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3.0T Single shot brain imaging

ExamCard
de Kok, Wendy Philips Healthcare

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ExamCard purpose

Random patient motion during MR image acquisition may create artifacts and decrease image quality. Fast scanning can help to reduce motion effects.

 

This brain ExamCard contains single shot sequences only.

 

In the single shot TSE sequences the scan time per slice is very short (~300 ms), so that image quality will remain good, even if some random motion occurs.

 

In single shot sequences random motion will only affect image quality on a slice-by-slice basis, while in multislice sequences, the motion will affect all slices of a stack and possible artifacts will be present in all slices.

ExamCard overview

ExamCard images

SSh_TSE 24 slices 4.0 mm, TE 90 ms, scan time per slice 337 msSSh_TSE_165 24 slices 4.0 mm, TE 165 ms, scan time per slice 325 ms
SSh_TSE
SSh_TSE_165
24 slices 4.0 mm, TE 90 ms, scan time per slice 337 ms
24 slices 4.0 mm, TE 165 ms, scan time per slice 325 ms
SSh_FLAIR 24 slices 5.0 mm, TE 120 ms, scan time per slice 320 msSSh_T1W_TFE 24 slices 5.0 mm, scan time per slice 1260 ms
SSh_FLAIR
SSh_T1W_TFE
24 slices 5.0 mm, TE 120 ms, scan time per slice 320 ms
24 slices 5.0 mm, scan time per slice 1260 ms

 

SSh_TSE is a T2-weighted single shot sequence with a scan time per slice of 337 ms. SENSE is used to reduce the total scan time per slice. Halfscan is used to obtain a relatively short TE of 90 ms. Echo spacing is small to minimize blurring effects.

 

SSh_TSE_165 is also a T2-weighted single shot sequence, with very long TE and thus heavier T2-weighting. Halfscan is not used in this sequence. To reduce the total shot length, a SENSE reduction factor of 3 is applied. Scan time per slice is 325 ms.

 

SSh_FLAIR is a T2-weighted single shot Inversion Recovery sequence, with CSF suppression. Scan time per slice is 320 ms. Again, SENSE is used to reduce the scan time per slice.

 

These 3 sequences could be referred to as snapshot imaging, as the scan time per slice is so short that random motion will hardly ever affect image quality.

 

SSh_T1W_TFE is a gradient echo T1-weighted single shot sequence. The scan time per slice is 1260 ms. Even though the scan time per slice is not short enough to guarantee motion free imaging, random motion will only affect image quality on slice-by-slice basis, leaving the other slices unaffected.

 

Comparison of multislice vs. single shot during head motion

The left image examples below demonstrate a multislice T2W_TSE  with very short scan time, in which random motion occurred. The images are affected by the movement and image quality is poor. 

 

For comparison, the SSh_TSE was repeated in the same subject while the head was moving. In this case, the resulting image quality is good.

 

MSh_T2W_TSE Multislice acquisition, scan time 38 seconds.SSh_T2W_TSE Single shot acquisition, scan time per slice 330 ms.
MSh_T2W_TSE
SSh_T2W_TSE
Multislice acquisition, scan time 38 seconds.
Single shot acquisition, scan time per slice 330 ms.


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Apr 20, 2006

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ExamCard
Achieva 3.0T
Release 1
Brain, Neuro
 

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