GATE 2020 BM – Question 51
An MRI RF coil at 1 T has induced voltage magnitude $|V|=2\pi\gamma_0V_sM_0(\sin\alpha)B^r$, with γ₀ the Larmor frequency, Vₛ slice volume, M₀ equilibrium magnetization and Bʳ receive-coil sensitivity. Using the same coil at 3 T, slice thickness is halved and other stated factors fixed. Find V₂/V₁.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: (C) 4.5
Explanation
Larmor frequency scales linearly with static field, giving a factor three. Equilibrium magnetization also scales with field, giving another three. Halving slice thickness halves slice volume, while coil sensitivity and flip angle remain the same. Total ratio=3×3×.5=4.5, C.