Magnetic Resonance - Technology Information Portal Welcome to MRI Technology
Info
  Sheets

Out-
      side
 

Next big thing in MRI will be :
AI 
remote operator 
personalized protocols 
helium-free 
molecular MRI 
portable MRI 




 
MRI Forum
'Gradient'
SEARCH FORUM FOR   
 
Result: Searchterm 'Gradient' found in 38 messages
Result Pages: 1 [2] 3 4 5 6 7 8 
More Results: Database  (316)  News Service  (6)  Resources  (7)  
Forum Overview
 bottom
Steven Ford

Fri. 26 Oct.18,
02:29

[Reply (1 of 2) to:
'When to shim?'
started by: 'Matt H'
on Fri. 27 Oct.17]


 
  Category: 
General

 
When to shim?
you ask a complex question. Any sequence that is not a standard spin echo can benefit from shimming, but its not always worth it.

If you are scanning a knee in the center of the magnet, or nearly so, you might not see much difference in gradient echo scans, which in general are quite sensitive to shim problems. But if you are doing fat-water separation or fatsat images, you will see a difference even in this example.

Because hardware varies, its hard to say in one blanket statement for every case. For sure, do it on fatsat or fat-water imaging. The next most sensitive studies are off-center imaging such as shoulders. Beyond that, you should experiment a little. Of course, erring on the side of caution is a good idea.
 
 

Steven Ford
Professional Imaging Services, Inc.
 View the whole thread
John Smith

Wed. 11 Nov.15,
22:14

[Start of:
'Faster pulse sequences'
0 Reply]


 
  Category: 
General

 
Faster pulse sequences
Hi,
I have been learning about faster MRI sequences and have two questions

1) With "Fast (Turbo) gradient echo", in which we apply a spoiler gradient, do we not eventually end up with no longitudinal magnetization because TR is always shorter than T1? Hence shouldn't we eventually get no signal at all?


2) in SSFP (Steady-state free precession) we can apply an RF pulse of 90 degrees (in which T1>>T2) to get heart-blood contrast. How is this any different to a standard spin-echo sequence in terms of timing?

Thank you
Reply to this thread
(login or register first)
Sai Mahathi Yasa

Sun. 29 Mar.15,
04:58

[Start of:
'Re: Calculation of Resolution and Tr'
0 Reply]


 
  Category: 
Basics and Physics

 
Re: Calculation of Resolution and Tr
Tacq= 32s
Gradient strength= 10mT/m
Matrix size=256x256 pixels
dwell time= 0.03ms

How to calculate resolution and Tr?
Reply to this thread
(login or register first)
aaron yonts`

Thu. 19 Sep.13,
07:56

[Reply (1 of 3) to:
'why there is T2* but not T1*'
started by: 'Isa Toni Toni'
on Wed. 24 Jul.13]


 
  Category: 
Sequences and Imaging Parameters

 
why there is T2* but not T1*
i may just be giving general info but a t2* is aquired from a gradient echo compared to a t2 with a spin echo. according to mri in practice a t2* can help show some things a normal t2 would not, such as ms plaques in a cervical spine
 View the whole thread
Brent Johnson

Wed. 21 Aug.13,
19:38

[Start of:
'Hitachi Airis II question'
0 Reply]


 
  Category: 
Sequences and Imaging Parameters

 
Hitachi Airis II question
I have a question for a Hitachi Airis II .3T non-upgraded gradients
On T2 FSE sequences especially on thumb sagittal slices. Image quality very poor, grainy. What is ideal bandwidth and TE settings for improving image quality? Also is positioning and angle of slice a factor in image quality. The closer the anatomy is to edge of coil, does that effect image quality.

Thanks Brent
Reply to this thread
(login or register first)

Result Pages : 1 [2] 3 4 5 6 7 8 
 top
 
Share This Page
FacebookTwitterLinkedIn

MR-TIP    
Community   
User
Pass
Forgot your UserID/Password ?    



Look
      Ups






MR-TIP.com uses cookies! By browsing MR-TIP.com, you agree to our use of cookies.

Magnetic Resonance - Technology Information Portal
Member of SoftWays' Medical Imaging Group - MR-TIP • Radiology-TIP • Medical-Ultrasound-Imaging • 
Copyright © 2003 - 2024 SoftWays. All rights reserved. [ 18 December 2024]
Terms of Use | Privacy Policy | Advertising
 [last update: 2024-02-26 03:41:00]