PETRA

Leise klinische MR-Bildgebung
D. Grodzki, Siemens Healthcare
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Answers for life.
Acoustic noise in MRI
• Main source of acoustic noise: gradient coil
• Gradient coil acts like a membrane due to fast gradient
switching
• Reduction of acoustic noise with hardware measures
• Dampening of the coil, vacuum chamber, …
• Reduction of acoustic noise with software measures
• Minimization of gradient activity in sequence design
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Magnetic Resonance
Sequences with low gradient activity: Techniques
• Best case: Gradients are always constant
• Sequences with (almost) constant gradients:
PETRA1*, SILENZ / zTE2, SWIFT3
• No noise from gradient system
• Gradients switched on before none-selective excitation4
• zTE: Very fast Tx/Rx switching needed (< 10µs)
• PETRA: Cartesian sampling of k-space center
• Can be used with every coil
[1]: Grodzki et al, MRM 2012; [2]: Weiger et al. MRM 2011; [3]: Idiyatullin et al. JMR 2006; [4]: Grodzki et al, JMR 2012
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*The products/features (here mentioned) may not be commercially available in all countries. Due to regulatory reasons their future
availability cannot be guaranteed. Please contact your local Siemens organization for further details.
Magnetic Resonance
Sequences with low gradient activity: Contrasts
• Contrast w/o pre-pulses in the PD to T1 range
• Ultrashort echo times, signal from bones etc.
• Pre-pulses needed for other contrasts: T1, T2, MRA
• T1 contrast with inversion pulses
• Acquisition scheme comparable to MPRAGE
• PETRA*: reordering of k-space center for high SNR and CNR
180°
TI
180°
TACQ
TW
Acquisition of 200-500 repetitions
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*The products/features (here mentioned) may not be commercially available in all countries. Due to regulatory reasons their future
availability cannot be guaranteed. Please contact your local Siemens organization for further details.
Magnetic Resonance
PETRA* volunteer scanning (MAGNETOM Trio, 3T)+
MPRAGE
95.0 dB(A)
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PETRA*
64.9 dB(A)
*The products/features (here mentioned) may not be commercially available in all countries. Due to regulatory reasons their future
availability cannot be guaranteed. Please contact your local Siemens organization for further details.
Magnetic Resonance
+Data on file; results may vary.
PETRA* patient scanning (M 57, MAGNETOM Trio, 3T)
MPRAGE
95.0 dB(A)
PETRA*
MPRAGE
PETRA
TE
2.44 ms
0.07 ms
Res.
0.952 x 1.0 mm
0.953mm
TScan
5:54
5:51
PAT
2
-
Courtesy Dr. Ida of Ebara Hospital Tokyo, Japan
64.9 dB(A)
 PETRA can be a quiet alternative for the MPRAGE sequence1
[1]: Ida et al, JMRI 2014
Unrestricted © Siemens AG 2014 All rights reserved.
*The products/features (here mentioned) may not be commercially available in all countries. Due to regulatory reasons their future
availability cannot be guaranteed. Please contact your local Siemens organization for further details.
Magnetic Resonance
Automated sequence optimization
• Gradient “Translation” algorithm
• Sequence independent approach
• Can be attached to every sequence
• Automated gradient smoothing
Principle:
1. Segment incoming sequence into CHANGE and KEEP (TX, RX, FC, DW)
2. Optimize gradients in CHANGE intervals
3. Send out optimized sequence
Optimization
IDEA Sequence
Framework
Measurement
System
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Magnetic Resonance
T2 TSE head imaging+
Conventional TSE
matrix 512, TA 2:06 min
88.8 dB(A)
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QuietX* TSE
matrix 512, TA 2:08 min
74.4 dB(A)
*The products/features (here mentioned) may not be commercially available in all countries. Due to regulatory reasons their future availability cannot be
guaranteed. Please contact your local Siemens organization for further details.
+Data on file; results may vary. Magnetic Resonance
QuietX+
Complete, quiet orthopedic examinations
QuietX+
Conventional
QuietX+
Conventional
QuietX+
Conventional
80%
72%
70%
reduction*
reduction*
reduction*
PD TSE, 88 dBA, TA 3:53
PD TSE, 74 dBA, TA 3:53
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T1 TSE, 92 dBA, TA 0:58
T1 TSE, 81 dBA, TA 0:58
T2 TSE, 89 dBA, TA 4:14
T2 TSE, 79 dBA, TA 4:14
*Reduction in sound pressure. Data on file. Results may vary.
not be commercially available in countries outside the U.S., future availability cannot be guaranteed.
+May
Magnetic Resonance
Results*
• Complete quiet Neuro and MSK examinations, including EPI DWI+
• Noise reduction of 10-25 dB(A)
• Optimization can be attached to any sequence
• Inaudible scanning with PETRA+
• No hardware changes needed
Unrestricted © Siemens AG 2014 All rights reserved.
+The products/features (here mentioned) may not be commercially available in all countries. Due to regulatory reasons their future
availability cannot be guaranteed. Please contact your local Siemens organization for further details
Magnetic Resonance
* Data on file; results may vary.
Vielen Dank
für Ihre Aufmerksamkeit!
Unrestricted © Siemens AG 2014 All rights reserved.
Answers for life.
Magnetic Resonance

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