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| Primary controlling parameter of T1 is ___ |
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Definition
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| Primary controlling parameter of T2 is _____ |
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| In the spin echo pulse sequence, when is the echo collected? |
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Definition
| after the 180 degree pulse |
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| what are the two purposes of the 180 degree pulse in the spin echo sequence? |
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Definition
1. to rephase/refocus the spins in the transverse plane
2. to correct magnetic field inhomogeneities. |
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| What is a pulse sequence? |
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Definition
| A series of RF and gradient applications that has carefully controlled durations and timings. |
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| What are the two main types of spin echo pulse sequences? |
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Definition
SE spin echo
FSE fast spin echo |
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| STIR and FLAIR sequences are types of ______ pulse sequences. |
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Definition
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Definition
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| which pulse sequence was the first one developed and is still considered the "gold standard" for quality against which newer ones are compared - however it is slower. |
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spin echo sequence goes:
90..._____....180..._____ |
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| which type of weighting(s) are possible with SE? |
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| The SE sequence fills how many lines of K-space? |
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| The first line of a pulse sequence diagram (PSD) is always ____ |
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Definition
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| The bottom three lines of a PSD are the gradient functions - SS, PE, and FE. These stand for: |
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Definition
SS = slice select
PE = phase encoding
FE = frequency encoding |
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| When is the SS gradient on in the SE? |
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Definition
| during the 90 and 180 pulses. |
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| when is PE gradient on in the SE? |
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Definition
| just before the 180 pulse. |
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| when is the FE gradient on in the SE? |
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Definition
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| The FE is often called the _______. |
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Definition
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| Why is the FE often called the readout gradient in the SE sequence? |
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Definition
| because it is on during the echo, which gives us our signal. |
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| The three advantages of the SE sequence are: |
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Definition
Good SNR
Versatility (planes, image weightings, etc)
Minimizes imaging artifacts |
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| T1 SE's main strength is: |
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Definition
| demonstration of anatomy with high SNR |
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| For good demonstration of pathology on T1 SE, you need ______ |
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Definition
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| T2 SE's main strength is: |
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Definition
| demonstration of pathology |
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| PD SE is mainly used for: |
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Definition
| information on the QUANTITY of tissue in an area (for example, how much edema is in an area) |
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| A T1 SE would use _____ TR and ____ TE |
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Definition
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| A T2 SE would use _____ TR and ____ TE |
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Definition
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| A PD SE would use ______ TR and _____ TE |
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Definition
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| The main thing that makes spin echo pulse sequence unique from other sequences is: |
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Definition
| the use of the 180 RF pulse to rephase the NMV for signal creation |
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| What does "NEX" stand for? |
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Definition
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Definition
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Definition
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| What is the formula for SE scan time? |
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Definition
| NEX x TR x Phase encoding |
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| what is the sequence for multi-echo spin echo? |
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Definition
| 90...fid....180....echo....180....echo |
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| how many lines of k-space are filled with a multi-echo spin echo? |
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Definition
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| a multi-echo spin echo develops which two types of images? |
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Definition
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| which 3 parameters do we set for ME/SE? |
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Definition
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| what length TRs and TEs for ME/SE? |
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Definition
| long TR, one short TE (for PD) and one long TE (for T2) |
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| What is the main reason to do ME/SE? |
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Definition
| two image sets for one scan time - efficiency |
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Definition
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Definition
rapid acquisition relaxation enhanced (RARE)
turbo spin echo (TSE) |
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| The main feature of the FSE pulse sequence is... |
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Definition
| many 180 pulses after the initial 90 pulse. |
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| the number of 180 pulses done after the 90 in FSE is known as the ______ _______ ______ |
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Definition
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| The number of lines of data (k-space) filled by a FSE is the same at the _____ |
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Definition
| ETL or number of 180 pulses after the 90 |
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| another name for the ETL is _____ _____ |
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Definition
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| A FSE for T1 image would use a maximum of _____ ETL |
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Definition
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| Using long ETLs on FSE T1 would result in image _________ |
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Definition
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| T2 FSE requires ______ (long/short) ETL, up to ____ on some scans |
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Definition
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| using an effective TE will reorder phase steps so that a _______ ______ phase steps are centered around the chosen TE to get the best info |
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Definition
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| images created with FSE are similar to those made with SE, except ____ remains bright on all weighting. |
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Definition
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| What can be used to correct for the brightness of fat on all weightings using FSE? |
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Definition
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| what type of weightings can be obtained with FSE? |
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Definition
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| FSE may be lower in quality, but the advantage is: |
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Definition
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| Why is fat always bright on FSE? |
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Definition
| Because of the repeated 180 pulses which don't allow for full fat relaxation. |
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| What is the pulse sequence for an Inversion Recovery? |
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Definition
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| An inversion recovery (IR) generates _____ echo and fills in _____ line of k-space |
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Definition
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| For inversion recovery, when is the 90 degree RF pulse applied? |
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Definition
| At the TI (time of inversion) |
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| For inversion recovery, the initial 180 degree RF pulse inverts the vector to _____ ________ |
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Definition
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| What is the time of inversion? (TI) |
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Definition
| The time we wait after the 180 until we apply the 90 |
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| TI controls the image ________ |
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Definition
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| when you increase the TI, you increase the _____ weighting of the image |
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Definition
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| In MR, we typically use TI that gives us _____ weighted images |
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Definition
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| What is the main clinical use of IR sequence? |
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Definition
| T1 images for good anatomy to differentiate between structures with similar T1 relaxation times such as grey/white matter, abdominal |
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