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Clifford Thornton

Thu. 30 Jun.16,
17:48

[Start of:
'Max. SAR per second - Whole Body (Normal, 1st Controlled, 2nd Control)'
0 Reply]


 
  Category: 
Safety

 
Max. SAR per second - Whole Body (Normal, 1st Controlled, 2nd Control)
Hello fellow imaging technologists & professionals!

I'm involved in the development of a new type of cardiovascular medical device.

This device employs MRI technology/scans to power, guide, and control the medical devices and their active elements.

I conducted some research into the following question, "How much x-ray energy is allowed within a human every sec from a MRI machine?"

With regards to SAR rates, I understand that these are the upper-limits for the various settings for a full-body scan:

Normal setting: Whole body SAR - 2

1st Level Controlled: Whole body SAR - 4

2nd Level Controlled: Whole body SAR - >4

Would you agree with these calculations that I performed, and if not, why? And what would be a better way to calculate this?

For WHOLE BODY SAR:

-SO IF IN NORMAL MODE FOR MRI, THE MAX. ALLOWABLE SAR IS "2" OVER A 6 MIN. PERIOD, THEN
-6 MIN. = 360 SECONDS
-2 / 360 = 0.00555

FOR 1ST LEVEL CONTROLLED:

-SO IF IN 1ST LEVEL CONTROLLED FOR MRI, THE MAX. ALLOWABLE SAR IS "4" OVER A 6 MIN. PERIOD, THEN
-6 MIN. = 360 SECONDS
-4/ 360 = 0.01111

Other questions -- What is the difference between normal setting, 1st conrolled and 2nd controlled?

What is the clinical purpose of these various settings?

Any insights that you would be willing to share in regards to the above would be greatly appreciated!

I was trained and registred as a diagnostic echocardiographer, specializing in cardiovascular ultrasound, therefore I need help with MRI information/specifications. I am now focusing on the medical device field, but this technology/device happens to be highly dependent on MRI technology.


Any help from the group would be greatly appreciated!!

Thanks & regards,


Clifford Thornton
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Jason Mondoro

Mon. 20 Jun.16,
20:41

[Start of:
'What am I looking at?'
0 Reply]


 
  Category: 
General

 
What am I looking at?
My wife has had severe back pain for months and the insurance finally allowed us to get an MRI. Can anyone tell me what we are looking at here? and maybe a guess at a diagnosis? Our doctor is on vacation and we won't have an answer for about another week. http://imgur.com/a/spxfp Thank you in advance!
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Jon Selby

Tue. 26 Apr.16,
07:57

[Start of:
'Susceptibility artifact query'
0 Reply]


 
  Category: 
General

 
Susceptibility artifact query
As an MRI 'newbie' would someone be willing to help me with a question on magnetic susceptibility. If you have two metal implants of the same external geometrical form but one of these is hollow, would you you get the same size artifact? I'm basically wondering whether a metallic implant has a finite sphere of influence or whether it is compounded by the volume of material. Much appreciated, Jon
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Charlie Goulder

Fri. 8 Apr.16,
20:39

[Start of:
'What is the meaning of this?'
0 Reply]


 
  Category: 
General

 
What is the meaning of this?
Please help. My doctor will not explain this to me and I need help. The picture attached has my comparison from an mri 2 years ago. Please help me understand. I am 28 years old.
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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
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