MRI uses the spatial frequency and phase of proton magnetization to form images, rather than projection or reflection methods. The signal is influenced by a frequency-encoding gradient that varies along the horizontal axis, impacting the effective magnetic field at each pixel. Additionally, each pixel encompasses a range of frequencies due to its finite width.

2. MRI does not use Projection, reflection or refraction mechanism which is commonly used in optical
imaging methods to form image.

3. The Spatial information of the proton pools contributing MR
signal is determined by the spatial frequency and phase of their
magnetization.
S(t) = A sin(ωot − ϕ)
where S(t) is the signal as a function of time, A is the amplitude, ωo is the
angular frequency, and ϕ is the instantaneous phase.

4. • Here a frequency-encoding gradient (Gf) begins on the
left of the image at position x=0 and increases linearly
along the horizontal axis.
• If the main (static) magnetic field is Bo, then the
effective field B(x) at any point (x) along the horizontal
axis is given by
B(x) = Bo + xGf
From the Larmor equation (f = γB),
• Each pixel has a finite width, so actually contains a
small range of frequencies (called the per pixel
bandwidth) rather than just a single frequency.
• A linearly increasing frequency-encoding gradient (Gf)
applied along the horizontal (x-) axis. Pixels A, B, and C
all resonate at the same lower frequency; D, E and F at
the same higher frequency.

17. Slice selection-along Z axis