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Rad229 (2020) Lecture-02C: MRI Signal Equation and k-space
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@xFurioCopter 10 ай бұрын
Probably a stupid question: If we go from k space to image, dont we get the axes inverted as (F(F f)) (x) = f(-x). The second fft is applied by computers from k space to xy space, the first one by using nmr, i.e. imaging space in the frequency domain, correct?
@jacobvandijk6525 2 жыл бұрын
It seems the position-vector r is important. But where is its origin located? By the way, if we integrate over the object, then this equation and the following ones (from 11:38 to 18:21) should end with (dr)^3.
@stanford-rad2299 Жыл бұрын
The origin is the so-called "isocenter" of the MRI system. The B0 field is designed to be spatially homogeneous, but active gradients superpose linear B-fields on top of B0. Hence, isocenter is actually defined by the geometric alignment of the three gradient systems and corresponds to the spatial position that maintains B=B0 (G•r=G•0=0) when the gradients are active.
@stanford-rad2299 Жыл бұрын
d\vec{r} is effectively (dr)^3.
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