Some CT and MR techniques require a good contrast bolus (CTA, CT perfusion, MR perfusion)
Q: What arm should be used for injection?
A: The right arm. The left arm is prone to restriction from tortuosity of arch vessels.
Reference:
http://www.ajronline.org/doi/pdfplus/10.2214/ajr.170.6.9609192
Imaging/Computer Graphics
Q: What is a voxel?
A: In cross sectional imaging, it is the “volume element” of anatomy that is represented in an image by a pixel.
Q: What is an isotropic voxel?
A: It is a voxel with equal dimensions. Source images made from isotropic voxels are used to create multiplanar refromatted images that have resolution independent of plane angulation.
Q: What is a pixel?
A: It is the the basic subunit of a digital image, a “picture element”. In imaging it represents the attenuation/signal of a corresponding unit of anatomy or “voxel” For CT and MR pixel size can be calculated:
pixel size(mm)=FOV(mm)/matrix (is in the dicom header 0028,0010 and 0028,0011)
FOV=field of view (field of view is in the DICOM header 0018,1100)
e.g. a 25cm field of view and a 256X256 matrix would produce an image with a pixel representing about 1 square mm of anatomy. The voxel volume could be determined if you knew what?
A: slice thickness, e.g. 5mm.
Q: What is a typical voxel dimension for a brain MR?
A: assuming the factors above are typical 1x1x5 mm is a good approximation.