Slice selection gradient

CORRECT. The slice thickness is governed by the following equation:

thk = BW_trans / (ω₀·G_S)

where thk is the slice thickness, BW_trans is the transmitted RF bandwidth (the range of frequencies it covers), γ₀ is the gyromagnetic ratio and G_S is the magnitude of the slice selection magnetic field gradient.

So, slice thickness is inversely proportional to G_S; increasing G_S will yield a thinner imaging slice.

Slice selection method

INCORRECT. Increasing the slice-selection gradient magnitude means (for the duration of the gradient field) a larger range of Larmor frequencies exists along the patient.

Before a gradient increase, the RF excitation pulse bandwidth excited a particlar range of frequencies (which corresponded to a particular image slice). If the slice-selection gradient is increased, to what does the same range of frequencies correspond now?

Try again.

INCORRECT. A change of the slice-selection gradient magnitude cannot effect a change of slice location.

Try again.