Comouted Tomography (CT)
X-rays, different layers, 3D
Magnetic Resonance Therapy (MRI)
water molecules relay on magnetic field —> low energy absobs radio waves —> release energy again
Positron Emission Tomography (PET)
X-ray, radioactive sugar, combined with CT
Imaging Modalities
Structural information: X-ray (2D), CT, MRI, …
Temporal/Dynamic information: Ultrasound, dynamic CT, MRI
Physiologic metabolic information: perfusion imaging, flow imaging, PET, …
Microscopic information: OCT, Micro CR
Medical image analysis
Algorithms for automatic interpretation of biomedical images_ detect, segment, reconstruct, enhance, predict, analyze,…
Importance of MIA
Increasing num of images/modalities but not enough doctors to analyse
Increase the throughput
Enhancement
At each pixel/voxel assign a new value or a set of values
New value represents: noise free intensities, higher resolution, artifact free intesities,…
Information at each pixel: intersity around and at different modalities
Enhancement algorithm: J(X)=G(f(x))
Segmentation
At each pixel assing label
Labels can be: organs, lesions, etc.
L(x)=S(f(x))
Segmentation techniques overview: Clustering (K-means), Graph partitioning, Region growing, PDE-based, DIscriminative modeling based (supervised, DNNs) , Generative modeling based (Expectation max)
Registration
Determine spatial transformation between 2 images I(x) und J(x)
J(T(x)) = I(x) —> map the images
T can be linear or non-linear
Techniques: Problem-based, transformation based, non-linear, ladmark based, dense field models, discrete optimization,…
Classification/Regression
^- Mappping from image to label
Anatomical axes
Body Planes
Image Properties
Image size: number of pixels
Pixel size: the size the pixel occupies in the real worls
Field of view (FOV): the size the entire image occupies in the real world: Image size * Pixel size
DICOM
Standard for storing and transmitting data
Mostly common used format in practice
There are also some volumetric formats like NIFT, ITK snap
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