Card 21
Question
Pros of voxel-based representation
Answer
- Directly related to the source image
- Dense resolution
MIA Intro
Discover MIA Intro: 41 flashcards with questions and answers.
- Subject
- Sciences / Medical science
- Language of creation
- English
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Card 22
Question
Cons of voxel-based representation
Answer
Very large amount of data
- Time consuming
- Complex to handle (e.g., interaction with the structure)
Card 23
Question
Take home message of voxel-based representation:
Answer
- Home-take message here is to think whether your clinical application requires the level of detail provided by voxel-based representations. Think of the computational and memory requirements of the clinical scenario you are dealing with.
Card 24
Question
Landmark based methods:
Answer
- On the other end of the spectrum regarding the amount of represented information (comparison with voxel-based rep.)
-
Store very little data, corresponding tp location of a set of (anatomically meaningful or otherwise chosen) landmarks
- Landmarks: Points, curves, surfaces
Card 25
Question
Point landmarks
Answer
- Can be used to derive measures (e.g. distances between two points), drive an elastic thin-plate representation (middle bottom) characterizing shape changes in the human skull, etc.
- It is crucial to select landmarks that describe the shape, and it can be time consuming to annotate data
Card 26
Question
Curves landmarks
Answer
Curves are not very popular but can be very descriptive in certain cases
E.g., brain sulci and gyri
Card 27
Question
Pros of landmark-based methods:
Answer
- Compact representation
- Computationally efficient
Card 28
Question
Cons of landmark-based methods:
Answer
- Incomplete information (how to place landmarks)
- Need accurate localization of landmarks (not evident in 3D)
Card 29
Question
Automated landmark detection:
Answer
- Manual landmarks can also be used to evaluate automated methods developed to perform landmark detection, or to evaluate the accuracy of registration techniques.
- Slicer3D software and its annotation module.
Card 30
Question
Discrete meshes are composed of:
Answer
- A set of nodes (typically 3D points)
- A connective function, which determines the connection between nodes
Card 31
Question
What is the most common mesh representation?
Answer
Triangulations
Card 32
Question
Famous mesh algorithm and its properties?
Answer
- Marching cubes algorithm
- Based on defining sets of intersection cases of a surface and a voxel
- Set of 15 configuration suffice covers all possible combination of background/ forground voxels.
Card 33
Question
When are meshes a good choice?
Answer
Good choice when developing a lightweight but rich shape representation.
Card 34
Question
Pros of meshes:
Answer
- Topological flexibility (just by changing the connectivity function)
- Simple and easy to manipulate
- There exist simplification and refinement methods to reduce the number of nodes
Card 35
Question
Cons of meshes:
Answer
Not dense (may lack detail)
Card 36
Question
Distance maps:
Answer
- Shape is defined in a relative way
- Each point inside of the shape is non-zero
- Each point on the boundary of the shape is zero
- Distance maps are then an implicit way of representing shape.
Card 37
Question
Are distance maps implicit or explicit representation?
Answer
Distance maps are an implicit representation of the anatomy.
Card 38
Question
For what are distance map used?
Answer
They are commonly be used as a probabilistic map, guide registration of images (registering distance maps, statistics of shapes, etc.
Card 39
Question
How to compute distance maps?
Answer
To compute distance maps is very simple:
- for each voxel inside an structure, compute the closest boundary point and assign its distance as voxel value.
Card 40
Question
Pros and cons of distance maps???
Answer
- mümmer no usesueche
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