Body Diffusion MRI: Basics and Beyondmri/seminars/slides/Spring 2016/BodyDiff_XZhong...Physics Pulse sequence ... Body Diffusion MRI: Basics and Beyond ...
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Body Diffusion MRI:Basics and BeyondXiaodong Zhong, PhDSenior R&D Expert, MR R&D Collaborations, Siemens HealthcareAdjunct Assistant Professor, Radiology and Imaging Science, Emory UniversityAtlanta, GA
Diffusion weighting factor, b-value Sets the measurement sensitivity to diffusion Determined by strength of diffusion gradient (G), duration of gradient ()
and duration between the two gradients () Direction of sensitivity can be altered by changing diffusion gradient
DW images (b-value images) Reflect the estimate of the water diffusion rate at that pixel The greater the b-value, the stronger the diffusion weighting, and the higher
the contrast (hyperintense) in pathogenic regions (reduced diffusion) Primary application for early detection of cerebral ischemic stroke, more
sensitive to early changes after a stroke than T1 or T2 weighted images*
* S. Warach et al., J. Cereb. Blood Flow Metab. 16 (1996)
Apparent diffusion coefficient (ADC) A measure of the strength (velocity) of diffusion in tissue Free of the influence of T1 and T2 effects The stronger the diffusion, the greater the diffusion coefficient Exhibits darker contrast (hypointense) in pathogenic regions (reduced
patient with multiple metastases along thespine from a primary prostate tumour
The contrast in the computed image isimproved compared to the acquired imageas signal from tissues such as the kidneys,testes and salivary glands (red, green and
• Reduced susceptibility and blurring artefacts due to reduced TE and echo spacing
• Insensitivity to motion-induced phase errors
• Reduced SAR in comparison to TSE-based methods
Conventional single shot epi
k-space trajectory
Single shot
Long TE
Long Echo Spacing
RESOLVE
k-space trajectory
Readout direction (kx)
Ph
as
e-e
nc
od
e d
ire
cti
on
(k
y)
1st shot 2nd shot 3rd shot 4th shot 5th shot
RESOLVEBetter delineation of tumor boundaries for prostate carcinoma
T2 TSE
T2 TSE
RS-EPI DW images showed improved image quality compared to SS-EPI technique at 3T and is a feasible technique in the pelvis for producing high-resolution DWI.
National University Hospital, Singapore
Conventional
b0
Conventional
b800
Conventional
ADC
RESOLVE
b0
RESOLVE
b800
RESOLVE
ADC
Thian YL. (2014). Readout-segmented echo-planar imaging for diffusion-weighted imaging in the pelvis at 3T – A feasibility study. Acad Radiol, 21, 531-537.
•*The statements by Siemens' customers described herein are based on results that were achieved in the customer's unique setting. Since there is no "typical“
•hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.
Handout 8
RESOLVEExcellent correspondence to anatomy for rectal carcinoma
T1 3D VIBE FatSat, post contrast
T2 TSE fused with RESOLVE b1000
RESOLVE
b1000 ADC mapb0
Conventional DWI
National University Hospital, Singapore
b1000b0 ADC map
RESOLVESuperior delineation of breast tumor boundaries
Conventional DWI, b750 and ADC map, matrix 192, SL 4 mm, TA 2:47 min
Seoul St. Mary s Hospital, Seoul, South Korea
RESOLVE, b750 and ADC map, matrix 192, SL 4 mm, TA 4:10 min
Rs-EPI was superior to ss-EPI […] for anatomical structure distinction, ghosting artifact and overall image quality […]. Rs-EPI was superior to ss-EPI in SNR and CNR.
•*The statements by Siemens' customers described herein are based on results that were achieved in the customer's unique setting. Since there is no "typical“
•hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.
Kim, HJ, Kim SH et al. (2014) . Readout-segmented echo-planar imagingin diffusion-weighted MR imaging in breastcancer: Comparison w ith single-shot echo-planarimaging in image quality. Korean J Radiol, 15(4), 403-410.
Syngo ZoomItNew Sequence
syngo ZOOMit
Shapeyour
image
ZoomItPrinciple
• Utilizes 2 orthogonal pulses for slice selection
• No need for oversampling
• Reduced distortion
• Utilized in Prostate, Pelvis, Kidney, Pancreas
• Only available currently on pTX systems (Skyra, Prisma)
https://www.healthcare.si emens.com/magnetic-resonance-imaging/options-and-upgrades/clinical-applicati ons /syngo-zoomit/features
ZoomIt in ProstateLess distortions, better tumor delineation
ZOOMit DWI, matrix 58 x 98, FoV 71 x 120, SL 3 mm, TA 4:21
b100 b400 b800 b1200 ADC
Conventional DWI, matrix 96 x 128, FoV 190 x 190, SL 3 mm, TA 4:28Kantonsspital Aarau, Aarau, Switzerland
ZoomIt in KidneyHigher resolution, better differentiation of cortex & medulla
Conventional DWI2.1 mm x 2.1 mm
ZOOMit DWI1.4 mm x 1.4 mm
Handout 9
ZoomIt in RectumBetter delineation of rectal carcinoma with less distortions
University Hospital IKRN, Mannheim, Germany
Conventional DWI b=50, ADC
ZOOMit
3D T2 SPACE - morphology
Emerging New Improvements in Body Diffusion (1)Motion-compensation*
A series of correction/refinement algorithms can be applied on b-value images Inplane-registration of images Filtering of images Denoising of images Rescaling of images to
compensate signal loss due tomotion
Improvements Correction for the left
lobe signal loss Correction for the
misregistration of diffusion weighted images for ADC calculation
* Siemens research w ork-in-progress development.
Original Moco
Emerging New Improvements in Body Diffusion (1)Motion-compensation*
* Siemens research w ork-in-progress development.
b=50, 6 acqs b=400, 9 acqs b=800, 15 acqs
Original
Moco
Emerging New Improvements in Body Diffusion (1)Motion-compensation*
* Siemens research w ork-in-progress development.
b=50, 6 acqs b=400, 9 acqs b=800, 15 acqs
Original
Moco
Emerging New Improvements in Body Diffusion (1)Motion-compensation*
* Siemens research w ork-in-progress development.
Original
Moco
ADC~ 610
ADC~ 90
Emerging New Improvements in Body Diffusion (2)Simultaneous Multi-Slice*
Simultaneous excitation of multiple slices with blipped CAIPIRINHA1
* Siemens research w ork-in-progress development. 1 Setsompop, K. (2012). Blipped-controlled aliasing in parallel imaging for simultaneous multislice echo planar imaging
w ith reduced f-factorpenalty. Magn Reson Med, 67, 1210-1224.
Handout 10
Emerging New Improvements in Body Diffusion (2)About 40% time reduction without compromise2
* Siemens research w ork-in-progress development.
NYU School of Medicine, MAGNETOM Skyra, Head/Neck 20
Conventional
TA 2:20
SMS 2TA 1:211
(42% reduction in scan time)
1 Note that scan time reduction may not be an exact factor of slice acceleration as scan times depends on the TR value specif ied and also because of a fast reference scan required for slice separation. 2 Young, MG, Shepherd TM et al. Multiband sequence reduces scan time for diffusion MRI and tractography in