2. Concept of Image Registration
Image registration is an image
processing technique used to align
multiple scenes into a single integrated
image. It helps overcome issues such as
image rotation, scale, and skew that
are common when overlaying images.
Image registration is often used in
medical image to align images from
different camera sources. Digital
cameras use image registration to align
and connect adjacent images into a
single panoramic image.
Image registration process:
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3. Now What is The Medical Image Registration?
In medical diagnosis and treatment, there are a wide interest in integrating
information from multiple images using different modalities. This process is
known as image registration.
So, basically it is a process where we are aligning two or more input images
into single image to get some important information.
In this registration process basically source image is translated, rotated,
scaled and deformed respect to another fixed image.
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+ =
MRI SPECT
Registered
4. “
The goal of image registration is to compensate for the
patient motion between different image acquisitions, be it
follow-up acquisitions, image stitching or acquisitions in
different imaging modalities such as :
CT, MRI or PET/SPECT.”
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6. Classification of Medical Image Registration
Nature of the transformation based Image registration (IR):
In this method, the interested points obtained from moving object is mapped into fixed
image by applying various transformation methods i.e. Rigid, Non – rigid
◦ Rigid Registration
The transformation between the
images is limited to only rotations
and translations. This method is
used to establish a link between
different scanner coordinate
systems or to account for rigid
body movements
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◦ Non-Rigid registration
Techniques allow far more degrees
of freedom compared to rigid
registration. It can be used
to compute complex
deformations between images, for
example due to breathing motion
and soft tissue deformations. Even
inter-patient registration is possible
in order to build atlases of various
subjects
7. Work Case
◦ PET-CT Registration of Melanoma Patient
Compensation of breathing motion in PET-CT image pair of a melanoma patient. The
images have been acquired at different times with single scanners. The example
shows an exemplary slice from the 3-D volumes
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Initial image placement. The offset is
due to the different scanner coordinate
systems
Result of non-rigid
registration. The breathing
motion was corrected along
with motion at the heart.
Result of automatic rigid registration,
establishment of link
between scanner coordinate systems.
8. Classification of Medical Image Registration
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Domain of the transformation based
registration
In this method, registration is carried out
by performing transformation on image
domain.
◦ This image registration type plays an important
role in extracting significant features from
images.
◦ This technique also removes blurring and add
sharpness to the input images.
◦ The purpose of this image registration is to
obtain more detailed and significant
information.
Registration based on dimensionality
Image dimensions are critical in the
registration process because
transformation between a moving
image (source image) and a fixed
image (target image) is done either on
the image coordinate system or
between an image and physical space.
Registration techniques are further divided
into 2D/2D, 2D/3D and 3D/3D.
Registration of medical images obtained at
different time intervals is used for the
examination of disease progress such as
tumor growth, bone growth in children and
post-operative monitoring of healing.
9. Classification of Medical Image Registration
Registration based on modalities
Registration techniques based on modalities align medical images based on
different modalities such as Monomodal , multimodal, etc.
Monomodal registration maps two or more images obtained from a single
modality.
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Aligning images in order to detect subtle changes in shape or
intensity
10. Classification of Medical Image Registration
Multi-modality :
Complementry anatomic and functional information from multiple modalities can be
obtained for the precise diagnosis and treatment .
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Input images acquired from different types of modalities such as PET
and CT.
11. Precise registration
Obtain more precise rigid
registration compared to
ordinary registration
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Reduce turnaround time
In current clinical
practice and healthcare
centers
Increase diagnosis
quality , Through good
alignment of the images
pathologies are easier to
detect
Features of Medical Image Registration & Applications
Applications
• Cardiac: motion compensation
• Intensity inhomogeneity correction (MR)
• Cancer detection –Medical image registration (MRI) plays an very
important role in cancer detection and cancer therapy
