Question

An RF pulse is applied to acquire an axial MR image at the isocenter of a 1.5T MRI scanner with slice thickness of 2.5 mm. Assuming a gradient field strength of 2 Gauss/cm is applied and Gyromagnetic ratio of protons is 42.58 MHz/T, the RF pulse bandwidth required for slice selection is \(\underline{\hspace{2cm}}\) kHz.

• A. 1.06
• B. 2.13
• C. 6.66
• D. 13.31

Hint:

The RF bandwidth for MRI slice selection depends on the slice thickness, gradient strength, and gyromagnetic ratio.

Answer 1

The Correct Option is B

The RF pulse bandwidth for slice selection in MRI can be calculated using the formula: \[ \Delta f = \frac{\Delta z \cdot \gamma \cdot B}{\text{Slice thickness}}, \] where:
- \( \Delta z \) is the slice thickness in cm,
- \( \gamma \) is the gyromagnetic ratio (42.58 MHz/T),
- \( B \) is the gradient field strength in Gauss/cm.
Given:
- Slice thickness \( \Delta z = 2.5 \, \text{mm} = 0.25 \, \text{cm} \),
- Gradient field \( B = 2 \, \text{Gauss/cm} \), - \( \gamma = 42.58 \, \text{MHz/T} \),
We calculate the bandwidth: \[ \Delta f = \frac{0.25 \times 42.58 \times 2}{2.5} = 2.13 \, \text{kHz}. \] Final Answer: 2.13 kHz