Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
4 PULSE SEQUENCES
SPIN ECHO PULSE SEQUENCES
| Question | Answer |
|---|---|
| Considered to produce the standard in T1 T2 contrast | The spin echo pull sequence |
| Charts the timing of each event that occurs during an MRI exam | Pulse sequence timing diagram |
| Charts the time at which the RF energy is transmitted and received and the time in duration of each gradient pulse | A pulse sequence timing diagram |
| The first line in the spin Eco pulse sequence timing diagram usually consist of the events related to | The transmission of RF energy |
| TE, is? | The time from the 90° RF pulse to the center of the spin echo |
| The 180° RF pulse is applied? | Halfway between the initial RF excitation and the echo, or 1/2 TE |
| Is applied to rephase the magnetization and allow a spin echo to be collected | A 180° RF pulse |
| The second line of the pulse sequence timing diagram illustrates? | The timing of the received RF energy, in other words the MR signal. |
| In spin Echo pulse sequence, the FID is formed? | Initially a free induction decay, or FID is formed but not sampled, the signal decays before I can properly specially encode |
| One TE period After the 90° pulse, what is formed: | The spin echo forms( after the 180° RF pulse) one TE period after the 90° pulse |
| The received RF line (pulse sequence timing diagram) indicates that the spin echo forms____? | The spin echo forms one TE. After the 90° pulse |
| In order to restrict the external energies disturbance to a single slice what must happen? | The slice gradient must be turned on whenever the RF energy is being transmitted |
| The slice select gradient is turned on whenever the ____ is being transmitted | RF energy |
| Contrast information is specially localized within a selected slice through what two processes: | Frequency encoding and phasing encoding |
| The amplitude of the readout gradient determines the range of frequencies encoded in the echo, known as the? | Receiver bandwidth |
| True or false: the exact position of the phase encoding event, need not be as precise, as that of the slice select or read out gradients | TRUE |
| Is generally turned on sometime between the 90° RF pulse and 180° RF pulse | The phasing encoding event, |
| An important point is that each collected echo has a_____ amount of phase applied to it | Unique |
| The TE period must have as many phase encoding repetitions per slice as the matrix has___? | phase lines |
| The phase encoding gradient is depicted as a table of_____? | values. Indicating that it is applied at different amplitude each time the sequence repeats. Its position in time is not critical as other gradient events |
| Phase is used to uniquely locate the____? | Position of the signal |
| Each time a gradient is applied, a linear change in the magnetic field is created, causing a variation in the precessional frequencies of the protons net magnetization, and therefore creates: | Dispersion in phase. Phase dispersion is only allowed by the phase encoding gradient since phase is used to uniquely locate the position of the signal |
| Extra gradient pulses in a slice and read out directions back to balance the positive and negative frequencies and can cancel the____? | Accumulated phase before the echo is recorded |
Created by:
tomvilla21
Popular Radiology sets