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Culture Myograph System Model 202CM

If the analysis rectangle contains a “valid” vessel but only has the outer edges

determined by edge detection, VediView



will indicate that an estimation algorithm

is being used to determine the inner (or lumen) edges (Fig. 3.22 and 3.23). This

condition will be clear from the analysis results window showing the green "model"

icon .

In this particular example VediView

™

assumes that, since the analysis rectangle

contains "one wall", a model is required to determine the position of the inner edges

(or lumen). This assumption is made to cope with images of contracting vessels.

There are two possible models invoked by this condition and the user has to select

which to use. The choice can be made from the conguration dialog box, which is

accessed by selecting the "congure analysis" icon on the tool bar or select the

"congure analysis" menu item from the pop up menu (click on ) on the analysis

control bar (Fig. 3.24).

The two models available for estimating the lumen dimensions, when edge detection

is inaccurate or impossible, are the “incompressible” and the “extinction” models.

Both models are adaptive with respect to earlier edge detection of the lumen. In

other words, they use the properties of the vessel determined in the uncontracted

state to estimate the dimensions in the partially or fully contracted state. The

“incompressible” model assumes that the vessel walls contract without changing

their cross-sectional area. The “extinction” model is a unique feature of VediView



which uses an imaging model of the vessel and a measure of the total light

absorption by the vessel to estimate the lumen size. The user has to determine,

by experience, which model to be used in a particular experimental setup. Since

the analysis is effective in real time, the user will be able to make appropriate

adjustments, whilst viewing their effect, until the edge detection is optimal.

Figure 3.20

Invalid vessel

Figure 3.21

No image analysis possible

Figure 3.22

One edge detec-

tion

Figure 3.23

One edge analysis

Figure 3.24

Conguration of vessel

detection and analysis.

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