Dear Kim,

I am not knowledgeable about VBM - but can suggest from the MRI side  
that your sentence is unlikely to always be true.

At 3T you will suffer from reduced spatial uniformity of the B1 field  
used for signal excitation, leading to increased spatial  
non-uniformity. Depending on the pulse sequence used this will  
normally also make your contrast spatially varying as well (and this  
is much harder to correct for).

It is also possible (again depending on your pulse sequence) that you  
get greater artefacts in your 3T image such as distortion or point  
spread function degradation that could also influence your detection  
negatively.

At 3T you will always get better signal to noise in the images all  
other things being equal (though they rarely are - and you always need  
different parameters to optimise sequences at each field strength!)  
and this can be exchanged for better resolution.

In short it will depend on optimisation of both your acquisition and  
VBM processing. When well optimised 3T is likely to give a better  
result.

David Carmichael

MR Physicist
UCL Institute of Neurology

Quoting ??? <[log in to unmask]>:

> Dear experts,
>
> Is the following sentence always true?
> "When compared to a 1.5T scanner, VBM analysis using a 3T MR scanner has an
> increased sensitivity for detecting subtle gray matter abnormalities and a
> better segmentation of gray matter/white matter"
> If so, please let me know reliable references.
>
>
> Thanks a million.
>
> Kim
>