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4 PULSE SEQUENCES
FAST SPIN ECHO PULSE SEQUENCES
| Question | Answer |
|---|---|
| Fast spin echo pulse sequences are also called? | Rapid spin echo, Turbo spin Echo, or RARE |
| fast spin echo pulse sequence differ from standard pulse sequences in how: | frequently the echoes are collected and where the echoes are placed in the raw data |
| A fast spin echo pulse sequence is faster than a conventional sequence, because more than one echo is collected during a single repetition for a single slice | |
| The fast spin echo sequence requires less RF energy than a traditional spin echo sequence. | However the fast repetition of 180° RF pulse in fast spin delivers a much greater amount of RF energy into the patient's body per time |
| The number of echoes collected in fast spin is called the: | |
| Fast spin echoes are placed into raw data file in a particular order to generate an image | In order to get desired image contrast |
| Information located at the periphery of the raw data is said to contain? | High special frequencies, since this is where the amplitude of the phase encoding and read out gradients are greatest |
| The high spatial frequencies correspond to? | The edge definition or spatial resolution of the resulting image |
| Information located toward the center of the raw data is said to contain? | Low spatial frequencies, since this is where the amplitude of phase encoding and readout gradients are the lowest |
| Low spatial frequencies correspond to? | The contrast of the resulting image |
| Determine the image contrast, and located in the center of the raw data file? | Low spatial frequency |
| Determines the edges and find details of the image, that are located at the periphery of raw data file | High spacial frequencies |
| Every echo contributes the entire image, but those towards the center of the raw data contribute more contrast information and those towards the periphery contribute more? | Resolution information |
| Fast spin echo pulse sequences, organize their echoes such that the desired TE's are placed in the central lines of raw data | Placing those echoes in the central raw data lines ensure the tissue exhibited in the final image is what we expect at the desired TE |
| Specified TE parameters such as 90 MS, replace the echo of the 90 in the center of raw data | |
| Fast spin echo pulse sequences are most noted for reducing the scan times of_____ images. | T2 weighted |
| Because of its relatively short scan time, fast spin echo pulse sequences can be used for most____? | Clinical applications in all parts of the body |
| In a fast spin echo sequence many echoes may be collected during a single TR period. Also each recorded echo is not added in sequential order in the raw data | each Echo collected is still uniquely phase encoded and placed in a single line of the raw data, but more echoes are collected per TR thus fewer repetitions are required to fill the remainder of the raw data |
| Every echo contributes the entire image but those towards the center of the raw data contribute more contrast information in those towards the periphery contribute more resolution information | To better manage the contrast the echoes need to be re-ordered as they are placed into the raw data |
Created by:
tomvilla21
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