Digital Signal Processing Reference
In-Depth Information
Signal
Piezoelectric
Transducer
Projection-space
Filtering
Subject
Raw image
Data
Anisotropic Diffusion or
Median Filtering
Scan conversion
2D/3D
Image(s)
Quantitative
Data
Registration
Segmentation
Visualization
Physician
Fig. 2
physics of the imaging modality (e.g., speckle noise in ultrasound or noise in CT
images due to scattered radiation) and noise introduced by the electronics of the
imaging device. Basic preprocessing is performed to account for these artifacts,
either on the raw image data before reconstruction or on the reconstructed image
data. These processing steps generally involve some filtering operations, ranging
from the basic median and averaging filtering to the more sophisticated adaptive
filtering techniques such as anisotropic diffusion filtering.
Advanced image analysis techniques can then be applied on the filtered image
data. Examples of these techniques include image registration used for aligning
images acquired from different modalities, different patients, or at different times;
image segmentation to identify different anatomic features of specific pathology
such as tumors for images; and quantitative analysis techniques to numerically
characterize size and shape of the different features in the image. These advanced
processing steps are useful to extract specific information from the images and/or
prepare images for presentation in a specific format to maximize the value of
the available image information. The final stage of the imaging pipeline is the
visualization component that is used to display the processed image data, together
with the quantitative information, to the physician. Several special visualization
algorithms are available based on the dimensionality of image data (2D/3D/four-
dimensional [4D]) and the specific needs of the application (e.g., interactive display,
real-time updates to images, etc.) Visualization is a vital step of the imaging
pipeline, because the image information is useful and effective for the physician
only if displayed in a manner that is appropriate for the specific application.
applications: (1) left ventricle functional analysis using 3D echocardiography, and
(2) multimodality fusion of whole-body PET/CT.
