4
Sequence Parameters and Options
There will be 38 questions in the MRI advanced-level examination on sequence parameters and options. They will address the interdependence of the parameters and options below and how these affect image quality (contrast-to-noise, signal-to-noise, spatial resolution, and acquisition time) and contrast (T1 weighted, T2 weighted, and spin (proton) density)
- Imaging parameters
- Imaging options
Q40 The time between excitation pulses is known as the:
| (a) | T1 |  |
| (b) | TE |  |
| (c) | TR |  |
| (d) | PR |  |
Q41 In a spin echo sequence, the time between the 90° pulse and the 180° pulse is:
| (a) | TE |  |
| (b) | TR |  |
| (c) | T1 |  |
| (d) | ½ TE |  |
Q42 Presaturation pulses are often used to:
| (a) | Improve spatial resolution |  |
| (b) | Reduce flow artifacts |  |
| (c) | Reduce scan time |  |
| (d) | Turn flowing blood bright |  |
Q43 The presaturation pulses usually occur:
| (a) | Prior to the excitation pulse |  |
| (b) | After the 180° pulse |  |
| (c) | Between the 90° and 180° pulses |  |
| (d) | Prior to the TE |  |
Q44 Gradient echo sequences use flip angles:
| (a) | Less than 90° |  |
| (b) | That vary between pulse repetitions |  |
| (c) | To control saturation effects |  |
| (d) | To reduce SAR for larger patients |  |
Q45 Complete saturation is a condition where:
| (a) | Not enough time is given to allow the T2 decay to complete |  |
| (b) | The image becomes brighter |  |
| (c) | Longitudinal magnetization is not allowed to recover between excitations |  |
| (d) | Proton density effects predominate |  |
Q46 Increasing the TE:
| (a) | Increases the contrast based on T2 relaxation times of the tissues |  |
| (b) | Reduces the contrast based on T2 relaxation times of the tissues |  |
| (c) | Reduces the contrast based on T1 relaxation times of the tissues |  |
| (d) | a and c |  |
Q47 Reducing the TR:
| (a) | Decreases the signal-to-noise ratio (SNR) of the image |  |
| (b) | Reduces the contrast based on T2 relaxation times of the tissues |  |
| (c) | Increases saturation effects |  |
| (d) | a and c |  |
Q48 Reducing the TE:
| (a) | Increases the contrast based on T1 relaxation times |  |
| (b) | Increases the spin density contrast weighting |  |
| (c) | Reduces saturation effects |  |
| (d) | Reduces contrast based on T2 relaxation times |  |
Q49 In a gradient echo sequence, reducing the flip angle while holding the TR constant reduces:
| (a) | T2* contrast weighting |  |
| (b) | Spin density contrast weighting |  |
| (c) | Saturation |  |
| (d) | Scan time |  |
Q50 In a 2D conventional spin echo multislice pulse sequence, scan time is given by the equation:
| (a) | Time × number of phase encodings × TR |  |
| (b) | TR × FOV × number of signals averaged |  |
| (c) | TR × number of slices × number of signals averaged |  |
| (d) | TR × number of signals averaged × number of |  |
Q51 In an inversion recovery pulse sequence, image contrast is controlled by:
| (a) | TR and TE only |  |
| (b) | TI only |
