
Monday, 3 December 2012   by www2.warwick.ac.uk    
MRI Resources 
Resources - RIS - MRI Centers - Stent - Crystallography - Jobs
 
Echo Train Length
 
The number of series of 180° RF rephasing pulses and their corresponding echoes for a fast or turbo spin echo pulse sequence.

See Fast Spin Echo.
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• View the DATABASE results for 'Echo Train Length' (4).Open this link in a new window

 
Further Reading:
  Basics:
Fast Spin Echo(.pdf)
Tuesday, 24 January 2006   by www.81bones.net    
  News & More:
Comparison of Fast Spin-Echo Versus Conventional Spin-Echo MRI forEvaluating Meniscal Tears
June 2005   by www.ajronline.org    
MRI Resources 
Cochlear Implant - Pacemaker - Coils - Portals - Contrast Enhanced MRI - Manufacturers
 
Fast Spin EchoForum -
related threadsInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
Fast Spin Echo Diagram (FSE) In the pulse sequence timing diagram, a fast spin echo sequence with an echo train length of 3 is illustrated. This sequence is characterized by a series of rapidly applied 180° rephasing pulses and multiple echoes, changing the phase encoding gradient for each echo.
The echo time TE may vary from echo to echo in the echo train. The echoes in the center of the K-space (in the case of linear k-space acquisition) mainly produce the type of image contrast, whereas the periphery of K-space determines the spatial resolution. For example, in the middle of K-space the late echoes of T2 weighted images are encoded. T1 or PD contrast is produced from the early echoes.
The benefit of this technique is that the scan duration with, e.g. a turbo spin echo turbo factor / echo train length of 9, is one ninth of the time. In T1 weighted and proton density weighted sequences, there is a limit to how large the ETL can be (e.g. a usual ETL for T1 weighted images is between 3 and 7). The use of large echo train lengths with short TE results in blurring and loss of contrast. For this reason, T2 weighted imaging profits most from this technique.
In T2 weighted FSE images, both water and fat are hyperintense. This is because the succession of 180° RF pulses reduces the spin spin interactions in fat and increases its T2 decay time. Fast spin echo (FSE) sequences have replaced conventional T2 weighted spin echo sequences for most clinical applications. Fast spin echo allows reduced acquisition times and enables T2 weighted breath hold imaging, e.g. for applications in the upper abdomen.
In case of the acquisition of 2 echoes this type of a sequence is named double fast spin echo / dual echo sequence, the first echo is usually density and the second echo is T2 weighted image. Fast spin echo images are more T2 weighted, which makes it difficult to obtain true proton density weighted images. For dual echo imaging with density weighting, the TR should be kept between 2000 - 2400 msec with a short ETL (e.g., 4).
Other terms for this technique are:
Turbo Spin Echo
Rapid Imaging Spin Echo,
Rapid Spin Echo,
Rapid Acquisition Spin Echo,
Rapid Acquisition with Refocused Echoes
 
Images, Movies, Sliders:
 Lumbar Spine T2 FSE Sagittal  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 MRI - Anatomic Imaging of the Foot  Open this link in a new window
    
SlidersSliders Overview

 Lumbar Spine T2 FSE Axial  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 
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• View the DATABASE results for 'Fast Spin Echo' (31).Open this link in a new window

 
Further Reading:
  Basics:
MYELIN-SELECTIVE MRI: PULSE SEQUENCE DESIGN AND OPTIMIZATION
   by www.imaging.robarts.ca    
Advances in Magnetic Resonance Neuroimaging
Friday, 27 February 2009   by www.ncbi.nlm.nih.gov    
  News & More:
New MR sequence helps radiologists more accurately evaluate abnormalities of the uterus and ovaries
Thursday, 23 April 2009   by www.eurekalert.org    
Spin echoes, CPMG and T2 relaxation - Introductory NMR & MRI from Magritek
2013   by www.azom.com    
Searchterm 'Echo Train' was also found in the following services: 
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Double Inversion Recovery T1 MeasurementInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
(DIR or DIRT1) Double inversion recovery T1 measurement is a T1 weighted black blood MRA sequence in which the signal from blood is suppressed. The inversion time to suppress blood is described as the duration between the initial inversion pulse and time point that the longitudinal magnetization of blood reaches the zero point. The readout starts at the blood suppression inversion time (BSP TI) and blood in the imaging slice gives no signal. This inversion time is around 650 ms with a 60 beat per minute heart rate at 1.5 T.
The TI can be decreased by using a wider receive bandwidth, shorter echo train length and/or narrow trigger window. Wide bandwidth also decreases the blurring caused by long echo trains at the expense of signal to noise ratio. In case of in plane or slow flow the suppression of the signal from blood may be incomplete. With increased TE or change of the image plane the blood suppression can be improved.
Double inversion recovery is a breath hold technique with one image per acquisition used in cardiovascular imaging. The patient is instructed to hold the breath in expiration (if not possible also inspiration can be taken), so that the end diastolic volume in the cardiac chambers would be the same during entire scanning. DIR provides fine details of the boundary between the lumen and the wall of the cardiac chambers and main vascular and heart structures, pericardium, and mediastinal tissues.
 
Images, Movies, Sliders:
 Normal Dual Inversion Fast Spin-echo  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 
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• View the DATABASE results for 'Double Inversion Recovery T1 Measurement' (2).Open this link in a new window

 
Further Reading:
  News & More:
Artificial double inversion recovery images can substitute conventionally acquired images: an MRI-histology study
Wednesday, 16 February 2022   by www.nature.com    
MRI Resources 
Journals - Stent - Colonography - Cochlear Implant - Service and Support - Breast MRI
 
Asymmetrical Echoes
 
The echo time TE vary from echo to echo in the echo train.
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• View the DATABASE results for 'Asymmetrical Echoes' (2).Open this link in a new window

MRI Resources 
Shoulder MRI - Veterinary MRI - Guidance - Societies - Supplies - Mobile MRI Rental
 
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