Image Analysis

Region of Interest (ROI) can be used to create several regions of various types (curves, lines, polygons, rectangles, etc.) on a slice by using the mouse buttons and the cursor. Each region type has corresponding statistics and graphics options. Features such as move, rotate, and scale exist to edit and/or reshape defined regions. Regions can also be cut, copied and pasted as desired on the same slice, across slices, or across time. Regions created freehand can be smoothed and adjusted to fit nearby edges (for example, edges of blood vessels or airways). Once regions have been defined, regional statistics (mean intensity, area, pixel count, length, etc.) can be extracted and stored as text files. Time-intensity plots and other graphs can also be generated for single or multiple regions.

Contour-Based Cardiac Mechanics imports epicardial and endocardial borders defined in the Region of Interest module and computes regional ejection fractions, regional wall thickness, percent of wall thickening, etc. There are a number of user-selectable parameters, such as fixed or floating centroids, algorithm for calculating wall thickness, algorithm for identification of centroid, myocardial mass, number and location of wedges to be used for regional analysis, number of samples to be taken within a wedge, and so forth. A graphing package within this module can display any of the computed parameters.

Homogeneous Strain Analysis was developed specifically to evaluate regional myocardial strain by calculating the distortion of triangles generated from nodal points embedded within the myocardium, noninvasively through spatial modulation of magnetization (SPAMM). Nodal points can be manually identified using the Region of Interest module by tracking the tag intersections in one time point, copying and pasting the identified intersections to the next time point, and then manually adjusting each point to follow the motion of the SPAMM line intersections. These intersection locations are saved to disk and analyzed along with the slice image within the Homogeneous Strain Analysis module. The strain information for a particular triangle can be displayed by double-clicking on that triangle. A number of options are available to colorcode the strains, map motion of the triangle centroids throughout the cardiac cycle, display the principal strain vectors, graph strain over time, etc.

Tube Geometry Analysis (TGA) is used for making 3D geometric measurements, such as regional cross-sectional area, regional anterior-posterior length, and lateral length of presegmented vessels or tubes. Given a presegmented non-branching vessel segment of interest such as upper airway or pulmonary artery, this module first automatically computes a three-dimensional center line of the structure using an iterative bisection algorithm specifically developed for this module. Double oblique planes perpendicular to the local vessel's center line are then displayed for making quantitative measurements that are presented by a graphing package within this module. The user can interact with the graph to display interposed lines on a set of standard projections and to see the location of measurements in the anatomy.

Image Based Perfusion Analysis (IBPA) automates the analysis of cine X-ray CT images, for computing physiological variables such as regional blood flow, regional tissue, blood and air contents, and mean transit times. This module allows users to incorporate other blood flow models utilizing a single input, single output function, and its application can be extended to dynamic data other than cine CT. Pointing and clicking on an area of the displayed image in this module produces a graph of the time-intensity curve of that region. This module also has an automated, noninteractive, batch processing mode for data collection designed to quickly respond to changes in selection criteria. Color coded images of all physiological parameters are also generated and may be saved to disk. A special feature of this module combines the complementary information from high-resolution CT (anatomy) and dynamic CT (function) by automatically mapping any of the color-coded functional images into a corresponding high-resolution volumetric scan of the same subject.

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