Model-Based Registration of X-ray Mammograms and MR Images of the
Female Breast
N.V. Ruiter, T.O. Müller, R. Stotzka, H. Gemmeke,Forschungszentrum Karlsruhe, Germany
Motivation
• Locate lesion in complementary modality
MR image
X-ray mammogram
Registration: Find geometric correspondence
Support multimodal breast cancer diagnosis:
Registration Problem
• MR image:
• Volume image
• Undeformed breast
• Prone position
• X-ray mammography:
• 2D projection
• Large deformation
• Only one projection per deformation
Images not directly comparable !
Add information using a biomechanical model
X-ray mammogram
MR image
Process of Registration
Deformation process
Biomechanical model Deformed model
Projection of artificial MR image
Problems of Deformation Model• Large deformation of soft tissue
• Details of deformation process unknown:• Exact patient position
• 3D shape of breast
• Thickness of deformed breast
• Compression force
• Tissues of the breast:• Only large scale structures
resolved in MR image
• Material models in literature:• Inconclusive
• Not plausible for large deformation
Plate compression
L‘
Fatty tissue
Glandulartissue
Skin
Specification of Deformation Model• Adapt global parameters:
• Projection angle by non-linear scaling• Volume is preserved estimate thickness
• Finite Element Model• Large deformations (>>5%), (nearly) incompressible
materials
• Material model• Evaluation of models for breast tissue: Neo Hookean model,
homogeneous tissues
• Two step modeling of deformation1st step: Mammographic deformation 2nd step: Fine tuning using mammogram
Mammographicdeformation
Results with Clinical Datasets• Six clinical data sets:
Lesion position in X-ray mammograms and MR image known
• Smallest visible lesions in MR images: 5 mm
• X-ray MRI:• Mean center distance: 3.9 mm (1.6 – 6.4 mm)
• Mean volume overlap: 91%
• Prediction of lesion position
• MRI X-ray:
• Mean center distance: 4.3 mm (2.3 – 6 mm)
• Mean area overlap: 81%
Results with Clinical DatasetsMRI X-ray : craniocaudal example
X-ray mammogramDirect MR projection
MR projection after simulation
Center lesion distance 2.3 mm Lesion overlap 100%
24mm
Conclusions• Registration overcomes 3D deformation• Successful first evaluation:
Localization with approx. 5 mm deviation (smallest visible lesion)
Clinical evaluation
• Possible applications: • Support multimodal breast cancer diagnosis (also alternative 3D modalities)• Simulation of breast deformation
Thank you !