- involves reprocessing raw data to produce new images. This can be performed from the operator’s console.
RETROSPECTIVE RECONSTRUCTION
-Commonly used for helical data in Single detector CT (SDCT) and MDCT.
-Creates overlapping images for multiplanar and 3D reformations
-Typically uses 50% overlap to improve image quality
OVERLAPPING RECONSTRUCTION
when the slice thickness is equal to the pixel size (Ideal for MPR and 3D).
Isotropic Voxel
: overlapping reconstructions are more beneficial when voxel dimensions are unequal.
Non-isotropic Voxel
-Also known as image rendering, this technique generates images in planes or orientation different from the original scan.
IMAGE REFORMATION
-Generates a 2D representation in various planes: axial, coronal, sagittal and obliques.
MULTIPLANAR REFORMATION (MPR)
- operator inputs parameters (thickness, plane, incrementation)
Manual MPR
interactive adjustment of image planes using a dynamic interface
Real Time MPR
- automatic generation of basic planes.
Scanner Created MPR
allows for custom and interactive images manipulation post-scan
Workstation Created MRP
- Also known as shaded-surface display (SSD), is similar to taking a photograph of the surface structure, uses voxels on the edge of the structure to outline the outer shell.
SURFACE RENDERING
Applications:
For visualizing tubular structures.
Valuable for orthopedic imaging due to its ability to depict bone surface
SSR
- selects the voxel with the highest value along a line through the data set.
- ideal visualizing high-attenuation structures such as bones and contrast
filled vessels.
Maximum-Intensity Projection (MIP)
- selects the voxel with the lowest value
- useful for visualization of low attenuation structures (bronchial tree)
- reduces superimposition by focusing on a portion of data-set
Minimum-intensity Projection (MinIP)
-A technique to create MIP or MinIP images from selected portions of the data set.
-Helps to minimize obscuration by other structure
VARIABLE SLIDING METHOD
-Is a 3D semitransparent representation of imaged structures. It is the
preferred 3d imaging method due to its ability to incorporate all voxel data.
VOLUME RENDERING
A specialized form of VR that visualizes the inside of hollow structures.
ENDOLUMINAL IMAGING
The process of selectively removing or isolating information from the data set
referred to as ______ or segmentation. To better demonstrate the areas of interest by removing obscuring structures
REGION OF INTEREST EDITING
- refers to the process by which a user identifies and selects data to be saved
or removed. This can be done on either 2D or 3D images. Manual segmentation
can be straightforward or time-consuming, depending on the complexity of the anatomy
Manual Segmentation
Automatic segmentation software can segment data without user input, but it
may struggle with complex images and low-contrast structures, leading to
errors
Fully Automated Segmentation
This method blends manual guidance with automated processes, allowing users to fine-tune the segmentation. Users must carefully check for errors and correct them as needed
Semiautomatic Segmentation
occur when important structures, such as vessels, are inadvertently edited out of the dataset.
Segmentation Errors
• Excessive ____ significantly diminishes image quality and low-contrast resolution, which can obscure tissue differentiation. This is especially problematic in vascular studies
where distinguishing between soft tissue and iodine-enhanced vessels is critical.
Image Noise
occur when slice thickness exceeds the pixel dimensions in the source data, causing smooth structures to appear jagged
Stair-Step Artifacts
