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High Resolution 3D FSE Diffusion Imaging

High Resolution 3D FSE Diffusion Imaging. Seong-Eun Kim, Eun-Kee Jeong, Dennis L. Parker Dept. of Radiology Medical Imaging Research Lab. University of Utah. Multi-shot, 3D pulse sequence for higher SNR. Motion induced phase correction needed.

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High Resolution 3D FSE Diffusion Imaging

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  1. High Resolution 3D FSE Diffusion Imaging Seong-Eun Kim, Eun-Kee Jeong, Dennis L. Parker Dept. of Radiology Medical Imaging Research Lab. University of Utah

  2. Multi-shot, 3D pulse sequence for higher SNR. Motion induced phase correction needed. Motion correction or motion insensitive pulse sequence Navigator echo technique is not used. Diffusion Preparation technique Used! Small motion may not degrade the resultant images. No specialized hardware requirement technique EPI, SSFP demand higher performance of gradient and rf system PURPOSE

  3. Nonselective 180 pulse Shorten Echo Spacing  Reducing T2* blurring effect Extra 90 pulse after acquisition To drive the transverse magnetization into z axis. SSFT type of 3DFSE. METHODS

  4. 3D FSE with hard 180 pulse 3dfse act_esp=8.5msec 3dfseuu act_esp= 6.4msec

  5. 3D FSE with hard 180 pulse 256x192x12 etl:16 BW : 62.5kHz Sl.Thick: 1.5 mm TR/TE: 400/20 mm Act_esp=6.8ms

  6. 3D FSE DW Diffusion is encoded as Prep. Pulses DW Prep is applied in between two segmentations. Any phase error caused by DW Prep will be lost by 90-x  amplitude modulation. Square Sum of images To eliminate the signal loss due to eddy current effect Two images with different phase of last 90 pulse p/2+x p+y p-y p/2-x 3D FSE RF GD METHODS

  7. Pulse Sequence Diagram 180 non-selective hard pulses, DW Preparation, act_esp down to 6.5msec Diff.Prep 90 180 180 180 - ……… Echo Train ……… 180 -90 Diff.Prep 90 180 180 180 - ……… Echo Train ……… 180 -90

  8. Square Sum Image of Phantom 0 4000 8000 12000 16000 20000 24000 28000 32000 -32000 -28000 -24000 -20000 -16000 -12000 -8000 -4000

  9. I-x :tipup=90o-x I-y :tipup=90o-y I-x2 + I-y2 b=500 Square Sum Image of Dog’s Heart 256x160x16 16 FOV 2.0 mm etl=16 bw;32 TE/TR=30/500 b=0 SI AP RL

  10. Quantification of Diffusion Coefficient 256x160x16 16 FOV 2.0 mm etl=16 bw;32 TE/TR=30/500 b=0 b=100 b=200 b=300 b=400 b=500 1.6x10-3 D=1.6x10-3 mm2/sec

  11. Dog’s Heart 256x160x16 16 FOV 3.0 mm etl=16 bw;32 TE/TR=30/500 b=0 100 200 300 400 500

  12. Human Brain 256x160x12 22 FOV 2.0 mm etl;16 bw;32.5 TE/TR=25/500 b=0 b=200 b=500

  13. CONCLUSION • The multi shot 3D FSE technique delivered motion free, high resolution DW imaging with less susceptibility effect. • Can be applied to spine or knee diffusion imaging. • The square root summing method corrected the artifact due to eddy current. • The cardiac gating technique may improve the phase errors caused by CSF pulsation. • Employing sense technique in EPI may achieve the high resolution EPI diffusion imaging within shorter time.

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