Chapter 8: Post Processing

Question 1

Is ised when raw data are manipulated to create pixels that are then used to create an image

Answer 1

Reconstruction

Question 2

Is used when image data are assembled to produced images in diff planes or to produce 3D images

Answer 2

Reformation

Question 3

TRUE OR FALSE

Overlapping reconstructions of data for use as source images in MPR or 3D reformation are particularly useful when the slice thickness substantially exceeds pixel size. They are less beneficial when the voxel size is isotropic.

Answer 3

TRUE

Question 4

The goal of using a thin slice for scanning and reconstructing thicker slices for viewing and storing is to maintain the advantage of _____________ but also create image files that are manageable and more easily reviewed by radiologist.

Answer 4

High-resolution imaging

Question 5

Image reformation os also called

Answer 5

Image rendering

Question 6

To reformat a CT study all the source images must have an identical _______, __________, and __________, and they must be contiguous. Even a small amount of motion can seriously degrade the reformation.

Answer 6

☑️DFOV
☑️image center
☑️gantry tilt

Question 7

Ises only image data (not raw data) to generate images in plane or orientation diff from the prospective image

Answer 7

Image Reformation

Question 8

Reformation that is done to show anatomy in various planes is referred to as

Answer 8

Multiplanar Reformation (MPR)

Question 9

MPR’s are _____ in nature. Unlike 3D displays, ______image displays always represent the original CT attenuation values.

Answer 9

2D

Question 10

Setting the appropriate CT value for _____________ is critical.

Answer 10

Surface Rendering

Question 11

Explain what is meant by manual MPR, real time MPR, scanner created MPR and workstation-created MPR?

Answer 11

Manual method
☑️require that the operator input the criteria such as thickness of the MPR, the plane desired and the number of incrementation of the resulting planar images.

Real Time (interactive)
☑️ refers to the feature that allows the operatorto manually change (typically by moving a mouse) the image plane while the software continually updates the image. Permits the operator to ise trial and error to obtain ideal image plane

Scanner Created MPR
☑️they ensure the MPR’s are always done and they save time for technologist

Workstation-Created MPR
☑️PACS or specialized independent workstations allow user to generate MPR’s directly on the monitor.

Question 12

Two common 3D techniques are

Answer 12

MIP
☑️examines each voxel along a line from the viewer’s eye through the data set and selects only the voxel with the highest value for inclusion in the displayed image
☑️tends to display bones and contrast filled structure, lower attenuation structures are not well visualized

MinIP
☑️involves selecting the voxel with the minimum value from the line for display

Question 13

Select voxels with the highest value to display

Select voxels with the lowest value

Answer 13

MIP

MinIP

Question 14

_________ has become the favored 3D imaging technique. Advantage is that all voxels contribute to the image allowing the image to display multiple tissues and show their relationship to one another.

Answer 14

Volume Rendering (VR)

Question 15

Is a form of VR designed to reveal the inside of a structure. The technique is also called virtual endoscopy, virtual bronchscopynand virtual colonoscopy.

Answer 15

Endoluminal imaging

Question 16

Refers to process by which a user identifiesband selects databto be sabed or removed.

Answer 16

Manual segmentation

Question 17

Are usually impractical because of image complexity and the variety of image types and clinical indications

Answer 17

Fully automated segmentation

Question 18

Combine many of the benefits of manual and automatic segmentation techniques.

Answer 18

Semiautomatic segmentation

Question 19

Result when wide slices are used as source images for MRP. Are present when smooth objects such as the aorta appear to have edges that resemble a flight of stairs.

Answer 19

Stair-step artifacts