Question
Question Posted 03/09/17:
Hi,
I'm trying to decide whether the DTI images acquired in ADNI2 will be suitable for my research. In order to qualify, I need an isotropic voxel size of 2 mm. From the protocol manuals, I see that the FOV is 35, frequency and phase are 128 each. From what I understand about MR images, voxel size = (FOV/frequency)*(FOV/phase)*slice thickness. This gives me 0.27*0.27*2.7 as the voxel size. I would like to get a confirmation if this is correct; and the images have anisotropic pixels?
Hi,
I'm trying to decide whether the DTI images acquired in ADNI2 will be suitable for my research. In order to qualify, I need an isotropic voxel size of 2 mm. From the protocol manuals, I see that the FOV is 35, frequency and phase are 128 each. From what I understand about MR images, voxel size = (FOV/frequency)*(FOV/phase)*slice thickness. This gives me 0.27*0.27*2.7 as the voxel size. I would like to get a confirmation if this is correct; and the images have anisotropic pixels?
Response posted 03/09/17 by ADNI MRI Core:
Thank you for your question to the ADNI MRI Core.
Your calculation is almost correct, but you are off by a factor of 10 because of a cm/mm mixup. The ADNI2 DTI resolution is 2.7x2.7x2.7mm. The resolution is isotropic, but the images were reconstructed with 1.35x1.35x2.7mm voxels (i.e. they were zero padded in x and y). If needed, the voxels can be binned into (2.7mm)^3 voxels without really losing anything.
ADNI3?s diffusion scan has isotropic 2.0 mm voxels, but it is just getting started.
ADNI MRI
Your calculation is almost correct, but you are off by a factor of 10 because of a cm/mm mixup. The ADNI2 DTI resolution is 2.7x2.7x2.7mm. The resolution is isotropic, but the images were reconstructed with 1.35x1.35x2.7mm voxels (i.e. they were zero padded in x and y). If needed, the voxels can be binned into (2.7mm)^3 voxels without really losing anything.
ADNI3?s diffusion scan has isotropic 2.0 mm voxels, but it is just getting started.
ADNI MRI
