new quantitative analysis of high-field 3t mri/dti to assess neonatal brain development 1,2 g gerig,...
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New quantitative analysis of high-field 3T MRI/DTI to assess neonatal brain development1,2G Gerig, 2Pierre Fillard, 2M Prastawa, 3W Lin, 1John Gilmore,
Departments of 1Psychiatry, 2Computer Science, 3RadiologyUniversity of North Carolina, Chapel Hill,NC 27614, USA, [email protected] / http://www.cs.unc.edu/~gerig
SUMMARY
Structural MRI
• It is feasible to study brain development in unsedated newborns using 3T MRI
• Study will likely provide a vastly improved understanding of early brain development and its relationship to neuropsychiatric disorders.
• Novelty: Tissue model for segmentation of myelinated/nonmyel. white matter.
• Novelty: Use of tractography for complex regions of interest analysis
CONCLUSIONS
Building of Atlas Template
• Research: Quantitative MRI to study unsedated newborns at risk for neurodevelopmental disorders.
• Clinical Study: 120 newborns recruited at UNC, age at MRI about 2 weeks
• Motivation: Early detection of abnormalities Possibility for early intervention and therapy.
• Imaging: High field (3T Siemens Allegra), high resolution (T1 1mm3, FSE 0.9x0.9x3mm3), high-speed imaging (12’ for T1, FSE and DTI).
• Preliminary Study: 20 normal neonates (10 males, 10 females)
• Age 16 ± 4 days• Siemens 3T head-only scanner• Neonates were fed prior to scanning,
swaddled, fitted with ear protection and had their heads fixed in a vac-fix device
• A pulse oximeter was monitored by a physician or research nurse
• Most neonates slept during the scan• Motion-free scans in 13-15 infants• Conte Center: Total of 120 infants
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Brain Tissue Volume Neonates
wm-myel
csf
gm
wm-nonmyel
T1 3D MPRage1x1x1 mm3
FSE T2w1x1x3 mm3
FSE PDw1x1x3 mm3
Here TextHere Text
Template MRI white mattercsf
gray matter
Tissue Probability Maps
NeonateAdult
Approach:
• Atlas-moderated EM segmentation (cf. Leemput and Warfield)
• Tissue intensity model for white matter (non-myelinated and myelinated wm form bimodal distribution) (cf. Cocosco, Prastawa)
• Challenge: Very low CNR, heterogeneous tissue, early myelination regions, reverse contrast wm/gm.
• Standard brain tissue segmentation fails.
Preliminary Results UNC Neonate Study
Supported by NIH Conte Center MH064065, Neurodevelopmental Disorders Research Center HD 03110 and the Theodore and Vada Stanley Foundation
Literature
• Gilmore JH, Gerig G, Specter B, Charles HC, Wilber JS, Hertzberg BS, Kliewer MA (2001a): Neonatal cerebral ventricle volume: a comparison of 3D ultrasound and magnetic resonance imaging. Ultrasound Med and Biol 27:1143-1146.
• Huppi PS, Warfield S, Kikinis R, Barnes PD, Zientara GP, Jolesz FA, Tsuji MK, Volpe JJ (1998b): Quantitative magnetic resonance imaging of brain development in premature and normal newborns. Ann Neurol 43: 224-235.
• Zhai G, Lin W, Wilber K, Gerig G, Gilmore JH (2003): Comparisons of regional white matter fractional anisotrophy in healthy neonates and adults using a 3T head-only scanner. Radiology (in press).
• Warfield, S., Kaus, M., Jolesz, F., Kikinis, R.: Adaptive template moderated spa-tially varying statistical classification. In Wells, W.M.e.a., ed.: Medical Image Computing and Computer-Assisted Intervention (MICCAI’98). Volume 1496 of LNCS., Springer 1998
• Van Leemput, K., Maes, F., Vandermeulen, D., Suetens, P.: Automated model-based tissue classification of MR images of the brain. IEEE Transactions on Medical Imaging 18 (1999) 897–908
• Pierre Fillard, John Gilmore, Weili Lin, Guido Gerig, "Quantitative Analysis of White Matter Fiber Properties along Geodesic Paths", MICCAI 2003 Conference, Full Paper, LNCS Springer, Nov. 2003
• Guido Gerig, Marcel Prastawa, Weili Lin and John Gilmore, "Assessing Early Brain Development in Neonates by Segmentation of High-Resolution 3T MRI", Short Paper, MICCAI 2003 Conference, LNCS Springer, Nov. 2003
T1-only segmentation
white
gray
csf
myelin.
earlymyelinatedcorticospinaltract
hyper-intensemotor cortex
Conventional ROI Analysis (one axial slice only)
Fractional Anisotropy
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FA
(%
)
Neonates
Adults
Apparent Diffusion Coefficient
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splen
ium genu
Inte
rnal
cap
occip
ital
front
alGM
AD
C (
mm
2/se
c)
Neonates
Adults
Apparent Diffusion Coefficient
020406080
100120140160180200
splen
ium genu
Inte
rnal
cap
occip
ital
front
alGM
AD
C (
mm
2/se
c)
Neonates
Adults
Hypothesis:•DTI reflects degree of myelination and structure of fiber tracts.•Decrease of fractional anisotropy (FA) from interior to the periphery.•Higher ADC values compared to a matured brain (adult).•Lower FA values compared to adults.•DTI reflects degree of axon pruning and myelination.
Zhai G, Lin W, Wilber K, Gerig G, Gilmore JH (2003): Zhai G, Lin W, Wilber K, Gerig G, Gilmore JH (2003): Comparisons of regional white matter fractional Comparisons of regional white matter fractional anisotropy in healthy neonates and adults using a 3T anisotropy in healthy neonates and adults using a 3T head-only scanner. head-only scanner. Radiology Radiology (in print).(in print).
New Method: Diffusion along fiber tract via Tractography
Tracing of the commissural fiber tracts through the genu in five Tracing of the commissural fiber tracts through the genu in five neonatesneonates
spleniumsplenium
FAFA
Diffusion Tensor Imaging (DTI)
Fractional Anisotropy (FA) along splenium/genu bundles
Change of FA along splenium/genu across time
• Fractional Anisotropy (FA) quickly drops with increasing distance from midsagittal plane
• Drop off more pronounced in genu than in splenium
• Comparisum adults, 2yrs olds and neonates
• FA in neonates significantly lower than in 2 yrs old subjects and adults
• 2yrs old subjects show similar values as adults
adult neonate
adult neonate