software development for correction of gradient-nonlinearity distortions in mr images
DESCRIPTION
Software Development For Correction of Gradient-Nonlinearity Distortions in MR Images. T.S. Lee, K.E. Schubert Computer Science CSUSB. R.W. Schulte Radiation Medicine LLUMC. Functional Proton Radiosurgery. Functional Neurosurgery Trigeminal Neuralgia Parkinson’s Disease - PowerPoint PPT PresentationTRANSCRIPT
Software Development For Software Development For Correction of Gradient-Correction of Gradient-
Nonlinearity Distortions in MR Nonlinearity Distortions in MR ImagesImages
T.S. Lee, K.E. Schubert
Computer Science
CSUSB
R.W. Schulte
Radiation Medicine
LLUMC
Functional Proton Radiosurgery Functional Neurosurgery
– Trigeminal Neuralgia
– Parkinson’s DiseaseParkinson’s Disease
– Brain regions (< 1 cm)
Proton Radiosurgery– Accurate to less than 1 mm
MRI for target localization– Distinguish tissue types
– 512512 images
– 262,144 pixels/study
– Gradient nonlinearity distortions (~2mm)
Example MR Phantom Images
Sagittal Plane
Coronal Plane
Axial Plane
Bad SlidesPa
rtia
l Ph
anto
m
Part
ial
Phan
tom
No
Phan
tom
Off
Cen
ter
Phan
tom
Finding EdgesFinding Edges
DisconnectsDisconnects
Remove Extraneous FeaturesRemove Extraneous Features
Can We Fix it?A
ir B
ubbl
eL
eaky
Sl
ice
Example Edge Images
Axial Plane
Coronal Plane
Sagittal Plane
MidplanesMidplanes
Calculate Midpoints Fit Midplane
Ideal shape, size, and orientation of phantom’s faces
Stack Midpoints
Ideal PlanesShift ±½ the phantom dimensionPerpendicular to face
Distortion ModelingMagnetic Field of CylinderSum of spherical harmonics:
5
4322
3
2222
31
220
44
2223
2222
21
220
44
2223
2222
21
220
,,
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zKzyzKzzyxfZ
yzKyzyxKyyxK
yzKyyxKyzyxfY
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xzKxyxKxzyxfX
xzz
zzz
yyy
yyy
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Distortion ModelingMeasured
Corrected
Applying Distortion CorrectionAxial Plane
Applying Distortion CorrectionCoronal Plane
Applying Distortion CorrectionSagittal Plane
ResultsTheoretical undistorted points vs. corrected pointsStandard deviations of correction
+X face: Standard Deviation = 0.23503 mm
-X face: Standard Deviation = 0.25168 mm
+Y face: Standard Deviation = 0.15322 mm
-Y face: Standard Deviation = 0.15823 mm
+Z face: Standard Deviation = 0.13548 mm
-Z face: Standard Deviation = 0.14173 mm
Conclusions3 range 0.4 – 0.8 mm
–1-2 pixels on each image–Originally 2mm (5-6 pixels)
Accurate localization of anatomical targets
Future WorkFurther verification and testingClinical trialsFDA approvalTreatment on humans