quantitative analysis of diffusion tensor measurements along white matter tracts
DESCRIPTION
Quantitative Analysis of Diffusion Tensor Measurements along White Matter Tracts. Isabelle Corouge. Postdoctoral fellow, Dept of Computer Science and Psychiatry, UNC-Chapel Hill. Gray matter. DT MRI. White matter. Diffusion Tensor MRI (DT MRI). Reveals white matter structure. - PowerPoint PPT PresentationTRANSCRIPT
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 1 - October 7, 2005
Quantitative Analysis of Diffusion Quantitative Analysis of Diffusion Tensor Measurements along White Tensor Measurements along White Matter TractsMatter Tracts
Postdoctoral fellow,Postdoctoral fellow,Dept of Computer Science Dept of Computer Science and Psychiatry,and Psychiatry,UNC-Chapel HillUNC-Chapel Hill
Isabelle CorougeIsabelle Corouge
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 2 - October 7, 2005
Diffusion Tensor MRI (DT MRI)
• Reveals white matter structure
Gray matter
White matterCourtesy of Susumu Mori, JHU
DT MRI
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 3 - October 7, 2005
Diffusion of Water Molecules
• Diffusion of water moleculesFrom Beaulieu[02]
• Isotropic vs Anistropic diffusion• Underlying structures of the tissues
– Faster diffusion along fibers than perpendicular to them– Water diffusion anisotropy used to track fibers, estimate white matter integrity
(v, )
(v, )
(v, )
Isotropic Diffusion
vi : principal directions of diffusion
i : associated diffusivities
• Tensor model
Anisotropic Diffusion
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 4 - October 7, 2005
Tensor field
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Diffusion Properties
• Mean diffusivity (MD) • Fractional anisotropy (FA)
3MD 321
Isotropic diffusion
Highly directional
diffusion
0 1Low High
Whitematter
Cerebrospinalfluid
Tensor size 23
22
21
231
232
221 )()()(
21FA
Tensor shape
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 6 - October 7, 2005
DTI Analysis in Clinical Study• One concept: Region-based Analysis
• Co-registration of DTI
• Registration of DTI of each subject with:
• structural MRI
• segmentation maps
• lobe parcellation
• user-defined ROIs
• Statistical analysis per ROI
Group 1
Group 2
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 7 - October 7, 2005
Alternative Concept
• Quantitative Analysis of Fiber Tracts– Fiber-tract oriented analysis– Measurements across/along fiber bundles with complex geometry– Statistics of diffusion properties (FA,MD)– Statistics of tensors (non-Euclidean metric)
• Analysis scheme
Tracking/Clustering
Selection FA FA along tract
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 8 - October 7, 2005
Fiber Tracking & Clustering into Bundles
Fornix clusterLongitudinal fasciculus(2312 streamlines)
6 clusters
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Diffusion Properties: Adult vs NeonateAd
ult
Neo
nate
FA FA: Mean ± σ
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 10 - October 7, 2005
Diffusion Properties: Adult vs NeonateAd
ult
Neo
nate
MD MD: Mean ± σ
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 11 - October 7, 2005
Example: Early Brain Development Study
• White Matter Diffusion Corpus Callosum
– Extraction and clustering of genu and splenium bundles– Measurement of diffusion properties in cross-sections along the
bundles– Selection of center and left/right off-center locations
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 12 - October 7, 2005
WM Diffusion of Neonates: Genu Tract
• DTI properties measured at midsagittal position and +/- 21 mm
Genu: FA at 0 and at distance 7
00.10.20.30.40.50.60.7
250 300 350 400
MGestAge
FA
FA at 0
FA at dist 7Linear (FA at 0)Linear (FA at dist 7)
21mmGenu: ADC at 0 and at distance 7
0
5
10
15
20
250 300 350 400
MGestAge
ADC
ADC at 0
ADC at dist 7
Linear (ADC at 0)
Linear (ADC at dist7)
21mm
Genu Diffusion Tensor EV: Midsagittal
0
5
10
15
20
25
250 300 350 400
MGestAge
Lam
bda
Lbd1 at 0Lbd2 at 0Lbd3 at 0Linear (Lbd1 at 0)Linear (Lbd2 at 0)Linear (Lbd3 at 0)
Genu Diffusion Tensor EV: Distance 7
0
5
10
15
20
25
250 300 350 400
MGestAge
Lam
bda
Lbd1 at 0Lbd2 at 0Lbd3 at 0Linear (Lbd1 at 0)Linear (Lbd2 at 0)Linear (Lbd3 at 0)
21mm
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White Matter Diffusion Corpus Callosum
Diffusion tensor representation at the midsagittal plane and off-center (24mm along bundles).
• Tensors get “thinner” → less diffusivity across fibers → more structure, ev. marker for maturation
• Genu shows change, but not splenium
280d GestAge at MRI 360d GestAge at MRI
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 14 - October 7, 2005
• Genu and splenium
Tensor Statistics: Neonate to 1 year
MD MD
FA FA
Neonate 1 year old
Neo
nate
1 ye
ar o
ld
Neonate1 year old
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Tensor Statistics: Neonate to 1 year
Genu
Splenium
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In Practice… the Tools !
FiberTracking FiberViewer
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Demo
• Data: Brockton VA/Harvard – Case HUVA00102397– Resampled to isotropic resolution (2x2x2mm3)– Tracts: cingulate, motor, genu, splenium,…
NAMIC: UNC – PNL collaborationNAMIC: UNC – PNL collaboration - 18 - October 7, 2005
Fiber Tracking and Fiber Viewer
• Easy to use and easy to learn• Download: http://www.ia.unc.edu/dev • Online tutorial (same url)
• Compatibility Slicer/FiberViewer
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Acknowledgements
• The team– Guido Gerig (UNC)– Casey Goodlett (UNC)– Weili Lin (UNC)– Sampath Vetsa (UNC)– Tom Fletcher (Utah)– Xiadong Tao (GE)– Rémi Jean– Matthieu Jomier (France)– Sylvain Gouttard (France)– Clément Vachet (France)
• Software development– ITK, VTK, Qt– Julien Jomier (UNC)