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Just curious...what do ya'll think about the open scanners. While they say image quality is not lost, it looks like these machines are .0001 tesla. Lol. Just want some opinions.
open MRI scanners
- Thread starter pedroclinton
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They serve their purpose. If truly indicated, an MRI with a low field strength is better than no MRI. But there is no way that the image quality is equivalent. No way.
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Low field isn't always bad field. In the patient with metallic implants, a lower field might be the only way to get an acceptable quality MR due to susceptibility artifacts (these scale linearly with field strength). As always, these questions depend on the body part and the question being asked. Still, in general you're going to get higher SNR images on the closed bore scanner. This is why closed bore systems still represent the engineering of choice. Nobody wants to make patients uncomfortable unnecessarily, so we do what we have to do.
If you consider your typical open system you're looking at .2-.35T, versus your typical 1.5T closed system. You will get more than 5x gain in SNR going to a small joint coil. So, the resolution on a wrist at .3T will still be higher than the resolution on a head coil at 1.5T. Again, it all depends on the question being asked. A 5x SNR gain in SNR will get you about a 2-fold reduction in voxel size in two dimensions. So if you were getting 1x1x3cm slices at 1.5T, are 2x2x3cm slices still going to answer your question at 0.2T? If that's all that claustrophobic patient will tolerate, that's what you're going to get. A lot of current research focuses on getting those interventional MR-guided procedures done, and open MR provides a much greater ability for that to happen.
In most cases, the reason closed bore systems are superior is because you'll have higher B0 homogeneity and higher field. I know you were exaggerating, but .0001T is only 2x greater than Earth's magnetic field. That being said, I have seen images taken from Earth field, and there are groups working on higher quality Earth field imaging by increasing signal detection and decreasing electronic noise. Maybe it'll happen someday...
Also open bore systems have been increasing in their field strengths and all sorts of design considerations mean you have everything from body part MR, to "open" bores of various sizes. When will someone start selling a "semi-open" scanner? The newer 1.5T bores are getting shorter and wider to accommodate increasing patient girths and all that claustrophobia.
A quick literature search reveals:
http://www.ajronline.org/cgi/content/abstract/181/5/1211 (open MRI not so good for shoulders)
http://scitation.aip.org/getabs/ser...00029000011002541000001&idtype=cvips&gifs=yes (open MRI fine for rad onc planning)
Review of open MR for interventional purposes
http://linkinghub.elsevier.com/retrieve/pii/S0720048X05001221
If you consider your typical open system you're looking at .2-.35T, versus your typical 1.5T closed system. You will get more than 5x gain in SNR going to a small joint coil. So, the resolution on a wrist at .3T will still be higher than the resolution on a head coil at 1.5T. Again, it all depends on the question being asked. A 5x SNR gain in SNR will get you about a 2-fold reduction in voxel size in two dimensions. So if you were getting 1x1x3cm slices at 1.5T, are 2x2x3cm slices still going to answer your question at 0.2T? If that's all that claustrophobic patient will tolerate, that's what you're going to get. A lot of current research focuses on getting those interventional MR-guided procedures done, and open MR provides a much greater ability for that to happen.
In most cases, the reason closed bore systems are superior is because you'll have higher B0 homogeneity and higher field. I know you were exaggerating, but .0001T is only 2x greater than Earth's magnetic field. That being said, I have seen images taken from Earth field, and there are groups working on higher quality Earth field imaging by increasing signal detection and decreasing electronic noise. Maybe it'll happen someday...
Also open bore systems have been increasing in their field strengths and all sorts of design considerations mean you have everything from body part MR, to "open" bores of various sizes. When will someone start selling a "semi-open" scanner? The newer 1.5T bores are getting shorter and wider to accommodate increasing patient girths and all that claustrophobia.
A quick literature search reveals:
http://www.ajronline.org/cgi/content/abstract/181/5/1211 (open MRI not so good for shoulders)
http://scitation.aip.org/getabs/ser...00029000011002541000001&idtype=cvips&gifs=yes (open MRI fine for rad onc planning)
Review of open MR for interventional purposes
http://linkinghub.elsevier.com/retrieve/pii/S0720048X05001221
